[Federal Register Volume 78, Number 155 (Monday, August 12, 2013)]
[Notices]
[Pages 48944-48994]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-19380]
[[Page 48943]]
Vol. 78
Monday,
No. 155
August 12, 2013
Part II
Department of Commerce
-----------------------------------------------------------------------
National Oceanic and Atmospheric Administration
-----------------------------------------------------------------------
Endangered and Threatened Wildlife and Plants; Endangered Species Act
Listing Determination for Alewife and Blueback Herring; Notice
Federal Register / Vol. 78 , No. 155 / Monday, August 12, 2013 /
Notices
[[Page 48944]]
-----------------------------------------------------------------------
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[Docket No. 111024651-3630-02]
RIN 0648-XA739
Endangered and Threatened Wildlife and Plants; Endangered Species
Act Listing Determination for Alewife and Blueback Herring
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice of a listing determination.
-----------------------------------------------------------------------
SUMMARY: We, NMFS, have completed a comprehensive review of the status
of river herring (alewife and blueback herring) in response to a
petition submitted by the Natural Resources Defense Council (NRDC)
requesting that we list alewife (Alosa pseudoharengus) and blueback
herring (Alosa aestivalis) as threatened under the Endangered Species
Act (ESA) throughout all or a significant portion of their range or as
specific distinct population segments (DPS) identified in the petition.
The Atlantic States Marine Fisheries Commission (ASMFC) completed a
comprehensive stock assessment for river herring in May 2012 which
covers over 50 river specific stocks throughout the range of the
species in the United States. The ASMFC stock assessment contained much
of the information necessary to make an ESA listing determination for
both species; however, any deficiencies were addressed through focused
workshops and working group meetings and review of additional sources
of information. Based on the best scientific and commercial information
available, we have determined that listing alewife as threatened or
endangered under the ESA is not warranted at this time. Additionally,
based on the best scientific and commercial information available, we
have determined that listing blueback herring as threatened or
endangered under the ESA is not warranted at this time.
DATES: This finding is effective on August 12, 2013.
ADDRESSES: The listing determination, list of references used in the
listing determination, and other related materials regarding this
determination can be obtained via the Internet at: http://www.nero.noaa.gov/prot_res/CandidateSpeciesProgram/RiverHerringSOC.htm
or by submitting a request to the Assistant Regional Administrator,
Protected Resources Division, Northeast Region, NMFS, 55 Great Republic
Drive, Gloucester, MA 01930.
FOR FURTHER INFORMATION CONTACT: Kim Damon-Randall, NMFS Northeast
Regional Office, (978) 282-8485; or Marta Nammack, NMFS, Office of
Protected Resources (301) 427-8469.
SUPPLEMENTARY INFORMATION:
Background
On August 5, 2011, we, the National Marine Fisheries Service
(NMFS), received a petition from the Natural Resources Defense Council
(NRDC), requesting that we list alewife (Alosa pseudoharengus) and
blueback herring (Alosa aestivalis) under the ESA as threatened
throughout all or a significant portion of their ranges. In the
alternative, they requested that we designate DPSs of alewife and
blueback herring as specified in the petition (Central New England,
Long Island Sound, Chesapeake Bay, and Carolina for alewives, and
Central New England, Long Island Sound, and Chesapeake Bay for blueback
herring). The petition contained information on the two species,
including the taxonomy, historical and current distribution, physical
and biological characteristics of their habitat and ecosystem
relationships, population status and trends, and factors contributing
to the species' decline. The petition also included information
regarding potential DPSs of alewife and blueback herring as described
above. The following five factors identified in section 4(a)(1) of the
ESA were addressed in the petition: (1) Present or threatened
destruction, modification, or curtailment of habitat or range; (2)
over-utilization for commercial, recreational, scientific, or
educational purposes; (3) disease or predation; (4) inadequacy of
existing regulatory mechanisms; and (5) other natural or man-made
factors affecting the species' continued existence.
We reviewed the petition and determined that, based on the
information in the petition and in our files at the time we received
the petition, the petitioned action may be warranted. Therefore, we
published a positive 90-day finding on November 2, 2011, and as a
result, we were required to review the status of the species (e.g.,
anadromous alewife and blueback herring) to determine if listing under
the ESA is warranted. We formed an internal status review team (SRT)
comprised of nine NMFS staff members (Northeast Regional Office (NERO)
Protected Resources Division and Northeast Fisheries Science Center
staff) to compile the best commercial and scientific data available for
alewife and blueback herring throughout their ranges.
In May 2012, the ASMFC completed a river herring stock assessment,
which covers over 50 river-specific stocks throughout the ranges of the
species in the United States (ASMFC, 2012; hereafter referred to in
this determination as ``the stock assessment''). In order to avoid
duplicating this extensive effort, we worked cooperatively with ASMFC
to use this information in the review of the status of these two
species and identify information not in the stock assessment that was
needed for our listing determination. We identified the missing
required elements and held workshops/working group meetings focused on
addressing information on stock structure, extinction risk analysis,
and climate change.
Reports from each workshop/working group meeting were compiled and
independently peer reviewed (the stock structure and extinction risk
reports were peer reviewed by reviewers selected by the Center for
Independent Experts, and the climate change report was peer reviewed by
4 experts identified during the workshops). These reports did not
contain any listing advice or reach any ESA listing conclusions--such
synthesis and analysis for river herring is solely within the agency's
purview. We used this information to determine which extinction risk
method and stock structure analysis would best inform the listing
determination, as well as understand how climate change may impact
river herring, and ultimately, we are using these reports along with
the stock assessment and all other best available information in this
listing determination.
Alewife and blueback herring are collectively referred to as
``river herring.'' Due to difficulties in distinguishing between the
species, they are often harvested together in commercial and
recreational fisheries, and managed together by the ASMFC. Throughout
this finding, where there are similarities, they will be collectively
referred to as river herring, and where there are distinctions, they
will be identified by species.
Range
River herring can be found along the Atlantic coast of North
America, from the Southern Gulf of St. Lawrence, Canada to the
southeastern United States (Mullen et al., 1986; Schultz et al., 2009).
The coastal ranges of the two
[[Page 48945]]
species overlap. Blueback herring range from Nova Scotia south to the
St. John's River, Florida; and alewife range from Labrador and
Newfoundland south to South Carolina, though their occurrence in the
extreme southern range is less common (Collette and Klein-MacPhee,
2002; ASMFC, 2009a; Kocik et al., 2009).
In Canada, river herring (i.e., gaspereau) are most abundant in the
Miramichi, Margaree, LaHave, Tusket, Shubenacadie and Saint John Rivers
(Gaspereau Management Plan, 2001). They are proportionally less
abundant in smaller coastal rivers and streams (Gaspereau Management
Plan, 2001). Generally, blueback herring in Canada occur in fewer
rivers than alewives and are less abundant in rivers where both species
coexist (DFO 2001).
Habitat and Migration
River herring are anadromous, meaning that they mature in the
marine environment and then migrate up coastal rivers to estuarine and
freshwater rivers, ponds, and lake habitats to spawn (Collette and
Klein-MacPhee, 2002; ASMFC, 2009a; Kocik et al., 2009). In general,
adult river herring are most often found at depths less than 328 feet
(ft) (100 meters (m)) in waters along the continental shelf (Neves,
1981; ASMFC, 2009a; Schultz et al., 2009). They are highly migratory,
pelagic, schooling species, with seasonal spawning migrations that are
cued by water temperature (Collette and Klein-MacPhee, 2002; Schultz et
al., 2009). Depending upon temperature, blueback herring typically
spawn from late March through mid-May. However, they spawn in the
southern parts of their range as early as December or January, and as
late as August in the northern portion of their range (ASMFC, 2009a).
Alewives have been documented spawning as early as February in the
southern portion of their range, and as late as August in the northern
portion of the range (ASMFC, 2009a). The river herring migration in
Canada extends from late April through early July, with the peak
occurring in late May and early June. Blueback herring generally make
their spawning runs about 2 weeks later than alewives do (DFO, 2001).
River herring conform to a metapopulation paradigm (e.g., a group of
spatially separated populations of the same species which interact at
some level) with adults frequently returning to their natal rivers for
spawning but with some limited straying occurring between rivers
(Jones, 2006; ASMFC, 2009a).
Throughout their life cycle, river herring use many different
habitats, including the ocean, estuaries, rivers, and freshwater lakes
and ponds. The substrate preferred for spawning varies greatly and can
include gravel, detritus, and submerged aquatic vegetation. Blueback
herring prefer swifter moving waters than alewives do (ASMFC, 2009a).
Nursery areas include freshwater and semi-brackish waters. Little is
known about their habitat preference in the marine environment
(Meadows, 2008; ASMFC, 2009a).
Landlocked Populations
Landlocked populations of alewives and blueback herring also exist.
Landlocked alewife populations occur in many freshwater lakes and ponds
from Canada to North Carolina as well as the Great Lakes (Rothschild,
1966; Boaze & Lackey, 1974). Many landlocked populations occur as a
result of stocking to provide a forage base for game fish species
(Palkovacs et al., 2007).
Landlocked blueback herring occur mostly in the southeastern United
States and the Hudson River drainage. The occurrence of landlocked
blueback herring is primarily believed to be the result of accidental
stockings in reservoirs (Prince and Barwick, 1981), unsanctioned
stocking by recreational anglers to provide forage for game fish, and
also through the construction of locks, dams and canal systems that
have subsequently allowed for blueback herring occupation of several
lakes and ponds along the Hudson River drainage up to, and including
Lake Ontario (Limburg et al., 2001).
Recent efforts to assess the evolutionary origins of landlocked
alewives indicate that they rapidly diverged from their anadromous
cousins between 300 and 5,000 years ago, and now represent a discrete
life history variant of the species, Alosa pseudoharengus (Palkovacs et
al., 2007). Though given their relatively recent divergence from
anadromous populations, one plausible explanation for the existence of
landlocked populations may be the construction of dams by either native
Americans or early colonial settlers that precluded the downstream
migration of juvenile herring (Palkovacs et al., 2007). Since their
divergence, landlocked alewives have evolved to a point they now
possess significantly different mouthparts than their anadromous
cousins, including narrower gapes and smaller gill raker spacings to
take advantage of year round availability of smaller prey in freshwater
lakes and ponds (Palkovacs et al., 2007). Furthermore, the landlocked
alewife, compared to its anadromous cousin, matures earlier, has a
smaller adult body size, and reduced fecundity (Palkovacs et al.,
2007). At this time, there is no substantive information that would
suggest that landlocked populations can or would revert back to an
anadromous life history if they had the opportunity to do so (Gephard,
CT DEEP, Pers. comm. 2012; Jordaan, UMASS Amherst, Pers. comm. 2012).
The discrete life history and morphological differences between the
two life history variants (anadromous and landlocked) provide
substantial evidence that upon becoming landlocked, landlocked
populations become largely independent and separate from anadromous
populations and occupy largely separate ecological niches (Palkovacs
and Post, 2008). There is the possibility that landlocked alewife and
blueback herring may have the opportunity to mix with anadromous river
herring during high discharge years and through dam removals which
could provide passage over dams and access to historic spawning
habitats restored for anadromous populations, where it did not
previously exist. The implications of this are not known at this time.
In summary, genetics indicate that anadromous alewife populations
are discrete from landlocked populations, and that this divergence can
be estimated to have taken place from 300 to 5,000 years ago. Some
landlocked populations of blueback herring do occur in the Mid-Atlantic
and southeastern United States. Given the similarity in life histories
between anadromous alewife and blueback herring, we assume that
landlocked populations of blueback herring would exhibit a similar
divergence from anadromous blueback herring, as has been documented
with alewives.
A Memorandum of Understanding (MOU) between the U.S. Fish and
Wildlife Service (USFWS) and NMFS (collectively, the Services)
regarding jurisdictional responsibilities and listing procedures under
the ESA was signed August 28, 1974. This MOU states that NMFS shall
have jurisdiction over species ``which either (1) reside the major
portion of their lifetimes in marine waters; or (2) are species which
spend part of their lifetimes in estuarine waters, if the major portion
of the remaining time (the time which is not spent in estuarine waters)
is spent in marine waters.''
Given that landlocked populations of river herring remain in
freshwater throughout their life history and are genetically divergent
from the anadromous species, pursuant to the aforementioned MOU, we did
not
[[Page 48946]]
include the landlocked populations of alewife and blueback herring in
our review of the status of the species and do not consider landlocked
populations in this listing determination in response to the petition
to list these anadromous species.
Listing Species Under the Endangered Species Act
We are responsible for determining whether alewife and blueback
herring are threatened or endangered under the ESA (16 U.S.C. 1531 et
seq.). Accordingly, based on the statutory, regulatory, and policy
provisions described below, the steps we followed in making our listing
determination for alewife and blueback herring were to: (1) Determine
how alewife and blueback herring meet the definition of ``species'';
(2) determine the status of the species and the factors affecting them;
and (3) identify and assess efforts being made to protect the species
and determine if these efforts are adequate to mitigate existing
threats.
To be considered for listing under the ESA, a group of organisms
must constitute a ``species.'' Section 3 of the ESA defines a
``species'' as ``any subspecies of fish or wildlife or plants, and any
distinct population segment of any species of vertebrate fish or
wildlife which interbreeds when mature.'' Section 3 of the ESA further
defines an endangered species as ``any species which is in danger of
extinction throughout all or a significant portion of its range'' and a
threatened species as one ``which is likely to become an endangered
species within the foreseeable future throughout all or a significant
portion of its range.'' Thus, we interpret an ``endangered species'' to
be one that is presently in danger of extinction. A ``threatened
species,'' on the other hand, is not presently in danger of extinction,
but is likely to become so in the foreseeable future (that is, at a
later time). In other words, the primary statutory difference between a
threatened and endangered species is the timing of when a species may
be in danger of extinction, either presently (endangered) or in the
foreseeable future (threatened).
On February 7, 1996, the Services adopted a policy to clarify our
interpretation of the phrase ``distinct population segment of any
species of vertebrate fish or wildlife'' (61 FR 4722). The joint DPS
policy describes two criteria that must be considered when identifying
DPSs: (1) The discreteness of the population segment in relation to the
remainder of the species (or subspecies) to which it belongs; and (2)
the significance of the population segment to the remainder of the
species (or subspecies) to which it belongs. As further stated in the
joint policy, if a population segment is discrete and significant
(i.e., it meets the DPS policy criteria), its evaluation for endangered
or threatened status will be based on the ESA's definitions of those
terms and a review of the five factors enumerated in section 4(a)(1) of
the ESA.
As provided in section 4(a) of the ESA, the statute requires us to
determine whether any species is endangered or threatened because of
any of the following five factors: (1) The present or threatened
destruction, modification, or curtailment of its habitat or range; (2)
overutilization for commercial, recreational, scientific, or
educational purposes; (3) disease or predation; (4) the inadequacy of
existing regulatory mechanisms; or (5) other natural or manmade factors
affecting its continued existence (section 4(a)(1)(A)(E)). Section
4(b)(1)(A) of the ESA further requires that listing determinations be
based solely on the best scientific and commercial data available after
taking into account efforts being made to protect the species.
Distribution and Abundance
United States
The stock assessment (described above) was prepared and compiled by
the River Herring Stock Assessment Subcommittee, hereafter referred to
as the `subcommittee,' of the ASMFC Shad and River Herring Technical
Committee. Data and reports used for this assessment were obtained from
Federal and state resource agencies, power generating companies, and
universities.
The subcommittee conducted its assessment on the coastal stocks of
alewife and blueback herring by individual rivers as well as coast-wide
depending on available data. The subcommittee concluded that river
herring should ideally be assessed and managed by individual river
system, but that the marine portion of their life history likely
influences survival through mixing in the marine portion of their
range. However, coast-wide assessments are complicated by the complex
life history of these species as well, given that factors influencing
population dynamics for the freshwater portion of their life history
can not readily be separated from marine factors. In addition, it was
noted that data quality and availability varies by river and is mostly
dependent upon the monitoring efforts that each state dedicates to
these species, which further complicated the assessment.
The subcommittee also noted that most state landings records listed
alewife and blueback herring together as `river herring' rather than
identifying by species. These landings averaged 30.5 million pounds
(lbs) (13,847 metric tons (mt)) per year from 1889 to 1938, and severe
declines were noted coast-wide starting in the 1970s. Beginning in
2005, states began enacting moratoria on river herring fisheries, and
as of January 2012, all directed harvest of river herring in state
waters is prohibited unless states have submitted and obtained approved
sustainable fisheries management plans (FMP) under ASMFC's Amendment 2
to the Shad and River Herring FMP.
The subcommittee summarized its findings for trends in commercial
catch-per-unit-effort (CPUE); run counts; young-of-the-year (YOY) seine
surveys; juvenile-adult fisheries independent seine, gillnet and
electrofishing surveys; juvenile-adult trawl surveys; mean length;
maximum age; mean length-at-age; repeat spawner frequency; total
mortality (Z) estimates; and exploitation rates. Because the stock
assessment contains the most recent and comprehensive description of
this information and the subcommittee's conclusions, the following
sections were taken from the stock assessment (ASMFC, 2012).
Commercial CPUE
Since the mid-1990s, CPUE indices for alewives showed declining
trends in the Potomac River and James River (VA), no trend in the
Rappahannock River (VA), and increasing trends in the York River (VA)
and Chowan River (NC). CPUE indices available for blueback herring
showed a declining trend in the Chowan River and no trend in the Santee
River (SC). Combined species CPUE indices showed declining trends in
Delaware Bay and the Nanticoke River, but CPUE has recently increased
in the Hudson River (ASMFC, 2012).
Run Counts
Major declines in run sizes occurred in many rivers from 2001 to
2005. These declines were followed by increasing trends (2006 to 2010)
in the Androscoggin River (ME), Damaraiscotta River (ME), Nemasket
River (MA), Gilbert-Stuart River (RI), and Nonquit River (RI) for
alewife and in the Sebasticook River (ME), Cocheco River (NH), Lamprey
River (NH), and Winnicut River (NH) for both species combined. No
trends in run sizes were evident following the recent major declines in
the Union River (ME), Mattapoisett River (MA), and
[[Page 48947]]
Monument River (MA) for alewife and in the Exeter River (NH) for both
species combined. Run sizes have declined or are still declining
following recent and historical major declines in the Oyster River (NH)
and Taylor River (NH) for both species, in the Parker River (MA) for
alewife, and in the Monument River (MA) and Connecticut River for
blueback herring (ASMFC, 2012).
Young-of-the-Year Seine Surveys
The young-of-the-year (YOY) seine surveys were quite variable and
showed differing patterns of trends among rivers. Maine rivers showed
similar trends in alewife and blueback herring YOY indices after 1991,
with peaks occurring in 1995 and 2004. YOY indices from North Carolina
and Connecticut showed declines from the 1980s to the present. New
York's Hudson River showed peaks in YOY indices in 1999, 2001, 2005,
and 2007. New Jersey and Maryland YOY indices showed peaks in 1994,
1996, and 2001. Virginia YOY surveys showed peaks in 1993, 1996, 2001,
and 2003 (ASMFC, 2012).
Juvenile-Adult Fisheries-Independent Seine, Gillnet and Electrofishing
Surveys
The juvenile-adult indices from fisheries-independent seine,
gillnet and electrofishing surveys showed a variety of trends in the
available datasets for the Rappahanock River (1991-2010), James River
(2000-2010), St. John's River, FL (2001-2010), and Narragansett Bay
(1988-2010). The gillnet indices from the Rappahannock River (alewife
and blueback herring) showed a low and stable or decreasing trend after
a major decline after 1995 and has remained low since 2000 (except for
a rise in alewife CPUE during 2008). The gillnet and electrofishing
indices in the James River (alewife and blueback herring) showed a
stable or increasing trend. Blueback herring peak catch rates occurred
in 2004, and alewife peak catch rates occurred in 2005. The blueback
herring index from electrofishing in the St. John's River, FL, showed
no trend after a major decline from 2001-2002. The seine indices in
Narragansett Bay, RI (combined species) and coastal ponds (combined
species) showed no trends over the time series. The CPUE for
Narragansett Bay fluctuated without trend from 1988-1997, increased
through 2000, declined and then remained stable from 2001-2004. The
pond survey CPUE increased during 1993-1996, declined through 1998,
increased in 1999, declined through 2002, peaked in 2003 and then
declined and fluctuated without trend thereafter. The electrofishing
indices showed opposing trends and then declining trends in the
Rappahannock River (alewife and blueback herring) with catch rates of
blueback herring peaking during 2001-2003, and catch rates of alewives
lowest during the same time period (ASMFC, 2012).
Juvenile and Adult Trawl Surveys
Trends in trawl survey indices varied greatly with some surveys
showing an increase in recent years, some showing a decrease, and some
remaining stable. Trawl survey data were available from 1966-2010 (for
a complete description of data see ASMFC (2012)). Trawl surveys in
northern areas tended to show either an increasing or stable trend in
alewife indices, whereas trawl surveys in southern areas tended to show
stable or decreasing trends. Patterns in trends across surveys were
less evident for blueback herring. The NMFS surveys showed a consistent
increasing trend coast-wide and in the northern regions for alewife and
the combined river herring species group (ASMFC, 2012).
Mean Length
Mean sizes for male and female alewife declined in 4 of 10 rivers,
and mean sizes for female and male blueback herring declined in 5 of 8
rivers. Data were available from 1960-2010 (for a complete description
of data see ASMFC (2012)). The common trait among most rivers in which
significant declines in mean sizes were detected is that historical
length data were available for years prior to 1990. Mean lengths
started to decline in the mid to late 1980s; therefore, it is likely
that declines in other rivers were not detected because of the
shortness of their time series. Mean lengths for combined sexes in
trawl surveys were quite variable through time for both alewives and
blueback herring. Despite this variability, alewife mean length tended
to be lowest in more recent surveys. This pattern was less apparent for
blueback herring. Trend analysis of mean lengths indicated significant
declines in mean lengths over time for alewives coast-wide and in the
northern region in both seasons, and for blueback coast-wide and in the
northern region in fall (ASMFC, 2012).
Maximum Age
Except for Maine and New Hampshire, maximum age of male and female
alewife and blueback herring during 2005-2007 was 1 or 2 years lower
than historical observations (ASMFC, 2012).
Mean Length-at-Age
Declines in mean length of at least one age were observed in most
rivers examined. The lack of significance in some systems is likely due
to the absence of data prior to 1990 when the decline in sizes began,
similar to the pattern observed for mean length. Declines in mean
lengths-at-age for most ages were observed in the north (NH) and the
south (NC). There is little indication of a general pattern of size
changes along the Atlantic coast (ASMFC, 2012).
Repeat Spawner Frequency
Examination of percentage of repeat spawners in available data
revealed significant, declining trends in the Gilbert-Stuart River
(RI--combined species), Nonquit River (RI--combined species), and the
Nanticoke River (blueback herring). There were no trends in the
remaining rivers for which data are available, although scant data
suggest that current percentages of repeat spawners are lower than
historical percentages in the Monument River (MA) and the Hudson River
(NY) (ASMFC, 2012).
Total Mortality (Z) Estimates
With the exception of male blueback herring from the Nanticoke
River, which showed a slight increase over time, there were no trends
in the Z estimates produced using age data (ASMFC, 2012).
Exploitation Rates
Exploitation of river herring appears to be declining or remaining
stable. In-river exploitation estimates have fluctuated, but are lower
in recent years. A coast-wide index of relative exploitation showed a
decline following a peak in the 1980s, and the index indicates that
exploitation has remained fairly stable over the past decade. The
majority of depletion-based stock reduction analysis (DB-SRA) model
runs showed declining exploitation rates coast-wide. Exploitation rates
estimated from the statistical catch-at-age model for blueback herring
in the Chowan River also showed a slight declining trend from 1999 to
2007, at which time a moratorium was instituted. There appears to be a
consensus among various assessment methodologies that exploitation has
decreased in recent times. The decline in exploitation over the past
decade is not surprising because river herring populations are at low
levels and more restrictive regulations or moratoria have been enacted
by states (ASMFC, 2012).
[[Page 48948]]
Summary of Stock Assessment Conclusions
Of the in-river stocks of alewife and blueback herring for which
data were available and were considered in the stock assessment, 22
were depleted, 1 was increasing, and the status of 28 stocks could not
be determined because the time-series of available data was too short.
In most recent years, 2 in-river stocks were increasing, 4 were
decreasing, and 9 were stable, with 38 rivers not having enough data to
assess recent trends. The coast-wide meta-complex of river herring
stocks in the United States is depleted to near historical lows. A
depleted status indicates that there was evidence for declines in
abundance due to a number of factors, but the relative importance of
these factors in reducing river herring stocks could not be determined.
Commercial landings of river herring peaked in the late 1960s, declined
rapidly through the 1970s and 1980s and have remained at levels less
than 3 percent of the peak over the past decade. Estimates of run sizes
varied among rivers, but in general, declining trends in run size were
evident in many rivers over the last decade. Fisheries-independent
surveys did not show consistent trends and were quite variable both
within and among surveys. Those surveys that showed declines tended to
be from areas south of Long Island. A problem with the majority of
fisheries-independent surveys was that the length of their time series
did not overlap the period of peak commercial landings that occurred
prior to 1970. There appears to be a consensus among various assessment
methodologies that exploitation has decreased in recent times. The
decline in exploitation over the past decade is not surprising because
river herring populations are at low levels and more restrictive
regulations or moratoria have been enacted by states (ASMFC, 2012).
Canada
The Department of Fisheries and Oceans (DFO) monitors and manages
river herring runs in Canada. River herring runs in the Miramichi River
in New Brunswick and the Maragree River in Cape Breton, Nova Scotia
were monitored intensively from 1983 to 2000 (DFO, 2001). More recently
(1997 to 2006) the Gaspereau River alewife run and harvest has been
intensively monitored and managed partially in response to a 2002
fisheries management plan that had a goal of increasing spawning
escapement to 400,000 adults (DFO, 2007). Elsewhere, river herring runs
have been monitored less intensively, though harvest rates are
monitored throughout Atlantic Canada through license sales, reporting
requirements, and a logbook system that was enacted in 1992 (DFO,
2001).
At the time DFO conducted their last stock assessment in 2001, they
identified river herring harvest levels as being low (relative to
historical levels) and stable, to low and decreasing across most rivers
where data were available (DFO, 2001). With respect to the commercial
harvest of river herring, reported landings of river herring peaked in
1980 at slightly less than 25.5 million lbs (11,600 mt) and declined to
less than 11 million lbs (5,000 mt) in 1996. Landings data reported
through DFO indicate that river herring harvests have continued to
decline through 2010.
Consideration as a Species Under the ESA
Distinct Population Segment Background
According to Section 3 of the ESA, the term ``species'' includes
``any subspecies of fish or wildlife or plants, and any distinct
population segment of any species of vertebrate fish or wildlife that
interbreeds when mature.'' Congress included the term ``distinct
population segment'' in the 1978 amendments to the ESA. On February 7,
1996, the Services adopted a policy to clarify their interpretation of
the phrase ``distinct population segment'' for the purpose of listing,
delisting, and reclassifying species (61 FR 4721). The policy described
two criteria a population segment must meet in order to be considered a
DPS (61 FR 4721): (1) It must be discrete in relation to the remainder
of the species to which it belongs; and (2) it must be significant to
the species to which it belongs.
Determining if a population is discrete requires either one of the
following conditions: (1) It is markedly separated from other
populations of the same taxon as a consequence of physical,
physiological, ecological, or behavioral factors. Quantitative measures
of genetic or morphological discontinuity may provide evidence of this
separation; or (2) it is delimited by international governmental
boundaries within which differences in control of exploitation,
management of habitat, conservation status, or regulatory mechanisms
exist that are significant in light of section 4(a)(1)(D) of the ESA.
If a population is deemed discrete, then the population segment is
evaluated in terms of significance. Factors to consider in determining
whether a discrete population segment is significant to the species to
which it belongs include, but are not limited to, the following: (1)
Persistence of the discrete population segment in an ecological setting
unusual or unique for the taxon; (2) evidence that loss of the discrete
population segment would result in a significant gap in the range of
the taxon; (3) evidence that the discrete population segment represents
the only surviving natural occurrence of a taxon that may be more
abundant elsewhere as an introduced population outside its historic
range; or (4) evidence that the discrete population segment differs
markedly from other populations of the species in its genetic
characteristics.
If a population segment is deemed discrete and significant, then it
qualifies as a DPS.
Information Related to Discreteness
To obtain expert opinion about anadromous alewife and blueback
herring stock structure, we convened a working group in Gloucester, MA,
on June 20-21, 2012. This working group meeting brought together river
herring experts from state and Federal fisheries management agencies
and academic institutions. Participants presented information to inform
the presence or absence of stock structure such as genetics, life
history, and morphometrics. A public workshop was held to present the
expert working group's findings on June 22, 2012, and during this
workshop, additional information on stock structure was sought from the
public. Subsequently, a summary report was developed (NMFS, 2012a), and
a peer review of the document was completed by three independent
reviewers. The summary report and peer review reports are available on
the NMFS Web site (see the ADDRESSES section above).
Steve Gephard of the Connecticut Department of Energy and
Environmental Protection (CT DEP) presented a preliminary U.S. coast-
wide genetic analysis of alewife and blueback herring data (Palkovacs
et al., 2012, unpublished report). Palkovacs et al., (2012, unpublished
report) used 15 novel microsatellite markers on samples collected from
Maine to Florida. For alewife, 778 samples were collected from spawning
runs in 15 different rivers, and 1,201 blueback herring samples were
collected from 20 rivers.
Bayesian analyses identified five genetically distinguishable
stocks for alewife with similar results using both STRUCTURE and
Bayesian Analysis of Population Structure (BAPS) software models. The
alewife stock complexes identified were: (1) Northern New England; (2)
Southern New England; (3)
[[Page 48949]]
Connecticut River; (4) Mid-Atlantic; and (5) North Carolina. For
blueback herring, no optimum solution was reached using STRUCTURE,
while BAPS suggested four genetically identifiable stock complexes. The
stock complexes identified for blueback herring were: (1) Northern New
England; (2) Southern New England; (3) Mid Atlantic; (4) and Southern.
However, it should be noted that these Bayesian inferences of
population structure provide a minimum number of genetically
distinguishable groups. In the future, in order to better define
potential stock complexes, further tests examining structure within
designated stocks should be conducted using hierarchical clustering
analysis and genetic tests.
The study also examined the effects of geography and found a strong
effect of latitude on genetic divergence, suggesting a stepping stone
model of population structure, and a strong pattern of isolation by
distance, where gene flow is most likely among neighboring spawning
populations. The preliminary results from the study found significant
differentiation among spawning rivers for both alewife and blueback
herring. Based on the results of their study, the authors' preliminary
management recommendations suggest that river drainage is the
appropriate level of management for both of the species. This inference
was also supported by genetic tests which were conducted later. These
tests suggest that there is substantial population structure at the
drainage scale.
The authors noted a number of caveats for their study including:
(1) Collection of specimens on their upstream spawning run may pool
samples from what are truly distinct spawning populations within the
major river drainages sampled, thereby, underestimating genetic
structure within rivers (Hasselman, 2010); (2) a more detailed analysis
of population structure within the major stocks identified (i.e., using
hierarchical Bayesian clustering methods and genic test) would be
useful for identifying any substructure within these major stocks; (3)
neutral genetic markers used in this study represent the effects of
gene flow and historical population isolation, but not the effects of
adaptive processes, which are important to consider in the context of
stock identification; (4) the analysis is preliminary, and there are a
number of issues that need to be further investigated, including the
effect of deviations in the Hardy-Weinberg Equilibrium model
encountered in four alewife loci and the failure of STRUCTURE to
perform well on the blueback herring dataset; and (5) hybridization may
be occurring between alewife and blueback herring and may influence the
results of the species-specific analyses.
Following the Stock Structure Workshop, additional analyses were
run on the alewife dataset to examine the uniqueness of the
(tentatively) designated Connecticut River alewife stock complex.
Hybrids and misidentified samples were found and subsequently removed
for this analysis, and the results were refined. By removing these
samples from the Connecticut River alewife dataset, Palkovacs et al.
(2012, unpublished report) found that, for alewife, the Connecticut and
Hudson Rivers belong to the Southern New England stock. The analyses
were further refined and Palkovacs et al. (2012, unpublished report)
provided an updated map of the alewife genetic stock complexes,
combining the tentative North Carolina stock with the Mid-Atlantic
stock. This information and analysis is complete and is currently being
prepared for publication. Thus, the refined genetic stock complexes for
alewife in the coastal United States include Northern New England,
Southern New England, and the Mid-Atlantic. For blueback herring, the
identified genetic stocks include Northern New England, Southern New
England, Mid-Atlantic and Southern (Palcovacs et al., 2012, unpublished
report).
Bentzen et al. (2012) implemented a two-part genetic analysis of
river herring to evaluate the genetic diversity of alewives in Maine
and Maritime Canada, and to assess the regional effects of stocking on
alewives and blueback herring in Maine. The genetic analysis of
alewives and blueback herring along mid-coast Maine revealed
significant genetic differentiation among populations. Despite
significant differentiation, the patterns of correlation did not
closely correspond with geography or drainage affiliation. The genetic
analysis of alewives from rivers in Maine and Atlantic Canada detected
isolation by distance, suggesting that homing behavior indicative of
alewives' metapopulation conformance does produce genetically
distinguishable populations. Further testing also suggested that there
may be interbreeding between alewives and blueback herring (e.g.,
hybrids), especially at sample sites with impassible dams.
The unusual genetic groupings of river herring in Maine are likely
a result of Maine's complex stocking history, as alewife populations in
Maine have been subject to considerable within and out of basin
stocking for the purpose of enhancement, recolonization of extirpated
populations, and stock introduction. Alewife stocking in Maine dates
back at least to 1803 when alewives were reportedly moved from the
Pemaquid and St. George Rivers to create a run of alewives in the
Damariscotta River (Atkins and Goode, 1887). These efforts were largely
responsive to considerable declines in alewife populations following
the construction of dams, over exploitation and pollution. Although
there has been considerable alewife stocking and relocation throughout
Maine, there are very few records documenting these efforts. In
contrast, considerably less stocking of alewives has occurred in
Maritime Canada. These genetic analyses suggest that river herring from
Canadian waters are genetically distinct from Maine river herring.
All of the expert opinions we received during the Stock Structure
Workshop suggested evidence of regional stock structure exists for both
alewife and blueback herring as shown by the recent genetics data
(Palkovacs et al., 2012, unpublished report; Bentzen et al.,
unpublished data). However, the suggested boundaries of the regional
stock complexes differed from expert to expert. Migration and mixing
patterns of alewives and blueback herring in the ocean have not been
determined, though regional stock mixing is suspected. Therefore, the
experts suggested that the ocean phase of alewives and blueback herring
should be considered a mixed stock until further tagging and genetic
data become available. There is evidence to support regional
differences in migration patterns, but not at a level of river-specific
stocks.
In the mid-1980s, Rulifson et al. (1987) tagged and released
approximately 19,000 river herring in the upper Bay of Fundy, Nova
Scotia with an overall recapture rate of 0.39 percent. Alewife tag
returns were from freshwater locations in Nova Scotia, and marine
locations in Nova Scotia and Massachusetts. Blueback herring tag
returns were from freshwater locations in Maryland and North Carolina
and marine locations in Nova Scotia. Rulifson et al. (1987) suspected
from recapture data that alewives and blueback herring tagged in the
Bay of Fundy were of different origins, hypothesizing that alewives
were likely regional fish from as far away as New England, while the
blueback herring recaptures were likely not regional fish, but those of
U.S. origin from the mid-Atlantic region. However, the low tag return
numbers (n = 2) made it difficult to generalize about the natal rivers
of
[[Page 48950]]
blueback herring caught in the Bay of Fundy. The results of this
tagging study show that river herring present in Canadian waters may
originate from U.S. waters and vice versa.
Metapopulations of river herring are believed to exist, with adults
frequently returning to their natal rivers for spawning and some
straying occurring between rivers--straying rates have been estimated
up to 20 percent (Jones, 2006; ASMFC, 2009a; Gahagan et al., 2012).
Given the available information on genetic differentiation coast-wide
for alewife and blueback herring, it appears that stock complexes exist
for both species.
River herring originating from Canadian rivers are delimited by
international governmental boundaries. Differences in control of
exploitation, management of habitat, conservation status, or regulatory
mechanisms exist and, therefore, meet the discreteness criterion under
the DPS policy; however, intermixing between both alewife and blueback
herring from U.S. and Canadian coastal waters occurs, and the extent of
this mixing is unknown.
Given the best available information, it is possible to determine
that the various stocks of both alewife and blueback herring are
discrete. The best available information suggests that the delineation
of the stock complexes is as described above; however, future work will
likely further refine these preliminary boundaries. Additionally,
further information is needed on the oceanic migratory patterns of both
species.
Information Related to Significance
If a population is deemed discrete, the population is evaluated in
terms of significance. Significance can be determined using the four
criteria noted above. Since the best available information indicates
that the stock complexes identified for alewives and blueback herring
are most likely discrete, the SRT reviewed the available information to
determine if they are significant.
In evaluating the significance criterion, the SRT considered all of
the above criteria. As indicated earlier, both alewives and blueback
herring occupy a large range spanning almost the entire East Coast of
the United States and into Canada. They appear to migrate freely
throughout their oceanic range and return to freshwater habitats to
spawn in streams, lakes and rivers. Therefore, they occupy many
different ecological settings throughout their range.
As described earlier, the Palkovacs et al. (2012, unpublished
report) study assessed the genetic composition of alewife and blueback
herring stocks within U.S. rivers using 15 neutral loci and documented
that there are at least three stock complexes of alewife in the United
States and four stock complexes of blueback herring in the United
States. Palkovac et al. (2012, unpublished report) showed a strong
effect of latitude on genetic divergence, suggesting that although most
populations are genetically differentiated, gene flow is greater among
neighboring runs than among distant runs. The genetic data are
consistent with the recent results of the ASMFC stock assessment
(2012), which noted that even among rivers within the same state, there
are differences in trends in abundance indices, size-at-age, age
structure and other metrics, indicating there are localized factors
affecting the population dynamics of both species.
Neutral genetic markers such as microsatellites have a longstanding
history of utilization in stock designation for many anadromous fish
species (Waples, 1998). However, these markers represent the effects of
gene flow and historical population isolation and not the effects of
adaptive processes. The effects of adaptive genetic and phenotypic
diversity are also extremely important to consider in the context of
stock designation, but are not captured by the use of neutral genetic
markers. Therefore, the available genetic data are most appropriately
used in support of the discreteness criterion, rather than to determine
significance.
Determining whether a gap in the range of the taxon would be
significant if a stock were extirpated is difficult to determine with
anadromous fish such as river herring. River herring are suspected to
migrate great distances between their natal rivers and overwintering
areas, and therefore, estuarine and marine populations are comprised of
mixed stocks. Consequently, the loss of a stock complex would mean the
loss of riverine spawning subpopulations, while the marine and
estuarine habitat would most likely still be occupied by migratory
river herring from other stock complexes. As it has been shown that
gene flow is greater among neighboring runs than among distant runs, we
might expect that river herring would re-colonize neighboring systems
over a relatively short time frame. Thus, the loss of one stock complex
in itself may not be significant; the loss of contiguous stock
complexes may be. The goal then for river herring stock complexes is to
maintain connectivity between genetic groups to support proper
metapopulation function (spatially separated populations of the same
species that interact, recolonize vacant habitats, and occupy new
habitats through dispersal mechanisms (Hanski and Gilpin, 1991)).
DPS Determination
Evidence for genetic differentiation exists for both alewife and
blueback herring, allowing for preliminary identification of stock
complexes; however, available data are lacking on the significance of
each of these individual stock complexes. Therefore, we have determined
that there is not enough evidence to suggest that the stock complexes
identified through genetics should be treated under the DPS policy as
separate DPSs. The stock complexes may be discrete, but under the DPS
policy, they are not significant to the species as a whole.
Furthermore, given the unknown level of intermixing between Canadian
and U.S. river herring in coastal waters, the Canadian stock complex
should also not be considered separately under the DPS policy.
Throughout the rest of this determination, the species will be
referred to by species (alewife or blueback herring), as river herring
where information overlaps, and by the identified stock complexes
(Palkovacs et al., 2012, unpublished report) for each species as
necessary. While the individual stock complexes do not constitute
separate DPSs, they are important components of the overall species and
relevant to the evaluation of whether either species may be threatened
or endangered in a significant portion of their overall range.
Therefore, we have evaluated the threats to, and extinction risk of the
overall species and each of the individual stock complexes as presented
below. For this analysis, the identified stock complexes for alewife
(Figure 1) in the coastal United States for the purposes of this
finding will include Northern New England, Southern New England, the
Mid-Atlantic, and Canada; and stock complexes for blueback herring
(Figure 2) will include Northern New England, Southern New England,
Mid-Atlantic, Southern Atlantic, and Canada. While the SRT concluded
that there was not sufficient information at this time to determine
with any certainty whether alewife or blueback herring stock complexes
constitute separate DPSs, they recognized that future information on
behavior, ecology and genetic population structure may reveal
significant differences, showing fish to be uniquely adapted to each
stock complex. We agree with this conclusion. Thus, we are not
identifying DPSs for either species.
[[Page 48951]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.004
[[Page 48952]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.005
Foreseeable Future and Significant Portion of Its Range
The ESA defines an ``endangered species'' as ``any species which is
in danger of extinction throughout all or a significant portion of its
range,'' while a ``threatened species'' is defined as ``any species
which is likely to become an endangered species within the foreseeable
future throughout all or a significant portion of its range.'' NMFS and
the U.S. Fish and Wildlife Servce (USFWS) recently published a draft
policy to clarify the interpretation of the phrase ``significant
portion of the range'' in the ESA definitions of ``threatened'' and
``endangered'' (76 FR 76987; December 9, 2011). The draft policy
provides that: (1) If a species is found to be endangered or threatened
in only a significant portion of its range, the entire species is
listed as endangered or threatened, respectively, and the ESA's
protections apply across the species' entire range; (2) a portion of
the range of a species is ``significant'' if its
[[Page 48953]]
contribution to the viability of the species is so important that,
without that portion, the species would be in danger of extinction; (3)
the range of a species is considered to be the general geographical
area within which that species can be found at the time USFWS or NMFS
makes any particular status determination; and (4) if the species is
not endangered or threatened throughout all of its range, but it is
endangered or threatened within a significant portion of its range, and
the population in that significant portion is a valid DPS, we will list
the DPS rather than the entire taxonomic species or subspecies.
The Services are currently reviewing public comment received on the
draft policy. While the Services' intent is to establish a legally
binding interpretation of the term ``significant portion of the
range,'' the draft policy does not have legal effect until such time as
it may be adopted as final policy. Here, we apply the principles of
this draft policy as non-binding guidance in evaluating whether to list
alewife or blueback herring under the ESA. If the policy changes in a
material way, we will revisit the determination and assess whether the
final policy would result in a different outcome.
While we have determined that DPSs cannot be defined for either of
these species based on the available information, the stock complexes
do represent important groupings within the range of both species.
Thus, in our analysis of extinction risk and threats assessment below,
we have evaluated whether either species is at risk rangewide and
within any of the individual stock complexes so that we can evaluate
whether either species is threatened or endangered in a significant
portion of its range.
We established that the appropriate period of time corresponding to
the foreseeable future is a function of the particular type of threats,
the life-history characteristics, and the specific habitat requirements
for river herring. The timeframe established for the foreseeable future
takes into account the time necessary to provide for the conservation
and recovery of each species and the ecosystems upon which they depend,
but is also a function of the reliability of available data regarding
the identified threats and extends only as far as the data allow for
making reasonable predictions about the species' response to those
threats. As described below, the SRT determined that dams and other
impediments to migration have already created a clear and present
threat to river herring that will continue into the future. The SRT
also evaluated the threat from climate change from 2060 to 2100 and
climate variability in the near term (as described in detail below).
Highly productive species with short generation times are more
resilient than less productive, long lived species, as they are quickly
able to take advantage of available habitats for reproduction (Mace et
al., 2002). Species with shorter generation times, such as river
herring (4 to 6 years), experience greater population variability than
species with long generation times, because they maintain the capacity
to replenish themselves more quickly following a period of low survival
(Mace et al., 2002). Given the high population variability among
clupeids, projecting out further than three generations could lead to
considerable uncertainty in the probability that the model will provide
an accurate representation of the population trajectory for each
species. Thus, a 12 to 18 year timeframe (e.g., 2024-2030), or a three-
generation time period, for each species was determined by the Team to
be appropriate for use as the foreseeable future for both alewife and
blueback herring. We agree with the Team that a three-generation time
period (12-18 years) is a reasonable foreseeable future for both
alewife and blueback herring.
Connectivity, population resilience and diversity are important
when determining what constitutes a significant portion of the species'
range (Waples et al., 2007). Maintaining connectivity between genetic
groups supports proper metapopulation function, in this case, anadromy.
Ensuring that river herring populations are well represented across
diverse habitats helps to maintain and enhance genetic variability and
population resilience (McElhany et al., 2000). Additionally, ensuring
wide geographic distribution across diverse climate and geographic
regions helps to minimize risk from catastrophes (e.g., droughts,
floods, hurricanes, etc.; McElhany et al., 2000). Furthermore,
preventing isolation of genetic groups protects against population
divergence (Allendorf and Luikart, 2007).
Threats Evaluation
As described above, Section 4(a)(1) of the ESA and NMFS
implementing regulations (50 CFR 424) states that we must determine
whether a species is endangered or threatened because of any one or a
combination of the following factors: (A) Current or threatened habitat
destruction or modification or curtailment of habitat or range; (B)
overutilization for commercial, recreational, scientific, or
educational purposes; (C) disease or predation; (D) inadequacy of
existing regulatory mechanisms; and (E) other natural or man-made
factors affecting the species' continued existence. This section
briefly summarizes the findings regarding these factors.
A. The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
Past, present, and reasonably foreseeable future factors that have
the potential to affect river herring habitat include, but are not
limited to, dams and hydropower facilities, dredging, water quality
(including land use change, water withdrawals, discharge and
contaminants), climate change and climate variability. As noted above,
river herring occupy a variety of different habitats including
freshwater, estuarine and marine environments throughout their lives,
and thus, they are subjected to habitat impacts occurring in all of
these different habitats.
Dams and Other Barriers
Dams and other barriers to upstream and downstream passage (e.g.,
culverts) can block or impede access to habitats necessary for spawning
and rearing; can cause direct and indirect mortality from injuries
incurred while passing over dams, through downstream passage
facilities, or through hydropower turbines; and can degrade habitat
features necessary to support essential river herring life history
functions. Man-made barriers that block or impede access to rivers
throughout the entire historical range of river herring have resulted
in significant losses of historical spawning habitat for river herring.
Dams and other man-made barriers have contributed to the historical and
current declines in abundance of both blueback and alewife populations.
While estimates of habitat loss over the entire range of river herring
are not available, estimates from studies in Maine show that less than
5 percent of lake spawning habitat and 20 percent of river habitat
remains accessible for river herring (Hall et al., 2010). As described
in more detail below, dams are also known to impact river herring
through various mechanisms, such as habitat alteration, fish passage
delays, and entrainment and impingement (Ruggles 1980; NRC 2004). River
herring can undergo indirect mortality from injuries such as scale
loss, lacerations, bruising, eye or fin damage, or internal
hemorrhaging when passing through turbines, over spillways, and through
bypasses (Amaral et al., 2012).
[[Page 48954]]
The following summary of the effects of dams and other barriers on
river herring is taken from Amendment 2 to the Interstate Fishery
Management Plan for Shad and River Herring (hereafter, referred to as
``Amendment 2'' and cited as ``ASMFC, 2009''). Because it includes a
detailed description of barriers to upstream and downstream passage, it
is the best source of comprehensive information on this topic. Please
refer to Amendment 2 for more information.
Dams and spillways impeding rivers along the East Coast of the
United States have resulted in a considerable loss of historical
spawning habitat for shad and river herring. Permanent man-made
structures pose an ongoing barrier to fish passage unless fishways are
installed or structures are removed. Low-head dams can also pose a
problem, as fish are unable to pass over them except when tides or
river discharges are exceptionally high (Loesch and Atran, 1994).
Historically, major dams were often constructed at the site of natural
formations conducive to waterpower, such as natural falls. Diversion of
water away from rapids at the base of falls can reduce fish habitat,
and in some cases cause rivers to run dry at the base for much of the
summer (MEOEA, 2005; ASMFC, 2009).
Prior to the early 1990s, it was thought that migrating shad and
river herring suffered significant mortality going through turbines
during downstream passage (Mathur and Heisey, 1992). Juvenile shad
emigrating from rivers have been found to accumulate in larger numbers
near the forebay of hydroelectric facilities, where they become
entrained in intake flow areas (Martin et al., 1994). Relatively high
mortality rates were reported (62 percent to 82 percent) at a
hydroelectric dam for juvenile American shad and blueback herring,
depending on the power generation levels tested (Taylor and Kynard,
1984). In contrast, Mathur and Heisey (1992) reported a mortality rate
of 0 percent to 3 percent for juvenile American shad (2 to 6 in fork
length (55 to 140 mm)), and 4 percent for juvenile blueback herring (3
to 4 in fork length (77 to 105 mm)) through Kaplan turbines. Mortality
rate increased to 11 percent in passage through a low-head Francis
turbine (Mathur and Heisey, 1992). Other studies reported less than 5
percent mortality when large Kaplan and fixed-blade, mixed-flow
turbines were used at a facility along the Susquehanna River (RMC,
1990; RMC, 1994). At the same site, using small Kaplan and Francis
runners, the mortality rate was as high as 22 percent (NA, 2001). At
another site, mortality rate was about 15 percent where higher
revolution, Francis-type runners were used (RMC, 1992; ASMFC, 2009).
Additional studies reported that changes in pressure had a more
pronounced effect on juveniles with thinner and weaker tissues as they
moved through turbines (Taylor and Kynard, 1984). Furthermore, some
fish may die later from stress, or become weakened and more susceptible
to predation, and as such, losses may not be immediately apparent to
researchers (Gloss, 1982) (ASMFC, 2009).
Changes to the river system, resulting in delayed migration among
other things, were also identified in Amendment 2 as impacting river
herring. Amendment 2 notes that when juvenile alosines delay out-
migration, they may concentrate behind dams and become more susceptible
to actively feeding predators. They may also be more vulnerable to
anglers that target alosines as a source of bait. Delayed out-migration
can also make juvenile alosines more susceptible to marine predators
that they may have avoided if they had followed their natural migration
patterns (McCord, 2005a). In open rivers, juvenile alosines gradually
move seaward in groups that are likely spaced according to the spatial
separation of spawning and nursery grounds (Limburg, 1996; J. McCord,
South Carolina Department of Natural Resources, personal observation).
Releasing water from dams and impoundments (or reservoirs) may lead to
flow alterations, altered sediment transport, disruption of nutrient
availability, changes in downstream water quality (including both
reduced and increased temperatures), streambank erosion, concentration
of sediment and pollutants, changes in species composition,
solubilization of iron and manganese and their absorbed or chelated
ions, and hydrogen sulfide in hypolimnetic (water at low level outlets)
releases (Yeager, 1995; Erkan, 2002; ASMFC, 2009).
Many dams spill water over the top of the structure where water
temperatures are the warmest, essentially creating a series of warm
water ponds in place of the natural stream channel (Erkan, 2002).
Conversely, water released from deep reservoirs may be poorly
oxygenated, at below-normal seasonal water temperature, or both,
thereby causing loss of suitable spawning or nursery habitat in
otherwise habitable areas (ASMFC, 2009).
Reducing minimum flows can reduce the amount of water available and
cause increased water temperature or reduced dissolved oxygen levels
(ASMFC, 1985; ASMFC, 1999; USFWS et al., 2001). Such conditions have
occurred along the Susquehanna River at the Conowingo Dam, Maryland,
from late spring through early fall, and have historically caused large
fish kills below the dam (Krauthamer and Richkus, 1987; ASMFC, 2009).
Disruption of seasonal flow rates in rivers can impact upstream and
downstream migration patterns for adult and juvenile alosines (ASMFC,
1985; Limburg, 1996; ASMFC, 1999; USFWS et al., 2001). Changes to
natural flows can also disrupt natural productivity and availability of
zooplankton that larval and early juvenile alosines feed on (Crecco and
Savoy, 1987; Limburg, 1996; ASMFC, 2009).
Although most dams that impact diadromous fish are located along
the lengths of rivers, fish can also be affected by hydroelectric
projects at the mouths of rivers, such as the large tidal hydroelectric
project at the Annapolis River in the Bay of Fundy, Canada. This
particular basin and other surrounding waters are used as foraging
areas during summer months by American shad from all runs along the
East Coast of the United States (Dadswell et al., 1983). Because the
facilities are tidal hydroelectric projects, fish may move in and out
of the impacted areas with each tidal cycle. While turbine mortality is
relatively low with each passage, the repeated passage in and out of
these facilities may cumulatively result in substantial overall
mortalities (Scarratt and Dadswell, 1983; ASMFC, 2009).
Additional man-made structures that may obstruct upstream passage
include: tidal and amenity barrages (barriers constructed to alter
tidal flow for aesthetic purposes or to harness energy); tidal flaps
(used to control tidal flow); mill, gauging, amenity, navigation,
diversion, and water intake weirs; fish counting structures; and
earthen berms (Durkas, 1992; Solomon and Beach, 2004). The impact of
these structures is site-specific and will vary with a number of
conditions including head drop, form of the structure, hydrodynamic
conditions upstream and downstream, condition of the structure, and
presence of edge effects (Solomon and Beach, 2004). Road culverts are
also a significant source of blockage. Culverts are popular, low-cost
alternatives to bridges when roads must cross small streams and creeks.
Although the amount of habitat affected by an individual culvert may be
small, the cumulative impact of multiple culverts within a watershed
can be substantial (Collier and Odom, 1989; ASMFC, 2009).
Roads and culverts can also impose significant changes in water
quality.
[[Page 48955]]
Winter runoff in some states may include high concentrations of road
salt, while stormwater flows in the summer may cause thermal stress and
bring high concentrations of other pollutants (MEOEA, 2005; ASMFC,
2009).
Sampled sites in North Carolina revealed river herring upstream and
downstream of bridge crossings, but no herring were found in upstream
sections of streams with culverts. Additional study is underway to
determine if river herring are absent from these areas because of the
culverts (NCDENR, 2000). Even structures only 8 to 12 in (20 to 30 cm)
above the water can block shad and river herring migration (ASMFC,
1999; ASMFC, 2009).
Rivers can also be blocked by non-anthropogenic barriers, such as
beaver dams, waterfalls, log piles, and vegetative debris. These
blockages may hinder migration, but they can also benefit by providing
adhesion sites for eggs, protective cover, and feeding sites (Klauda et
al., 1991b). Successful passage at these natural barriers often depends
on individual stream flow characteristics during the fish migration
season (ASMFC, 2009).
Dredging
Wetlands provide migratory corridors and spawning habitat for river
herring. The combination of incremental losses of wetland habitat,
changes in hydrology, and nutrient and chemical inputs over time, can
be extremely harmful, resulting in diseases and declines in the
abundance and quality. Wetland loss is a cumulative impact that results
from activities related to dredging/dredge spoil placement, port
development, marinas, solid waste disposal, ocean disposal, and marine
mining. In the late 1970s and early 1980s, the United States was losing
wetlands at an estimated rate of 300,000 acres (1,214 sq km) per year.
The Clean Water Act and state wetland protection programs helped
decrease wetland losses to 117,000 acres (473 sq km) per year, between
1985 and 1995. Estimates of wetlands loss vary according to the
different agencies. The U.S. Department of Agriculture (USDA)
attributes 57 percent of wetland loss to development, 20 percent to
agriculture, 13 percent to the creation of deepwater habitat, and 10
percent to forest land, rangeland, and other uses. Of the wetlands lost
between 1985 and 1995, the USFWS estimates that 79 percent of wetlands
were lost to upland agriculture. Urban development and other types of
land use activities were responsible for 6 percent and 15 percent of
wetland loss, respectively.
Amendment 2 identifies channelization and dredging as a threat to
river herring habitat. The following section, taken from Amendment 2,
describes these threats.
Channelization can cause significant environmental impacts (Simpson
et al., 1982; Brookes, 1988), including bank erosion, elevated water
velocity, reduced habitat diversity, increased drainage, and poor water
quality (Hubbard, 1993). Dredging and disposal of spoils along the
shoreline can also create spoil banks, which block access to sloughs,
pools, adjacent vegetated areas, and backwater swamps (Frankensteen,
1976). Dredging may also release contaminants, resulting in
bioaccumulation, direct toxicity to aquatic organisms, or reduced
dissolved oxygen levels (Morton, 1977). Furthermore, careless land use
practices may lead to erosion, which can lead to high concentrations of
suspended solids (turbidity) and substrate (siltation) in the water
following normal and intense rainfall events. This can displace larvae
and juveniles to less desirable areas downstream and cause osmotic
stress (Klauda et al., 1991b; ASMFC, 2009).
Spoil banks are often unsuitable habitat for fishes. Suitable
habitat is often lost when dredge disposal material is placed on
natural sand bars and/or point bars. The spoil is too unstable to
provide good habitat for the food chain. Draining and filling, or both,
of wetlands adjacent to rivers and creeks in which alosines spawn has
eliminated spawning areas in North Carolina (NCDENR, 2000; ASMFC,
2009).
Secondary impacts from channel formation include loss of vegetation
and debris, which can reduce habitat for invertebrates and result in
reduced quantity and diversity of prey for juveniles (Frankensteen,
1976). Additionally, stream channelization often leads to altered
substrate in the riverbed and increased sedimentation (Hubbard, 1993),
which in turn can reduce the diversity, density, and species richness
of aquatic insects (Chutter, 1969; Gammon, 1970; Taylor, 1977).
Suspended sediments can reduce feeding success in larval or juvenile
fishes that rely on visual cues for plankton feeding (Kortschal et al.,
1991). Sediment re-suspension from dredging can also deplete dissolved
oxygen, and increase bioavailability of any contaminants that may be
bound to the sediments (Clark and Wilber, 2000; ASMFC, 2009).
Migrating adult river herring avoid channelized areas with
increased water velocities. Several channelized creeks in the Neuse
River basin in North Carolina have reduced river herring distribution
and spawning areas (Hawkins, 1979). Frankensteen (1976) found that the
channelization of Grindle Creek, North Carolina removed in-creek
vegetation and woody debris, which had served as substrate for
fertilized eggs (ASMFC, 2009).
Channelization can also reduce the amount of pool and riffle
habitat (Hubbard, 1993), which is an important food-producing area for
larvae (Keller, 1978; Wesche, 1985; ASMFC, 2009).
Dredging can negatively affect alosine populations by producing
suspended sediments (Reine et al., 1998), and migrating alosines are
known to avoid waters of high sediment load (ASMFC, 1985; Reine et al.,
1998). Fish may also avoid areas that are being dredged because of
suspended sediment in the water column. Filter-feeding fishes, such as
alosines, can be negatively impacted by suspended sediments on gill
tissues (Cronin et al., 1970). Suspended sediments can clog gills that
provide oxygen, resulting in lethal and sub-lethal effects to fish
(Sherk et al., 1974 and 1975; ASMFC, 2009).
Nursery areas along the shorelines of the rivers in North Carolina
have been affected by dredging and filling, as well as by erection of
bulkheads; however, the degree of impact has not been measured. In some
areas, juvenile alosines were unable to enter channelized sections of a
stream due to high water velocities caused by dredging (ASMFC, 2000 and
2009).
Water Quality
Nutrient enrichment has become a major cumulative problem for many
coastal waters. Nutrient loading results from the individual activities
of coastal development, marinas and recreational boating, sewage
treatment and disposal, industrial wastewater and solid waste disposal,
ocean disposal, agriculture, and aquaculture. Excess nutrients from
land based activities accumulate in the soil, pollute the atmosphere,
pollute ground water, or move into streams and coastal waters. Nutrient
inputs are known to have a direct effect on water quality. For example,
nutrient enrichment can stimulate growth of phytoplankton that consumes
oxygen when they decay, which can lead to low dissolved oxygen that may
result in fish kills (Correll, 1987; Tuttle et al., 1987; Klauda et
al., 1991b); this condition is known as eutrophication.
In addition to the direct cumulative effects incurred by
development activities, inshore and coastal habitats are also
threatened by persistent increases in certain chemical discharges. The
combination of incremental losses of wetland habitat, changes in
hydrology, and nutrient and chemical inputs produced over time can
[[Page 48956]]
be extremely harmful to marine and estuarine biota, including river
herring, resulting in diseases and declines in the abundance and
quality of the affected resources.
Amendment 2 identified land use changes including agriculture,
logging/forestry, urbanization and non-point source pollution as
threats to river herring habitat. The following section, taken from
Amendment 2, describes these threats.
The effects of land use and land cover on water quality, stream
morphology, and flow regimes are numerous, and may be the most
important factors determining quantity and quality of aquatic habitats
(Boger, 2002). Studies have shown that land use influences dissolved
oxygen (Limburg and Schmidt, 1990), sediments and turbidity (Comeleo et
al., 1996; Basnyat et al., 1999), water temperature (Hartman et al.,
1996; Mitchell, 1999), pH (Osborne and Wiley, 1988; Schofield, 1992),
nutrients (Peterjohn and Correll, 1984; Osborne and Wiley, 1988;
Basnyat et al., 1999), and flow regime (Johnston et al., 1990; Webster
et al., 1992; ASMFC, 2009).
Siltation, caused by erosion due to land use practices, can kill
submerged aquatic vegetation (SAV). SAV can be adversely affected by
suspended sediment concentrations of less than 15 ppm (15 mg/L)
(Funderburk et al., 1991) and by deposition of excessive sediments
(Valdes-Murtha and Price, 1998). SAV is important because it improves
water quality (Carter et al., 1991). SAV consumes nutrients in the
water and as the plants die and decay, they slowly release the
nutrients back into the water column. Additionally, through primary
production and respiration, SAV affects the dissolved oxygen and carbon
dioxide concentrations, alkalinity, and pH of the waterbody. SAV beds
also bind sediments to the bottom resulting in increased water clarity,
and they provide refuge habitat for migratory fish and planktonic prey
items (Maldeis, 1978; Monk, 1988; Killgore et al., 1989; ASMFC, 2009).
Decreased water quality from sedimentation became a problem with
the advent of land-clearing agriculture in the late 18th century
(McBride, 2006). Agricultural practices can lead to sedimentation in
streams, riparian vegetation loss, influx of nutrients (e.g., inorganic
fertilizers and animal wastes), and flow modification (Fajen and
Layzer, 1993). Agriculture, silviculture, and other land use practices
can lead to sedimentation, which reduces the ability of semi-buoyant
eggs and adhesive eggs to adhere to substrates (Mansueti, 1962; ASMFC,
2009).
From the 1950s to the present, increased nutrient loading has made
hypoxic conditions more prevalent (Officer et al., 1984; Mackiernan,
1987; Jordan et al., 1992; Kemp et al., 1992; Cooper and Brush, 1993;
Secor and Gunderson, 1998). Hypoxia is most likely caused by
eutrophication, due mostly to non-point source pollution (e.g.,
industrial fertilizers used in agriculture) and point source pollution
(e.g., urban sewage).
Logging activities can modify hydrologic balances and in-stream
flow patterns, create obstructions, modify temperature regimes, and add
nutrients, sediments, and toxic substances into river systems. Loss of
riparian vegetation can result in fewer refuge areas for fish from
fallen trees, fewer insects for fish to feed on, and reduced shade
along the river, which can lead to increased water temperatures and
reduced dissolved oxygen (EDF, 2003). Threats from deforestation of
swamp forests include: siltation from increased erosion and runoff;
decreased dissolved oxygen (Lockaby et al., 1997); and disturbance of
food-web relationships in adjacent and downstream waterways (Batzer et
al., 2005; ASMFC, 2009).
Urbanization can cause elevated concentrations of nutrients,
organics, or sediment metals in streams (Wilber and Hunter, 1977; Kelly
and Hite, 1984; Lenat and Crawford, 1994). More research is needed on
how urbanization affects diadromous fish populations; however, Limburg
and Schmidt (1990) found that when the percent of urbanized land
increased to about 10 percent of the watershed, the number of alewife
eggs and larvae decreased significantly in tributaries of the Hudson
River, New York (ASMFC, 2009).
Water Withdrawal/Outfall
Water withdrawal facilities and toxic and thermal discharges have
also been identified as impacting river herring, and the following
section is summarized from Amendment 2.
Large volume water withdrawals (e.g., drinking water, pumped-
storage hydroelectric projects, irrigation, and snow-making) can alter
local current characteristics (e.g., reverse river flow), which can
result in delayed movement past a facility or entrainment in water
intakes (Layzer and O'Leary, 1978). Planktonic eggs and larvae
entrained at water withdrawal projects experience high mortality rates
due to pressure changes, shear and mechanical stresses, and heat shock
(Carlson and McCann, 1969; Marcy, 1973; Morgan et al., 1976). While
juvenile mortality rates are generally low at well-screened facilities,
large numbers of juveniles can be entrained (Hauck and Edson, 1976;
Robbins and Mathur, 1976; ASMFC, 2009).
Fish impinged against water filtration screens can die from
asphyxiation, exhaustion, removal from the water for prolonged periods
of time, removal of protective mucous, and descaling (DBC, 1980).
Studies conducted along the Connecticut River found that larvae and
early juveniles of alewife, blueback herring, and American shad
suffered 100-percent mortality when temperatures in the cooling system
of a power plant were elevated above 82[emsp14][deg]F (28[deg]C); 80
percent of the total mortality was caused by mechanical damage, 20
percent by heat shock (Marcy, 1976). Ninety-five percent of the fish
near the intake were not captured by the screen, and Marcy (1976)
concluded that it did not seem possible to screen fish larvae
effectively (ASMFC, 2009).
The physical characteristics of streams (e.g., stream width, depth,
and current velocity; substrate; and temperature) can be altered by
water withdrawals (Zale et al., 1993). River herring can experience
thermal stress, direct mortality, or indirect mortality when water is
not released during times of low river flows and water temperatures are
higher than normal. Water flow disruption can also result in less
freshwater input to estuaries (Rulifson, 1994), which are important
nursery areas for river herring and other anadromous species (ASMFC,
2009).
Industrial discharges may contain toxic chemicals, such as heavy
metals and various organic chemicals (e.g., insecticides, solvents,
herbicides) that are harmful to aquatic life (ASMFC, 1999). Many
contaminants can have harmful effects on fish, including reproductive
impairment (Safe, 1990; Mac and Edsall, 1991; Longwell et al., 1992).
Chemicals and heavy metals can move through the food chain, producing
sub-lethal effects such as behavioral and reproductive abnormalities
(Matthews et al., 1980). In fish, exposure to polychlorinated biphenyls
(PCBs) can cause fin erosion, epidermal lesions, blood anemia, altered
immune response, and egg mortality (Post, 1987; Kennish et al., 1992).
Steam power plants that use chlorine to prevent bacterial, fungal, and
algal growth present a hazard to all aquatic life in the receiving
stream, even at low concentrations (Miller et al., 1982; ASMFC, 2009).
Pulp mill effluent and other oxygen-consuming wastes discharged
into rivers and streams can reduce dissolved oxygen concentrations
below what is
[[Page 48957]]
required for river herring survival. Low dissolved oxygen resulting
from industrial pollution and sewage discharge can also delay or
prevent upstream and downstream migrations. Everett (1983) found that
during times of low water flow when pulp mill effluent comprised a
large percentage of the flow, river herring avoided the effluent.
Pollution may be diluted in the fall when water flows increase, but
fish that reach the polluted waters downriver before the water has
flushed the area will typically succumb to suffocation (Miller et al.,
1982; ASMFC, 2009).
Effluent may also pose a greater threat during times of drought.
Such conditions were suspected of interfering with the herring
migration along the Chowan River, North Carolina, in 1981. In the years
before 1981, the effluent from the pulp mill had passed prior to the
river herring run, but drought conditions caused the effluent to remain
in the system longer that year. Toxic effects were indicated, and
researchers suggested that growth and reproduction might have been
disrupted as a result of eutrophication and other factors (Winslow et
al., 1983; ASMFC, 2009).
Klauda et al. (1991a) provides an extensive review of temperature
thresholds for alewife and bluback herring. In summary, the spawning
migration for alewives most often occurs when water temperatures range
from 50-64 [deg]F (10-18 [deg]C), and for bluebacks when temperatures
range from 57-77 [deg]F (14-25 [deg]C). Alewife egg deposition most
often occurs when temperatures range between 50-72 [deg]F (10 and 22
[deg]C), and for bluebacks when temperatures range between 70-77 [deg]F
(21 and 25 [deg]C). Alewife egg and larval development is optimal when
temperatures range from 63--70 [deg]F (17-21 [deg]C), and for bluebacks
when temperatures range from 68-75 [deg]F (20-24 [deg]C) (temperature
ranges were also presented and discussed at the Climate Workshop (NMFS,
2012b)). Thermal effluent from power plants outside these temperature
ranges when river herring are present can disrupt schooling behavior,
cause disorientation, and may result in death. Sewage can directly and
indirectly affect anadromous fish. Major phytoplankton and algal blooms
that reduced light penetration (Dixon, 1996) and ultimately reduced SAV
abundance (Orth et al., 1991) in tidal freshwater areas of the
Chesapeake Bay in the 1960s and early 1970s may have been caused by
ineffective sewage treatment (ASMFC, 2009).
Water withdrawal for irrigation can cause dewatering or reduced
streamflow of freshwater streams, which can decrease the quantity of
both spawning and nursery habitat for anadromous fish. Reduced
streamflow can reduce water quality by concentrating pollutants and/or
increasing water temperature (ASMFC, 1985). O'Connell and Angermeier
(1999) found that in some Virginia streams, there was an inverse
relationship between the proportion of a stream's watershed that was
agriculturally developed and the overall tendency of the stream to
support river herring runs. In North Carolina, cropland alteration
along several creeks and rivers significantly reduced river herring
distribution and spawning areas in the Neuse River basin (Hawkins,
1979; ASMFC, 2009).
Atmospheric deposition occurs when pollutants (e.g. nitrates,
sulfates, ammonium, and mercury) are transferred from the air to the
earth's surface. Pollutants can get from the air into the water through
rain and snow, falling particles, and absorption of the gas form of the
pollutants into the water. Atmospheric pollutants can result in
increased eutrophication (Paerl et al., 1999) and acidification of
surface waters (Haines, 1981). Atmospheric nitrogen deposition in
coastal estuaries can lead to accelerated algal production (or
eutrophication) and water quality declines (e.g., hypoxia, toxicity,
and fish kills) (Paerl et al., 1999). Nitrate and sulfate deposition is
acidic and can reduce stream pH (measure of the hydronium ion
concentration) and elevate toxic forms of aluminum (Haines, 1981). When
pH declines, the normal ionic salt balance of the fish is compromised
and fish lose body salts to the surrounding water (Southerland et al.,
1997). Sensitive fish species can experience acute mortality, reduced
growth, skeletal deformities, and reproductive failure (Haines, 1981).
Climate Change and Climate Variability
Possible climate change impacts to river herring were noted in the
stock assessment (ASMFC, 2012) based on regional patterns in trends
(e.g., trawl surveys in southern regions showed declining trends more
frequently compared to those in northern regions). However, additional
information was needed on this topic to inform our listing decision,
and as noted above, we held a workshop to obtain expert opinion on the
potential impacts of climate change on river herring (NMFS, 2012b).
As discussed at the workshop, both natural climate variability and
anthropogenic-forced climate change will affect river herring (NMFS,
2012b). Natural climate variability includes the Atlantic Multidecadal
Oscillation, the North Atlantic Oscillation, and the El Ni[ntilde]o
Southern Oscillation. During the workshop, it was noted that impacts
from global climate change induced by human activities are likely to
become more apparent in future years (Intergovernmental Panel on
Climate Change (IPCC), 2007). Results presented from the North American
Regional Climate Change Assessment Program (NARCCAP--a group that uses
fields from the global climate models to provide boundary conditions
for regional atmospheric models covering most of North America and
extending over the adjacent oceans) suggest that temperature will warm
throughout the years over the northeast, mid-Atlantic and Southeast
United States (comparing 1968-1999 to 2038-2069; NMFS, 2012b).
Additionally, it was noted that there is an expected but less certain
increase in precipitation over the northeast United States during fall
and winter during the same years (NMFS, 2012b). In conjunction with
increased evaporation from warmer temperatures, the Northeast and mid-
Atlantic may experience decrease in runoff and decreased stream flow in
late winter and early spring (NMFS, 2012b). Additionally, enhanced
ocean stratification could be caused by greater warming at the ocean
surface than at depth (NMFS, 2012b).
Many observed changes in river herring biology related to
environmental conditions were noted at the workshop, but few detailed
analyses were available to distinguish climate change from climate
variability. One analysis by Massachusetts Division of Marine Fisheries
showed precipitation effects on spawning run recruitment at Monument
River, MA (1980-2012; NMFS, 2012b). Jordaan and Kritzer (unpublished
data) showed normalized run counts of alewife and blueback herring have
a stronger correlation with fisheries and predators than various
climate variables at broad scales (NMFS, 2012b). Once fine-scale (flow
related to fishways and dams) data were used, results indicate that
summer and fall conditions were more important. Nye et al. (2012)
investigated climate-related mechanisms in the marine habitat of the
United States that may impact river herring. Their preliminary results
indicate the following: (1) A shift in northern ocean distribution for
both blueback herring and alewife depending on the season; (2) decrease
in ocean habitat within the preferred temperature for alewife and
blueback herring in the spring; and (3) effects of climate change on
river herring populations may depend on the current condition (e.g.,
[[Page 48958]]
abundance and health) of the population, assumptions, and temperature
tolerances (e.g., blueback herring have a higher temperature tolerance
than alewife).
Although preliminary, Nye et al. (2012) indicate that climate
change will impact river herring. The results (also supported by Nye et
al., 2009) indicate that both blueback herring and alewife have and
will continue to shift their distribution to more northerly waters in
the spring, and blueback herring has also shifted its distribution to
more northerly waters in the fall (1975-2010) (Nye et al., 2012).
Additionally, Nye et al. (2012) found a decrease in habitat (bottom
waters) within the preferred temperature for alewife and blueback
herring in the spring under future climate predictions (2020-2060 and
2060-2100). They concluded that an expected decrease in optimal marine
habitat and natal spawning habitat will negatively affect river herring
populations at the southern extent of their range. Additionally, Nye et
al. (2012) infer that this will have negative population level effects
and cause population declines in southern rivers, resulting in an
observed shift in distribution which has already been observed. Nye et
al. (2012) also found that the effects of climate change on river
herring populations may depend on the current condition (e.g.,
abundance and health) of the population, assumptions, and temperature
tolerances. Using the model, projections of alewife distribution and
abundance can be predicted for each year, but for ease of
interpretation, 2 years of low and high relative abundance were chosen
to illustrate the effects of population abundance and temperature on
alewife distribution. The low and high abundance years were objectively
chosen as the years closest to -1 and +1 standard deviation from
overall mean abundance. Two years closest to the -1 and +1 standard
deviation from mean population abundance were selected to reflect the
combined effect of warming with low and high abundance of blueback
herring. The difference in species response (as noted below) may
reflect the different temperature tolerances (9-11 [deg]C for blueback
herring and 4-11 [deg]C for alewife) as indicated by the southern limit
of their ranges. Blueback herring may be able to tolerate higher
temperature as their range extends as far south as Florida, but the
southern extent of the alewife's range is limited to North Carolina.
For both species, the Nye et al. (2012) analysis indicates that, if
robust populations of these species are maintained, declines due to the
effects of climate change will be reduced. Their specific results
include the following:
Alewife: At low population size, coast-wide abundance is
projected to decrease with less suitable habitat and patchy areas of
high density in the Gulf of Maine and Georges Bank in 2060-2100. At
high population size, abundance is projected to increase slightly from
2020-2060 (+4.64 percent) but is projected to decrease (-39.14 percent)
and become more patchy in 2060-2100.
Blueback herring: Abundance is projected to increase at
both high and low population size throughout the Northeast United
States, especially in the mid-Atlantic and Georges Bank. However, at
low abundance the increase is minimal and remains at a level below the
40-year mean. The percentage change due to climate change (factoring
only temperature) is +29.93 percent for the time period 2020-2060 and
+55.81 percent from 2060-2100.
We hoped to obtain information during the workshop on potential
impacts of climate change by region, including information on species,
life stage, indicators, potential impacts, and available data/relevant
references (NMFS, 2012b). Although we did obtain information on each of
these categories, substantial data gaps in the species information were
apparent (NMFS, 2012b). For example, although no specific information
on impacts of ocean acidification on river herring was presented,
possible effects on larval development, chemical signaling (olfaction),
and de-calcification of prey were noted (NMFS, 2012b). Additional
research is needed to identify the limiting factor(s) for river herring
populations. As Nye et al. (2012) noted, the links between climate and
river herring biology during freshwater stages are unclear and will
require additional time to research and thoroughly analyze. This
conclusion is supported by the results of the workshop, which noted
numerous potential climate effects on the freshwater stages, but little
synthesis has been accomplished to date. The preliminary analysis of
Nye et al. (2012) indicates that water temperatures in the rivers will
be warmer, and there will be a decrease in the river flow in the
northeast and Mid-Atlantic in late winter/early spring.
Although current information indicates climate change is and will
continue to impact river herring (e.g., Nye et al., 2012), climate
variability rather than climate change is expected to have more of an
impact on river herring from 2024-2030. Several studies have shown that
the climate change signal is readily apparent by the end of the 21st
century (Hare et al., 2010; Hare et al., 2012). At intermediate time
periods (e.g., 2024-2030), the signal of natural climate variability is
likely similar to the signal of climate change. Thus, a large component
of the climate effect on river herring in 2024-2030 will be composed of
natural climate variability, which could be either warming or cooling.
Summary and Evaluation of Factor A
Dams and hydropower facilities, water quality and water withdrawals
from urbanization and agricultural runoff, dredging and other wetland
alterations are likely the causes of historical and recent declines in
abundance of alewife and blueback herring populations. Climate
variability rather than climate change is expected to have more of an
impact on river herring from 2024-2030 (NMFS' foreseeable future for
river herring). Nye et al., (2012) conducted a preliminary analysis
investigating climate-related mechanisms in the marine habitat of the
United States that may impact river herring, and found that changes in
the amount of preferred habitat and a potential northward shift in
distribution as a result of climate change may affect river herring in
the future (e.g., 2020-2100). Thus, the level of threat posed by these
potential stressors is evaluated further in the qualitative threats
assessment as described below.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Directed Commercial Harvest
This following section on river herring fisheries in the United
States is from the stock assessment (ASMFC, 2012).
Fisheries for anadromous species have existed in the United States
for a very long time. They not only provided sustenance for early
settlers but a source of income as the fisheries were commercialized.
It is difficult to fully describe the characteristics of these early
fisheries because of the lack of quantifiable data.
The earliest commercial river herring data were generally reported
in state and town reports or local newspapers. In 1871, the U.S. Fish
Commission was founded (later became known as the U.S. Fish and
Fisheries Commission in 1881). This organization collected fisheries
statistics to characterize the biological and economic aspects of
commercial fisheries. Data describing historical river herring
fisheries were
[[Page 48959]]
available from two of this organization's publications--the Bulletin of
the U.S. Fish Commission (renamed Fishery Bulletin in 1971; Collins and
Smith, 1890; Smith, 1891) and the U.S. Fish Commission Annual Report
(USFC, 1888-1940). In the stock assessment, the river herring data were
transcribed and when available, dollar values were converted to 2010
dollar values using conversion factors based on the annual average
consumer price index (CPI) values, which were obtained from the U.S.
Bureau of Labor Statistics. Note that CPI values are not available for
years prior to 1913 so conversion factors could not be calculated for
years earlier than 1913 (ASMFC, 2012).
There are several caveats to using the historical fisheries data.
There is an apparent bias in the area sampled. In most cases, there was
no systematic sampling of all fisheries; instead, sampling appeared to
be opportunistic, concentrating on the mid-Atlantic States. It is also
difficult to assess the accuracy and precision of these data. In some
instances, the pounds were reported at a fine level of detail (e.g., at
the state/county/gear level), but details regarding the specific source
of the data were often not described. The level of detail provided in
the reports varied among states and years. Additionally, not all states
and fisheries were canvassed in all years, so absence of landings data
does not necessarily indicate the fishery was not active as it is
possible that the data just were not collected. For these reasons,
these historical river herring landings should not be considered even
minimum values because of the variation in detail and coverage over the
time series. No attempt was made to estimate missing river herring data
since no benchmark or data characteristics could be found, and the
stock assessment subcommittee also did not attempt to estimate missing
data in a time series at a particular location because of the bias
associated with these estimates (ASMFC, 2012).
During 1880 to 1938, reported commercial landings of river herring
along the Atlantic Coast averaged approximately 30.5 million lbs
(13,835 mt) per year. The majority of river herring landed by
commercial fisheries in these early years are attributed to the mid-
Atlantic region (NY-VA). The dominance of the mid-Atlantic region is,
in part, due to the apparent bias in the spatial coverage of the
canvass (see above). From 1920 to 1938, the average annual weight of
reported commercial river herring landings was about 22.8 million lbs
(10,351 mt). The value of the commercial river herring landings during
this same time period was approximately 2.87 million dollars (2010 USD)
(ASMFC, 2012).
Domestic commercial landings of river herring were presented in the
stock assessment by state and by gear from 1887 to 2010 where
available. Landings of alewife and blueback herring were collectively
classified as ``river herring'' by most states. Only a few states had
species-specific information recorded for a limited range of years.
Commercial landings records were available for each state since 1887
except for Florida and the Potomac River Fisheries Commission (PRFC),
which began recording landings in 1929 and 1960, respectively. It is
important to note that historical landings presented in the stock
assessment do not include all landings for all states over the entire
time period and are likely underestimated, particularly for the first
third of the time series, since not all river landings were reported
(ASMFC, 2012).
Total domestic coast-wide landings averaged 18.5 million lb (8,399
mt) from 1887 to 1928 (See table 2.2 in ASMFC (2012)). During this
early time period, landings were predominately from Maryland, North
Carolina, Virginia, and Massachusetts (overall harvest is likely
underestimated because landings were not recorded consistently during
this time). Virginia made up approximately half of the commercial
landings from 1929 until the 1970s, and the majority of Virginia's
landings came from the Chesapeake Bay, Potomac River, York River, and
offshore harvest. Coast-wide landings started increasing sharply in the
early 1940s and peaked at over 68.7 million lb (31,160 mt) in 1958 (See
Table 2.2, ASMFC, 2012). In the 1950s and 1960s, a large proportion of
the harvest came from Massachusetts purse seine fisheries that operated
offshore on Georges Bank targeting Atlantic herring (G. Nelson,
Massachusetts Division of Marine Fisheries, Pers. comm., 2012).
Landings from North Carolina were also at their highest during this
time and originated primarily from the Chowan River pound net fishery.
Severe declines in landings began coast-wide in the early 1970s and
domestic landings are now a fraction of what they were at their peak,
having remained at persistently low levels since the mid-1990s.
Moratoria were enacted in Massachusetts (commercial and recreational in
2005), Rhode Island (commercial and recreational in 2006), Connecticut
(commercial and recreational in 2002), Virginia (for waters flowing
into North Carolina in 2007), and North Carolina (commercial and
recreational in 2007). As of January 1, 2012, river herring fisheries
in states or jurisdictions without an approved sustainable fisheries
management plan, as required under ASMFC Amendment 2 to the Shad and
River Herring FMP, were closed. As a result, prohibitions on harvest
(commercial or recreational) were extended to the following states: New
Jersey, Delaware, Pennsylvania, Maryland, DC, Virginia (for all
waters), Georgia and Florida (ASMFC, 2012).
Pound nets were identified as the dominant gear type used to
harvest river herring from 1887 through 2010. Seines were more
prevalent prior to the 1960s, but by the 1980s, they were rarely used.
Purse seines were used only for herring landed in Massachusetts, but
made up a large proportion of the landings in the 1950s and 1960s.
Historically, gill nets made up a small percentage of the overall
harvest. However, even though the actual pounds landed continued to
decline, the proportion of gill nets that contributed to the overall
harvest has increased in recent years (ASMFC, 2012).
Foreign fleet landings of river herring (reported as alewife and
blueback shad) are available through the Northwest Atlantic Fisheries
Organization (NAFO). Offshore exploitation of river herring and shad
(generally <7.5 in (190 mm) in length) by foreign fleets began in the
late 1960s and landings peaked at about 80 million lbs (36,320 mt) in
1969 (ASMFC, 2012).
Total U.S. and foreign fleet harvest of river herring from the
waters off the coast of the United States (NAFO areas 5 and 6) peaked
at about 140 million lb (63,560 mt) in 1969, after which landings
declined dramatically. After 1977 and the formation of the Fishery
Conservation Zone, foreign allocation of river herring (to both foreign
vessels and joint venture vessels) between 1977 and 1980 was 1.1
million lb (499 mt). The foreign allocation was reduced to 220,000 lb
(100 mt) in 1981 because of the condition of the river herring
resource. In 1985, a bycatch cap of no more than 0.25 percent of total
catch was enacted for the foreign fishery. The cap was exceeded once in
1987, and this shut down the foreign mackerel fishery. In 1991, area
restrictions were passed to exclude foreign vessels from within 20
miles (32.2 km) of shore for two reasons: 1) In response to the
increased occurrence of river herring bycatch closer to shore and 2) to
promote increased fishing opportunities for the domestic mackerel fleet
(ASMFC, 2012).
In-river Exploitation
The stock assessment subcommittee calculated in-river exploitation
rates of the spawning runs for five rivers (Damariscotta River (ME--
alewife),
[[Page 48960]]
Union River (ME--alewife), Monument River (MA--both species combined),
Mattapoisett River (MA--alewife), and Nemasket River (MA--alewife)) by
dividing in-river harvest by total run size (escapement plus harvest)
for a given year. Exploitation rates were highest (range: 0.53 to 0.98)
in the Damariscotta River and Union River prior to 1985, while
exploitation was lowest (range: 0.26 to 0.68) in the Monument River.
Exploitation declined in all rivers through 1991 to 1992. Exploitation
rates of both species in the Monument River and of alewives in the
Mattapoisett River and Nemasket River were variable (average = 0.16)
and, except for the Nemasket River, declined generally through 2005
until the Massachusetts moratorium was imposed. Exploitation rates of
alewives in the Damariscotta River were low (<0.05) during 1993 to
2000, but they increased steadily through 2004 and remained greater
than 0.34 through 2008. Exploitation in the Damariscotta dropped to
0.15 in 2009 to 2010. Exploitation rates of alewives in the Union River
declined through 2005 but have remained above 0.50 since 2007 (ASMFC,
2012).
According to the stock assessment, exploitation of river herring
appears to be declining or remaining stable. In-river exploitation was
highest in Maine rivers (Damariscotta and Union) and has fluctuated,
but it is currently lower than levels seen in the 1980s. Also, in-river
exploitation in Massachusetts rivers (Monument and Mattapoisett) was
declining at the time a moratorium was imposed in 2005. The coast-wide
index of relative exploitation also declined following a peak in the
late 1980s and has remained fairly stable over the past decade.
Exploitation rates declined in the DB-SRA model runs except when the
input biomass-to-K ratio in 2010 was 0.01. Exploitation rates estimated
from the statistical catch-at-age model for blueback herring in the
Chowan River (see the NC state report in the stock assessment) also
showed a slight declining trend from 1999 to 2007, at which time a
moratorium was instituted. There appears to be a consensus among
various assessment methodologies that exploitation has decreased in
recent times. The stock assessment indicates that the decline in
exploitation over the past decade is not surprising because river
herring populations are at low levels and more restrictive regulations
or moratoria have been enacted by states (ASMFC, 2012).
Past high exploitation may also be a reason for the high amount of
variation and inconsistent patterns observed in fisheries-independent
indices of abundance. Fishing effort has been shown to increase
variation in fish abundance through truncation of the age structure,
and recruitment becomes primarily governed by environmental variation
(Hsieh et al., 2006; Anderson et al., 2008). When fish species are at
very low abundances, as is believed for river herring, it is possible
that the only population regulatory processes operating are stochastic
fluctuations in the environment (Shepherd and Cushing, 1990) (ASMFC,
2012).
Canadian Harvest
Fisheries in Canada for river herring are regulated through limited
seasons, gears, and licenses. Licenses may cover different gear types;
however, few new licenses have been issued since 1993 (DFO, 2001).
River-specific management plans include closures and restrictions.
River herring used locally for bait in other fisheries are not
accounted for in river-specific management plans (DFO, 2001). DFO
estimated river herring landings at just under 25.5 million lb (11,577
mt) in 1980, 23.1 million lb (10,487 mt) in 1988, and 11 million lb
(4,994 mt) in 1996 (DFO, 2001). The largest river herring fisheries in
Canadian waters occur in the Bay of Fundy, southern Gulf of Maine, New
Brunswick, and in the Saint John and Miramichi Rivers where annual
harvest estimates often exceed 2.2 million lb (1,000 mt) (DFO, 2001).
Recreational fisheries in Canada for river herring are limited by
regulations including area, gear and season closures with limits on the
number of fish that can be harvested per day; however, information on
recreational catch is limited. Licenses and reporting are not required
by Canadian regulations for recreational fisheries, and harvest is not
well documented.
Incidental Catch
The following section on river herring incidental catch in the
United States is from the stock assessment (ASMFC, 2012).
Three recent studies estimated river herring discards and
incidental catch (Cieri et al., 2008; Wigley et al., 2009; Lessard and
Bryan, 2011). The discard and incidental catch estimates from these
studies cannot be directly compared as they used different ratio
estimators based on data from the Northeast Fishery Observer Program
(NEFOP), as well as different raising factors to obtain total
estimates. Cieri et al. (2008) estimated the kept (i.e., landed)
portion of river herring incidental catch in the Atlantic herring
fishery. Cieri et al. (2008) estimated an average annual landed river
herring catch of approximately 71,290 lb (32.4 mt) in the Atlantic
herring fishery for 2005-2007, and the corresponding coefficient of
variation (CV) was 0.56. Cournane et al. (2010) extended this analysis
with additional years of data. Further work is needed to elucidate how
the landed catch of river herring in the directed Atlantic herring
fishery compares to total incidental catch across all fisheries. Since
this analysis only quantified kept river herring in the Atlantic
herring fishery, it underestimates the total catch (kept plus
discarded) of river herring across all fishing fleets. Wigley et al.
(2009) quantified river herring discards across fishing fleets that had
sufficient observer coverage from July 2007-August 2008. Wigley et al.
(2009) estimated that approximately 105,820 lb (48 mt) were discarded
during the 12 months (July 2007 to August 2008), and the estimated
precision was low (149 percent CV). This analysis estimated only river
herring discards (in contrast to total incidental catch), and noted
that midwater trawl fleets generally retained river herring while otter
trawls typically discarded river herring.
Lessard and Bryan (2011) estimated an average incidental catch of
river herring and American shad of 3.3 million lb (1,498 mt)/yr from
2000-2008. The methodology used in this study differed from the
Standardized Bycatch Reporting Methodology (SBRM) (the method used by
NOAA's Northeast Fisheries Science Center (NEFSC) to quantify bycatch
in stock assessments) (Wigley et al., 2007; Wigley et al., 2012). Data
from NEFOP were analyzed at the haul level; however, the sampling unit
for the NEFOP database is at the trip level. Within each gear and
region, all data, including those from high volume fisheries, appeared
to be aggregated across years from 2000 through 2008. However,
substantial changes in NEFOP sampling methodology for high volume
fisheries were implemented in 2005, limiting the interpretability of
estimates from these fleets in prior years. Total number of tows from
the fishing vessel trip report (VTR) database was used as the raising
factor to estimate total incidental catch. The use of effort without
standardization makes the implicit assumption that effort is constant
across all tows within a gear type, potentially resulting in a biased
effort metric. In contrast, the total kept weight of all species is
used as the raising factor in SBRM. When quantifying incidental catch
across multiple fleets, total kept weight of all species is an
appropriate surrogate for effective fishing power because it is
[[Page 48961]]
likely that all trips will not exhibit the same attributes. Lessard and
Bryan (2011) also did not provide precision estimates, which are
imperative for estimation of incidental catch.
The total incidental catch of river herring was estimated as part
of the work for Amendment 14 to the Atlantic Mackerel, Squid and
Butterfish (MSB) Fishery Management Plan, that includes measures to
address incidental catch of river herring and shads. From 2005-2010,
the total annual incidental catch of alewife ranged from 41,887 lb
(19.0 mt) to 1.04 million lb (472 mt) in New England and 19,620 lb (8.9
mt) to 564,818 lb (256.4 mt) in the Mid-Atlantic. The dominant gear
varied across years between paired midwater trawls and bottom trawls.
Corresponding estimates of precision (COV) exhibited substantial
interannual variation and ranged from 0.28 to 3.12 across gears and
regions. Total annual blueback herring incidental catch from 2005 to
2010 ranged from 30,643 lb (13.9 mt) to 389,111 lb (176.6 mt) in New
England and 2,645 lb (1.2 mt) to 843,479 lb (382.9 mt) in the Mid-
Atlantic. Across years, paired and single midwater trawls exhibited the
greatest blueback herring catches, with the exception of 2010 in the
mid-Atlantic where bottom trawl was the most dominant gear.
Corresponding estimates of precision ranged from 0.27 to 3.65. The
temporal distribution of incidental catches was summarized by quarter
and fishing region for the most recent 6-year period (2005 to 2010).
River herring catches occurred primarily in midwater trawls (76
percent, of which 56 percent were from paired midwater trawls and the
rest from single midwater trawls), followed by small mesh bottom trawls
(24 percent). Catches of river herring in gillnets were negligible.
Across gear types, catches of river herring were greater in New England
(56 percent) than in the Mid-Atlantic (44 percent). The percentages of
midwater trawl catches of river herring were similar between New
England (37 percent) and the Mid-Atlantic (38 percent). However,
catches in New England small mesh bottom trawls were three times higher
(18 percent) than those from the Mid-Atlantic (6 percent). Overall, the
highest quarterly catches of river herring occurred in midwater trawls
during Quarter 1 in the Mid-Atlantic (35 percent), followed by catches
in New England during Quarter 4 (16 percent) and Quarter 3 (11
percent). Quarterly catches in small mesh bottom trawls were highest in
New England during Quarter 1 (7 percent) and totaled 3 to 4 percent
during each of the other three quarters.
Recreational Harvest
The Marine Recreational Fishery Statistics Survey (MRFSS) provided
estimates of numbers of fish harvested and released by recreational
fisheries along the Atlantic coast. The stock assessment subcommittee
extracted state harvest and release estimates for alewives and blueback
herring from the MRFSS catch and effort estimates files available on
the web (http://www.sefsc.noaa.gov/about/mrfss.htm). Historically,
there were few reports of river herring taken by recreational anglers
for food. Most often, river herring were taken for bait. MRFSS
estimates of the numbers of river herring harvested and released by
anglers are very imprecise and show little trend. Thus, the stock
assessment concluded that these data are not useful for management
purposes. MRFSS concentrates their sampling strata in coastal water
areas and does not capture any data on recreational fisheries that
occur in inland waters. Few states conduct creel surveys or other
consistent survey instruments (diary or log books) in their inland
waters to collect data on recreational catch of river herring. Some
data are reported in the state chapters in the stock assessment; but
the stock assessment committee concluded that data are too sparse to
conduct any systematic comparison of trends (ASMFC, 2012).
Scientific Monitoring and Educational Harvest
Maine, New Hampshire, Massachusetts and Rhode Island estimate run
sizes using electronic counters or visual methods. Various counting
methods are used at the Holyoke Dam fish lift and fishways on the
Connecticut River. Young of year (YOY) surveys are conducted through
fixed seine surveys capturing YOY alewife and blueback herring
generally during the summer and fall in Maine, Rhode Island,
Connecticut, New York, New Jersey, Maryland, District of Columbia,
Virginia and North Carolina. Rhode Island conducts surveys for juvenile
and adult river herring at large fixed seine stations. Virginia samples
river herring using a multi-panel gill net survey and electroshocking
surveys. Florida conducts electroshocking surveys to sample river
herring. Maine, New Hampshire, Massachusetts, Rhode Island, Maryland,
and North Carolina collect age data from commercial and fisheries
independent sampling programs, and length-at-age data. All of these
scientific monitoring efforts are believed to have minimal impacts on
river herring populations.
Summary and Evaluation of Factor B
Historical commercial and recreational fisheries for river herring
likely contributed to the decline in abundance of both alewife and
blueback herring populations. Current directed commercial and
recreational alewife and blueback herring fisheries, as well as
commercial fishery incidental catch may continue to pose a threat to
these species. Since the 1970s, regulations have been enacted in the
United States on the directed harvest of river herring in an attempt to
halt or reverse their decline with the most recent regulations being
imposed in January 2012. Additionally, there are regulations in Canada
on river herring harvest. Historical landings data and current fishery
effort is the best available information to describe the impact that
the commercial fishery may be having on river herring.
Moratoria are in place on directed catch of these species
throughout most of the United States; however, they are taken as
incidental catch in several fisheries. The extent to which incidental
catch is affecting river herring has not been quantified and is not
fully understood. Thus, the level of threat posed by directed and
indirect catch is evaluated further in the qualitative threats
assessment as described below. Scientific collections or collections
for educational purposes do not appear to be significantly affecting
the status of river herring, as they result in low mortality.
C. Disease and Predation
Disease
Little information exists on diseases that may affect river
herring; however, there are reports of a variety of parasites that have
been found in both alewife and blueback herring. The most comprehensive
report is that of Landry et al. (1992) in which 13 species of parasites
were identified in blueback herring and 12 species in alewives from the
Miramichi River, New Brunswick, Canada. The parasites found included
one monogenetic trematode, four digenetic trematodes, one cestode,
three nematodes, one acanthocephalan, one annelid, one copepod and one
mollusk. The same species were found in both alewife and blueback
herring with the exception of the acanthocephalan, which was absent
from alewives.
In other studies, Sherburne (1977) reported piscine erythrocytic
necrosis (PEN) in the blood of 56 percent of prespawning and 10 percent
of
[[Page 48962]]
postspawning alewives in Maine coastal streams. PEN was not found in
juvenile alewives from the same locations. Coccidian parasites were
found in the livers of alewives and other finfish off the coast of Nova
Scotia (Morrison and Marryatt, 1990). Marcogliese and Compagna (1999)
reported that most fish species, including alewife, in the St. Lawrence
River become infected with trematode metacercariae during the first
years of life. Examination of Great Lakes fishes in Canadian waters
showed larval Diplostomum (trematode) commonly in the eyes of alewife
in Lake Superior (Dechtiar and Lawrie, 1988) and Lake Ontario (Dechtiar
and Christie, 1988), though intensity of infections was low (<9/host).
Heavy infections of Saprolegnia, a fresh and brackish water fungus,
were found in 25 percent of Lake Superior alewife examined, and light
infections were found in 33 percent of Lake Ontario alewife (Dechtiar
and Lawrie, 1988). Larval acanthocephala were also found in the guts of
alewife from both lakes. Saprolegnia typically is a secondary
infection, invading open sores and wounds, and eggs in poor
environmental conditions, but under the right conditions it can become
a primary pathogen. Saprolegnia infections usually are lethal to the
host.
More recently, alewives were found positive for Cryptosporidium for
the first time on record by Ziegler et al. (2007). Mycobacteria, which
can result in ulcers, emaciation, and sometimes death, have been found
in many Chesapeake Bay fish, including blueback herring (Stine et al.,
2010).
Predation
Information on predation of river herring was compiled and
published in Volume I of the River Herring Benchmark Assessment (2012)
by ASMFC. The following section on predation was compiled by Dr. Katie
Drew from this assessment.
Alewife and blueback herring are an important forage fish for
marine and anadromous predators, such as striped bass, spiny dogfish,
bluefish, Atlantic cod, and pollock (Bowman et al., 2000; Smith and
Link, 2010). Historically, river herring and striped bass landings have
tracked each other quite well, with highs in the 1960s, followed by
declines through the 1970s and 1980s. Although populations of Atlantic
cod and pollock are currently low, the populations of striped bass and
spiny dogfish have increased in recent years (since the early 1980s for
striped bass and since 2005 for spiny dogfish), while the landings and
run counts of river herring remain at historical lows. This has led to
speculation that increased predation may be contributing to the decline
of river herring and American shad (Hartman, 2003; Crecco et al., 2007;
Heimbuch, 2008). Quantifying the impacts of predation on alewife and
blueback herring is difficult. The diet of striped bass has been
studied extensively, and the prevalence of alosines varies greatly
depending on location, season, and predator size (Walter et al., 2003).
Studies from the northeast U.S. continental shelf show low rates of
consumption by striped bass (alewife and blueback herring each make up
less than 5 percent of striped bass diet by weight) (Smith and Link,
2010), while studies that sampled striped bass in rivers and estuaries
during the spring spawning runs found much higher rates of consumption
(greater than 60 percent of striped bass diet by weight in some months
and size classes) (Walter and Austin, 2003; Rudershausen et al., 2005).
Translating these snapshots of diet composition into estimates of total
removals requires additional data on both annual per capita consumption
rates and estimates of annual abundance for predator species.
The diets of other predators, including other fish (e.g., bluefish,
spiny dogfish), along with marine mammals (e.g., seals) and birds
(e.g., double-crested cormorant), have not been quantified nearly as
extensively, making it more difficult to assess the importance of river
herring in the freshwater and marine food webs. As a result, some
models predict a significant negative effect from predation (Hartman,
2003; Heimbuch, 2008), while other studies did not find an effect
(Tuomikoski et al., 2008; Dalton et al., 2009).
In addition to predators native to the Atlantic coast, river
herring are vulnerable to invasive species such as the blue catfish
(Ictalurus furcatus) and the flathead catfish (Pylodictis olivaris).
These catfish are large, opportunistic predators native to the
Mississippi River drainage that were introduced into rivers on the
Atlantic coast. They have been observed to consume a wide range of
species, including alosines, and ecological modeling on flathead
catfish suggests they may have a large impact on their prey species
(Pine, 2003; Schloesser et al., 2011). In August 2011, ASMFC approved a
resolution calling for efforts to reduce the population size and
ecological impacts of invasive species and named blue and flathead
catfish specifically, as species of concern, due to their increasing
abundance and potential impacts on native anadromous species. Non-
native species are a particular concern because of the lack of native
predators, parasites, and competitors to keep their populations in
check.
Predation and multispecies models, such as the MS-VPA (NEFSC,
2006), have tremendous data needs, and more research needs to be
conducted before they can be applied to river herring. However, given
the potential magnitude of predatory interactions, it is an area of
research worth pursuing (ASMFC, 2012).
Two papers have become available since the ASMFC (2012) stock
assessment that discuss striped bass predation on river herring in
Massachusetts and Connecticut estuaries and rivers, showing temporal
and spatial patterns in predation (Davis et al., 2012; Ferry and
Mather, 2012). Davis et al. (2012) estimated that approximately 400,000
blueback herring are consumed annually by striped bass in the
Connecticut River spring migration. In this study, striped bass were
found in the rivers during the spring spawning migrations of blueback
herring and had generally left the system by mid-June (Davis et al.,
2012). Many blueback herring in the Connecticut River are thought to be
consumed prior to ascending the river on their spawning migration, and
are, therefore, being removed from the system before spawning.
Alternatively, Ferry and Mather (2012) discuss the results of a similar
study conducted in Massachusetts watersheds with drastically different
findings for striped bass predation. Striped bass were collected and
stomach contents analyzed during three seasons from May through October
(Ferry and Mather, 2012). The stomach contents of striped bass from the
survey were examined and less than 5 percent of the clupeid category
(from 12 categories identified to summarize prey) consisted of
anadromous alosines (Ferry and Mather, 2012). Overall, the Ferry and
Mather (2012) study observed few anadromous alosines in the striped
bass stomach contents during the study period. These two recent studies
echo similar contradictory findings from previous studies showing a
wide variation in predation by striped bass with spatial and temporal
effects; however, they exhibit no consistent trends along the coast.
Summary and Evaluation for Factor C
While data are limited, the best available information indicates
that river herring are not likely affected to a large degree by
diseases caused by viruses, bacteria, protozoans, metazoans, or
microalgae. Much of the
[[Page 48963]]
information on diseases in alewife or blueback herring comes from
studies on landlocked species; therefore, even if studies indicated
that landlocked alewife and blueback herring were highly susceptible to
diseases and suffered high mortality rates, it is not known whether
anadromous river herring would be affected in the same way. While it
may be possible that disease threats to river herring could increase in
prevalence or magnitude under various climate change scenarios, there
are currently no data available to support this supposition. We have
included disease as a threat in the qualitative threats assessment
described in detail below.
Alewife and blueback herring are considered to be an important
forage fish for many marine and anadromous predators, and therefore,
may be affected by predation, especially if some populations of
predators (e.g., striped bass, spiny dogfish) continue to increase.
There may also be effects from predation by invasive species such as
the blue and flathead catfish. Some predation and multispecies models
have estimated an effect of predation on river herring, while others
have not. In general, the effect of predation on the persistence of
river herring is not fully understood; however, predation may be
affecting river herring populations and consequently, it is included as
a threat in the qualitative threats assessment described below.
D. Inadequacy of Existing Regulatory Mechanisms
As wide-ranging anadromous species, alewife and blueback herring
are subject to numerous Federal (U.S. and Canadian), state and
provincial, Tribal, and inter-jurisdictional laws, regulations, and
agency activities. These regulatory mechanisms are described in detail
in the following section.
International
The Canadian DFO manages alewife and blueback herring fisheries
that occur in the rivers of the Canadian Maritimes under the Fisheries
Act (R.S.C., 1985, c. F-14). The Maritime Provinces Fishery Regulations
includes requirements when fishing for or catching and retaining river
herring in recreational and commercial fisheries (DFO, 2006; http://laws-lois.justice.gc.ca).
Commercial and recreational river herring fisheries in the Canadian
Maritimes are regulated by license, fishing gear, season and/or other
measures (DFO, 2001). Since 1993, DFO has issued few new licenses for
river herring (DFO, 2001). River herring are harvested by various gear
types (e.g., gillnet, dip nets, trap) and the regulations depend upon
the river and associated location (DFO, 2001). The primary management
measures are weekly closed periods and limiting the number of licenses
to existing levels in all areas (DFO, 2001). Logbooks are issued to
commercial fishermen in some areas as a condition of the license, and
pilot programs are being considered in other areas (DFO, 2001). The
management objective is to maintain harvest near long-term mean levels
when no specific biological and fisheries information is available
(DFO, 2001).
DFO (2001) stated that additional management measures may be
required if increased effort occurs in response to stock conditions or
favorable markets. There has been concern as fishery exploitation rates
have been above reference levels and fewer licenses are fished than
have been issued (DFO, 2001). In 2001, DFO reported that in some rivers
river herring were being harvested at or above reference levels (e.g.,
Miramichi), while in other rivers river herring were harvested at or
below the reference point (e.g., St. John River at Mactaquac Dam). DFO
(2001) believes precautionary management involving no increase or
decrease in exploitation is important for Maritime river herring
fisheries, given that biological and harvest data are not widely
available. Additionally, DFO (2001) added that river-specific
management plans based on stock assessments should be prioritized over
general management initiatives.
Eastern New Brunswick is currently the only area in the Canadian
Maritimes with a river herring integrated fishery management plan (DFO,
2006). The DFO uses Integrated Fisheries Management Plans (IFMPs) to
guide the conservation and sustainable use of marine resources (DFO,
2010). An IFMP manages a fishery in a given region by combining the
best available science on the species with industry data on capacity
and methods for harvesting (DFO, 2010). The 6-year management plan
(2007-2012) for river herring for Eastern New Brunswick is implemented
in conjunction with annual updates to specific fishery management
measures (e.g., seasons). For example, it notes a management problem of
gear congestion in some rivers and an approach to establish a carrying
capacity of the river and find a solution to the gear limit by working
with fishermen (DFO, 2006). At this time, an updated Eastern New
Brunswick IFMP is not available.
Federal
ASMFC and Enabling Legislation
Authorized under the terms of the Atlantic States Marine Fisheries
Compact, as amended (Pub. L. 81-721), the purpose of the ASMFC is to
promote the better utilization of the fisheries (marine, shell, and
anadromous) of the Atlantic seaboard ``by the development of a joint
program for the promotion and protection of such fisheries, and by the
prevention of the physical waste of the fisheries from any cause.''
Given management authority in 1993 under the Atlantic Coastal
Fisheries Cooperative Management Act (16 U.S.C. 5101-5108), the ASMFC
may issue interstate FMPs that must be administered by state agencies.
If the ASMFC believes that a state is not in compliance with a coastal
FMP, it must notify the Secretaries of Commerce and Interior. If the
Secretaries find the state not in compliance with the management plan,
the Secretaries must declare a moratorium on the fishery in question.
Atlantic Coastal Fisheries Cooperative Management Act
We manage river herring stocks under the authority of section
803(b) of the Atlantic Coastal Fisheries Cooperative Management Act
(Atlantic Coastal Act) 16 U.S.C. 5101 et seq., which states, in the
absence of an approved and implemented FMP under the Magnuson-Stevens
Act (MSA, 16 U.S.C. 1801 et seq.) and, after consultation with the
appropriate Fishery Management Council(s), the Secretary of Commerce
may implement regulations to govern fishing in the Exclusive Economic
Zone (EEZ), i.e., from 3 to 200 nautical mi (nm) offshore. The
regulations must be: (1) Compatible with the effective implementation
of an Interstate Fishery Management Plan for American Shad and River
Herring (ISFMP) developed by the ASMFC; and (2) consistent with the
national standards set forth in section 301 of the MSA.
The ASMFC adopted Amendment 2 to the ISFMP in 2009. Amendment 2
establishes the foundation for river herring management. It was
developed to address concerns that many Atlantic coast populations of
river herring were in decline or are at depressed but stable levels,
and that the ability to accurately assess the status of river herring
stocks is complicated by a lack of fishery independent data.
Amendment 2 requires states to close their waters to recreational
and commercial river herring harvest, unless they have an approved
sustainable management plan in place. To be approved, a state's plan
must clearly
[[Page 48964]]
meet the Amendment's standard of a sustainable fishery defined as ``a
commercial and/or recreational fishery that will not diminish the
potential future stock reproduction and recruitment.'' The plans must
meet the definition of sustainability by developing and maintaining
sustainability targets. States without an approved plan were required
to close their respective river herring fisheries as of January 1,
2012, until such a plan is submitted and approved by the ASMFC's Shad
and River Herring Management Board. Proposals to re-open closed
fisheries may be submitted annually as part of a state's annual
compliance report. Currently, the states of ME, NH, RI, NY, NC, and SC
have approved river herring management plans (see ``State section of
Factor D'' for more information).
In addition to the state sustainability plan mandate, Amendment 2
makes recommendations to states for the conservation, restoration, and
protection of critical river herring habitat. The Amendment also
requires states to implement fisheries-dependent and independent
monitoring programs, to provide critical data for use in future river
herring stock assessments.
While these measures address problems to the river herring
populations in coastal areas, incidental catch in small mesh fisheries,
such as those for sea herring, occurs outside state jurisdiction and
remains a substantial source of fishing mortality according to the
ASMFC. Consequently, the ASMFC has requested that the New England and
Mid-Atlantic Fishery Management Councils (NEFMC and MAFMC) increase
efforts to monitor river herring incidental catch in small-mesh
fisheries (See section on ``NEFMC and MAFMC recommendations for future
river herring bycatch reduction efforts'').
Magnuson-Stevens Fishery Conservation and Management Act (MSA)
The Magnuson-Stevens Fishery Conservation and Management Act (MSA)
is the primary law governing marine fisheries management in Federal
waters. The MSA was first enacted in 1976 and amended in 1996 and 2006.
Most notably, the MSA aided in the development of the domestic fishing
industry by phasing out foreign fishing. To manage the fisheries and
promote conservation, the MSA created eight regional fishery management
councils. A 1996 amendment focused on rebuilding overfished fisheries,
protecting Essential Fish Habitat (EFH), and reducing bycatch. A 2006
amendment mandated the use of Annual Catch Limits (ACL) and
Accountability Measures (AM) to end overfishing, provided for
widespread market-based fishery management through limited access
privilege programs, and called for increased international cooperation.
The MSA requires that Federal FMPs contain conservation and
management measures that are consistent with the ten National
Standards. National Standard 9 states that conservation and
management measures shall, to the extent practicable, (A) minimize
bycatch and (B) to the extent bycatch cannot be avoided, minimize the
mortality of such bycatch. The MSA defines bycatch as fish that are
harvested in a fishery, but which are not sold or kept for personal
use. This includes economic discards and regulatory discards. River
herring is encountered both as bycatch and incidental catch in Federal
fisheries. While there is no directed fishery for river herring in
Federal waters, river herring co-occur with other species that have
directed fisheries (Atlantic mackerel, Atlantic herring, whiting, squid
and butterfish) and are either discarded or retained in those
fisheries.
Essential Fish Habitat Under the MSA
Under the MSA, there is a requirement to describe and identify EFH
in each Federal FMP. EFH is defined as ``. . . those waters and
substrate necessary to fish for spawning, breeding, feeding, or growth
to maturity.'' The rules promulgated by the NMFS in 1997 and 2002
further clarify EFH with the following definitions: (1) Waters--aquatic
areas and their associated physical, chemical, and biological
properties that are used by fish and may include aquatic areas
historically used by fish where appropriate; (2) substrate--sediment,
hard bottom, structures underlying the waters, and associated
biological communities; (3) necessary--the habitat required to support
a sustainable fishery and the managed species' contribution to a
healthy ecosystem; and (4) spawning, breeding, feeding, or growth to
maturity--stages representing a species' full life cycle.
EFH has not been designated for alewife or blueback herring, though
EFH has been designated for numerous other species in the Northwest
Atlantic. Measures to improve habitats and reduce impacts resulting
from those EFH designations may directly or indirectly benefit river
herring. Conservation measures implemented in response to the
designation of Atlantic salmon EFH and Atlantic herring EFH likely
provide the most conservation benefit to river herring over any other
EFH designation. Habitat features used for spawning, breeding, feeding,
growth and maturity by these two species encompasses many of the
habitat features selected by river herring to carry out their life
history. The geographic range in which river herring may benefit from
the designation of Atlantic salmon EFH extends from Connecticut to the
Maine/Canada border. The geographic range in which river herring may
benefit from the designation of Atlantic herring EFH designation
extends from the Maine/Canada border to Cape Hatteras.
The Atlantic salmon EFH includes most freshwater, estuary and bay
habitats historically accessible to Atlantic salmon from Connecticut to
the Maine/Canada border (NEFMC, 2006). Many of the estuary, bay and
freshwater habitats within the current and historical range of Atlantic
salmon incorporate habitats used by river herring for spawning,
migration and juvenile rearing. Among Atlantic herring EFHs are the
pelagic waters in the Gulf of Maine, Georges Bank, Southern New
England, and middle Atlantic south to Cape Hatteras out to the offshore
U.S. boundary of the EEZ (see NEFMC 1998). These areas incorporate
nearly all of the U.S. marine areas most frequently used by river
herring for growth and maturity. Subsequently, in areas where EFH
designations for Atlantic salmon and Atlantic herring overlap with
freshwater and marine habitats used by river herring, conservation
benefits afforded through the designation of EFH for these species may
provide similar benefits to river herring.
Federal Power Act (FPA) (16 U.S.C. 791-828) and Amendments
The FPA, as amended, provides for protecting, mitigating damages
to, and enhancing fish and wildlife resources (including anadromous
fish) impacted by hydroelectric facilities regulated by the Federal
Energy and Regulatory Commission (FERC). Applicants must consult with
state and Federal resource agencies who review proposed hydroelectric
projects and make recommendations to FERC concerning fish and wildlife
and their habitat, e.g., including spawning habitat, wetlands, instream
flows (timing, quality, quantity), reservoir establishment and
regulation, project construction and operation, fish entrainment and
mortality, and recreational access. Section 10(j) of the FPA provides
that licenses issued by FERC contain conditions to protect, mitigate
damages to, and enhance fish and wildlife based
[[Page 48965]]
on recommendations received from state and Federal agencies during the
licensing process. With regard to fish passage, Section 18 requires a
FERC licensee to construct, maintain, and operate fishways prescribed
by the Secretary of the Interior or the Secretary of Commerce. Under
the FPA, others may review proposed projects and make timely
recommendations to FERC to represent additional interests. Interested
parties may intervene in the FERC proceeding for any project to receive
pertinent documentation and to appeal an adverse decision by FERC.
While the construction of hydroelectric dams contributed to some
historical losses of river herring spawning habitat, only a few new
dams have been constructed in the range of these species in the last 50
years. In some areas, successful fish passage has been created; thus,
restoring access to many habitats once blocked. Thus, river herring may
often benefit from FPA fishway requirements when prescriptions are made
to address anadromous fish passage and during the re-licensing of
existing hydroelectric dams when anadromous species are considered.
Anadromous Fish Conservation Act (16 U.S.C. 757a-757f) as Amended
This law authorizes the Secretaries of Interior and Commerce to
enter into cost sharing with states and other non-Federal interests for
the conservation, development, and enhancement of the nation's
anadromous fish. Investigations, engineering, biological surveys, and
research, as well as the construction, maintenance, and operations of
hatcheries, are authorized. This Act was last authorized in 2002, which
provided 5 million dollars for the fiscal years 2005 and 2006 (Pub. L.
107-372). There was an attempt to reauthorize the Act in 2012; however,
this action has not yet been authorized.
Fish and Wildlife Coordination Act (FWCA) (16 U.S.C. 661-666)
The FWCA is the primary law providing for consideration of fish and
wildlife habitat values in conjunction with Federal water development
activities. Under this law, the Secretaries of Interior and Commerce
may investigate and advise on the effects of Federal water development
projects on fish and wildlife habitat. Such reports and
recommendations, which require concurrence of the state fish and
wildlife agency(ies) involved, must accompany the construction agency's
request for congressional authorization, although the construction
agency is not bound by the recommendations.
The FWCA applies to water-related activities proposed by non-
Federal entities for which a Federal permit or license is required. The
most significant permits or licenses required are Section 404 and
discharge permits under the Clean Water Act and Section 10 permits
under the Rivers and Harbors Act. The USFWS and NMFS may review the
proposed permit action and make recommendations to the permitting
agencies to avoid or mitigate any potential adverse effects on fish and
wildlife habitat. These recommendations must be given full
consideration by the permitting agency, but are not binding.
Federal Water Pollution Control Act, and amendments (FWPCA) (33 U.S.C.
1251-1376)
Also called the ``Clean Water Act,'' the FWPCA mandates Federal
protection of water quality. The law also provides for assessment of
injury, destruction, or loss of natural resources caused by discharge
of pollutants.
Of major significance is Section 404 of the FWPCA, which prohibits
the discharge of dredged or fill material into navigable waters without
a permit. Navigable waters are defined under the FWPCA to include all
waters of the United States, including the territorial seas and
wetlands adjacent to such waters. The permit program is administered by
the Army Corps of Engineers (ACOE). The Environmental Protection Agency
(EPA) may approve delegation of Section 404 permit authority for
certain waters (not including traditional navigable waters) to a state
agency; however, the EPA retains the authority to prohibit or deny a
proposed discharge under Section 404 of the FWPCA.
The FWPCA (Section 401) also authorizes programs to remove or limit
the entry of various types of pollutants into the nation's waters. A
point source permit system was established by the EPA and is now being
administered at the state level in most states. This system, referred
to as the National Pollutant Discharge Elimination System (NPDES), sets
specific limits on discharge of various types of pollutants from point
source outfalls. A non-point source control program focuses primarily
on the reduction of agricultural siltation and chemical pollution
resulting from rain runoff into the nation's streams. This effort
currently relies on the use of land management practices to reduce
surface runoff through programs administered primarily by the
Department of Agriculture.
Like the Fish and Wildlife Coordination and River and Harbors Acts,
Sections 401 and 404 of the FWPCA have played a role in reducing
discharges of pollutants, restricting the timing and location of dredge
and fill operations, and affecting other changes that have improved
river herring habitat in many rivers and estuaries over the last
several decades. Examples include reductions in sewage discharges into
the Hudson River (A. Kahnle, New York State DEC, Pers. comm. 1998) and
nutrient reduction strategies implemented in the Chesapeake Bay (R. St.
Pierre, USFWS, Pers. comm. 1998).
Rivers and Harbors Act of 1899
Section 10 of the Rivers and Harbors Act requires a permit from the
ACOE to place structures in navigable waters of the United States or
modify a navigable stream by excavation or filling activities.
National Environmental Policy Act of 1969 (NEPA) (42 U.S.C. 4321-4347)
The NEPA requires an environmental review process of all Federal
actions. This includes preparation of an environmental impact statement
for major Federal actions that may affect the quality of the human
environment. Less rigorous environmental assessments are reviewed for
most other actions, while some actions are categorically excluded from
formal review. These reviews provide an opportunity for the agency and
the public to comment on projects that may impact fish and wildlife
habitat.
Coastal Zone Management Act (16 U.S.C. 1451-1464) and Estuarine Areas
Act
Congress passed policy on values of estuaries and coastal areas
through these Acts. Comprehensive planning programs, to be carried out
at the state level, were established to enhance, protect, and utilize
coastal resources. Federal activities must comply with the individual
state programs. Habitat may be protected by planning and regulating
development that could cause damage to sensitive coastal habitats.
Federal Land Management and Other Protective Designations
Protection and good stewardship of lands and waters managed by
Federal agencies, such as the Departments of Defense, Energy and
Interior (National Parks and National Wildlife Refuges, as well as
state-protected park, wildlife and other natural areas), contributes to
the health of nearby aquatic systems that support important river
herring
[[Page 48966]]
spawning and nursery habitats. Relevant examples include the Great Bay,
Rachel Carson's and ACE Basin National Estuarine Research Reserves,
Department of Defense properties in the Chesapeake Bay, and many
National Wildlife Refuges.
Marine Protection, Research and Sanctuaries Act of 1972 (MPRSA), Titles
I and III and the Shore Protection Act of 1988 (SPA)
The MPRSA protects fish habitat through establishment and
maintenance of marine sanctuaries. The MPRSA and the SPA regulate ocean
transportation and dumping of dredge materials, sewage sludge, and
other materials. Criteria that the ACOE uses for issuing permits
include considering the effects dumping has on the marine environment,
ecological systems and fisheries resources.
Atlantic Salmon ESA Listing and Critical Habitat Designation
In 2009, the Gulf of Maine (GOM) DPS of Atlantic salmon was listed
as endangered under the Endangered Species Act (74 FR 29344). The GOM
DPS includes all anadromous Atlantic salmon whose freshwater range
occurs in the watersheds from the Androscoggin River northward along
the Maine coast to the Dennys River. Concurrently in 2009, critical
habitat was designated for the Atlantic salmon GOM DPS pursuant to
section 4(b)(2) of the ESA (74 FR 29300; August 10, 2009). The critical
habitat designation includes 45 specific areas occupied by Atlantic
salmon at the time of listing, and includes approximately 12,160 miles
(19,600 km) of perennial river, stream, and estuary habitat and 308
square miles (495 sq km) of lake habitat within the range of the GOM
DPS in the State of Maine.
Measures to improve habitats and reduce impacts to Atlantic salmon
as a result of the ESA listing may directly or indirectly benefit river
herring. Atlantic salmon are anadromous and spend a portion of their
life in freshwater and the remaining portion in the marine environment.
River herring occupy a lot of the same habitats as listed Atlantic
salmon for spawning, breeding, feeding, growth and maturity. Therefore,
protection measures such as improved fish passage or reduced discharge
permits may benefit river herring.
The critical habitat designation provides additional protections
beyond classifying a species as endangered by preserving the physical
and biological features essential for the conservation of the species
in designated waters in Maine. One of the biological features
identified in the critical habitat designation for Atlantic salmon was
freshwater and estuary migration sites with abundant, diverse native
fish communities to serve as a protective buffer against predation. Co-
evolved diadromous fish species such as alewives and blueback herring
are included in this native fish community. Because the ESA also
requires that any Federal agency that funds, authorizes, or carries out
an action ensure that the action does not adversely modify or destroy
designated critical habitat, the impacts to alewife and blueback
herring populations must be considered during consultation with NMFS to
ensure that Atlantic salmon critical habitat is not adversely affected
by a Federal action.
Atlantic Sturgeon ESA Listing
In 2012, five distinct population segments of Atlantic sturgeon
were listed under the ESA (77 FR 5914; 77 FR 5880). The Chesapeake Bay,
New York Bight, Carolina, and South Atlantic DPSs of Atlantic sturgeon
are listed as endangered, while the Gulf of Maine DPS is listed as
threatened.
Measures to improve habitats and reduce impacts to Atlantic
sturgeon may directly or indirectly benefit river herring. Atlantic
sturgeon are anadromous; adults spawn in freshwater in the spring and
early summer and migrate into estuarine and marine waters where they
spend most of their lives. As with Atlantic salmon, many of the
habitats that Atlantic sturgeon occupy are also habitats that river
herring use for spawning, migration and juvenile rearing. The
geographic range in which river herring may benefit from Atlantic
sturgeon ESA protections extends from the Maine/Canada border to
Florida. Therefore, any protection measures within this range such as
improved fish passage or a reduction of water withdrawals may also
provide a benefit to river herring.
State Regulations
A historical review of state regulations was compiled and published
in Volume I of the stock assessment. The following section on state
regulations includes current requirements only and is cited from Volume
I of the assessment as compiled by Dr. Gary Nelson and Kate Taylor
(ASMFC, 2012). Otherwise, updates are provided by Kate Taylor,
supplemental information from state river herring plans or state
regulations.
Maine
In Maine, the Department of Marine Resources (DMR), along with
municipalities granted the rights to harvest river herring resources,
cooperatively manage municipal fisheries. Each town must submit an
annual harvesting plan to DMR for approval that includes a 3-day per
week escapement period or biological equivalent to ensure conservation
of the resource. In some instances, an escapement number is calculated
and the harvester passes a specific number upstream to meet escapement
goals. River herring runs not controlled by a municipality and not
approved as sustainable by the ASMFC River Herring and American Shad
Management Board, as required under Amendment 2, are closed. Each run
and harvest location is unique, either in seasonality, fish
composition, or harvesting limitations. Some runs have specific
management plans that require continuous escapement and are more
restrictive than the 3-day closed period. Others have closed periods
shorter than the 3-day requirement, but require an escapement number,
irrespective of the number harvested during the season. Maine increased
the weekly fishing closure from a 24-hour closure in the 1960s to a 48-
hour closure beginning in 1988. The closed period increased to 72 hours
beginning in 1995 to protect spawning fish. Most towns operate a weir
at one location on each stream and prohibit fishing at any other
location on the stream. The state landings program compiles in-river
landings of river herring from mandatory reports provided by the
municipality under each municipal harvest plan or they lose exclusive
fishing rights. The state permitted 22 municipalities to fish for river
herring in 2011. The river specific management plans require the
remaining municipalities to close their runs for conservation and not
harvest. There are several reasons for these state/municipal imposed
restrictions on the fishery. Many municipalities voluntarily restrict
harvest to increase the numbers of fish that return in subsequent
years. Some of these runs are large but have the potential to become
even larger. The commercial fishery does not exploit the estimated 1.5
to 2.0 million river herring that return to the East Machias River
annually. These regulations have been approved through a sustainable
fisheries management plan, as required under ASMFC Amendment 2 to the
Shad and River Herring FMP (Taylor, Pers. Comm., 2013).
Recreational fishermen are allowed to fish for river herring year-
round. The limit is 25 fish per day and gear is restricted to dip net
and hook-and-line. Recreational fishermen may not fish in waters, or in
waters upstream, of a
[[Page 48967]]
municipality that owns fishing rights. Recreational fishermen are not
required to report their catch. The MRFSS and MRIP programs do sample
some of these fishermen based on results queried from the database.
Recreational fishing for river herring in Maine is limited and landings
are low. These regulations have been approved through a sustainable
fisheries management plan, as required under ASMFC Amendment 2 to the
Shad and River Herring FMP (Taylor, Pers. Comm., 2013).
New Hampshire
The current general regulations are: (1) No person shall take river
herring, alewives and blueback herring, from the waters of the state,
by any method, between sunrise Wednesday and sunrise Thursday of any
week; (2) any trap or weir used during a specified time period, shall
be constructed so as to allow total escapement of all river herring;
and (3) any river herring taken by any method during the specified time
period shall be immediately released back into the waters from which it
was taken. Specific river regulations are: Taylor River--from the
railroad bridge to the head of tide dam in Hampton shall be closed to
the taking of river herring by netting of any method; and Squamscott
River--during April, May and June, the taking of river herring in the
Squamscott River and its tributaries from the Rt. 108 Bridge to the
Great Dam in Exeter is open to the taking of river herring by netting
of any method only on Saturdays and Mondays, the daily limit shall be
one tote per person (``tote'' means a fish box or container measuring
31.5 in (80.01cm) x 18 in (45.72 cm) x 11.5 in (29.21cm)) and the tote
shall have the harvester's coastal harvest permit number plainly
visible on the outside of the tote. These regulations have been
approved through a sustainable fisheries management plan, as required
under ASMFC Amendment 2 to the Shad and River Herring FMP.
Massachusetts
As of January 1, 2012, commercial and recreational harvest of river
herring was prohibited in Massachusetts, as required by ASMFC Amendment
2 to the Shad and River Herring FMP (Taylor, Pers. Comm., 2013). The
exception is for federally permitted vessels which are allowed to land
up to 5 percent of total bait fish per trip (Taylor, Pers. Comm.,
2013).
Rhode Island
The Rhode Island Division of Fish and Wildlife (RIDFW) will
implement a 5 percent bycatch allowance for Federal vessels fishing in
the Atlantic herring fishery in Federal waters. RIDFW will also
implement a mandatory permitting process that will require vessels
wanting to fish in the Rhode Island waters Atlantic herring fishery to,
amongst other requirements, integrate in to the University of
Massachusetts Dartmouth, School for Marine Science and Technology,
river herring bycatch monitoring program to ensure monitoring of the
fishery and minimize bycatch. As of Jan 1, 2013, there is a prohibition
to land, catch, take, or attempt to catch or take river herring which
is a continuation of measures that RIDFW has had in place since 2006
when a moratorium was originally established (Taylor, Pers. comm.,
2013).
Connecticut
Since April 2002, there has been a prohibition on the commercial or
recreational taking of migratory alewives and blueback herring from all
marine waters and most inland waters. As of January 1, 2012, commercial
and recreational harvest of river herring was prohibited in
Connecticut, as required by ASMFC Amendment 2 to the Shad and River
Herring FMP (Taylor, Pers. Comm., 2013).
New York
Current regulations allow for a restricted river herring commercial
and recreational fishery in the Hudson River and tributaries, while all
other state waters prohibit river herring fisheries. These regulations
have been approved through a sustainable fisheries management plan, as
required under ASMFC Amendment 2 to the Shad and River Herring FMP.
New Jersey/Delaware
As of January 1, 2012, commercial harvest of river herring was
prohibited in New Jersey and Delaware, as required by ASMFC Amendment 2
to the Shad and River Herring FMP. Additionally, only commercial
vessels fishing exclusively in Federal waters while operating with a
valid Federal permit for Atlantic mackerel and/or Atlantic herring may
possess river herring up to a maximum of five percent by weight of all
species possessed (Taylor, Pers. Comm.).
Maryland
As of January 1, 2012, commercial harvest of river herring was
prohibited in Maryland, as required by ASMFC Amendment 2 to the Shad
and River Herring FMP. However, an exception is provided for anyone in
possession of river herring as bait, as long as a receipt indicating
where the herring was purchased is in hand (Taylor, Pers. comm). This
will allow bait shops to sell, and fishermen to possess, river herring
for bait that was harvested from a state whose fishery remains open, as
an ASMFC approved sustainable fishery (Taylor, Pers. Comm).
Potomac River Fisheries Commission (PRFC)/District of Columbia
The PRFC regulates only the mainstem of the river, while the
tributaries on either side are under Maryland and Virginia
jurisdiction. The District of Columbia's Department of the Environment
(DDOE) has authority for the Potomac River to the Virginia shore and
other waters within District of Columbia. Today, the river herring
harvest in the Potomac is almost exclusively taken by pound nets. In
1964, licenses were required to commercially harvest fish in the
Potomac River. After Maryland and Virginia established limited entry
fisheries in the 1990s, the PRFC responded to industry's request and,
in 1995, capped the Potomac River pound net fishery at 100 licenses. As
of January 1, 2010, harvest of river herring was prohibited in the
Potomac River, with a minimal bycatch provision of 50 lb (22 kg) per
licensee per day for pound nets. These regulations have been approved
through a sustainable fisheries management plan, as required under
ASMFC Amendment 2 to the Shad and River Herring FMP.
Virginia
Virginia's Department of Game and Inland Fisheries (VDGIF) is
responsible for the management of fishery resources in the state's
inland waters. As of January 1, 2008, possession of alewives and
blueback herring was prohibited on rivers draining into North Carolina
(4 VAC 15-320-25). The Virginia Marine Resources Commission (VMRC) is
responsible for management of fishery resources within the state's
marine waters. As of January 1, 2012, commercial and recreational
harvest of river herring was prohibited in all waters of Virginia, as
required by ASMFC Amendment 2 to the Shad and River Herring FMP.
Additionally, it is unlawful for any person to possess river herring
aboard a vessel on Virginia tidal waters, or to land any river herring
in Virginia (4 VAC 20-1260-30).
North Carolina
A no harvest provision for river herring, commercial and
recreational, within North Carolina was approved in 2007. A limited
research set aside of 7,500 lb (3.4 mt) was established, and to
implement this harvest, a Discretionary Herring Fishing Permit (DHFP)
was
[[Page 48968]]
created. Individuals interested in participating had to meet the
following requirements: (1) Obtain a DHFP, (2) harvest only from the
Joint Fishing Waters of Chowan River during the harvest period, (3)
must hold a valid North Carolina Standard Commercial Fishing License
(SCFL) or a Retired SCFL, and (4) participate in statistical
information and data collection programs. Sale of harvested river
herring had to be to a licensed and permitted River Herring Dealer.
Each permit holder was allocated 125-250 lb (56-113 kg) for the 4-day
season during Easter weekend. These regulations were approved through a
sustainable fisheries management plan, as required under ASMFC
Amendment 2 to the Shad and River Herring FMP. The North Carolina
Wildlife Resources Commission (NCWRC) has authority over the Inland
Waters of the state. Since July 1, 2006, harvest of river herring,
greater than 6 inches (15.24 cm) has been prohibited in the inland
waters of North Carolina's coastal systems.
South Carolina
In South Carolina, the South Carolina Division of Natural Resources
(SCDNR) manages commercial herring fisheries using a combination of
seasons, gear restrictions, and catch limits. Today, the commercial
fishery for blueback herring has a 10-bushel daily limit (500 lb (226
kg)) per boat in the Cooper and Santee Rivers and the Santee-Cooper
Rediversion Canal and a 250-lb-per-boat (113 kg) limit in the Santee-
Cooper lakes. Seasons generally span the spawning season. All licensed
fishermen have been required to report their daily catch and effort to
the SCDNR since 1998.
The recreational fishery has a 1-bushel (49 lb (22.7 kg)) fish
aggregate daily creel for blueback herring in all rivers; however, very
few recreational anglers target blueback herring. These regulations
have been approved through a sustainable fisheries management plan, as
required under ASMFC Amendment 2 to the Shad and River Herring FMP.
Georgia
The take of blueback herring is illegal in freshwater in Georgia.
As of January 1, 2012, harvest of river herring was prohibited in
Georgia, as required by ASMFC Amendment 2 to the Shad and River Herring
FMP.
Florida
The St. Johns River, Florida, harbors the southernmost spawning run
of blueback herring. There is currently no active management of
blueback herring in Florida. As of January 1, 2012, harvest of river
herring was prohibited, as required by ASMFC Amendment 2 to the Shad
and River Herring FMP.
Tribal and First Nation Fisheries
We have identified thirteen federally recognized East Coast tribes
from Maine to South Carolina that have tribal rights to sustenance and
ceremonial fishing, and which may harvest river herring for sustenance
and ceremonial purposes and/or engage in other river herring
conservation and management activities. The Mashpee Wampanoag tribe is
the only East Coast tribe that voluntarily reported harvest numbers to
the State of MA that were incorporated into the ASMFC Management Plan
as subsistence harvest. The reported harvest for 2006 and 2008 ranged
between 1,200 and 3,500 fish per year, with removals coming from
several rivers. Aside from the harvest reported by ASMFC for the
Mashpee Wampanoag tribe, information as to what tribes may harvest
river herring for sustenance and/or ceremonial purposes is not
available. Letters have been sent to all 13 potentially affected tribes
to solicit any input they may have on the conservation status of the
species and/or health of particular riverine populations, tribal
conservation and management activities for river herring, biological
data for either species, and comments and/or concerns regarding the
status review process and potential implications for tribal trust
resources and activities. To date, we have not received any information
from any tribes.
Summary and Evaluation for Factor D
As described in Factor A, there are multiple threats to habitat
that have affected and may continue to affect river herring including
dams/culverts, dredging, water quality, water withdrawals and
discharge. However, many of these threats are being addressed to some
degree through existing Federal legislation such as the Federal Water
Pollution Control Act, also known as the Clean Water Act, the Coastal
Zone Management Act, the Rivers and Harbors Act, the FPA, Marine
Protection, Research and Sanctuaries Act of 1972, the Shore Protection
Act of 1988, EFH designations for other species and ESA listings for
Atlantic salmon and Atlantic sturgeon.
Commercial harvest of alewife and blueback herring is occurring in
Canada with regulations, closures, and quotas in effect. In the United
States, commercial harvest of alewife and blueback herring is also
currently occurring in a few states with regulations that have been
approved through a sustainable fisheries management plan, as required
under ASMFC Amendment 2 to the Shad and River Herring FMP. All other
states had previously established moratoria or, as of January 1, 2012,
harvest of river herring was prohibited, as required by ASMFC Amendment
2 to the Shad and River Herring FMP. However, river herring are
incidentally caught in several commercial fisheries, but the extent to
which this is occurring has not been fully quantified. The New England
and Mid-Atlantic Fishery Management Councils have adopted measures for
the Atlantic herring and mackerel fisheries intended to decrease
incidental catch and bycatch of alewife and blueback herring. In the
United States, thirteen federally recognized East Coast tribes from
Maine to South Carolina have tribal rights to sustenance and ceremonial
fishing, and may harvest river herring for sustenance and ceremonial
purposes and/or engage in other river herring conservation and
management activities. We have further evaluated the existing
international, Federal, and state management measures in the
qualitative threats assessment section below.
E. Other Natural or Manmade Factors Affecting the Continued Existence
of the Species
Competition
Intra- and inter-specific competition were considered as potential
natural threats to alewife and blueback herring. The earlier spawning
time of alewife may lead to differences in prey selection from blueback
herring, given that they become more omnivorous with increasing size
(Klauda et al., 1991a). This could lead to differences in prey
selection given that juvenile alewife would achieve a greater age and
size earlier than blueback herring. Juvenile American shad are reported
to focus on different prey than blueback herring (Klauda et al.,
1991b). However, Smith and Link (2010) found few differences between
American shad and blueback herring diets across geographic areas and
size categories; therefore, competition between these two species may
be occurring. Cannibalism has been observed (rarely) in landlocked
systems with alewife. Additionally, evidence of hybridization exists
between alewife and blueback herring, but the implications of this are
unknown. Competition for habitat or resources has not been documented
with alewife/blueback herring hybrids, as there is little documentation
of hybridization in published literature, but given the
[[Page 48969]]
unknowns about their life history, it is possible that competition
between non-hybrids and hybrids could be occurring.
Artificial Propagation and Stocking
Genetics data have shown that stocking alewife and blueback herring
within and out of basin in Maine has had an impact on the genetic
groupings within Maine (Bentzen, 2012, unpublished data); however, the
extent to which this poses a threat to river herring locally or coast-
wide is unknown. Stocking river herring directly impacts a specific
river/watershed system for river herring in that it can result in
passing fish above barriers into suitable spawning and rearing habitat,
expanding populations into other watersheds, and introducing fish to
newly accessible spawning habitat.
The alewife restoration program in Merrymeeting Bay, Maine, focuses
on stocking lakes and ponds in the Sebasticook River watershed and
Seven Mile Stream drainage. The highest number of stocked fish was
2,211,658 in 2009 in the Sebasticook River and 93,775 in 2008 in the
Kennebec River. The annual stocking goal of the restoration projects
range from 120,000 to 500,000 fish, with most fish stocked in the
Androscoggin and Sebasticook watersheds. The Union River fishery in
Ellsworth, Maine, is sustained through the stocking of adult alewives
above the hydropower dam at the head-of-tide. Fish passage is not
currently required at this dam, but fish are transported around the dam
to spawning habitat in two lakes. The annual adult stocking rate (from
2011 forward) is 150,000 fish. Adult river herring are trapped at a
commercial harvest sites below the dam and trucked to waters upstream
of the dam. The highest number of stocked fish in the Union River was
1,238,790 in 1986. In the Penobscot River watershed, over 48,000 adult
fish were stocked into lakes in 2012, using fish collected from the
Kennebec (39,650) and Union Rivers (8,998). The New Hampshire Fish and
Game stocks river herring into the Nashua River, the Pine Island Pond,
and the Winnisquam Lake using fish from various rivers which have
included the Connecticut, Cocheco, Lamprey, Kennebec, and Androscoggin
Rivers. MA Division of Marine Fisheries (DMF) conducts a trap and
transport stocking program for alewife and blueback herring. Prior to
the moratorium in the state, the program transported between 30,000 and
50,000 fish per year into 10-15 different systems. Since the
moratorium, effort has been reduced to protect donor populations and
approximately 20,000 fish per year have been deposited into five to ten
systems. Many of the recent efforts have been within system, moving
fish upstream past multiple obstructions to the headwater spawning
habitat. Rhode Island's Department of Environmental Management (DEM)
has been stocking the Blackstone River with adult broodstock which was
acquired from existing Rhode Island river herring runs and other
sources out of state. In April 2012, over 2,000 river herring pre-
spawned adults were stocked into the Blackstone River. A small number
of alewife (200-400 fish) were stocked in the Bronx River, NY, in 2006
and 2007 from Brides Brook in East Lyme, CT. Furthermore, an
experimental stocking program exists in Virginia where hatchery
broodstock are marked and stocked into the Kimages Creek, a tributary
to the James River. A total of 319,856 marked river herring fry were
stocked in this creek in 2011.
The Edenton National Fish Hatchery (NFH) in North Carolina and the
Harrison Lake NFH in Virginia have propagated blueback herring for
restoration purposes. Edenton NFH is currently rearing blueback herring
for stocking in Indian Creek and Bennett's Creek in the Chowan River
watershed in Virginia. This is a pilot project to see if hatchery
contribution makes a significant improvement in runs of returning
adults (S. Jackson, USFWS, Pers. comm., 2012). Artificial propagation
through the Edenton NFH for the pilot program in the Chowan River
watershed is intended for restoration purposes, and it is not thought
that negative impacts to anadromous blueback herring populations will
be associated with these efforts.
Landlocked Alewife and Blueback Herring
As noted above, alewives and blueback herring maintain two life
history variants; anadromous and landlocked. It is believed that they
diverged relatively recently (300 to 5,000 years ago) and are now
discrete from each other. Landlocked alewife populations occur in many
freshwater lakes and ponds from Canada to North Carolina as well as the
Great Lakes (Rothschild, 1966; Boaze & Lackey, 1974). Landlocked
blueback herring occur mostly in the southeastern United States and the
Hudson River drainage. At this time, there is no substantive
information that would suggest that landlocked populations can or would
revert back to an anadromous life history if they had the opportunity
to do so (Gephard and Jordaan, Pers. comm., 2012). The discrete life
history and morphological differences between the two life history
variants provide substantial evidence that upon becoming landlocked,
landlocked herring populations become largely independent and separate
from anadromous populations. Landlocked populations and anadromous
populations occupy largely separate ecological niches, especially in
respect to their contribution to freshwater, estuary and marine food-
webs (Palkovacs and Post, 2008). Thus, the existence of landlocked life
forms does not appear to pose a significant threat to the anadromous
forms.
Interbreeding Among Alewife and Blueback Herring (Hybridization)
Recent genetic studies indicate that hybridization may be occurring
in some instances among alewife and blueback herring where populations
overlap (discussed in the River Herring Stock Structure Working Group
Report, NMFS, 2012a). Though interbreeding among closely related
species is uncommon, it does occasionally occur (Levin, 2002). Most
often, different reproductive strategies, home ranges, and habitat
differences of closely related species either prevent interbreeding, or
keep interbreeding at very low levels. In circumstances where
interbreeding does occur, natural selection often keeps hybrids in
check because hybrids are less fit in terms of survival or their
ability to breed successfully (Levin, 2002). Other times, intermediate
environmental conditions can provide an environment where hybrids can
thrive, and when hybrids breed with the member of the parent species,
this can lead to ``mongrelization'' of one or both parent species; a
process referred to as introgressive hybridization (Arnold, 1997).
Introgressive hybridization can also occur as a result of introductions
of closely related species, or man-made or natural disturbances that
create environments more suitable for the hybrid offspring than for the
parents (e.g., the introduction of mallards has led to the decline of
the American black duck through hybridization and introgression)
(Anderson, 1949; Rhymer, 2008).
Though evidence has come forward that indicates that some
hybridization may be occurring between alewife and blueback herring,
there is not enough evidence to conclude whether or not hybridization
poses a threat to one or both species of river herring. Most
importantly, there is not enough evidence to show whether hybrids
survive to maturity and, if so, whether they are capable of breeding
with each
[[Page 48970]]
other or breeding with either of the parent species.
Summary and Evaluation of Factor E
The potential for inter- and intra-specific competition has been
investigated with respect to alewife and blueback herring. Differences
have been observed in the diel activity patterns and in spawning times
of anadromous alosids, and this may reduce inter- and intra- specific
competition. However, it is possible that competition is occurring, as
similarities in prey choice have been identified. Stocking is a tool
that managers have used for hundreds of years with many different
species of fish. This tool has been used as a means of supporting
restoration (e.g., passing fish above barriers into suitable spawning
and rearing habitat, expanding populations into other watersheds, and
introducing fish to newly accessible spawning habitat). In addition,
stocking has been used to introduce species to a watershed for
recreational purposes. Stocking of river herring has occurred for many
years in Maine watersheds, but is less common throughout the rest of
the range of both species. Stocking in the United States has consisted
primarily of trap and truck operations that move fish from one river
system to another or over an impassible dam. Artificial propagation of
river herring is not occurring to a significant extent, though blueback
herring are being reared on a small scale for experimental stocking in
North Carolina.
We have considered natural or manmade factors that may affect river
herring, including competition, artificial propagation and stocking,
landlocked river herring, and hybrids. Several potential natural or
manmade threats to river herring were identified, and we have
considered the effects of these potential threats further in the
qualitative threats assessment described below.
Threats Evaluation for Alewife and Blueback Herring
During the course of the Status Review for river herring, 22
potential threats to alewife and blueback herring were identified that
relate to one or more of the five ESA section 4(a)(1) factors
identified above. The SRT conducted a qualitative threats assessment
(QTA) to help evaluate the significance of the threats to both species
of river herring now and into the foreseeable future. NMFS has used
qualitative analyses to estimate extinction risk in previous status
reviews on the West Coast (e.g., Pacific salmon, Pacific herring,
Pacific hake, rockfish, and eulachon) and East Coast (e.g., Atlantic
sturgeon, cusk, Atlantic wolffish), and the River Herring SRT developed
a qualitative ranking system that was adapted from these types of
qualitative analyses. The results from the threats assessment have been
organized and described according to the above mentioned section
4(a)(1) factors. They were used in combination with the results of the
extinction risk modeling to make a determination as to whether listing
is warranted.
When ranking each threat, Team members considered how various
demographic variables (e.g., abundance, population size, productivity,
spatial structure and genetic diversity) may be affected by a
particular threat. While Factor D, ``inadequacy of existing regulatory
mechanisms,'' is a different type of factor, the impacts on the species
resulting from unregulated or inadequately regulated threats should be
evaluated in the same way as the other four factors.
QTA Methods
All nine SRT members conducted an independent, qualitative ranking
of the severity of each of the 22 identified threats to alewives and
blueback herring. NERO staff developed fact sheets for the SRT that
contained essential information about the particular threats under each
of the five ESA section 4(a)(1) factors, attempts to ameliorate these
threats, and how the threats are or may be affecting both species.
These fact sheets were reviewed by various experts within NMFS to
ensure that they contained all of the best available information for
each of the factors.
Team members ranked the threats separately for both species at a
rangewide scale and at the individual stock complex level. Each Team
member was allotted five likelihood points to rank each threat. Team
members ranked the severity of each threat through the allocation of
these five likelihood points across five ranks ranging from ``low'' to
``high.'' Each Team member could allocate all five likelihood points to
one rank or distribute the likelihood points across several ranks to
account for any uncertainty. Each individual Team member distributed
the likelihood points as he/she deemed appropriate with the condition
that all five likelihood points had to be used for each threat. Team
members also had the option of ranking the threat as ``0'' to indicate
that in their opinion there were insufficient data to assign a rank, or
``N/A'' if in their opinion the threat was not relevant to the species
either throughout its range or for individual stock complexes. When a
Team member chose either N/A (Not Applicable) or 0 (Unknown) for a
threat, all 5 likelihood points had to be assigned to that rank only.
Qualitative descriptions of ranks for the threats listed for alewife
and blueback herring (Table 1, 2) are:
N/A--Not Applicable.
0--Unknown.
1 Low--It is likely that this threat is not significantly
affecting the species now and into the foreseeable future, and that
this threat is limited in geographic scope or is localized within the
species/stock complex' range.
2 Moderately Low--Threat falls between rankings 1 and 3.
3 Moderate--It is likely that this threat has some effect
on the species now and into the foreseeable future, and it is
widespread throughout the species/stock complex' range.
4 Moderately High--Threat falls between rankings 3 and 5.
5 High--It is likely that this threat is significantly
affecting the species now and into the foreseeable future, and it is
widespread in geographic scope and pervasive throughout the species/
stock complex' range.
The SRT identified and ranked 22 threats to both species both
rangewide and for the individual stock complexes. Threats included dams
and barriers, dredging, water quality and water withdrawals, climate
change/variability, harvest (both directed and incidental), disease,
predation, management internationally, federally, and at the state
level, competition, artificial propagation and stocking, hybrids, and
from landlocked populations.
QTA Results
The SRT unequivocally identified dams and barriers as the most
important threat to alewife and blueback herring populations both
rangewide and across all stock complexes (the qualitative ranking for
dams and barriers was between moderately high and high). Incidental
catch, climate change, dredging, water quality, water withdrawal/
outfall, predation, and existing regulation were among the more
important threats after dams for both species, and for all stock
complexes (qualitative rankings for these threats ranged between
moderately low and moderate). Water quality, water withdrawal/outfall,
predation, climate change and climate variability were generally seen
as greater threats to both species in the southern portion of their
ranges than in the northern portion of their ranges. In addition, the
Team identified commercial harvest as being notably
[[Page 48971]]
more important in Canada than in the United States. The results of the
threats analysis for alewives are presented in Tables 1-5 and Figure 3.
The results of the threats analysis for blueback herring are presented
in Tables 6-10 and Figure 4.
QTA Conclusion
The distribution of rankings across threat levels provides a way to
evaluate certainty in the threat level for each of the threats
identified. The amount of certainty for a threat is a reflection of the
amount of evidence that links a particular threat to the continued
survival of each species. For threats with more data, there tended to
be more certainty surrounding the threat level, whereas threats with
fewer data tended to have more uncertainty. The same holds true for
datasets that were limited over space and/or time.
The results of the threats assessment rangewide and for all stock
complexes reveal strong agreement and low uncertainty among the
reviewers that dams and barriers are the greatest threat to both
alewives and blueback herring. There was also strong agreement that
tribal fisheries, scientific monitoring, and educational harvest
currently pose little threat to the species. For the threats of state,
Federal and international management, dredging, climate change, climate
variability, predation, and incidental catch, there was more
uncertainty.
Among alewife and blueback stock complexes, Canada, the Mid-
Atlantic, and South Atlantic diverged the most from the other stock
complexes with respect to certainty of threats. In Canada there was
more certainty surrounding the threats of climate change and climate
variability for both species, and less certainty surrounding the threat
of directed commercial harvest and incidental catch for alewives
compared to the certainty surrounding these threats for the other stock
complexes. In the mid-Atlantic for alewives and South-Atlantic for
bluebacks, there was more uncertainty surrounding climate variability
and climate change compared to the certainty surrounding these threats
for the other stock complexes.
Based on the Team member rankings, dams and other barriers present
the greatest and most persistent threat rangewide to both blueback
herring and alewife (Tables 12-13). Dams and culverts block access to
historical migratory corridors and spawning locations, in some
instances, even when fish passage facilities are present. Centuries of
blocked and reduced access to spawning and rearing habitat have
resulted in decreased overall production potential of watersheds along
the Atlantic coast for alewives and blueback herring (Hall et al.,
2012). This reduced production potential has likely been one of the
main drivers in the decreased abundance of both species. The recent
ASMFC Stock Assessment (2012) attempted to quantify biomass estimates
for both alewife and blueback herring but was unable to develop an
acceptable model to complete a biomass estimate. Therefore, it is
difficult to accurately quantify the declines from historical biomass
to present-day biomass, though significant declines have been noted.
Studies from Maine show that dams have reduced accessible habitat to a
fraction of historical levels, 5 percent for alewives and 20 percent
for blueback herring (Hall et al., 2011).
Rangewide, for alewife and blueback herring, no other threats rose
to the level of dams, but several other stressors ranked near the
moderate threat level. The Team ranked incidental catch, water quality,
and predation as threats likely to have some effect on the species now
and into the foreseeable future that are widespread throughout the
species' range. Incidental catch is primarily from fisheries that use
small-mesh mobile gear, such as bottom and midwater trawls. Sources of
water quality problems vary from river to river and are therefore
unique to each of the stock complexes. And finally, predation by
striped bass, seals, double-crested cormorants (and other fish-eating
avian species, e.g., northern gannets) and other predators is known to
exist, but data are lacking on the overall magnitude. Overall, the
degree of certainty associated with these mid-level threats is much
lower, primarily due to lack of information on how these stressors are
affecting both species.
The SRT's qualitative rankings and analysis of threats for alewife
rangewide and for each stock complex:
BILLING CODE 3510-22-P
[[Page 48972]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.006
[[Page 48973]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.007
[[Page 48974]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.008
[[Page 48975]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.009
[[Page 48976]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.010
[[Page 48977]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.011
[[Page 48978]]
The SRT's qualitative rankings of threats for blueback herring
rangewide and for each stock complex:
[GRAPHIC] [TIFF OMITTED] TN12AU13.012
[[Page 48979]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.013
[[Page 48980]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.014
[[Page 48981]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.015
[[Page 48982]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.016
[[Page 48983]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.017
[[Page 48984]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.018
[[Page 48985]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.019
[[Page 48986]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.020
BILLING CODE 3510-22-C
Extinction Risk Analysis
In order to assess the risk of extinction for alewife and blueback
herring, trends in the relative abundance of alewife and blueback
herring were assessed for each species rangewide, as well as for each
species-specific stock complex. As noted previously, for alewife, the
stock complexes include Canada, Northern New England, Southern New
England and the mid-Atlantic. For blueback herring, the stock complexes
are Canada, Northern New England, Southern New England, mid-Atlantic
and Southern.
Criteria Established by SRT for Evaluating Risk
Prior to conducting the trend analysis modeling, the SRT
established criteria that would be used to evaluate the risk to both
species as well as to the individual stock complexes. At the SRT's
request, the NEFSC conducted modeling to develop trends in relative
abundance by estimating the population growth rate for both species
both rangewide and for each individual stock complex. The SRT
established two tiers that could be used separately or in combination
to interpret the results of the modeling in order to assess risk to
alewife and blueback herring rangewide and for the individual stock
complexes. We concur that these tiers are appropriate. Tier A relates
to what is known about the geographic distribution, habitat
connectivity and genetic diversity of each species, and Tier B relates
to the risk thresholds established for the trend analysis that was
conducted by the NEFSC. These tiers are subject to change in the future
as more information becomes available. For example, Tier A is based on
preliminary genetic data addressing possible stock complexes, which
could change in the future. Data related to both tiers were assessed to
determine if sufficient information was available to make a conclusion
under one or both of the tiers. The SRT decided that, because of
significant uncertainties associated with the available data and a
significant number of data deficiencies for both species, it was not
necessary to have information under both tiers in order to make a risk
determination, and we concur with this decision.
The goal of Tier A was to maintain three contiguous stock complexes
that are stable or increasing as this: (1) Satisfies the need to
maintain both geographic closeness and geographic distance for a
properly functioning metapopulation (see McElhany et al., 2000); (2)
ensures that the recovered population does not include isolated genetic
groups that could lead to genetic divergence (McDowall, 2003, Quinn,
1984); (3) provides some assurance that the species persists across a
relatively wide geographic area supporting diverse environmental
conditions and diverse habitat types; and (4) ensures that the entire
population does not share the same risk from localized environmental
catastrophe (McElhany et al., 2000).
Tier B information was used to directly interpret the results of
the trends in relative abundance modeling
[[Page 48987]]
conducted by the NEFSC. As described below, relative abundance of both
alewife and blueback herring was used to estimate growth rate (along
with the 95 percent confidence intervals for the growth rates) for each
species rangewide and for each stock complex. Tier B established risk
criteria depending on the outcomes of the population growth rate
modeling. As indicated in the foreseeable future section above, a 12-
to 18-year timeframe (e.g., 2024-2030) for each species was determined
to be appropriate. After subsequent discussions, the SRT decided that
the projections into the foreseeable future would not provide
meaningful information for the extinction risk analysis. As noted
previously, the trend analysis provides a steady population growth
rate. If the population growth rate is positive and everything else
remains the same into the foreseeable future (e.g., natural and
anthropogenic mortality rates do not change), the abundance into the
foreseeable future will continue to increase. If the population growth
rate is negative, then the abundance into the foreseeable future will
continue to decline. Currently, there is insufficient information
available to modify any of the factors that may change the growth rates
into the foreseeable future, and thus, performing these projections
will not provide meaningful information for the extinction risk of
either of these species.
The baseline for the overall risk assessment assumes that there has
already been a significant decline in abundance in both species due to
a reduction in carrying capacity and overfishing as indicated in
various publications (Limburg and Waldman, 2009; Hall et al., 2012), as
well as other threats. The estimated population growth rates reflect
the impacts from the various threats to which the species are currently
exposed. The SRT recommended that NEFSC use data from 1976 through the
present to minimize the overfishing influence from distant water fleets
that occurred in earlier years but has since been curtailed by
fisheries management measures. The SRT recommended that the NEFSC also
run a trajectory using a plus/minus 10-percent growth rate to test
model sensitivity with respect to changes in the model variables. This
approach has been used in analyses for other species (e.g., Atlantic
croaker, Atlantic cod) and can serve as a means of showing
sensitivities in the model to potential variables (e.g., population
growth rate changes, climate change) (Hare and Able, 2007; Hare, NMFS
Pers. comm., 2012). Following completion of the model results, we
determined that the plus/minus 10-percent change in population growth
rate would not provide additional information that would change the
conclusions as to whether the populations are significantly increasing,
stable or decreasing. Without the projections of the population growth
rate into the foreseeable future, the plus/minus 10-percent would
merely provide an additional set of bounds around the population growth
rate estimate, and, therefore, we determined that running the model
with the plus/minus 10-percent was not necessary.
The population growth rates derived from the analysis help identify
whether stability exists within the population. Mace et al. (2002) and
Demaster et al. (2004) recognized that highly fecund, short generation
time species like river herring may be able to withstand a 95 to 99
percent decline in biomass. Both alewives and blueback herring may
already be at or less than two percent of the historical baseline
(e.g., Limburg and Waldman, 2009), though these estimates are based on
commercial landings data, which are dependent upon management and are
not a reliable estimate of biomass. However, recognizing historical
declines for both species, the modeled population growth rates were
used to gauge whether these stock complexes are stable, significantly
increasing or decreasing. Relative abundance of a stock is considered
to be significantly increasing or decreasing if the 95-percent
confidence intervals of the population growth rate do not include zero.
In contrast, if the 95-percent confidence intervals do contain zero,
then the population is considered to be stable, as the increasing or
decreasing trend in abundance is not statistically significant.
The SRT determined and we agree that a stable or significantly
increasing trajectory suggests that these species may be within the
margins of being self-sustainable and thus, if all of the growth rates
for the coast-wide distribution and the stock complexes are stable or
significantly increasing, the species is at low risk of extinction (the
risk categories were defined by adapting the categories described above
for the QTA--Low risk--it is likely that the threats to the species'
continued existence are not significant now and/or into the foreseeable
future; Moderately Low--risk falls between low and moderate rankings;
Moderate--it is likely that the threats are having some effect on the
species continued existence now and/or into the foreseeable future;
Moderately High--the risk falls between moderate and high; High--it is
likely that the threats are significantly affecting the species'
continued existence now and/or into the foreseeable future). If the
coast wide population growth rate is stable or significantly increasing
and one stock complex is significantly decreasing but all others are
stable or significantly increasing, the species is at a moderate-low
risk. A significantly decreasing population growth rate for several
stock complexes would be an indicator that the current abundance may
not be sustainable relative to current management measures and,
therefore, may warrant further protections. Thus, if the population
growth rates for two of the stock complexes are significantly
decreasing but the coast-wide index is significantly increasing, the
species is at moderate-high risk. If the growth rates for three or more
of the stock complexes are significantly decreasing and/or the coast-
wide index is significantly decreasing, the species is at high risk.
Risk Scenarios
Low risk
[cir] Coast wide trajectory--Stable to significantly increasing
[cir] Stock complex trajectories--All stable to significantly
increasing
Moderate-Low risk
[cir] Coast wide trajectory--Stable to significantly increasing
[cir] Stock complex trajectories--One significantly decreasing, all
others stable to significantly increasing
Moderate-High risk
[cir] Coast wide trajectory--Stable to significantly increasing
[cir] Stock complex trajectories--Two or more significantly
decreasing
High risk
[cir] Coast wide trajectory--Significantly decreasing
[cir] Stock complex trajectories--Three or more significantly
decreasing
Trend Analysis Modeling
The sections below include summaries/excerpts from the NEFSC Report
to the SRT, ``Analysis of Trends in Alewife and Blueback Herring
Relative Abundance,'' June 17, 2013, 42 pp. (NEFSC, 2013). For detailed
information on the modeling conducted, please see the complete report
which can be found at http://www.nero.noaa.gov/prot_res/CandidateSpeciesProgram/RiverHerringSOC.htm or see FOR FURTHER
INFORMATION CONTACT section above for contacts.
[[Page 48988]]
Data Used in the Trend Analysis Modeling
Rangewide Data
Relative abundance indices from multiple fishery-independent survey
time series were considered as possible data inputs for the rangewide
analysis. These time series included the NEFSC spring, fall, and winter
bottom trawl surveys as well as the NEFSC shrimp survey. For alewife,
two additional time series were available: Canada's DFO summer research
vessel (RV) survey of the Scotian Shelf and Bay of Fundy (1970-
present), and DFO's Georges Bank RV survey (1987-present, conducted
during February and March).
For the NEFSC spring and fall bottom trawl surveys, inshore strata
from 8 to 27 m depth and offshore strata from 27 to 366 m depth have
been most consistently sampled by the RV Albatross IV and RV Delaware
II since the fall of 1975 and spring of 1976. Prior to these time
periods, either only a portion of the survey area was sampled or a
different vessel and gear were used to sample the inshore strata
(Azarovitz, 1981). Accordingly, seasonal alewife and blueback herring
relative abundance indices were derived from these trawl surveys using
both inshore and offshore strata for 1976-2012 in the spring and 1975-
2011 in the fall. Additional relative abundance indices were derived
using only offshore strata for 1968-2012 in the spring and 1967-2011 in
the fall (from 1963-1967 the fall survey did not extend south of Hudson
Canyon). These time series were developed following the same
methodology used in the ASMFC river herring stock assessment (ASMFC,
2012).
Through 2008, standard bottom trawl tows were conducted for 30
minutes at 6.5 km/hour with the RV Albatross IV as the primary survey
research vessel (Despres-Patanjo et al., 1988). However, vessel, door
and net changes did occur during this time, resulting in the need for
conversion factors to adjust survey catches for some species.
Conversion factors were not available for net and door changes, but a
vessel conversion factor for alewife was available to account for years
where the RV Delaware II was used. A vessel conversion factor of 0.58
was applied to alewife weight-per-tow indices from the RV Delaware II.
Alewife number-per-tow indices did not require a conversion factor
(Byrne and Forrester, 1991).
In 2009, the survey changed primary research vessels from the RV
Albatross IV to the RV Henry B. Bigelow. Due to the deeper draft of the
RV Henry B. Bigelow, the two shallowest series of inshore strata (8-18
m depth) are no longer sampled. Concurrent with the change in fishing
vessel, substantial changes to the characteristics of the sampling
protocol and trawl gear were made, including tow speed, net type and
tow duration (NEFSC, 2007). Calibration experiments, comprising paired
standardized tows of the two fishing vessels, were conducted to measure
the relative catchability between the two vessel-gear combinations and
develop calibration factors to convert Bigelow survey catches to RV
Albatross equivalents (Miller et al., 2010). In the modeling, the NEFSC
developed species-specific calibration coefficients which were
estimated for both catch numbers and weights using the method of Miller
et al. (2010) (Table 14). The calibration factors were combined across
seasons due to low within-season sample sizes from the 2008 calibration
studies (fewer than 30 tows with positive catches by one or both
vessels).
[GRAPHIC] [TIFF OMITTED] TN12AU13.021
Bottom trawl catches of river herring tend to be higher during the
daytime due to diel migration patterns (Loesch et al., 1982; Stone and
Jessop, 1992). Accordingly, only daytime tows were used to compute
relative abundance and biomass indices. In addition, the calibration
factors used to convert RV Bigelow catches to RV Albatross equivalents
were estimated using only catches from daytime tows. Daytime tows,
defined as those tows between sunrise and sunset, were identified for
each survey station based on sampling date, location, and solar zenith
angle using the method of Jacobson et al. (2011). Although there is a
clear general relationship between solar zenith and time of day, tows
carried out at the same time but at different geographic locations may
have substantially different irradiance levels that could influence
survey catchability (NEFSC, 2011). Preliminary analyses (Lisa
Hendrickson, NMFS, 2012--unpublished data) confirmed that river herring
catches were generally greater during daylight hours compared to
nighttime hours.
In addition to the NEFSC spring and fall trawl surveys, the NEFSC
winter and shrimp surveys were considered for inclusion in the
analysis. For the winter survey (February), the sampling area extended
from Cape Hatteras, NC, through the southern flank of Georges Bank, but
did not include the remaining portion of Georges Bank or the Gulf of
Maine. With the arrival of the RV Bigelow in late 2007, the NEFSC
winter survey was merged with the NEFSC spring survey and discontinued.
Alewife and blueback herring indices of relative abundance were
developed for the winter survey from 1992-2007 using daytime tows from
all sampled inshore and offshore strata. The shrimp survey is conducted
during the summer (July/August) in the western Gulf of Maine during
daylight hours. Relative abundance indices were derived for alewife and
blueback herring from 1983-2011 using all strata that were consistently
sampled across the survey time series in the NEFSC winter and shrimp
surveys.
Stratified mean indices of relative abundance of alewife from
Canada's summer RV survey and Georges Bank RV survey were provided by
Heath
[[Page 48989]]
Stone of Canada's DFO. In these surveys, alewife is the predominant
species captured; however, some blueback herring are likely included in
the alewife indices because catches are not always separated by river
herring species (Heath Stone, DFO Pers. comm., 2012). Furthermore, some
Georges Bank strata were not sampled in all years of the survey due to
inclement weather and vessel mechanical problems (Stone and Gross,
2012).
Due to the restricted spatial coverage of the winter, shrimp and
Canadian Georges Bank surveys, these surveys were not used in the final
rangewide analyses. Accordingly, relative abundance (number-per-tow)
from the NEFSC spring and fall surveys was used in the rangewide models
for blueback herring, and number-per-tow from the NEFSC spring survey,
NEFSC fall survey, and the Canadian summer survey were used in the
rangewide models for alewife.
Data from 1976 through the present were incorporated into the trend
analysis. This time series permitted the inclusion of the spring and
fall surveys' inshore strata. In addition, with this time series, the
required assumption that the population growth rate will remain the
same was reasonable. Prior to 1976, fishing intensity was much greater
due to the presence of distant water fleets on the East Coast of the
United States.
Years with zero catches were treated as missing data. For alewife,
there were no years with zero catches in the spring, fall and Scotian
shelf surveys. Zero catches of blueback herring occurred in the fall
survey in 1988, 1990, 1992 and 1998.
Stock-Specific Data
Stock-specific time series of alewife and blueback herring relative
abundance were obtained from the ASMFC and Canada's DFO. Available time
series varied among stocks and included run counts, as well as young-
of-year (YOY), juvenile and adult surveys that occurred solely within
the bays or sounds of the stock of interest (for alewife see Table 15
in the NEFSC's ``Analysis of Trends in Alewife and Blueback Herring
Relative Abundance,'' and for blueback herring, see Table 16). All
available datasets were included in the stock-specific analyses, with
the exception of run counts from the St. Croix and Union Rivers. These
datasets were excluded due to the artificial impacts of management
activities on run sizes. The closure of the Woodland Dam and Great
Falls fishways in the St. Croix River prevented the upstream passage of
alewives to spawning habitat. In contrast, fluctuations in Union River
run counts were likely impacted by lifting and stocking activities used
to maintain a fishery above the Ellsworth Dam. In the southern Gulf of
St. Lawrence trawl survey, all river herring were considered to be
alewife because survey catches were not separated by river herring
species (Luc Savoie DFO, Pers. comm., 2012). No blueback herring
abundance indices were available for the Canadian stock. Select strata
were not used to estimate stock-specific indices from the NEFSC trawl
surveys because mixing occurs on the continental shelf. Accordingly,
any NEFSC trawl survey indices, even estimated using only particular
strata, would likely include individuals from more than one stock.
Each available dataset in the stock-specific analyses represented a
particular age or stage (spawners, young-of-year, etc.) of fish.
Consequently, each time series was transformed using a running sum over
4 years. The selection of 4 years for the running sum was based on the
generation time of river herring. For age- and stage-specific data, a
running sum transformation is recommended to obtain a time series that
more closely approximates the total population (Holmes, 2001). In order
to compute the running sums for each dataset, missing data were imputed
by computing the means of immediately adjacent years. For both species
4 years were imputed for the Monument River, and 1 year was imputed for
the DC seine survey. For alewife, 1 year was also imputed for the
Mattapoisett River, Nemasket River, and the southern Gulf of St.
Lawrence trawl survey. For blueback herring, 1 year was also imputed
for the Long Island Sound (LIS) trawl survey and Santee-Cooper catch-
per-unit-effort (CPUE).
If possible data from 1976 through the present were incorporated
into each stock-specific model, with the first running sum
incorporating data from 1976 through 1979. However, for some stocks,
observation time series began after 1976. In these cases, the first
modeled year coincided with the first running sum of the earliest
survey.
MARRS Model Description
Multivariate Autoregressive State-Space models (MARSS) were
developed using the MARSS package in R (Holmes et al., 2012a). This
package fits linear MARSS models to time series data using a maximum
likelihood framework based on the Kalman smoother and an Expectation
Maximization algorithm (Holmes et al., 2012b).
Each MARSS model is comprised of a process model and an observation
model (Holmes and Ward, 2010; Holmes et al., 2012b). The model is
described in detail in the NEFSC (2013) final report to the SRT (posted
on the Northeast Regional Office's Web site--http://www.nero.noaa.gov/prot_res/CandidateSpeciesProgram/RiverHerringSOC.htm). Population
projections and model analysis.
For each stock complex, the estimated population growth rate and
associated 95 percent confidence intervals were used to classify
whether the stock's relative abundance was stable, significantly
increasing or decreasing. As noted previously, relative abundance of a
stock was considered to be significantly increasing or decreasing if
the 95 percent confidence intervals of the population growth rate did
not include zero. In contrast, if the 95 percent confidence intervals
included zero, the population was considered to be stable because the
increasing or decreasing trend in abundance was not significant.
Model Results
Rangewide Analyses
For the rangewide analysis, as shown in Table 15 below, the
preferred model run for alewife indicates that the 95-percent
confidence intervals spanning the estimated population growth rate do
not include 0 and are statistically significantly increasing. For
blueback herring rangewide, however, the 95-percent confidence
intervals do include 0, and thus, it is not possible to state that the
trend rangewide for this species is increasing. We, therefore, conclude
based on our criteria described above that blueback herring rangewide
are stable.
[[Page 48990]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.022
Stock-Specific Analyses
As shown in Table 16 below, the 95-percent confidence intervals
spanning the estimated population growth rate for the Canadian stock
complex do not include 0 and are statistically significantly
increasing. For the other three stock complexes, however, the
confidence intervals do include 0, and thus, the Northern New England,
Southern New England and mid-Atlantic alewife stock complexes are
stable.
As Canada does not separate alewife and blueback herring in their
surveys (e.g., they indicate that all fish are alewife), we were unable
to obtain data from Canada specifically for blueback herring. For three
of the remaining four stock complexes, the 95-percent confidence
intervals spanning the estimated population growth rate do include 0
and thus, the trend for these stock complexes is stable. For the mid-
Atlantic stock complex, the population growth rate and both 95-percent
confidence intervals are all statistically significantly decreasing.
Thus, we conclude that this stock complex is significantly decreasing.
BILLING CODE 3510-22-P
[[Page 48991]]
[GRAPHIC] [TIFF OMITTED] TN12AU13.023
[[Page 48992]]
BILLING CODE 3510-22-C
Model Assumptions and Limitations
The available data for each analysis varied considerably among
species and stocks. Some stocks such as Southern New England blueback
herring had only one available data set; however, other stocks such as
Southern New England alewife and mid-Atlantic blueback herring had
eight or more available time series. Within each analysis, all input
time series must be weighted equally, regardless of the variability in
the dataset. Furthermore, only the annual point estimates of relative
abundance are inputs to the model; associated standard errors for the
time series are not inputted.
However, some observation time series may be more representative of
the stock of interest than other time series. For example, for Northern
New England alewife, available datasets included run counts from five
rivers and Maine's juvenile alosine seine survey. Each time series of
run counts represents the spawning population in one particular river,
whereas the juvenile seine survey samples six Maine rivers including
Merrymeeting Bay (ASMFC, 2012). Accordingly, it is possible that the
juvenile seine survey provides a better representation of Northern New
England alewife than the run counts from any particular river because
the seine survey samples multiple populations. Likewise, for Southern
New England alewife, available datasets included the Long Island Sound
(LIS) trawl survey, New York juvenile seine survey, and run counts from
six rivers. The LIS trawl survey samples Long Island Sound from New
London to Greenwich Connecticut with stations in both Connecticut and
New York state waters, including the mouths of several rivers including
the Thames, Connecticut, Housatonic, East and Quinnipiac (CTDEP, 2011;
ASMFC, 2012). The NY juvenile seine survey samples the Hudson River
estuary (ASMFC, 2012), and run counts are specific to particular
rivers. As a consequence, the LIS trawl survey may be more
representative of the Southern New England alewife stock because it
samples not only a greater proportion of the stock, but also samples
LIS where mixing of river-specific populations likely occurs.
Several sources of uncertainty are described in detail in the
modeling report. It is important to understand and document these
sources of uncertainty. However, even with several assumptions and
these sources of uncertainty, we are confident that the model results
are useful in determining the population growth rates both coast-wide
and for the individual stock complexes, and thus, for providing
information to be used in assessing the risk to these species and stock
complexes.
Extinction Risk Conclusion
In performing our analysis of the risk of extinction to the
species, we considered the current status and trends and the threats as
they are impacting the species at this time. Currently, neither species
is experiencing high rates of decline coast-wide as evidenced by the
rangewide trends (significantly increasing for alewife and stable for
blueback herring). Thus, using the extinction risk tiers identified by
the SRT, we have concluded the following:
Alewife--
Tier A: There is sufficient information available to
conclude that there are at least three contiguous populations that are
stable to significantly increasing.
Tier B: The species is at ``Low risk'' as the coast-wide
trajectory is significantly increasing and all of the stock complexes
are stable or significantly increasing.
Blueback herring--
Tier A: There is insufficient information available to
make a conclusion under Tier A as we were unable to obtain data from
Canada to determine the population growth rate for rivers in Canada.
Thus, we were only able to obtain information for four of the five
stock complexes identified for the species.
Tier B: The species is at ``Moderate-low risk ``as the
coast-wide trajectory is stable and three of the four stock complexes
are stable. The estimated population growth rate of the mid-Atlantic
stock complex is significantly decreasing based on the available
information. However, the relative abundance of the species throughout
its range (as demonstrated through the coast-wide population growth
rate) is stable, and thus, the SRT concluded that the mid-Atlantic
stock complex does not constitute a significant portion of the species
range. We concur with this conclusion. In other words, the data
indicate that the mid-Atlantic stock complex does not contribute so
much to the species that, without it, the entire species would be in
danger of extinction.
Many conservation efforts are underway that may lessen the impact
of some of these threats into the foreseeable future. One of the
significant threats identified for both species is bycatch in Federal
fisheries, such as the Atlantic herring and mackerel fisheries. The New
England and Mid Atlantic Fishery Management Councils have recommended
management measures under the MSA that are expected to decrease the
risk from this particular threat. Under both the Atlantic Herring
Fishery Management Plan and the Mackerel/Squid/Butterfish Fishery
Management Plan, the Councils have recommended a suite of reporting,
vessel operation, river herring catch cap provisions, and observer
provisions that would improve information on the amount and extent of
river herring catch in the Atlantic herring and mackerel fisheries.
NMFS has partially approved the measures as recommended by the New
England Council and will be implementing the measures in September or
October 2013. Another threat that has been identified for both species
is loss of habitat or loss of access to spawning habitats. We have been
working to restore access to spawning habitats for river herring and
other diadromous fish species through habitat restoration projects.
While several threats may lessen in the future, given the extensive
decline from historical levels, neither species is thought to be
capable of withstanding continued high rates of decline.
Research Needs
As noted above, there is insufficient information available on
river herring in many areas. Research needs were recently identified in
the ASMFC River Herring Stock Assessment Report (ASMFC, 2012); NMFS
Stock Structure, Climate Change and Extinction Risk Workshop/Working
Group Reports (NMFSa, 2012; NMFSb, 2012; NMFSc, 2012) and associated
peer reviews; and New England and Mid-Atlantic Fishery Management
Council documents (NEFMC, 2012; MAFMC, 2012). We have identified below
some of the most critical and immediate research needs to conserve
river herring taking the recently identified needs into consideration,
as well as information from this determination. However, these are
subject to refinement as a coordinated and prioritized coast-wide
approach to continue to fill in data gaps and conserve river herring
and their habitat is developed (see ``Listing Determination'' below).
Gather additional information on life history for all
stages and habitat areas using consistent and comprehensive coast-wide
protocols (i.e., within and between the United States and Canada). This
includes information on movements such as straying rates and migrations
at sea. Improve methods to develop biological benchmarks used in
assessment modeling.
[[Page 48993]]
Continue genetic analyses to assess genetic diversity,
determine population stock structure along the coast (U.S. and Canada)
and determination of river origin of incidental catch in non-targeted
ocean fisheries. Also, obtain information on hybridization and
understand the effects of stocking on genetic diversity.
Further assess human impacts on river herring (e.g.,
quantifying bycatch through expanded observer and port sampling
coverage to quantify fishing impact in the ocean environment and
improve reporting of commercial and recreational harvest by waterbody
and gear, ocean acidification)
Continue developing models to predict the potential
impacts of climate change on river herring. This includes, as needed to
support these efforts, environmental tolerances and thresholds (e.g.,
temperature) for all life stages in various habitats.
Develop and implement monitoring protocols and analyses to
determine river herring population responses and targets for rivers
undergoing restoration (e.g., dam removals, fishways, supplemental
stocking). Also, estimate spawning habitat by watershed (with and
without dams).
Assess the frequency and occurrence of hybridization
between alewife and blueback herring and possible conditions that
contribute to its occurrence (e.g., occurs naturally or in response to
climate change, dams, or other anthropogenic factors).
Continue investigating predator prey relationships.
Listing Determination
The ESA defines an endangered species as any species in danger of
extinction throughout all or a significant portion of its range, and a
threatened species as any species likely to become an endangered
species within the foreseeable future throughout all or a significant
portion of its range. Section 4(b)(1) of the ESA requires that the
listing determination be based solely on the best scientific and
commercial data available, after conducting a review of the status of
the species and after taking into account those efforts, if any, that
are being made to protect such species.
We have considered the available information on the abundance of
alewife and blueback herring, and whether any one or a combination of
the five ESA factors significantly affect the long-term persistence of
these species now or into the foreseeable future. We have reviewed the
information received following the positive 90-day finding on the
petition, the reports from the stock structure, extinction risk
analysis, and climate change workshops/working groups, the population
growth rates from the trends in relative abundance estimates and
qualitative threats assessment, the Center for Independent Experts peer
reviewers' comments, other qualified peer reviewer submissions, and
consulted with scientists, fishermen, fishery resource managers, and
Native American Tribes familiar with river herring and related research
areas, and all other information encompassing the best available
information on river herring. Based on the best available information,
the SRT concluded that alewife are at a low risk of extinction from the
threats identified in the QTA (e.g., dams and other barriers to
migration, incidental catch, climate change, dredging, water quality,
water withdrawal/outfall, predation, and existing regulation), and
blueback herring are at a moderate-low risk of extinction from similar
threats identified and discussed in the QTA discussion above. We concur
with this conclusion, and we have determined that as a result of the
extinction risk analysis for both species, these two species are not in
danger of extinction or likely to become so in the foreseeable future.
Therefore, listing alewife and blueback herring as either endangered or
threatened throughout all of their ranges is not warranted at this
time.
Significant Portion of the Range Evaluation
Under the ESA and our implementing regulations, a species warrants
listing if it is threatened or endangered throughout all or a
significant portion of its range. In our analysis for this listing
determination, we initially evaluated the status of and threats to the
alewife and blueback herring throughout the entire range of both
species. As stated previously, we have concluded that there was not
sufficient evidence to suggest that the genetically distinct stock
complexes of alewife or blueback constitute DPSs. We also then assessed
the status of each of the individual stock complexes in order to
determine whether either species is threatened or endangered in a
significant portion of its range.
As noted above in the QTA section, the SRT determined that the
threats to both species are similar and the threats to each of the
individual stock complexes are similar with some slight variation based
on geography. Water quality, water withdrawal/outfall, predation,
climate change and climate variability were generally seen as greater
threats to both species in the southern portion of their ranges than in
the northern portion of their ranges. In light of the potential
differences in the magnitude of the threats to specific areas or
populations, we next evaluated whether alewife or blueback herring
might be threatened or endangered in any significant portion of its
range. In accordance with our draft policy on ``significant portion of
its range,'' our first step in this evaluation was to review the entire
supporting record for this listing determination to ``identify any
portions of the range[s] of the species that warrant further
consideration'' (76 FR 77002; December 9, 2011). Therefore, we
evaluated whether there is substantial information suggesting that the
hypothetical loss of any of the individual stock complexes for either
species (e.g., portions of the species' ranges) would reasonably be
expected to increase the demographic risks to the point that the
species would then be in danger of extinction, (i.e., whether any of
the stock complexes within either species' range should be considered
``significant''). As noted in the extinction risk analysis section, all
of the alewife stock complexes as well as the coastwide trend are
either stable or increasing. For blueback herring, 3 of the stock
complexes and the coastwide trend are all stable, but the mid-Atlantic
stock complex is decreasing. The SRT determined that the mid-Atlantic
stock complex is not significant to the species, given that even though
it is decreasing, the overall coastwide trend is stable. Thus, the loss
of this stock complex would not place the entire species at risk of
extinction. We concur with this conclusion. Because the portion of the
blueback herring stock complex residing in the mid-Atlantic is not so
significant that its hypothetical loss would render the species
endangered, we conclude that the mid-Atlantic stock complex does not
constitute a significant portion of the blueback herring's range.
Consequently, we need not address the question of whether the portion
of the species occupying this portion of the range of blueback herring
is threatened or endangered.
Conclusion
Our review of the information pertaining to the five ESA section
4(a)(1) factors does not support the assertion that there are threats
acting on either alewife or blueback herring or their habitat that have
rendered either species to be in danger of extinction or likely to
become so in the foreseeable future, throughout all or a significant
portion of its range. Therefore, listing alewife or blueback herring as
threatened or endangered under the ESA is not warranted at this time.
[[Page 48994]]
While neither species is currently endangered or threatened, both
species are at low abundance compared to historical levels, and
monitoring both species is warranted. We agree with the SRT that there
are significant data deficiencies for both species, and there is
uncertainty associated with available data. There are many ongoing
restoration and conservation efforts and new management measures that
are being initiated/considered that are expected to benefit the
species; however, it is not possible at this time to quantify the
positive benefit from these efforts. Given the uncertainties and data
deficiencies for both species, we commit to revisiting both species in
3 to 5 years. We have determined that this is an appropriate timeframe
for considering this information in the future as a 3- to 5-year
timeframe equates to approximately one generation time for each
species, and it is therefore unlikely that a detrimental impact to
either species could occur within this period. Additionally, it allows
for time to complete ongoing scientific studies (e.g., genetic
analyses, ocean migration patterns, climate change impacts) and for the
results to be fully considered. Also, it allows for the assessment of
data to determine whether the preliminary reports of increased river
counts in many areas along the coast in the last 2 years represent
sustained trends. During this 3- to 5-year period, we intend to
coordinate with ASMFC on a strategy to develop a long-term and dynamic
conservation plan (e.g., priority activities and areas) for river
herring considering the full range of both species and with the goal of
addressing many of the high priority data gaps for river herring. We
welcome input and involvement from the public. Any information that
could help this effort should be sent to us (see ADDRESSES section
above).
References Cited
A complete list of all references cited in this rulemaking can be
found on our Web site at http://www.nero.noaa.gov/prot_res/CandidateSpeciesProgram/RiverHerringSOC.htm and is available upon
request from the NMFS office in Gloucester, MA (see ADDRESSES).
Authority: The authority for this action is the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: August 6, 2013.
Alan D. Risenhoover,
Director, Office of Sustainable Fisheries, performing the functions and
duties of the Deputy Assistant Administrator for Regulatory Programs
National Marine Fisheries Service.
[FR Doc. 2013-19380 Filed 8-9-13; 8:45 am]
BILLING CODE 3510-22-P