[Federal Register Volume 68, Number 183 (Monday, September 22, 2003)]
[Rules and Regulations]
[Pages 55140-55166]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-23919]



[[Page 55139]]

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Part III





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Notice of Remanded 
Determination of Status for the Sacramento splittail (Pogonichthys 
macrolepidotus); Final Rule

  Federal Register / Vol. 68, No. 183 / Monday, September 22, 2003 / 
Rules and Regulations  

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[RIN 1018-AH73]


Endangered and Threatened Wildlife and Plants; Notice of Remanded 
Determination of Status for the Sacramento splittail (Pogonichthys 
macrolepidotus)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule; revised determination.

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SUMMARY: On January 6, 1994, we, the U.S. Fish and Wildlife Service 
(Service) proposed to list the Sacramento splittail (Pogonichthys 
macrolepidotus), a fish species native to central California, as a 
threatened species under the Endangered Species Act of 1973, as amended 
(Act). We published a final rule to list the species as threatened on 
February 8, 1999. Our final decision to list the Sacramento splittail 
was subsequently challenged in the cases San Luis & Delta-Mendota Water 
Authority v. Anne Badgley, et al. and State Water Contractors, et al. 
v. Michael Spear, et al. On June 23, 2000, the Federal Eastern District 
Court of California found our final rule to be unlawful and on 
September 22, 2000, remanded the determination back to us for a re-
evaluation of our final decision. However, because the District Court 
did not vacate our previous final decision, the decision remained in 
place until we issued a new determination. After a thorough review and 
consideration of all the best scientific and commercial information 
available, we are removing the Sacramento splittail from the list of 
threatened species. In accordance with the Administrative Procedure 
Act, the Service has determined that this rule relieves an existing 
restriction, and good cause exists to make the effective date of this 
rule immediate.

EFFECTIVE DATE: In compliance with the Federal Eastern District Court 
of California order, this rule is effective September 22, 2003.

ADDRESSES: Comments and materials received, as well as supporting 
documentation used in the preparation of this final decision, are 
available for public inspection, by appointment, during normal business 
hours at the Sacramento Fish and Wildlife Office, U.S. Fish and 
Wildlife Service, 2800 Cottage Way, Suite W-2605, Sacramento, CA 95825.

FOR FURTHER INFORMATION CONTACT: Wayne White (see ADDRESSES), 
(telephone: 916/414-6600; facsimile: 916/414-6713). Information is 
available in alternate formats upon request.

SUPPLEMENTARY INFORMATION: 

Background

    The Sacramento splittail (hereafter referred to as splittail) is a 
fish species native to central California and represents the only 
extant species in its genus in North America. We have previously 
discussed the taxonomic history of the splittail along with the 
physical description of the taxon in our final listing rule (64 FR 
5963). Please refer to that document for a detailed discussion of these 
subjects. It is our intent, in this document, to reiterate and discuss 
only those topics directly relevant to this decision.
    To assist the reader in understanding terminology used in this 
determination, we have provided below several terms with their 
corresponding definitions as they are used in this document. As used in 
this determination, the term ``Delta'' refers to all tidal waters 
contained within the legal definition of the San Francisco Bay-
Sacramento-San Joaquin River Delta, as delineated by section 12220 of 
the State of California's Water Code. Generally, the Delta is contained 
within a triangular area that extends south from the City of Sacramento 
to the confluence of the Stanislaus and San Joaquin Rivers at the 
southeast corner and Chipps Island in Suisun Bay at the southwest 
corner. The term ``Estuary,'' as used in this determination, refers to 
tidal waters contained in the Sacramento and San Joaquin Rivers, the 
Delta, and San Pablo and San Francisco bays. ``Export facilities,'' as 
used in this determination, refers to the Bureau of Reclamation (USBR) 
Central Valley Project (CVP) and the California Department of Water 
Resources (CDWR) State Water Project (SWP) water export facilities in 
the South Delta.
    Splittail are native to California's Central Valley. Historically, 
splittail were found as far north as Redding on the Sacramento River 
(Rutter 1908). Splittail were also found in the tributaries of the 
Sacramento River as far as the current Oroville Dam site on the Feather 
River and Folsom Dam site on the American River (Rutter 1908). Along 
the San Joaquin River, historic distribution is unclear. Girard (1854) 
reported two Pogonichthys species in the San Joaquin River. These 
reports do not make a distinction between which of the two species was 
found at particular locations on the San Joaquin River. In the southern 
Central Valley, Tulare Lake was likely to have supported many native 
fish species, including splittail (Moyle 1976) but has since been 
drained and reclaimed. Splittail were present within Buena Vista and 
Kern Lakes (Moyle 2002), both of which are reclaimed.
    Some researchers (Sommer et al. (1997)) indicate that splittail 
still occur, at least during optimal conditions, through as much as 78 
percent of their former range in terms of river reaches. However, 
others (Moyle and Yoshiyama 1992) believe the species appears to be 
restricted to a small portion of its former range, with dams and 
diversions preventing access to upstream habitat in large rivers and 
streams beyond the valley floor (Moyle and Yoshiyama 1992). The State 
of California indicates that splittail still occur in a large portion 
of its range (80% in the Sacramento, and 70% in the San Joaquin). There 
appears to be consensus that at least 20% and possibly more of the 
species range has been reduced. Baxter (2001b) found that the range of 
the splittail extends away from the Delta, though detections on the 
periphery of its range appear to be part of a single, mobile, 
Sacramento and San Joaquin River/Bay-Delta population that includes 
fish from the Napa and Petaluma River systems. Their distribution in 
the Estuary suggests that brackish water may characterize optimal 
rearing habitat for fish greater than 75 millimeters (mm) (3.0 inches 
(in)) standard length (SL) (Moyle et al. 2001). Suisun Marsh includes 
the largest areal extent of shallow water habitat available to the 
splittail and likely has the greatest concentrations of the species.
    Splittail are relatively long-lived and larger fish may be 8 to 10 
years old (Moyle 2002). Splittail reach about 110 mm (4.3 in) SL in 
their first year, 170 mm (6.6 in) SL in their second year, and 215 mm 
(8.4 in) SL in their third year (Moyle 2002). Male and female splittail 
may mature by the end of their second year (Daniels and Moyle 1983), 
but some males mature in their first year and some females do not 
mature until their third year (Caywood 1974).
    The largest females can produce over 250,000 eggs per year (Daniels 
and Moyle 1983). Other and more current estimates of splittail 
fecundity have shown high variability and occasionally, lower numbers. 
Caywood (1974) found a mean of 165 eggs per mm (6.5 in) of SL of fish 
sampled and reported a maximum of 100,800 eggs in one female. Daniels 
and Moyle (1983) observed approximately 17,500 to 266,000 eggs per 
female splittail. Feyrer and Baxter (1998) found a mean of 261 eggs per 
mm (10.2 in) of SL and estimated maximum fecundity at 150,000 eggs. 
Bailey et al. (1999) examined fish held for a considerable time in 
captivity and found that

[[Page 55141]]

fecundity ranged from 24,753 to 72,314 eggs per female, which agrees 
with Caywood's (1974) observations.
    Although primarily a freshwater species, splittail can tolerate 
salinities as high as 10 to 18 parts per thousand (ppt) (Moyle 1976; 
Moyle and Yoshiyama 1992). Salinity tolerance in splittail increases in 
proportion to length; adults can tolerate salinities as high as 29 ppt 
for short periods (Young and Cech 1996). Splittail populations 
fluctuate annually, depending on spawning success, which is well 
correlated with freshwater outflow and the availability of shallow 
water habitat with submerged vegetation (Daniels and Moyle 1983; Sommer 
et al. 1997). Fish typically reach sexual maturity by the end of their 
second year. The onset of spawning is associated with rising water 
levels, increasing water temperatures, and increasing day length. Peak 
spawning occurs from February through May, although records of spawning 
exist for late January to early July (Wang 1986). In some years, most 
spawning may take place within a limited period of time. For instance, 
in 1995, a year of high spawning activity, most splittail spawned over 
a short period in April, even though larval splittail were captured 
from February through early July (Moyle et al. 2001). Within each 
spawning season older fish reproduce first, followed by younger 
individuals (Caywood 1974).
    Splittail spawning occurs over flooded vegetation in tidal 
freshwater and brackish water habitats of estuarine marshes and sloughs 
and slow-moving, shallow reaches of large rivers. Observations of 
splittail spawning have indicated spawning at depths of less than 1.5 
meters (m) (4.9 feet (ft)) in the Cosumnes River floodplain (Moyle et 
al. 2001), and at depths of less than 2 m (6.6 ft) in Sutter Bypass 
(Moyle et al. 2001). Sommer and Harrell (1999) postulated that 
individual splittail may not spawn in the year following a successful 
effort.
    Splittail larvae remain in shallow, weedy areas close to spawning 
sites for 10 to 14 days and move into deeper water as they mature and 
swimming ability increases (Wang 1986; Sommer et al. 1997). Bailey 
(1994) has documented that splittail eggs hatch in 3 to 5 days at 18.5 
degrees centigrade ([deg]C), (65.3 degrees Fahrenheit ([deg]F)). Bailey 
(1994) also found that at 5 to 7 days after hatching, the yolk sac is 
absorbed and the diet begins to include small rotifers. Moyle et al. 
(2001) states that splittail of 20 to 25 mm (0.8 to 1.0 in) total 
length (TL) ``* * * are essentially small juveniles, capable of fairly 
active swimming'' and that 4 to 5 weeks post-hatch are required to 
reach this size class.
    It is speculated that Suisun Marsh is the likely late stage rearing 
area for juvenile splittail hatched and reared in the extensive 
spawning habitat found within the Yolo Bypass, as a hydrologic 
connection apparently exists between these waters (N. Monsen, unpubl. 
data referenced in Moyle et al. 2001). Splittail use of Suisun Marsh 
varies with outflow (Baxter 1999a).
    Splittail are benthic foragers. In Suisun Marsh, adults feed 
primarily on opossum shrimp (Neomysis mercedis, and presumably, non-
native shrimp species of the genus Acanthomysis as well), benthic 
amphipods (Corophium spp.), and other small crustaceans, although 
detrital material makes up a large percentage of their stomach contents 
(Daniels and Moyle 1983). In the Delta, clams, crustaceans, insect 
larvae, and other invertebrates also are found in the adult diet. More 
recently, research has indicated a shift in adult splittail diet 
towards the non-native Asiatic clam (Potamocorbula amurensis) in Suisun 
Marsh.
    Historically, Eurytemora affinis, the native euryhaline copepod, 
has been the most important food for larval fishes in the Estuary. 
Three non-native species of euryhaline copepods (Sinocalanus doerrii, 
Pseudodiaptomus forbesi, and Pseudodiaptomus marinus) became 
established in the Delta between 1978 and 1987 (Carlton et al. 1990), 
while native E. affinis populations have declined since 1980. It is not 
known if the non-native species have displaced E. affinis or whether 
changes in the estuarine ecosystem now favor S. doerrii and the two 
Pseudodiaptomus species. Meng and Orsi (1991) reported that S. doerrii 
is more difficult for larval striped bass to catch than native copepods 
because it is fast swimming and has an effective escape response. It is 
not known if this difference in copepod swimming and escape behavior 
has affected the feeding success of young splittail. Zeug et al. (2002) 
and Hieb (2002) reported a high abundance of an introduced, predatory 
Palaemonid shrimp (Exopalaemon modestus) in the Yolo Bypass and Delta. 
It is not known what effect(s) this invasive species will have on the 
trophic (food) pyramid of the estuary, though Moyle (2002b) speculates 
it is likely to prey on mysid shrimp and thus, may compete with 
splittail for food. Juvenile feed mainly on plankton composed of small 
animals (zooplankton), and then small crustaceans and insect larvae as 
body size increases.
    Predators of splittail include striped bass (Morone saxatilis), 
largemouth bass (Micropterus salmoides) and other centrarchids, and 
other native and non-native piscivores (Moyle 1976, Moyle 2002a). 
Introduced, non-native benthic foragers such as shokihaze goby 
(Tridentiger barbatus), chameleon goby (T. trigonocephalus), and 
yellowfin goby (Acanthogobius flavimanus), may feed on splittail eggs. 
Introduced planktivorous, threadfin shad (Dorosoma petenense) and 
inland silverside (Menidia beryllina), compete directly with larval and 
juvenile splittail for food. Other non-native cyprinids, such as golden 
shiner (Notemigonus crysoleucas), red shiner (Notropis lutrensis), and 
fathead minnow (Pimephales promelas) are also likely to compete with 
splittail. In recent years, splittail have been found most often in 
slow moving sections of rivers, sloughs, and in dead end sloughs (Moyle 
1976, Daniels and Moyle 1983). Reports from the 1950's, however, 
mention Sacramento River spawning migrations and catches of splittail 
during fast tides in Suisun Bay (Caywood 1974). Current accounts place 
splittail as far upstream as the Red Bluff Diversion Dam on the 
Sacramento River (Baxter 1999a). Splittail have been recorded in recent 
times from within Salt Slough and at the Merced River confluence on the 
San Joaquin River, and within the Napa and Petaluma Rivers (Baxter 
1999a, 1999b; USACE 2002a, 2002b).
    Splittail are frequently found in areas subject to flooding because 
they require flooded vegetation for spawning and rearing. Historically, 
the major flood basins (e.g., Colusa, Sutter, American, and Yolo 
basins; Tulare, Buena Vista, and Kern lakes) distributed throughout the 
Sacramento and San Joaquin valleys provided spawning and rearing 
habitat. These flood basins have all been reclaimed or modified for 
flood control purposes (i.e. as bypasses), and much of the floodplain 
area adjacent to the rivers is now inaccessible behind levees. The Yolo 
Bypass may approximate some of the Yolo Basin's former role, and the 
Butte Creek, Butte Sink, Sutter Bypass system remains somewhat intact. 
Meng and Moyle (1995) reported that the core distribution of splittail 
extends from Suisun Bay and Marsh through the western Delta.
    The Yolo and Sutter bypasses and the Cosumnes River floodplain 
serve as important splittail spawning and early rearing habitat (Sommer 
et al. 1997), as they approximate the large, open, shallow water areas 
which have been extensively reduced. The Yolo and Sutter bypasses 
provide good habitat for fish, particularly splittail, when flooded for 
several weeks in March and April. To provide the best spawning

[[Page 55142]]

conditions for splittail, water must remain on the bypasses until fish 
have completed spawning, and larvae are able to swim out on their own, 
during the draining process. The Cosumnes River also possesses natural 
and restored floodplain features. This river is unique in that it is 
not dammed and the hydrograph is relatively natural. The contributions 
made by this habitat are somewhat limited by the fact that the Cosumnes 
River watershed is lower in elevation than most adjacent rivers. It is 
therefore somewhat less dominated by the extended spring peak flow 
characteristic of a higher altitude watershed with greater snowmelt 
potential.
    In summary, the current distribution of splittail habitat is 
certainly reduced at least 20% and may be much more reduced in extent 
from that which may have historically been present. Clearly, perhaps 
the largest portion of the splittail's habitat is contained in the 
natural and newly restored floodplains of the Cosumnes River, managed 
floodplains such as the Yolo and Sutter bypasses, disjunct segments 
adjacent to the Sacramento and San Joaquin rivers and in lower reaches 
of their respective tributaries.
    In years where the Yolo and Sutter bypasses are not sufficiently 
inundated, splittail spawning is confined primarily to the natural and 
newly restored floodplains of the Cosumnes River and the margins of 
rivers and other floodplain features that are inundated at lower river 
stages. These areas likely represent only a fraction of the area which 
was historically subject to inundation; levees preclude access to 
reclaimed floodplains and basins. There are indications, based on 
presence of larvae and juveniles, that spawning in the Sacramento River 
occurs relatively far upstream at Colusa (Baxter 1999a; 1999b). 
Splittail appear to utilize the San Joaquin River in wet years when 
appreciable runoff exceeds the capacity for storage and diversion of 
runoff. The Tuolumne, Cosumnes, Feather, American, Napa, and Petaluma 
rivers, and numerous other smaller waters support splittail spawning 
activity. Early indications are that the Napa River may contain a 
robust subpopulation of splittail (USACE 2002a, 2002b).

Abundance

    Seven sampling programs capture splittail frequently enough to 
allow the calculation of useful abundance indices. These programs are: 
(1) CDFG's Fall Midwater Trawl (Fall MWT); (2) CDFG's San Francisco Bay 
Midwater Trawl (Bay Study MW); (3) CDFG's San Francisco Bay Otter Trawl 
(Bay Study OT); (4) University of California (UC) Davis's Suisun Marsh 
Otter Trawl (Suisun Marsh OT); (5) Service's Chipps Island Trawl survey 
(Chipps Is. Trawl); (6) fish salvage operations (which repatriate fish 
taken from water intake screens) at the CVP Tracy Fish Collection 
Facility (CVP); and (7) fish salvage at the SWP Skinner Delta Fish 
Protective Facility in the south Delta (SWP).
    Four other sampling programs provide additional splittail 
information but the data are insufficient to support useful indices. 
These are: (1) Service's Delta Beach Seine Survey; (2) CDFG's Summer 
Townet Survey; (3) U.S. Army Corps of Engineers' (USACE) Napa River 
Survey; and (4) CDFG's Creel Census.

Surveys Employed in Abundance Analyses

    The data available even today on splittail abundance are not 
optimal. There are a number of survey programs which generate data, 
each of which have more or less limiting factors. This has made 
analysis of the status of the species based on this survey data 
problematic. Descriptions of all fisheries sampling programs that 
routinely detect splittail follow, and are differentiated into two 
categories: those that were used in the calculation of abundance 
indices and those that were not.

Fall Midwater Trawl Survey

    The Fall MWT was initiated by CDFG in 1967 to sample striped bass, 
a non-native sport fish. In addition to striped bass, CDFG has 
maintained records of other fish species captured in the samples in 
most years. This monitoring program currently samples 100 sites from 
San Pablo Bay in the west to Rio Vista on the lower Sacramento River 
and to Stockton on the San Joaquin River. Data are collected from 
September through December using a midwater trawl with a 3.7 square m 
(39.8 square ft) wide mouth. Unlike the summer townet survey, the Fall 
MWT survey catches all splittail size classes, although larger fish are 
more likely to evade capture. Catches of splittail are generally low in 
number because splittail generally reside and feed on the channel 
bottom. Furthermore, splittail apparently use shallow (less than 6 m 
(19.7 ft)) and near-shore waters to a higher degree than open channels. 
The Fall MWT does not sample edge waters, and the proportion of samples 
in shallow water stations varies by region: 20 of 35 stations in San 
Pablo Bay; 1 of 18 in Carquinez Strait; 8 of 25 in Suisun Bay/Marsh; 
and 1 of 38 in the Delta. A monthly abundance index for splittail 
captured by the Fall MWT is calculated by grouping the samples by area 
(17 areas) and then calculating an area weighted average catch from 
each area; the index is the sum of these area weighted mean catches. 
The annual Fall MWT Index is the sum of the four monthly indices. 
Splittail lengths were not recorded until 1975, so for data collected 
prior to 1975, Young Of Year (YOY) (age 1) fish could not be 
differentiated from other age classes. Fall MWT data from 1967 through 
2002 was used in our abundance analysis.

San Francisco Bay Studies

    The San Francisco Bay Studies sample waters west of the Delta 
seaward to south San Francisco Bay using both a midwater trawl (Bay 
Study MWT) and an otter trawl (Bay Study OT) (Baxter 1999a). These 
programs capture relatively few splittail, but are still considered 
important because they involve two types of sampling equipment and 
frequent sampling (Baxter 1999a). Much of the sampling takes place in 
San Francisco Bay in deep water channels that are not characteristic 
splittail habitat. Monthly indices are calculated as the sum of 
regional volume-weighted average catch per 10,000 cubic meters (m\3\) 
(353,147 cubic feet (cf)) for the Bay Study MWT and the sum of regional 
area-weighted average catch per 10,000 m \3\ (353,147 cf) for the Bay 
Study OT (Sommer et al. 1997). During the 1997 index period, the Bay 
Study MWT collected only one YOY, and the Bay Study OT collected none 
at index stations. The tremendous variability in this survey's catch is 
likely due to the rare or limited occurrence of individuals splittails 
at the periphery of its range, which would result in limited 
detectability during sampling. Splittail can be expected to be captured 
in San Francisco and San Pablo bays only during time of infrequent, 
high outflow, when captures appear to increase for all net-based gear 
types. San Francisco Bay Studies data from 1980 through 2002 was used 
in our abundance analysis.

Suisun Marsh Otter Trawl

    The Suisun Marsh OT surveys began in 1979 and are conducted by the 
University of California (UC) Davis as part of a long-term study of the 
ecology of the entire fish community of the marsh. Data from the 1979 
survey have been excluded from our abundance analysis as greater 
sampling effort was employed in 1979 than in all subsequent years (Dr. 
Peter Moyle, pers. comm.). The survey is funded by California 
Department of Water Resources (CDWR) in part to determine if management 
actions in Suisun Marsh are affecting fish communities. The program 
samples 21 sites monthly in

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nine sloughs with an otter trawl that drags along the bottom and 
samples much of the water column in the shallow sloughs. In small 
sloughs, the trawl samples much of the cross sectional area; in large 
sloughs, the sampling fraction is smaller. A monthly abundance index is 
calculated as mean catch per trawl. The annual abundance index is 
calculated as the mean of the monthly index values (Sommer et al. 
1997). While the splittail catches are dominated by YOY, the sampling 
also consistently catches larger fish. In this regard, the Suisun Marsh 
OT sampling of splittail is perhaps the most thorough of the various 
sampling programs. Splittail collection in the Marsh is enhanced by 
reduced gear avoidance in narrow, relatively shallow sloughs sampled as 
part of the monthly survey. In such conditions, the net samples a 
larger proportion of the channel cross sectional area than in any other 
survey. Larger sizes of splittail, however, apparently become 
progressively less vulnerable to the trawls, a limitation shared by all 
trawl-based surveys. Spawning occurs only sporadically in the marsh, 
and in most years YOY recruit from upstream in the Sacramento River, 
including the bypasses (Sommer et al. 1997). Recent modeling studies 
indicate that the Yolo Bypass, a major spawning and nursery area, may 
be hydrologically connected to Suisun Marsh (N. Monsen, Stanford 
University, unpubl. data) so juvenile trends in the marsh are likely to 
be heavily influenced by upstream production in the Yolo Bypass during 
those years when inundated for a sufficient period of time. Suisun 
Marsh Otter Trawl data from 1980 through 2001 was used in our abundance 
analysis.

Chipps Island Survey

    The U.S. Fish and Wildlife Service conducts a sampling program for 
juvenile salmon in the deep water channel near Chipps Island at the 
western terminus of the Delta. A midwater trawl is pulled at the 
surface in ten 20 minute hauls per day during May and June (Sommer et 
al. 1997). Data are compiled to produce an index based on the catch per 
hour of trawling for the months of May and June combined (Sommer et al. 
1997). The program was initiated in 1975, but data before 1979 must be 
viewed with some caution as many splittail were not measured (Baxter 
1999a); as only data related to the number of splittail caught were 
recorded. Length data from 1987 through 1993 was recorded such that 
determinations of age from the data cannot be done, and is therefore 
inadequate to calculate age-specific abundance indices. The Age 0 index 
reached minor peaks in 1982 and 1986, declined to low levels during the 
1987-1992 drought (based on total splittail catch), then increased 
sharply to a record level in 1995; minor peaks occurred in 1998 and 
2000, and remaining data tracked water year variability. For Age 1 
splittail, the Chipps Island index for the period 1976 to 2001 shows 
high variability.
    The Chipps Island trawl seems to sample splittail best in high 
outflow years when all age groups are more vulnerable to trawls due to 
increased turbidity, as is likely true for all gear types and surveys. 
It is, however, difficult to discern actual abundance from year biases, 
and turbidity can be high at Chipps Island regardless of outflow. 
Regardless, because the trawl captures fish only in the top couple of 
meters (or yards) of water in open channels, relatively low numbers of 
the benthic-foraging splittail are caught. The indices are probably 
less precise at low population levels due to the infrequent captures of 
splittail, a characteristic shared by all surveys. The Chipps Island 
Survey data from 1976 through 2002 was used in our abundance analysis.

Central Valley and State Water Project (CVP and SWP) Fish Salvage

    The CVP and SWP operate fish screening facilities to divert fish 
away from the pump intakes into holding facilities where they are 
counted, measured, and released. Data collection takes place at two 
hour intervals when the pumps are operating. Consequently, the fish 
salvage operations provide the highest number of splittail caught per 
survey, but the number of data points (annual indices) is comparable to 
the other surveys. All splittail age groups are collected, the surveys 
do not suffer from gear avoidance by fish, and sampling locations do 
not vary over time. Reliable CVP data and SWP data both start in 1979. 
The salvage abundance index is calculated based on the total number of 
fish salvaged divided by the volume of water pumped (Sommer et al. 
1997). However, the pumps are not operated as sampling programs per se 
so the amount of ``sampling'' is related to the amount of water 
exported, which in turn is related to the amount of water available, 
water demand, and, in recent years, changes in pump operations to 
protect migratory salmon, splittail, and delta smelt (Hypomesus 
transpacificus) and to maintain appropriate salinities in Suisun Bay 
and Marsh. Also, the Salvage index does not address catch per volume 
per unit time. Lacking a time factor, the Salvage index may not 
adequately describe the differential variability in catch that may 
occur as approach velocities at Clifton Court Forebay (SWP) or Old 
River (CVP) change.
    Unlike the CVP and SWP salvage, several surveys do not account for 
the volume per unit time sampled. Trawl data, presented as fish 
captured per volume of water sampled, do not describe the trawl speed, 
or the perceived trawl approach speed when pulled against a current. 
Seine indices are expressed as catch of fish per haul and do not 
include factors for catch per unit volume and/or per unit time. Seines 
are employed at sites with low water velocities, but variation in 
velocity within and between sampling locations likely exists. Trawls 
and seines may be more effective when employed through higher velocity 
waters; splittail may be more vulnerable to capture when already 
navigating swifter currents. Trawls, seines, and pumps therefore share 
a common difficulty in expressing catch per unit volume per unit time. 
Each of these techniques may also differentially detect splittail under 
turbid conditions. The pumps differ from trawling and seining, however, 
in that the pumps may differentially entrain (collect) weak swimming 
juvenile and fatigued post-spawn adult splittail as velocities towards 
the facilities vary. Regardless of boat or current speed, or turbidity, 
trawls and seines do not draw fish towards them, whereas the pumps may. 
The SWP catch also does not account for the predation that occurs in 
the Clifton Court Forebay, nor the latent mortality that may occur when 
salvaged fish are released.
    Comparisons between CVP and SWP salvage and other sampling 
operations have to be made with caution. Nevertheless, the general 
patterns are similar to other studies, with diminished catches of both 
adults and juveniles during periods of drought and large catches of 
juveniles following wet winters. The CVP and SWP fish salvage data from 
1979 through 2002 was used in our abundance analysis.

Surveys Not Employed in Abundance Analyses

US Fish and Wildlife Service Beach Seine Survey

    The survey provides the broadest geographical coverage of all of 
the sampling programs but is focused on outmigrating juvenile 
salmonids. The beach seine primarily captures YOY splittail but any 
fish less than 25 mm (1 in) long are not identified. The limited data 
show low catches of splittail during

[[Page 55144]]

dry years and higher catches during wet years, reinforcing the concept 
of a strong outflow-production relationship. This general relationship 
may, however, be due to other factors. For example, turbidity may be 
higher in high outflow years, thus rendering fish more vulnerable to 
capture.

Summer Townet Survey

    The CDFG summer townet survey began in 1959 to provide an index of 
striped bass abundance. It samples YOY fish twice monthly at 30 sites 
using oblique tows in mid-channel. Starting and ending dates vary from 
year to year. Sample sites are located throughout the Delta, Suisun 
Bay, and San Pablo Bay. Data for species other than striped bass were 
not regularly recorded until after 1962, but were also not recorded in 
1966, 1967, and 1968 (Sommer et al. 1997). The survey catches only low 
numbers of YOY splittail, presumably because it focuses on pelagic 
(open water) habitats while splittail are benthic in orientation. Not 
surprisingly, splittail catch varies widely and the index reflects only 
gross changes in YOY splittail abundance. The index peaked in 1982, was 
low during the 1987 to 1992 drought years, and abruptly rebounded in 
1995 and 1998 (Baxter 1999a, 1999b).

Napa River Survey

    This survey exists in association with a flood control and 
ecosystem restoration project in the Napa River. It is performed by 
consultants under contract to USACE, and involves a range of sampling 
techniques including beach seine, purse seine, otter trawl, fyke nets, 
and a 20 mm (0.8 in) size class surveys. The Napa River Survey began 
sampling in March 2001 and has detected splittail (USACE 2002a, 2002b) 
but the data are too recent and of too short a term (two years, 
including 2002 unpublished data) to be useful for an abundance index. 
The survey is scheduled to be completed in 2007 or 2008, after 7 years 
of data collection. Additionally, the Napa River is less well 
understood in terms of relationships between outflow, splittail 
habitat, and splittail production, than are the Central Valley rivers 
and the Delta. As such, the variables employed in our current analysis 
of abundance and trend (see Abundance section, below) cannot be applied 
to this distinct river system at this time.

California Department of Fish and Game Creel Census

    CDFG collects creel census data in association with the Sacramento 
River System Angler Survey. This survey was initially conducted from 
August, 1989, to December, 1994, and was resumed in 1999 and 2000. 
Adult splittail catch data were only recorded during 1991 through 1994, 
and in 1999 and 2000. This survey collected angler count, fishing 
effort and fish catch information on the Sacramento River from Redding 
to Carquinez Bridge year round with the same effort, 4 week days and 4 
weekend days per month per section, so changes in catch can reflect 
fish presence related to angler effort.
    To reflect only the presence of migrating fish, Baxter (2001b) 
analyzed only catch data from Garcia Bend (RKM 80 (RM 50)) and 
upstream. Creel census data from 1991 through 1994 indicated a total 
annual catch of 114, 266, 498, and 110 splittail, respectively. The 
1999 and 2000 censuses yielded an annual catch of 103 and 232 
splittail, respectively. These catches represent 96 days of survey 
effort each year and are useful primarily to help establish the periods 
in which adult splittail migrate upstream. No abundance indices were 
calculated by any agency, organization, or individual from these data, 
as they fail to meet the criteria established by Meng and Moyle (1995) 
and are generally considered inadequate to the task of quantifying 
splittail abundance.

Survey Summary

    All fish sampling methods may inherently suffer from a selection 
bias. This bias results from the particular method and must be 
considered when interpreting results. Because none of the surveys were 
designed specifically to monitor splittail populations, the survey 
equipment, survey locations, and sampling frequency must all be taken 
into consideration when interpreting the data. All the survey 
methodologies appear to sample young of the year (YOY) most 
effectively. As a result conclusions regarding YOY abundance appear to 
be the most accurate and reliable. Combined information from all survey 
efforts suggest that some successful reproduction occurs every year, 
but large numbers of young are produced only during years of relatively 
high outflow (wet years). This suggests that the majority of adult fish 
in the population result from spawning in wet years and lowest numbers 
are produced during drought years. The distribution and timing of YOY 
in the surveys also indicates that most spawning takes place in the 
bypasses, rivers or upper Delta, although some sporadic spawning also 
takes place in Suisun Marsh. It must be recognized, however, that YOY 
abundance may not be an entirely accurate indicator of adult abundance 
because there exists no observed stock-recruitment relationship 
(relationship between the number of adult fish and the number of 
offspring typically expected to join the adult population) in splittail 
(Sommer et al. 1997; Moyle 2002). Consequently, YOY abundance may not 
describe the current of future population sizes or trends.

Abundance Trend Analyses

    We initially evaluated and analyzed the aforementioned data series 
using a method published by Meng and Moyle (1995) in the Transactions 
of the American Fisheries Society. This method was used during the 
initial status review for the splittail and was again employed during 
the development of the proposed rule to list the splittail (59 FR 862). 
This same method was replicated during the development of the final 
listing rule published on February 8, 1999, (64 FR 5963) using 
abundance data provided and updated by CDFG, CDWR, and UC Davis. The 
Meng and Moyle (1995) methodology (see 66 FR 2828 for complete 
description of methods) has been superceded by more current models 
employed by CDFG, and was not used to help us make this final 
determination. Further, this removal does not discuss the more recently 
available analytical methods such as permutation-based exact 
calculations of p-values for stratified (as opposed to unstratified) 
Mann-Whitney U-tests, as appeared in the August 17, 2001, notice (66 FR 
43145) where we presented an updated statistical analysis of abundance 
data for the Sacramento splittail and requested comments on it. While 
these stratified Mann-Whitney U-tests represented an improvement on 
what essentially remained a Meng and Moyle (1995) statistical approach, 
and presented a major alternative to the categorical (i.e., ``before'' 
and ``after'') approaches of both Meng and Moyle (1995) and Sommer et 
al. (1997), substantive scientific and statistical issues raised during 
the August 17, 2001, (66 FR 43145) public comment period resulted in 
our using an alternative statistical analysis to help us make this 
final determination. The following details the history and findings of 
the current analysis.
    In an August 17, 2001, notice (66 FR 43145) we presented an updated 
statistical analysis of abundance data for the Sacramento splittail and 
invited public comments on the analysis and data, in specific technical 
review of the information. We concurrently sought peer review on the 
statistical analysis from five subject-area experts affiliated with a 
total of five agencies and organizations. Requests for peer review

[[Page 55145]]

were sent to: (1) Dr. Peter B. Moyle of UC Davis, Davis, California; 
(2) Dr. Charles H. Hanson of Hanson Environmental, Inc., Walnut Creek, 
California; (3) Randall D. Baxter of CDFG, Central Valley/Bay-Delta 
Branch, Stockton, California; (4) Michael Chotkowski of the USBR, Mid-
Pacific Region, Sacramento, California; and (5) Ted R. Sommer of CDWR, 
Environmental Services Office, Sacramento, California.
    Following careful consideration of comments received from numerous 
respondents to the August 17, 2001, notice, including those provided 
through the peer review process, we concluded that the abundance 
indices and Multiple Linear Regression (MLR) model jointly developed 
and submitted by CDFG (2001) and USBR (2001), hereafter referred to as 
the CDFG/USBR MLR Model, provided the best scientific data (method) 
available, for statistically evaluating temporal trends of splittail 
abundance information. The CDFG/USGS MLR Model thus superceded the 
permutation-based exact calculations of p-values for stratified (as 
opposed to unstratified) Mann-Whitney U-tests.
    On March 21, 2002, (67 FR 13095), we reopened the public comment 
period (67 FR 13095;67 FR 15337) to solicit comments on the CDFG/USBR 
MLR Model. We again sought peer review on the statistical analysis from 
the five individuals identified above. We have retained the CDFG/USBR 
MLR Model, albeit in a slightly modified form, after consideration of 
all public comments received, inclusive of this and preceding comment 
periods.
    The CDFG/USBR MLR Model includes HYDROLOGY and TIME (year) as 
independent variables and ABUNDANCE INDICES as the dependent variable. 
We consider this statistical approach superior to the previous practice 
of using Mann-Whitney U tests (Meng and Moyle 1995; Sommer et al. 1997) 
because it does not require arbitrarily dividing an inherently 
continuous data set into ``before'' and ``after'' categories (see 
previous discussion of this issue in the August 17, 2001, notice; 66 FR 
43145). We consider the CDFG/USBR MLR Model superior to the polynomial 
regression model presented in the August 17, 2001, notice (66 FR 43145) 
because existing abundance index monitoring programs have not been 
conducted for a sufficient duration to provide for reasonably 
conclusive application of the polynomial model (as concluded in the 
August 17, 2001, notice (66 FR 43145)). We also support use of the 
CDFG/USBR MLR Model because of the facility with which it can be 
applied to all sets of splittail age class data from all seven 
applicable abundance monitoring data sets (Fall MWT, Bay Study OT, Bay 
Study MWT, Chipps Island, Suisun Marsh, CVP salvage, and SWP salvage). 
The seven surveys include a total of 20 discrete sets of age-specific 
abundance monitoring data. These 20 datasets consist of the 2 age 
classes (0 and 1 or more) for the Suisun OT, in addition to the 3 age 
classes (0, 1, and 2 or more) for each of the other 6 surveys.
    The CDFG/USBR MLR Model explicitly controls for potential 
confounding effects of hydrological year type, the factor that is 
nearly unanimously viewed as the single strongest predictor of 
splittail year class strengths (e.g., Moyle et al. 2001), by utilizing 
the number of days total delta inflow (DAYFLOW, California Department 
of Water Resources' mathematical hydrology model) exceeds 1,557 cubic 
meters per second (cms) (55,000 cubic feet per second (cfs)) during the 
February through May spawning/rearing period as a predictor 
(independent variable). The 1,557 cms (55,000 cfs) variable was 
selected because it approximates the critical inflow value above which 
Delta floodplains, especially the key splittail spawning area in the 
Yolo Bypass, become inundated. The 1,557 cms (55,000 cfs) variable thus 
captures the existence of appreciable bypass and spawning habitat 
inundation. This is conceptually comparable, yet superior, to the 
stratified Mann-Whitney U tests presented in the August 17, 2001, 
notice (66 FR 43145), which also controlled for hydrological year type. 
There is, however, one potentially important assumption associated with 
the CDFG/USBR MLR Model that remains untested, and that concerns the 
assumption of a lack of interaction between the HYDROLOGY and TIME 
variables. In essence, the CDFG/USBR MLR Model assumes that the long 
term probabilities of high and low flow water years are random.

Discussion of CDFG/USBR MLR Model results

    The results addressed in this discussion differ somewhat from those 
published previously (67 FR 13095) due to the inclusion of new data for 
2001 and 2002 in some of the indices as it has become available (see 
discussion of each survey, above). We also removed from the analysis 
data taken for the Suisun OT in 1979, based on comments received from 
the USBR (2002) indicating that differing survey protocols were used in 
1979 as compared to other years.
    The question of how to analyze the less-than-optimal data we have 
on splittail was vexing. In large part we have accepted the statistical 
model provided to us by CDFG and USBR. However, while our approach was 
generally consistent with theirs, there are two major differences. 
First, we used all 20 data sets weighted equally; whereas the BOR and 
CDFG recommended that the data sets be weighted by their relative 
importance. Second, we accepted a 20 percent risk that we would wrongly 
conclude there is a downward trend in the population for each of the 20 
data sets in order to reduce the risk that we would fail to detect a 
trend if, in fact, one exist. We used this approach in order to ensure 
our assumptions were conservative. The effect was to establish a 
``worse-case'' scenario with respect to the status of the populations 
when we conducted our threats analysis. As a result, our interpretation 
of the model results differs from theirs.
    Our model results indicate that fifteen of twenty data sets have a 
downward trend, more downward trending data sets than we would expect 
based on chance. Typically, statisticians decide whether such trends 
are ``statistically significant'' or not. Interpreting the model 
results using the classic statistical standard (p  0.05) for 
determining significance, we find that five of the fifteen downward 
trends are statistically significant. CDFG and USBR believe that this 
result is insufficient to make a determination that the splittail is 
declining in abundance. By adopting the more relaxed standard (p 
 0.20), we increase the likelihood that a significant result 
will be identified, a conservative approach. Taking this approach (p 
 0.20), we find nine significant downward trending data sets 
and two significant upward trending data sets. We believe that the 
existing data sets constitute the best available scientific information 
and that our more conservative approach indicates a number of 
significant declining splittail population trends exist. Coupled with 
the CDFG and USBR results, we have bracketed the range of possibility 
regarding the population status of the species as a whole. We believe 
this range is the best context for us to use when we conduct our 
threats analysis.
    We fully concur with the statements of various respondents that 
abundance monitoring data for splittail have methodological weaknesses 
of one sort or another; none of the surveys were designed specifically 
to rigorously measure splittail population numbers (see Moyle et al. 
2001; Meng and Moyle 1995; and Sommer et al. 1997 for

[[Page 55146]]

descriptions of surveys). However, existing data sets do constitute the 
best available scientific information for the species.
    While our conservative approach to analyzing that information is 
more likely to produce results indicating that significant declining 
splittail population trends exist, we believe that using this ``worst 
case'' scenario in analyzing the impacts reported in the section 
entitled Summary of Factors Affecting the Species is most likely to 
result in a listing finding that is robust.
    Because we have chosen to adopt the CDFG/USBR MLR Model jointly 
submitted by CDFG and USBR (as our primary basis for abundance 
analyses), and are no longer using our analysis in our August 17, 2001 
notice (66 FR 43145), specific comments on our analysis in our August 
17, 2001 notice (66 FR 43145) will not be addressed in the section 
entitled Summary of Comments and Recommendations.

Previous Federal Action

    On February 8, 1999, we published a final rule listing the 
splittail as threatened under the Act (64 FR 5963). Please refer to the 
final rule for a discussion of Federal actions prior to the publication 
of the final rule. At the time of our final determination of threatened 
status for the splittail, the splittail population had declined in both 
numbers and range and was primarily threatened by changes in water flow 
and water quality resulting from the export of water from the 
Sacramento and San Joaquin Rivers, periodic prolonged drought, loss of 
shallow water habitat, introduced aquatic species, and agricultural and 
industrial pollutants.
    Subsequent to the publication of the final rule, plaintiffs in the 
cases San Luis & Delta-Mendota Water Authority v. Anne Badgley,[deg] et 
al. and State Water Contractors, et al. v. Michael Spear, et al. 
commenced action in the Federal Eastern District Court of California, 
challenging the listing of the splittail as threatened, alleging 
various violations of the Act and of the Administrative Procedure Act 
(5 U.S.C 551 et seq.), specifically that we: (1) Failed to use the best 
scientific and commercial data available; (2) ignored all pre-1980 and 
post-1992 data available and that we used only selected data from the 
1980 to 1992 period; (3) did not publish a summary of the available 
data, which data we considered, and the relationship between the data 
and our decision on the final rule; and (4) promulgated the final rule 
in a manner that was arbitrary, capricious, and not in accordance with 
law, in that the splittail did not meet the definition of a threatened 
species as set forth in the Act.
    On June 23, 2000, the Court rendered summary judgment in the two 
cases in favor of the plaintiffs, finding that our promulgation of the 
final rule listing the splittail as threatened was unlawful. On 
September 22, 2000, the court remanded the determination of whether or 
not the splittail is a threatened or endangered species to us. The 
court ordered us to re-evaluate our final determination and publish a 
new finding within 6 months of the date of the remand order, and kept 
the rule in effect during that period. The court used its equitable 
powers to retain the protections of the Act for the species during the 
remand of the rule to the Service.
    On January 12, 2001, we reopened the comment period for 30 days to 
seek information regarding the splittail's status, abundance and 
distribution, as well as information regarding issues identified by the 
District Court in its June 23, 2000, judgment (66 FR 2828). At that 
time, we were subject to a court-ordered deadline of March 22, 2001. On 
March 16, 2001, we received an extension from the District Court until 
June 22, 2001, so that we could reopen the comment period. Subsequent 
to that extension, we reopened the comment period for the second time 
since the remand, from May 8, 2001 to June 7, 2001 (66 FR 23181). On 
June 28, 2001, we received an additional extension from the court so 
that the comment period could be reopened and we could have additional 
time to obtain reviews of the revised statistical analyses which we 
employed in response to prior comments. The comment period was then 
opened on August 17, 2001 (66 FR 43145); while the court ordered 
decision date was established as January 31, 2002. We later received an 
additional extension from the court until October 15, 2002, so that we 
could seek comments on the MLR Model submitted by CDFG and USBR during 
the August 17, 2001, comment period. On March 21, 2002, we reopened the 
comment period for the fourth time since the remand (67 FR 13095) and 
on April 1, 2002, we corrected the duration of the comment period to 
reflect 60 days (67 FR 15337). On October 31, 2002, we received an 
additional extension from the court so that the comment period could be 
reopened for a fifth time since the remand (67 FR 66344) to solicit 
comments on the revised statistical analysis we had done, as described 
in our March 21, 2002 document (67 FR 13095). Finally, on February 28, 
2003, the court approved a joint stipulation requiring us to submit our 
final determination to the Federal Register for publication on or 
before September 15, 2003. This final determination is in compliance 
with that joint stipulation agreement.

Summary of Comments and Recommendations

    During the five comment periods following the remand, we contacted 
all appropriate State and Federal agencies, Tribes, county governments, 
elected officials, and other interested parties and invited them to 
comment. We have requested that all interested parties submit factual 
reports or information that might contribute to the development of a 
final determination. In addition, we have invited public comment 
through the publication of notices in various newspapers. We published 
notice of the January 12, 2001, reopening of the comment period in the 
Sacramento Bee, Fresno Bee and Contra Costa Times newspapers. For the 
May 8, 2001, notice, we invited public comment through publication of 
notices in the Antioch Ledger-Dispatch, the Marysville Appeal-Democrat, 
the Fresno Bee, and the Sacramento Bee. For the August 17, 2001, 
reopening notice we invited public comment through publication of 
notices in the Marysville Appeal-Democrat, the Fresno Bee, and the 
Sacramento Bee. An electronic mail address for submission of comments 
was provided in the May 8, 2001, and August 17, 2001, notices and was 
posted on the Sacramento Fish and Wildlife Office's official web site. 
For the March 21, 2002 reopening notice, we invited public comment 
through publication of notices on March 27, 2002, in the Marysville 
Appeal-Democrat, the Sacramento Bee, and the Fresno Bee. An electronic 
mail address was not provided for the March 21, 2002, reopening due to 
uncertainties regarding our internet access. An electronic mail address 
was, however, provided with our April 1, 2002, correction, and with our 
October 31, 2002, reopening. We also sent out notices of each reopening 
of the comment period to all parties on a mailing list for Sacramento 
splittail information.
    During the five comment periods opened since the remand, we 
received a total of 33 written comment letters representing 1 Federal 
agency, 2 State agencies, 2 local governments, and 13 private 
individuals or organizations. We reviewed all comments received for 
substantive issues and new information regarding the status of the 
Sacramento splittail. Of the comments we received, only 3 supported 
listing. Information contained in these comments was reviewed to 
determine if it raised any

[[Page 55147]]

new substantive issues that had not been raised in comments previously 
submitted, and subsequently addressed in this final determination.
    The following is a summary of comments we received during the 197 
days associated with the five comment periods opened since the remand 
of the final listing rule. For additional information on comments 
received during three previous comment periods before the current 
litigation, please see the previous final listing rule (64 FR 5963). 
Substantive comments and information raised or provided during the 
public comments periods have either been incorporated directly into 
this notice or addressed below.

Peer Review

    As previously discussed in the above abundance section, we 
requested 5 biologists to provide scientific review of the proposed 
listing of the splittail as threatened. Technical data provided by the 
peer reviewers have been incorporated into or addressed in this 
document, while other issues raised by the peer reviewers are addressed 
below.
    Peer Reviewer Comment 1: A peer reviewer cited the ``White Paper'' 
(Moyle et al. 2001) for splittail as raising the possibility that 
abundance may not be a reliable measure of population status for the 
splittail.
    Our Response: We acknowledge that abundance may not be the most 
reliable measure of population status, but assert that it is the best 
scientific measure available. The utility of abundance as a measure of 
splittail population status is reflected in its continued use by the 
scientific community including researchers (Meng and Moyle 1995, Sommer 
et al. 1997) and agencies (CDFG, CDWR, USBR).
    Peer Reviewer Comment 2: A peer reviewer cited the ``White Paper'' 
(Moyle et al. 2001) for splittail as reporting a tentative population 
model result that stated, ``* * * a long series of dry years is 
unlikely to drive the splittail to extinction, even if the population 
is greatly reduced.'' Another peer reviewer asserted that if the 
splittail were truly going extinct, all surveys would show a decline.
    Our Response: A species warrants listing as threatened under the 
Act if is in danger of becoming endangered in the foreseeable future 
throughout all or a significant portion of its range (16 U.S.C. 
1532(20)). It is possible for the splittail to be undergoing threats or 
declines in a significant portion of its range without declines showing 
in all surveys. Alternatively, threats to the splittail may support 
listing even in the absence of our ability to document current 
population declines. However, even considering our conservative 
analysis of the apparent splittail population declines and the threats 
analysis, we believe the conservation elements of the California State 
and Federal cooperative program (CALFED) and the Central Valley Project 
Improvement Act (CVPIA) programs adequately mitigate for these threats 
(please refer to Summary of Factors Affecting the Species section for a 
detailed discussion of CALFED and the CVPIA).
    Peer Reviewer Comment 3: A peer reviewer submitted comments that 
included an analysis using a modified version of Meng and Moyle's 
(1995) pre-decline and post-decline method. The peer reviewer also 
divided the data by year class and used data available from all years 
and requested we consider these analyses.
    Our Response: As discussed earlier in this notice, we acknowledge 
that there are other methods by which to analyze the available data, 
but that we have now employed an analysis using the CDFG/USBR MLR Model 
data series to describe population trends of the splittail. We refer 
the peer reviewer to our Abundance section for a discussion of our most 
recent statistical analysis of the species population trends.
    Peer Reviewer Comment 4: A peer reviewer criticized us for 
evaluating the results of the CDFG/USBR MLR Model for all 20 data 
series of splittail abundance index data, instead of limiting the 
evaluation to the nine data series that the respondents view as most 
representative of overall splittail populations. Another peer reviewer 
stated that Bay Study OT and Fall MWT data were more indicative of 
splittail abundance trends, rather than the trends made evident by data 
collected at the SWP Salvage facilities, Chipps Island, and in Suisun 
Marsh, which the respondent felt were narrow in geographic scope.
    Our Response: We note that these and other respondents have 
previously criticized us, while employing different analysis, for not 
treating all 20 data series equally and for not including all available 
data series in statistical evaluations of abundance trends. We refer 
the commentor to the section entitled Abundance for a discussion of our 
treatment of the data series.
    Peer Reviewer Comment 5: A peer reviewer reiterated his assessment 
that the statistical evidence for a declining trend in splittail 
abundance is weak, and cited an analysis that asserted that evidence 
for a time trend in 7 of 20 data series is not a compelling factor in 
determining that declines exist. The peer reviewer specifically cited 
Manly (2002) which states ``The Service claims that lack of power to 
detect a trend gives a reason for using a 20 [percent] level of 
significance in assessing whether or not there is evidence of a trend 
with individual series. This then allows [the Service] to claim 
evidence for a trend for 7 of the 20 series. Although this sounds 
impressive, it is less so when it is realized that by chance alone 4 of 
the 20 series (i.e., 20 [percent] of them) are expected to give a 
significant result if this level of significance is used.'' The peer 
reviewer also asserted that the weak nature of the MLR Model regression 
coefficients will be demonstrated with the calculation of splittail 
abundance indices for 2000, 2001, and 2002 and their inclusion into the 
models.
    Our Response: Using the most recent data, our analysis now 
indicates that 9 of 20 indices show significant negative trends at the 
20 percent level of significance, while 2 of 20 show significant 
positive trends at that significance level. As we noted earlier in the 
analysis, we achieved these results by a conscious choice of a variable 
that accepted a higher risk of incorrectly identifying downward trends 
in population in order to take a conservative position in our threats 
analysis.
    Peer Reviewer Comment 6: A peer reviewer criticized our acceptance 
of the ``sign'' (i.e., positive or negative) results of the CDFG/USBR 
MLR Model coefficients at face value because in most cases (16 of 20) 
the true signs (i.e., positive or negative) were just as likely to be 
positive as negative.
    Our Response: We cannot apply the respondent's reasoning to the 
available data. The p-value for a coefficient is what statistical 
analysis has indicated it should be; simply because a given p-value 
does not rise to the level of 95 percent significance criterion, does 
not indicate that the p-value automatically reverts to 50 percent.
    Peer Reviewer Comment 7: It was noted by a peer reviewer that in 
half the CDFG/USBR MLR Model runs the dependent variable was 
significantly non-normal and that as a consequence probability 
statements will be ``slightly'' in error.
    Our Response: We believe that the peer reviewer's comment is 
correct. This type of error alone, however, would not necessarily 
invalidate our evaluations of the signs and magnitudes of the 
regression coefficients. The error would have to be of a nature that 
creates bias. The peer reviewer did not provide any statistical or 
other argument to explain why such error would necessarily result

[[Page 55148]]

in bias. The unknown statistical effects of non-normality in half the 
model runs constitutes just the sort of uncertainty that leads us to be 
cautious about giving undue weight to any conclusions regarding the 
abundance index data for splittail.
    Peer Reviewer Comment 9: A peer reviewer believes that the extended 
drought of 1984 to 1992 created only a perception of decline and that 
it was the ``* * * accidental juxtaposition of a series of wet, strong 
splittail years with a series of dry, weak years that prompted [our] 
interest in the first place.''
    Our Response: We disagree with the peer reviewer's claims that the 
period of extended drought has been ignored, as well as with the 
contention that the splittail's drought-driven declines are the sole 
factor under consideration in our determination. We first note that the 
period of continuous drought is considered by most authoritative 
sources to have begun in 1987 (Moyle et al. 2001; Baxter 1999a; Sommer 
et al. 1997), not 1984 as reported by the respondent. We note, however, 
that 1985 and 1986 were dry years (Cannon 2001 in prep.).
    The declines noted during the 1987 to 1992 drought were the likely 
result of a paucity of spawning habitat being available. The drought 
decreased the amount of floodplain (i.e. Yolo Bypass and mainstem river 
margins) available for spawning and thus, spawning output was lower. 
Low splittail population densities were aggravated by the CVP and SWP's 
diversion of a greater proportion of water from the Delta than in prior 
years; fish were entrained at the facilities and the entrapment zone 
(location where fish become vulnerable to the export facilities' effect 
on currents in the Delta), was located well upstream of Suisun Marsh in 
increasingly suboptimal habitat. These events are described in detail 
in our February 8, 1999, final listing rule (64 FR 5963).
    The basis for the peer reviewer's claim that we are 
disproportionately concerned with splittail declines noted during the 
1984 (or 1987) to 1992 drought is unclear. True, the ``accidental 
juxtaposition'' of wet and dry years resulted in abundance data that 
appeared to illustrate a precipitous drop in the splittail population. 
There are, however, up to 10 years of pre-drought as well as up to 8 to 
10 years of post-drought data. The data collected during six years of 
continuous drought are but a subset of the nearly 20 years of extant 
splittail data. The splittail's relatively long life span and 
resilience following unfavorable conditions renders the declines 
exhibited during a discrete drought unlikely to influence the 
analytical findings from an ever-lengthening period of record. Most 
importantly, we now employ the CDFG/USBR MLR Model, which explicitly 
controls for potential confounding effects of hydrological year type. 
The respondent's concern would be more applicable to abandoned 
analytical techniques. The arbitrary pre- and post-decline cut point 
approach of Meng and Moyle (1985) was driven by trends noticed during 
the 1987 to 1992 drought, as was a formerly touted alternative analysis 
that involved the use of 1987 (the beginning of the drought) as a cut 
point (Sommer et al. 1997) for determining percent declines.
    We also disagree with the contention that the 1987 to 1992 drought 
serves as the only factor which triggered our investigations of the 
splittail's status. Our interest in the splittail was prompted 
initially by the statement in Daniels and Moyle (1983) that the 
splittail's and delta smelt's ``* * * abundance could decline rapidly 
if environmental conditions become unfavorable for them, possibly 
making them candidates for listing as threatened species.'' We 
subsequently included the Sacramento splittail as a category 2 
candidate species for possible future listing as endangered or 
threatened in the January 6, 1989, Animal Notice of Review (54 FR 554). 
The candidate category system was abandoned on February 28, 1996 (61 FR 
7457), and species meeting the definition of the former category 2 
(such as splittail) were no longer considered candidates. Our 
administrative proceedings on splittail resumed on November 5, 1992, 
when we received a petition from the Natural Heritage Institute to add 
the Sacramento splittail to the List of Endangered and Threatened 
Wildlife and to designate critical habitat for this species in the 
Sacramento and San Joaquin Rivers and associated estuary.
    Peer Reviewer Comment 10: A peer reviewer, in response to our March 
21, 2002 (67 FR 13095) notice, believed that we should not have adopted 
the CDFG/USBR MLR Model which was jointly submitted in CDFG's and 
USBR's respective peer review and comment letters. The CDFG/USBR MLR 
Model was advocated by its submitting agencies as an approach superior 
to our Meng and Moyle (1985) method utilized in our 1994 proposed 
listing (59 FR 862) and 1999 final listing (64 FR 5963) rules, the 
polynomial regression technique discussed in our August 17, 2001 (66 FR 
43145) notice, or the Sommer et al. (1997) technique formerly forwarded 
by CDFG and CDWR.
    Our Response: We agree that USBR's submission was labeled A Sample 
Alternative Model of Sacramento Splittail Abundance. However, USBR 
(2001) included no language in their agency comment letter and peer 
review submission to suggest their intent was to have us retain the 
polynomial regression analysis (66 FR 43145), revert to the Meng and 
Moyle (1985) analysis, adopt the Sommer et al. (1997) analysis, or 
employ any other analytical technique until the CDFG/USBR MLR Model and 
results reached a greater state of refinement.
    To the contrary, USBR's peer review and comment letter states, 
``Results presented in Table 1, include actual p-values for the 
Service's inspection.'' (USBR 2001). To advocate we abandon the model 
is to advocate we abandon analysis of p-values. Furthermore, USBR 
scientifically derived and submitted multiple conclusions in their peer 
review and comment letter, such as, ``In summary, the results [of the 
CDFG/USBR MLR Model] presented here clearly indicate that hydrologic 
variability strongly affects YOY splittail indices, and also affects 
some adult indices in succeeding years as cohorts propagate through the 
population.'' (USBR 2001). These conclusions were not accompanied by 
any disclaimers that the conclusions should be disregarded because the 
model was not yet sufficiently developed or that the conclusions should 
not be applied to the review of the splittail's population trends.
    The CDFG/USBR MLR Model was also submitted to us by CDFG. 
Consistent with the USBR peer review and comment letter, CDFG also 
derived and submitted multiple conclusions based on the specific runs 
of the CDFG/USBR MLR Model that the USBR is now criticizing us for 
accepting. CDFG advocated the use of the CDFG/USBR MLR Model (as 
submitted) in their peer review and comment letter (CDFG 2001) with the 
statement, ``Our response is composed of two parts: a discussion of 
individual analyses presented in our August 17, 2001, notice (66 FR 
43145), and a summary of the results of a multiple regression analysis 
[the CDFG/USBR MLR Model] that we believe is more useful in evaluating 
trends in survey indices.'' Again, consistent with the USBR's peer 
review and comment letter, CDFG's peer review and comment letter did 
not qualify any of the conclusions they derived from the CDFG/USBR MLR 
Model with disclaimers about the inappropriateness of employing the 
model.
    We independantly evaluated the structure and findings of the CDFG/

[[Page 55149]]

USBR MLR Model and determined that it represented the best available 
scientific and commercial information. We retain our conclusions 
regarding our analysis and meta-analysis of the model's results, 
regardless of its developers' current desire to secondarily qualify its 
application.
    Peer Reviewer Comment 11: A peer reviewer commented that it was 
unclear whether we had independently re-derived the CDFG/USBR MLR Model 
results submitted jointly by CDFG and USBR.
    Our Response: We did not independently re-derive those results. We 
accepted the results presented in CDFG (2001) and USBR (2001) at face 
value, as they were developed by subject area experts within CDFG and 
USBR during a peer review and public comment process.
    Peer Reviewer Comment 12: A peer reviewer believed that our that 
our statement, ``* * * [the] traditional [alpha-value] criteria assume 
a much higher standard of statistical power than the splittail data are 
able to meet * * *'' in our March 21, 2002, notice (67 FR 13095) is 
erroneous.
    Our Response: We agree with the peer reviewer that in a strictly 
literal sense, the choice of an alpha-value criterion can be made 
without any regard for statistical power. However, in practice, 
researchers are concerned with both type I error (determined by the 
choice of an alpha value) and type II error (directly related to the 
statistical power of a study). When conducting our analysis, we made a 
conscious choice to use the more conservative nontraditional approach 
of using an alpha value of 0.20.
    Peer Reviewer Comment 13: A peer reviewer asserted that the purpose 
of statistical hypothesis testing in the case of the MLR Model is to 
decide whether trends do or do not exist, not to evaluate gradients of 
reliability in evaluating trends.
    Our Response: The CDFG/USBR MLR Model is a probabilistic approach 
to examining time trends, it is not a categorical ``either/or'' 
approach (as the respondent appears to assert). We chose to evaluate 
the probabilities associated with competing hypotheses concerning the 
abundance status of splittail. It is for this reason that we stated 
that all trends, not just trends meeting an arbitrary traditional 
confidence criterion (95 percent confidence, or alpha-value of 0.05) 
were evaluated.
    Peer Reviewer Comment 14: A peer reviewer believes that a trawl's 
declining catch efficiency for adult splittail as compared to juvenile 
and YOY rendered trawl surveys less likely to reflect trends and stated 
that adult and juvenile indices should not be combined. The peer 
reviewer also suggested that Bay Study OT and Fall MWT were more 
representative measures of abundance.
    Our Response: While we concur that declining catch efficiency may 
be a characteristic of trawls, we do not agree that it should be used 
to exclude a trawl survey's data. Declining catch efficiency within a 
given trawl survey is expected to be uniform from year to year, thus 
rendering inter-annual analysis valid. Although an age bias will make 
data series for older age-class fish less sensitive for detecting 
change, it will not produce a long-term directional bias (i.e., we have 
no reason to believe that the capture efficiency for older age class 
splittail is becoming progressively worse over time). Thus, any trends 
in the older age class data series with a substantive p-value can be 
viewed to be roughly as accurate and reliable as for the Age-0 class of 
splittail showing trends at comparable p-values.
    We also concur that trawls' declining catch efficiency does 
preclude the combination of age class data. We report each index 
separately herein and do not combine adult and juvenile indices other 
than for meta-analytical purposes. We also acknowledge that, in certain 
situations, adult abundance for different age classes (of adults) is 
combined and reported because the data are collected in that manner, 
i.e., salvage data are reported as Age-1 and as Age-2 and greater with 
no differentiation made for individuals greater-than Age-2 classes. 
Situations such as this represent a relict of the sampling methodology 
but remain the best available information. We continue to believe that 
as long as the degree of age-based capture bias is constant over a 
survey period, all age classes should show approximately the same 
trends, and that combining age classes for meta-level statistical 
analyses is not problematic.
    We reiterate that the Suisun Marsh OT, which combines an efficient, 
bottom trawling technique with focused surveys in a small habitat at 
the core of the splittail's range, is the most likely to detect a trend 
and likely suffers from less sampling inefficiency than the Bay Study 
OT (low detection of splittail at periphery of range) and Fall MWT 
(unlikely to detect benthic fish and does not sample shallow water or 
near-shore areas).
    Peer Reviewer Comment 15: A peer reviewer asserted that the peer 
review process for scientific publications doesn't necessarily ensure 
that published papers are unbiased, scientifically sound, and without 
errors. The Transactions of the American Fisheries Society does not use 
the double-blind method for peer review. This issue was raised in 
regards to our past use of the Meng and Moyle (1995) methodology to 
determine splittail abundance.
    Our Response: We agree with this assertion. Each piece of 
scientific work, whether a peer reviewed published paper or an 
unpublished, unreviewed, draft report, must be objectively evaluated 
for the scientific merit of its content alone. Peer reviewed 
publication provides no guarantee of scientific merit. The test of 
time, following publication, provides the ultimate measure of 
scientific merit. Indeed, subsequent iterative examination of the 
splittail's status has resulted in our abandonment of Meng and Moyle 
(1995), Sommer et al., (1997) and our permutation-based exact 
calculations of p-values for stratified (as opposed to unstratified) 
Mann-Whitney U-tests (66 FR 43145).
    Peer Reviewer Comment 16: A peer reviewer claimed we ignored the 
draft ``White Paper'' published by Moyle et al. (2001, in prep.)
    Our Response: We use the various findings and hypotheses found in 
the draft and revised White Paper (Moyle et al. 2001 in prep.) 
extensively throughout this document.
    Peer Reviewer Comment 17: A peer reviewer stated that the range of 
the splittail is wider than was previously thought.
    Our Response: The greater range of the splittail was acknowledged 
in the January 12, 2001, notice (66 FR 2828). The above Background 
section of this final document contains a discussion of the range of 
the splittail.
    Peer Reviewer Comment 18: Several peer reviewers felt that we 
should not classify the Yolo and Sutter bypasses as a threat to the 
splittail, as we did in the January 12, 2001, reopening of comment 
period (66 FR 2828), based primarily upon the data found in Sommer et 
al. (1997) and Sommer (2001a). The bypasses have demonstrated the 
capability of producing large numbers of splittail when inundated. One 
peer reviewer also felt that the bypasses cannot be considered a threat 
simply because the conditions could be better. Another peer reviewer 
claimed that current operations in the bypasses do not harm splittail 
or their habitat. Another peer reviewer felt that the bypasses are not 
to be considered a threat because even though their splittail habitat 
conditions are not optimal, they are still sufficient to provide 
substantial benefits to the species. Finally, another peer reviewer

[[Page 55150]]

stated that the Yolo and Sutter bypasses are a ``net benefit'' to the 
splittail in that without their existence, the species might not have 
persisted to the present day.
    Our Response: We have determined, based on consideration of 
scientific data and information provided by respondents, that the Yolo 
and Sutter bypasses are not, in and of themselves, a threat to the 
splittail. Our reevaluation of this issue is discussed in Factor E of 
the section entitled Summary of Factors Affecting the Species.
    Peer Reviewer Comment 19: A peer reviewer felt that our 
determination that the Sutter and Yolo bypasses would require 
inundation for at least 30 continuous days between March and April in 
order for them to be considered a beneficial splittail spawning habitat 
was inaccurate and could affect water supply and flood management.
    Our Response: We have not proposed inundation of the bypasses for 
any specific interval, duration, or frequency. Rather, we have 
speculated that the bypasses would have their greatest benefits to 
splittail if they became inundated at a frequency and duration that as 
closely as possible mimics the natural, precipitation-driven 
hydrograph. The reference to 30 days is a statement regarding how the 
inundation patterns of the bypasses at times do not meet the life 
history requirements of the splittail. Inundation of bypasses in dry 
years would reduce the effects of drought on the splittail. We also 
speculate that if the bypasses were inundated at a frequency and 
duration that as closely as possible mimics the natural, precipitation-
driven hydrograph, then the numbers of non-native fish would be 
reduced, as non-native fishes favor ponded and continuously inundated 
habitats.
    Peer Reviewer Comment 20: A peer reviewer believed that full 
implementation of the CALFED Program would preclude the need to list 
the splittail and indicated that over $10 million had been spent on 
actions that could improve conditions for splittail.
    Our Response: We refer the peer reviewer to the section entitled 
Summary of Factors Affecting the Species.
    Peer Reviewer Comment 21: A peer reviewer asserted that the age-
based capture bias argues against combining data from different age 
groups.
    Our Response: We assume this comment refers to the pooling of data 
series from all age classes for meta-level statistical evaluation. We 
believe that as long as the degree of age-based capture bias is 
constant over a survey period, all age classes should show about the 
same trends, and that combining age classes for meta-level statistical 
analysis will not be a problem.

State Agencies

    We received comments from the following California State agencies: 
Department of Fish and Game (CDFG) and Department of Water Resources 
(CDWR). Technical data provided by the CDFG and CDWR have been 
incorporated into or addressed in this document, while other issues 
raised by State agencies are addressed below:
    State Agency Comment 1: CDFG submitted comments that included an 
analysis using a modified version of Meng and Moyle's (1995) pre-
decline and post-decline method. CDFG also divided the data by year 
class and used data available from all years and requested we consider 
these analyses.
    Our Response: As discussed earlier in this notice, we acknowledge 
that there are other methods by which to analyze the available data, 
but that we have now employed an analysis using the CDFG/USBR MLR Model 
data series to describe population trends of the splittail. We refer 
CDFG to our Abundance section for a discussion of our most recent 
statistical analysis of the species population trends.
    State Agency Comment 2: CDFG reiterated their assessment that the 
statistical evidence for a declining trend in splittail abundance is 
weak. CDFG cited an analysis that asserted that evidence for a time 
trend in 7 of 20 data series is not a compelling factor in determining 
that declines exist. CDFG specifically cited Manly (2002) which states 
``The Service claims that lack of power to detect a trend gives a 
reason for using a 20 [percent] level of significance in assessing 
whether or not there is evidence of a trend with individual series. 
This then allows [the Service] to claim evidence for a trend for 7 of 
the 20 series. Although this sounds impressive, it is less so when it 
is realized that by chance alone 4 of the 20 series (i.e., 20 [percent] 
of them) are expected to give a significant result if this level of 
significance is used.'' CDFG also asserted that the weak nature of the 
MLR Model regression coefficients will be demonstrated with the 
calculation of splittail abundance indices for 2000, 2001, and 2002 and 
their inclusion into the models.
    Our Response: As we note in our earlier analysis we made a 
conscious decision to use the more conservative, nontraditional 0.20 
alpha for analysis purposes.
    State Agency Comment 3: CDWR claimed we ignored the ``White Paper'' 
published by Moyle et al. (2001).
    Our Response: We agree with and use many of the various findings 
and hypotheses found in the draft and revised White Paper (Moyle et al. 
2001) extensively throughout this document. We believe that the White 
Paper is a useful resource and contributes to the knowledge on 
splittail biology. The paper has been referenced throughout this 
document.
    State Agency Comment 4: CDWR stated that the hypothetical 
analytical model presented at the January 29, 2001, CALFED Bay-Delta 
Program (CALFED Program) Splittail Science Conference and described in 
the White Paper (Moyle et al., 2001) indicates that the splittail, even 
during severe and lengthy drought, is unlikely to be driven to 
extinction.
    Our Response: We ultimately arrive at the same conclusion as Dr. 
Moyle, that the splittail is unlikely to be driven to extinction. 
However, at this point we are unwilling to accept that premise solely 
on the basis of the White Paper. To date, there remains no proven 
scientific method for determining the current splittail population size 
primarily because no extant survey was designed specifically to monitor 
splittail populations or to determine their absolute numbers. Further, 
the splittail exhibits relatively wide variation in annual abundance in 
response to prevailing hydrologic conditions; it is likely that the 
population size exhibits appreciable year to year variability which 
would confound size estimates.
    Calculating the current population's risk of and/or time to 
extinction would require estimates of absolute population size, rate of 
decline, and minimum viable or sustainable population size, none of 
which currently exist in a scientifically defensible form. Moreover, it 
must also be noted that the statutory and regulatory standard for 
ascertaining threatened status is not to determine whether or why a 
species will become extinct in the near future, but if, pursuant to 
section 3(19) of the Act, it ``* * * is likely to become an endangered 
species within the foreseeable future throughout all or a significant 
portion of its range''. An endangered species, pursuant to section 
3(19) of the Act, is that ``* * * which is in danger of extinction 
throughout all or a significant portion of its range * * *''. Our 
analysis, including a nontraditional conservative approach to 
estimating population trends examines the factors identified in the Act 
and in fact we find that the splittail does not warrant listing at this 
time.
    State Agency Comment 5: CDWR felt that we should not classify the 
Yolo and Sutter bypasses as a threat to the

[[Page 55151]]

splittail, as we did in the January 12, 2001, reopening of comment 
period (66 FR 2828), based primarily upon the data found in Sommer et 
al. (1997) and Sommer (2001a). The bypasses have demonstrated the 
capability of producing large numbers of splittail when inundated.
    Our Response: We have determined, based on consideration of 
scientific data and information provided by respondents, that the Yolo 
and Sutter bypasses are not, in and of themselves, a threat to the 
splittail. Our reevaluation of this issue is discussed in Factor E of 
the section entitled Summary of Factors Affecting the Species.
    State Agency Comment 6: CDWR felt that our determination that the 
Sutter and Yolo bypasses would require inundation for at least 30 
continuous days between March and April in order to for them to be 
considered a beneficial splittail spawning habitat was inaccurate and 
could affect water supply and flood management.
    Our Response: We have not proposed inundation of the bypasses for 
any specific interval, duration, or frequency. Rather, we have 
speculated that the bypasses would have their greatest benefits to 
splittail if they became inundated at a frequency and duration that as 
closely as possible mimics the natural, precipitation-driven 
hydrograph. The reference to 30 days is a statement regarding how the 
inundation patterns of the bypasses at times do not meet the life 
history requirements of the splittail. Inundation of bypasses in dry 
years would reduce the effects of drought on the splittail. We also 
speculate that if the bypasses were inundated at a frequency and 
duration that as closely as possible mimics the natural, precipitation-
driven hydrograph, then the numbers of non-native fish would be 
reduced, as non-native fishes favor ponded and continuously inundated 
habitats.
    State Agency Comment 7: CDWR commented that our classification of 
the Yolo Bypass as a threat in the January 12, 2001, notice (66 FR 
2828) would undermine potential ecosystem restoration actions that 
would benefit the splittail.
    Our Response: In this notice, we determine that the Sutter and Yolo 
bypasses are not in and of themselves threats.
    State Agency Comment 8: CDWR objected to our statements regarding 
the entrainment risks present in the bypasses based upon Sommer et 
al.'s (1997) findings that entrainment is not a significant threat 
within the bypasses. It is thought that the splittail's evolutionarily-
derived ability to emigrate prior to stranding reduces the risk of 
stranding. CDWR also felt that the magnitude of the entrainment threats 
presented by the bypasses was overestimated when we cited in the 
January 12, 2001, notice (66 FR 2828), the death of a number of 
juvenile splittail in an approximately 0.8 hectare (ha) (2 acre (ac)) 
borrow pit as statistically-significant and that the classification of 
``natural sinks'' as a threat was in error.
    Our Response: We have considered these data and now agree that 
entrainment in the Yolo Bypass is less than was originally thought. 
Information presented at the January 29, 2001, CALFED Splittail Science 
Conference indicates that a modest degree of topographic variability 
within an inundated area may be beneficial, as it may create a 
diversity of flow patterns and velocities which in turn may allow 
juvenile splittail to evade predation and forage more effectively 
during egress.
    State Agency Comment 9: CDWR believed that full implementation of 
the CALFED Program would preclude the need to list the splittail and 
indicated that over $10 million had been spent on actions that could 
improve conditions for splittail.
    Our Response: We refer CDWR to the section entitled Summary of 
Factors Affecting the Species.

Other Public Comments and Responses

    We address other substantive comments and accompanying information 
in the following summary. Relatively minor editing changes and 
reference updates suggested by commenters have been incorporated into 
this document, as appropriate.
    Comment 1: The court directed that we provide a more thorough 
response to the California Resources Agency comments, specifically 
comments submitted by CDFG and CDWR in July 1998. The court also 
directed that we address the perceived biases from the Meng and Moyle 
(1995) method. We also received specific comments on issues related to 
prior statistical analyses of abundance.
    Our Response: We have adopted a multiple linear regression approach 
proposed by CDFG and U.S. Bureau of Reclamation (USBR). CDFG, in 
comments submitted in association with the August 17, 2001, comment 
period, stated: ``Although CDFG reported Mann-Whitney U test results in 
previous comments (February 8, 2001), we now suggest greater reliance 
on a multiple regression approach to trend analysis, described in a 
following section of our comments. We no longer support use of the 
Mann-Whitney U procedure of time trend analysis.'' CDWR, in comments 
also submitted under the August 17, 2001, comment period, stated: ``A 
more defensible alternative would be to develop a multivariate model 
incorporating the effects of both flow and time.'' CDWR also made 
reference to the USBR application of regression techniques, which also 
were provided in USBR's comments. We have considered the CDFG, CDWR, 
and USBR recommendations to employ a multivariate, regression based 
model and have incorporated an analysis using the CDFG/USBR MLR Model 
data series as described in the section entitled Abundance. We will 
therefore forego providing responses to specific comments on the 
perceived bias of the Meng and Moyle (1995) and alternate methodologies 
previously employed because our analytical tools have been upgraded to 
utilize the modified methodology employed by CDFG and USBR.
    The CDFG/USBR MLR Model provided in CDFG and USBR comments 
addresses the shortcomings of other methods, thus allowing our analysis 
using the CDFG/USBR MLR Model data series to supercede abundance 
analyses based upon methods appearing in prior rules. In combination 
with meta-analyses to analyze the distribution of MLR Model results 
across the 20 indices, statistical inferences based on the CDFG/USBR 
MLR data series are informative.
    Our analysis using the CDFG/USBR MLR Model data series incorporates 
the results of seven surveys (Fall MWT, Bay Study OT, Bay Study MWT, 
Chipps Island, Suisun Marsh OT, CVP salvage, and SWP salvage), and 
includes separate indices of YOY, age 1 (juvenile) and age 2+ (adult) 
age class abundance. The independent examination of abundance of all 
age classes throughout these surveys helps mediate discrepancies among 
survey results, discrepancies that are a likely indication that 
splittail populations are not very evenly distributed over space and 
time and/or that different sampling methodologies are not very 
comparable. The model also does not require uninterrupted data; all 
available data from each survey's period of record is included. 
Further, our analysis controls for the confounding effects of 
hydrology, and involves no inherent or intentional bias towards either 
wet or dry water year types. Strict adherence to uniformity among all 
data series is also inconsistent with the precautionary nature of 
section 4 of the Act.
    We recognize a distinct danger in controlling for hydrological 
effects in our analyses, because systematic

[[Page 55152]]

changes in hydrological regimes, due to human manipulation or long term 
climate change, could just as feasibly be a causative factor as a 
confounding source of ``noise.'' If systematic changes in hydrological 
regimes were occurring, it would not be prudent to control for that 
factor. Our since-superceded polynomial regression analysis of 
abundance data (See Abundance section of the August 17, 2001, notice) 
controlled for influences of hydrological cycles without discarding 
hydrology as a potential directional factor determining long term 
trends of splittail abundance. We expect that the polynomial regression 
analysis presented in the August 17, 2001, notice may eventually inform 
the understanding of the effects of changed hydrology on the splittail, 
once the future, cumulative hydrologic analyses for potential water 
development projects have been developed by the responsible agencies.
    Comment 2: The court directed us to show the relationship between 
the data used in our decision-making analysis and the original final 
rule and how we reached the conclusion that the splittail was 
threatened.
    Our Response: We have provided a more detailed analysis in the 
section entitled Summary of Factors Affecting the Species. The threats 
to the species have also been summarized in an additional section 
entitled Conclusion Regarding Abundance, Distribution, and Factors 
Affecting the Species. We have also included in the Abundance section 
of this notice a discussion of our most recent statistical analysis of 
the species population trends.
    Comment 3: Several respondents cited the draft White Paper (Moyle 
et al. 2001 in prep) for splittail as reporting a tentative population 
model result that stated, `` * * * a long series of dry years is 
unlikely to drive the splittail to extinction, even if the population 
is greatly reduced.''
    Our Response: A species warrants listing as threatened under the 
Act if is in danger of becoming endangered in the foreseeable future 
throughout all or a significant portion of its range (16 U.S.C. 
1532(20)). It is possible for the splittail to be undergoing threats or 
declines in a significant portion of its range without declines showing 
in all surveys. Alternatively, threats to the splittail may support 
listing even in the absence of our ability to document current 
population declines. Finally, we believe the conservation elements of 
the California State and Federal cooperative program (CALFED) and the 
Central Valley Project Improvement Act (CVPIA) programs adequately 
mitigate for these threats (refer to Factor A for a detailed discussion 
of the CALFED program and the CVPIA programs).
    Comment 4: A respondent informed us that CDFG re-analyzed the 
striped bass egg and larval survey and found that splittail spawn in 
the mainstem of the Sacramento River, especially in dry years. This 
indicates that splittail occur in the Sacramento River upstream from 
the Delta.
    Our Response: CDFG and our survey results confirm that splittail 
use river margin habitat in the mainstem Sacramento River. Indeed, 
recent indications are that river margin habitat is where splittail 
spawning occurs through periods of drought.
    Comment 5: A respondent stated that young of the year (YOY) 
abundance was at near record levels in 2000, thus inferring the 
splittail is not in decline.
    Our Response: Data presented in the Spring 2001 Interagency 
Ecological Program Newsletter (Baxter 2001a), provided as an attachment 
to public comment submitted on this rulemaking, do indicate that 
splittail spawning was highly successful in 2000. This spike of 
juvenile fish is to be expected given the relatively wet conditions of 
2000, and the splittail's ability to exploit suitable habitat when 
available. Also, YOY are generally the most reliably sampled fish in 
any given survey, since their raw abundance is temporarily high and YOY 
splittail are likely less effective at evading sampling equipment. 
Population level conclusions drawn from such a spike must be made with 
caution because, though extremes in YOY abundance appear to be 
reflected in 2 to 3 year subsequent adult abundances, the splittail 
appears to exhibit no stock-recruitment relationship (Sommer et al. 
1997). Possible reasons for the lack of a stock-recruitment 
relationship may be variation in female growth, survivorship and 
fecundity from such causes as inter- and intra-annual hydrologic 
variation, environmental contaminants, years of non-spawning, 
predation, etc., which may be exerting independent or synergistic 
influences on recruitment of splittail into the population. Regardless 
of cause, large portions of YOY fail to survive to the adult, spawning 
population age class. Juvenile abundance may therefore be inadequate to 
fully describe the size of the standing or future adult populations and 
may also be inadequate to describe the ability of the population to 
persist. Population abundance cannot be accurately predicted based upon 
examination of juvenile abundance alone.
    We currently support use of the CDFG/USBR MLR Model because of the 
facility with which it can be applied to all sets of splittail age 
class data from all seven applicable abundance monitoring data sets (a 
total of 20 discrete sets of age-specific abundance monitoring data). 
This approach therefore includes consideration of YOY splittail without 
granting undue analytical weight to any single survey or age class or 
inappropriately combining different survey equipment types. Regardless 
of the strengths and weaknesses of year 2000 YOY abundance, these data 
were considered in our analysis using the CDFG/USBR MLR Model data 
series (see our Abundance section for a discussion of our most recent 
statistical analysis of the species population trends).
    Comment 6: The Court and numerous commenters requested that we 
address and clarify the issue of splittail resiliency and that the 
species may be able to withstand drought and produce high numbers of 
young of year (YOY) during wet periods.
    Our Response: We concur that splittail are a resilient species and 
that they can reproduce effectively in wet years. Sacramento splittail 
populations fluctuate annually depending upon the availability of 
shallow water habitat with submerged vegetation (Daniels and Moyle 
1983). Meng and Moyle (1995) and Sommer et al. (1997) have found that 
splittail year-class abundance is positively correlated with freshwater 
outflow occurring during the species' late winter and spring spawning 
season. The evolutionary strategy of the splittail therefore appears to 
be one of opportunism, whereby the population collectively invades and 
exploits spawning habitats if and when they become available. 
Historically, this resilience is likely to have maintained the 
population of splittail through extended droughts. This resilience also 
has allowed the splittail to persist in spite of the significant loss 
of habitat that has occurred since the species was first described by 
Ayres.
    Comment 7: A respondent wished to know why the Bay Study and CVP 
and SWP salvage data showed an increase in splittail abundance, and the 
commenter requested that we explain the variation in the study results.
    Our Response: This comment pertains to the Meng and Moyle (1995) 
methodology employed in our previous analyses of splittail population. 
We refer the respondent to our Abundance section for a discussion of 
our most recent statistical analysis of the species population trends.

[[Page 55153]]

    We believe that trends noted in the Bay Study are likely due to the 
large numbers of YOY fish that were collected during certain wet years. 
High outflows may transport juveniles from the Estuary to locations 
where Bay Study samples are collected. It is unclear what happens to 
these fish once they are transported to these areas. Fish transported 
to San Pablo Bay may survive to join, if not sustain, the Napa River 
and Petaluma River and Marsh subpopulations. Once located in these 
areas, it is not known what contribution is made to the Central Valley 
population as a whole.
    In regard to trends in CVP and SWP salvage data, we believe that 
these too are driven by seasonal variation in hydrology. Though it is 
true that hydrology and production are strongly correlated, and that 
salvage would be expected to rise as populations rise, there are 
concerns with the data's application (see discussion of surveys under 
Abundance section, above).
    In the case of splittail salvage, entrainment is likely influenced 
by the rate, or volume per unit of time, of export. As stated before, 
salvage data are expressed as fish captures per acre foot and lack a 
time value. At higher rates of export, splittail are likely to be 
disproportionately entrained because of higher velocities in the 
channels adjoining or approaching the facilities and thus, abundance 
could be overestimated. All sampling gears may be more effective at 
capturing splittail during high outflows due to increased velocity and 
turbidity, but only the pumps have the ability to draw fish towards 
them at different rates. The rate at which fish may become pulled 
towards the pumps cannot be described using existing data. Differing 
rates of export also introduce variability, which cannot be discerned 
without a time factor. Salvage data, as mentioned previously, do not 
effectively sample a large extent of the splittail population, as fish 
reared in the Sacramento River and/or Yolo Bypass are likely to largely 
avoid the pumps. Salvage data do however collect the largest number of 
splittail of any survey.
    Comment 9: Several respondents cited an analysis that took issue 
with us for adopting a non-traditional alpha-value of 0.20 (instead of 
0.05) for evaluating results of the CDFG/USBR MLR Model.
    Our Response: Available literature customarily demands a rigid 
adherence to the traditional alpha value of 0.05. In this particular 
analysis, we chose to take a far more conservative approach in terms of 
how we evaluated the splittail's abundance. Accordingly, we used the 
non-traditional alpha value of 0.20. We believe while unusual it is 
conservative, and results in a more robust determination of whether the 
species should be listed.
    Comment 10: Several respondents cited an analysis that criticized 
our treatment of separate surveys of splittail abundance indices as 
statistically independent.
    Our Response: We followed a long established practice in the peer-
reviewed literature on splittail of treating these surveys as 
statistically independent (e.g., Meng and Moyle 1995; Sommer et al. 
1997) including papers repeatedly cited by the respondents in 
previously submitted comments. We accept at face value Manly's (2002) 
conclusion that an analysis of corrections among residuals provides 
evidence for some degree of interdependence among the different sets of 
survey data (Manly 2002:4-6). We also accept at face value Manly's 
(2002) attempt to correct our meta-analysis of survey results to 
account for the interdependence in the data sets. We have consistently 
stated that the abundance index data for splittail suffer from several 
fundamental inadequacies that make them far from ideal for decision-
making purposes (an opinion with which the respondents and their 
statistical consultant concur (Manly 2002:3,8)).
    Comment 11: Several respondents criticized us for evaluating the 
results of the CDFG/USBR MLR Model for all 20 data series of splittail 
abundance index data, instead of limiting the evaluation to the nine 
data series that the respondents view as most representative of overall 
splittail populations.
    Our Response: We note that these and other respondents have 
previously criticized us, while employing different analysis, for not 
treating all 20 data series equally and for not including all available 
data series in statistical evaluations of abundance trends.
    We are aware of no other party who has rigorously evaluated 
abundance index data (e.g., Sommer et al. 1997; Meng and Moyle 1995; 
Moyle et al. 2001 in prep.) that has deemed it appropriate to limit the 
evaluation to the nine data series favored by the respondents. Further, 
CDFG and USBR elected to include all 20 data series in the CDFG/USBR 
MLR Model applications submitted to us as part of earlier comments.
    We disagree with the respondent's suggestion that only data from a 
select group of nine survey indices that sample a wide geographic area 
(we assume the respondent is referring to three age classes each of the 
Bay Study MWT, Bay Study OT, and Fall MWT) should be given greater 
weight for making population-scale determinations. Weighting such a 
select group of surveys necessarily could require inappropriately 
combining their indices. The nine surveys are a composite of 
appreciably different gear types, some of which suffer from the same 
detection limitations as were used by other respondents to advocate 
against accepting certain other surveys. Mid-water trawling is an 
inappropriate match to splittail habitat preferences and other aspects 
of splittail biology, so even geographically extensive mid-water 
surveying would not necessarily be any more representative of overall 
splittail populations than geographically more restricted surveys 
better matched to splittail biology.
    We disagree with respondents' claims that Bay Study MWT, Bay Study 
OT, and Fall MWT data are more indicative of splittail abundance trends 
than are those found in data collected at the SWP and CVP salvage 
facilities, Chipps Island, and in Suisun Marsh because they each suffer 
from gear or location difficulties. We postulate that each of these 
surveys is, to varying degrees, unsuited to the task of assessing 
splittail abundance. The Bay Study OT employs the efficient otter 
trawling technique but only infrequently captures splittail; surveys 
are conducted on the periphery of the species' range. The Bay Study MWT 
employs an inefficient (at capturing splittail) mid-water trawl. The 
Fall MWT fails to sample near-shore areas and the benthos (bottom), 
where splittail are most likely to occur. The Fall MWT does not sample 
shallow waters; in Suisun Bay/Marsh 8 of 25 sites are shallow, 1 of 38 
in the Delta are shallow. We acknowledge that the Chipps Island Survey 
is a midwater trawl of deep channels and that it too would suffer from 
a similar bias. The CVP and SWP salvage data may suffer from an 
unquantifiable differential entrainment based on export rates (see 
Abundance section, above).
    We also do not believe it is necessarily correct to infer that the 
wider geographical coverage of the nine surveys in question, alone, is 
sufficient to guarantee that those surveys are more representative of 
overall splittail populations. The Bay Study MWT, Bay Study OT, and 
Fall MWT are geographically wider in distribution, but given that 
estuarine conditions are specifically managed to maintain optimum 
habitat conditions within Suisun Marsh, the wider survey areas of the 
Bay Study MWT, Bay Study OT, and Fall MWT are not likely to contribute 
to a more informed trend analysis. Surveys need not cover large areas 
if a fixed

[[Page 55154]]

point is likely to result in detection of an appreciable number of 
individuals of a migratory species; splittail are as likely to arrive 
at a static survey point in a key location as they are to be captured 
by a mobile survey of varied habitats.
    We understand the respondent's logic in formulating a hypothesis 
that the nine surveys in question might be most representative of the 
overall splittail population due to geography, but note that at this 
point such an opinion is only a working hypothesis with no actual data 
available to either support or refute it. Until such data become 
available, we believe it is most conservative to follow the practice of 
evaluating all the data series rather than combining or rejecting 
discrete sets. We continue to believe that, of the individual indices, 
the Suisun Marsh Otter Trawl should be the most appropriate sampling 
method because it samples core splittail habitat, utilizes an 
effective, bottom-trawling gear, and samples a greater relative 
proportion of the habitat at the sampling site.
    Comment 12: A respondent claimed we employed ``Shifting approaches 
to the splittail listing'' in regard to statistical testing of 
available data.
    Our Response: Since we have published one listing notice for the 
splittail, on February 8, 1999 (64 FR 5963), we assume that this 
respondent is actually referring to our evolving evaluations of data 
relevant to the issue of whether the splittail should be listed or not, 
as have appeared in the January 12, 2001 (66 FR 2828); May 8, 2001 (66 
FR 23181); August 17, 2001 (66 FR 43145); and March 21, 2002 (67 FR 
13095); and October 31, 2002 (67 FR 66344), notices reopening public 
comment periods.
    It is common practice in science to continually formulate and 
revise hypotheses in response to new information. We have applied this 
scientific process during the review of the splittail's status, as have 
certain respondents (i.e. CDFG, CDWR, USBR). The evolving results of 
our various statistical analyses and the background information 
describing the bases for those analyses have each appeared in 
successive notices. Notices are solicitations for public comment and 
information, not final agency actions. As a result of new scientific 
information and comments received during the many comment periods, we 
have updated our analytical methodology based on the best 
scientifically and commercially available information. Note also that 
neither we, nor respondents, have advocated nor implemented a return to 
the superceded techniques used by Meng and Moyle (1995), Sommer et al. 
(1997), or the permutation-based exact calculations of p-values for 
stratified Mann-Whitney U-tests, published on August 17, 2001 (66 FR 
43145).
    Comment 13: A respondent claimed that we were incorrect in 
departing significantly from the analysis of CDFG and USBR.
    Our Response: We did not depart at all from the statistical 
analysis provided by CDFG and USBR in the form of the CDFG/USBR MLR 
Model. We have fully accepted the model results submitted by CDFG and 
USBR. We have noted earlier in our analysis where we have departed from 
the CDFG and BOR analysis and our reasons for doing so.
    Comment 14: Several respondents stated that the extended drought of 
1984 to 1992 created only a perception of decline and that it was the 
``* * * accidental juxtaposition of a series of wet, strong splittail 
years with a series of dry, weak years that prompted [our] interest in 
the first place.''
    Our Response: We disagree with the respondent's claims that the 
period of extended drought has been ignored, as well as with the 
contention that the splittail's drought-driven declines are the sole 
factor under consideration in our determination. We first note that the 
period of continuous drought is considered by most authoritative 
sources to have begun in 1987 (Moyle et al. 2001; Baxter 1999a; Sommer 
et al. 1997), not 1984 as reported by the respondent. We note, however, 
that 1985 and 1986 were dry years (Cannon 2001 in prep.).
    The declines noted during the 1987 to 1992 drought were the likely 
result of a paucity of spawning habitat being available. The drought 
decreased the amount of floodplain (i.e. Yolo Bypass and mainstem river 
margins) available for spawning and thus, spawning output was lower. 
Low splittail population densities were aggravated by the CVP and SWP's 
diversion of a greater proportion of water from the Delta than in prior 
years; fish were entrained at the facilities and the entrapment zone 
(location where fish become vulnerable to the export facilities' effect 
on currents in the Delta), was located well upstream of Suisun Marsh in 
increasingly suboptimal habitat. These events are described in detail 
in our February 8, 1999, final listing rule (64 FR 5963).
    The basis for the respondent's claim that we are disproportionately 
concerned with splittail declines noted during the 1984 (or 1987) to 
1992 drought is unclear. True, the ``accidental juxtaposition'' of wet 
and dry years resulted in abundance data that appeared to illustrate a 
precipitous drop in the splittail population. There are, however, up to 
10 years of pre-drought as well as up to 8 to 10 years of post-drought 
data. The data collected during six years of continuous drought are but 
a subset of the nearly 20 years of extant splittail data. The 
splittail's relatively long life span and resilience following 
unfavorable conditions renders the declines exhibited during a discrete 
drought unlikely to influence the analytical findings from an ever-
lengthening period of record. Most importantly, we now employ the CDFG/
USBR MLR Model, which explicitly controls for potential confounding 
effects of hydrological year type. The respondent's concern would be 
more applicable to abandoned analytical techniques. The arbitrary pre- 
and post-decline cut point approach of Meng and Moyle (1985) was driven 
by trends noticed during the 1987 to 1992 drought, as was a formerly 
touted alternative analysis that involved the use of 1987 (the 
beginning of the drought) as a cut point (Sommer et al. 1997) for 
determining percent declines.
    We also disagree with the contention that the 1984 to 1992 drought 
serves as the only factor which triggered our investigations of the 
splittail's status. Our interest in the splittail was prompted 
initially by the statement in Daniels and Moyle (1983) that the 
splittail's and delta smelt's `` * * * abundance could decline rapidly 
if environmental conditions become unfavorable for them, possibly 
making them candidates for listing as threatened species.'' We 
subsequently included the Sacramento splittail as a category 2 
candidate species for possible future listing as endangered or 
threatened in the January 6, 1989, Animal Notice of Review (54 FR 554). 
The candidate category system was abandoned on February 28, 1996 (61 FR 
7457), and species meeting the definition of the former category 2 
(such as splittail) were no longer considered candidates. Our 
administrative proceedings on splittail resumed on November 5, 1992, 
when we received a petition from the Natural Heritage Institute to add 
the Sacramento splittail to the List of Endangered and Threatened 
Wildlife and to designate critical habitat for this species in the 
Sacramento and San Joaquin Rivers and associated estuary.
    Comment 15: A respondent questioned how the data collected relate 
to a conclusion that the species is threatened. We had not provided 
analyses of population level outcomes that could be linked to threats 
analyses. Another respondent believed that our threats analysis is 
speculative,

[[Page 55155]]

imprecise, and meaningless absent any data or analysis concerning 
population level effects and that the threats analysis does not show 
why the species is threatened because of the factors, as required under 
section 4 of the Act
    Our Response: We refer the respondent to the sections entitled 
Summary of Factors Affecting the Species and Conclusion Regarding 
Abundance, Distribution, and Factors Affecting the Species. We believe 
that the splittail does not qualify for threatened status at this time 
based on our analysis of the threats.
    Comment 16: Several respondents asserted that the peer review 
process for scientific publications doesn't necessarily ensure that 
published papers are unbiased, scientifically sound, and without 
errors. The Transactions of the American Fisheries Society does not use 
the double-blind method for peer review. This issue was raised in 
regards to our past use of the Meng and Moyle (1995) methodology to 
determine splittail abundance.
    Our Response: We agree with this assertion. Each piece of 
scientific work, whether a peer reviewed published paper or an 
unpublished, unreviewed, draft report, must be objectively evaluated 
for the scientific merit of its content alone. Peer reviewed 
publication provides no guarantee of scientific merit. The test of 
time, following publication, provides the ultimate measure of 
scientific merit. Indeed, subsequent iterative examination of the 
splittail's status has resulted in our abandonment of Meng and Moyle 
(1995), Sommer et al., (1997) and our permutation-based exact 
calculations of p-values for stratified (as opposed to unstratified) 
Mann-Whitney U-tests (66 FR 43145).
    Comment 17: Several respondents claimed we ignored the ``White 
Paper'' published by Moyle et al. (2001)
    Our Response: We agree with and use the various findings and 
hypotheses found in the draft and revised White Paper (Moyle et al. 
2001) extensively throughout this document. We believe that the draft 
White Paper is a useful resource and contributes to the knowledge on 
splittail biology, though it has not yet been finalized. The paper has 
been referenced throughout this document.
    Comment 18: A respondent requested that we acknowledge that the 
Interagency Ecological Program (IEP) provides oversight for fisheries 
data collection.
    Our Response: We concur that the IEP has oversight of the various 
fishery programs. However, various agencies collect the data for the 
surveys mentioned previously in this document. CDFG conducts the Fall 
Midwater Trawl, summer townet, and the Bay study; we conduct the beach 
seine and Chipps Island Survey; UC Davis conducts the Suisun Marsh OT, 
and USBR and CDFG collect the salvage and creel census data.
    Comment 19: A respondent felt the 2000 Service beach seine survey 
data supported the respondent's earlier comments that splittail were 
not declining. The respondent stated that new insights include: (1) YOY 
abundance was at a near record level in 2000; (2) distribution data 
show that in years of low spring outflow (e.g., 1992, 1994, and 1997), 
the largest catches of young splittail occurred upstream in the 
Sacramento River, upstream of many sampling programs; and (3) splittail 
spawn and recruit even in dry years.
    Our Response: YOY abundance for a species with naturally high 
juvenile mortality does not necessarily equate with high recruitment. 
The respondent's statement that distributional data show that in years 
of low spring outflow (e.g. 1992, 1994, and 1997), the largest catches 
of young splittail occurred upstream in the Sacramento River, is 
inaccurate for two of the three years referenced, and faulty 
conclusions are drawn from the data.
    Water year 1992 exhibited similar abundances of splittail in upper 
Sacramento River and Far North Delta locations, and moderate abundance 
overall. Water year 1994 did exhibit relatively higher abundance in 
upstream locations, but abundance was low throughout all locations. 
Water year 1997 was wet, not dry as stated by the respondent. Also, 
regardless of being a wet year, water year 1997 exhibited low splittail 
abundance in all locations. Further, we expect that YOY spawned higher 
in the Sacramento River to suffer higher mortality, relative to fish 
spawned in the Delta, as they migrate downstream through progressively-
worsening habitat conditions to rejoin the core population. Increased 
mortality among splittail spawned upstream may explain why YOY tend to 
be captured less frequently in downstream trawl-based surveys in 
certain dry years. The final statement, that splittail spawned upstream 
exhibit successful spawning and recruitment in dry years, is not 
supported by survey data. While spawning success can be inferred from 
YOY abundance, YOY fish do not necessarily recruit to the adult 
population. There is some evidence that high or low YOY abundance is 
correlated, with a two to three year time lag, with adult abundance. 
For this reason, YOY abundance cannot be excluded entirely. Our we 
believe our analysis using the CDFG/USBR MLR Model data series (see 
section entitled Abundance) incorporates all applicable YOY and adult 
abundance data, though excludes the beach seine due to its lack of a 
reliable catch per unit time indicator (seine hauls do not accurately 
account for time, or unit area per time sampled). Beach seine data are 
best employed with regard to the splittail for determining range and 
timing of occurrence.
    Comment 20: A respondent stated that while splittail are able to 
persist in a few key areas, such as Suisun Marsh and the lower 
Sacramento River, during periods of low flow, the relatively smaller 
populations would be vulnerable to a large scale disaster (e.g., toxic 
spill), habitat loss, entrainment mortality, reduced outflows, non-
native species predation, and contaminants.
    Our Response: We refer the respondent to the section entitled 
Summary of Factors Affecting the Species.
    Comment 21: The respondent stated that the court requested that we 
provide: (1) An estimate of the current population size of the 
splittail; (2) determine whether or why the current populations size is 
inadequate to prevent extinction in the near future; (3) determine the 
rate of population decline of splittail; and (4) identify the minimum 
viable population size. In addition, a respondent stated that the 
hypothetical analytical model presented at the January 29, 2001, CALFED 
Bay-Delta Program (CALFED Program) Splittail Science Conference and 
described in the White Paper (Moyle et al., 2001) indicates that the 
splittail, even during severe and lengthy drought, is unlikely to be 
driven to extinction.
    Our Response: There remains no proven scientific method for 
determining the current splittail population size primarily because no 
extant survey was designed specifically to monitor splittail 
populations or to determine their absolute numbers. Further, the 
splittail exhibits relatively wide variation in annual abundance in 
response to prevailing hydrologic conditions; it is likely that the 
population size exhibits appreciable year to year variability which 
would confound size estimates.
    Calculating the current population's risk of and/or time to 
extinction would require estimates of absolute population size, rate of 
decline, and minimum viable or sustainable population size, none of 
which currently exist in a scientifically defensible form. Moreover, it 
must also be noted that the statutory and regulatory standard for 
ascertaining

[[Page 55156]]

threatened status is not to determine whether or why a species will 
become extinct in the near future, but if, pursuant to section 3(19) of 
the Act, it ``* * * is likely to become an endangered species within 
the foreseeable future throughout all or a significant portion of its 
range''. An endangered species, pursuant to section 3(19) of the Act, 
is that ``* * * which is in danger of extinction throughout all or a 
significant portion of its range * * *''.
    As stated above, analytical techniques do not exist to determine 
the rate of splittail population decline with current splittail data. 
Again, the absence of survey methodologies specifically designed to 
monitor splittail populations is a limiting factor in determining rate 
of decline. An estimate of splittail population decline, in the form of 
an exponential decay model, was included by in our August 17, 2001, 
notice (66 FR 43145) but was not used in this document because of 
respondents' concerns that it is insufficient to describe the 
interactions in a complex aquatic ecosystem. Further our exponential 
decay model relied upon the results of the CDFG Mann-Whitney U test 
results. The CDFG Mann-Whitney U test results have since been 
superceded by the CDFG/USBR MLR Model. Lastly, there exists no method 
to determine the splittail's minimum viable population because, again, 
no current survey was designed specifically to monitor splittail 
population size.
    Since the publication of the Final Rule listing the splittail as 
threatened, a hypothetical analytical model was developed and presented 
at the January 29, 2001, CALFED Bay-Delta Program (CALFED) Splittail 
Science Conference. The model is described in detail in the White Paper 
(Moyle et al., 2001). Service staff attended the aforementioned 
conference and are aware of the model. A second review draft was 
provided to us on June 18, 2001.
    We believe that the model is, at present, only a tool for testing 
existing hypotheses and for generating new hypotheses. Certain findings 
may be interpreted to support listing and others may counter it, but we 
have determined that neither is sufficiently robust to be included in 
this final document. Indeed, once refined by the incorporation of more 
accurate data, the model may be useful for determining those mitigation 
and restoration efforts likely to have the greatest benefit to the 
splittail.
    Comment 22: A respondent claimed that any decline evident in the 
Suisun Marsh OT data, or in any other survey demonstrating a decline, 
might be due to a shift in the splittail's distribution, rather than a 
decline in numbers.
    Our Response: Data do suggest that splittail shift their 
distribution in response to salinity conditions, and that they are 
quick to respond and move into an area when conditions become favorable 
(see Background section). However, we believe our survey information is 
robust enough to detect a decline (see Abundance section)
    Comment 23: One respondent objected to our determination in the 
January 12, 2001, notice (66 FR 2828), that rock revetment, or riprap, 
as it presently exists or is proposed, would have any significant 
impact upon the splittail.
    Our Response: While a general dismissal of riprap and other types 
of levee and bank protection is likely overly broad, the application of 
riprap and other bank treatments that has occurred throughout the 
splittail habitat has resulted in the decreases in habitat that have 
led to this examination of the status of the species. Bank protection 
can be placed on levees and riverbanks without damaging habitat, but it 
must be done so with explicit considerations for the habitat needs of 
the affected species. Our analysis in this rule accepts that premise as 
part of our underlying review of the CALFED and CVPIA contemplated 
actions.
    Comment 24: A respondent asked if we would address the impacts of 
boating and other activities affecting near-shore habitat.
    Our Response: The impacts of boating are not considered a 
significant source of habitat loss. In many regions of the Delta, wave 
wash is a natural phenomenon related to winds crossing areas of great 
fetch (open areas). The splittail evolved with the effects of wave wash 
within near-shore habitat.
    Comment 25: One respondent differed with the determination in our 
January 12, 2001, notice (66 FR 2828), that California's variable 
Mediterranean climate is a threat to native fish, and contended instead 
that it favors native fish over non-native fish. The respondent also 
stated that the splittail had evolved subject to the vagaries of 
California's climate and was adapted to survive them.
    Our Response: Our notice stated that ``The variability of 
California's Mediterranean climate exacerbates the threats (emphasis 
added) * * *'' to the splittail. The Mediterranean climate includes 
periods of extended normal and above-normal precipitation but may also 
include periods of extended drought. Splittail evolved under these 
conditions and are adapted to them. We agree with the respondent that 
the splittail had evolved subject to the variability of California's 
climate and has adapted to survive this variability.
    Comment 26: One respondent stated that pesticide application is not 
a threat to the splittail because no data were presented to support the 
assumption that pesticides bioaccumulate in fish to the point of 
causing morbidity, mortality, or reduced reproduction. Several 
respondents took similar exception to our statements regarding the need 
for pesticide use on crops to be assessed and possibly regulated. The 
respondent also claimed pesticides were no more of an environmental 
problem within the bypasses than in other areas and that there was no 
reason to justify separate or additional regulatory programs that would 
apply only to the bypasses. A respondent stated that pesticides may be 
present, but that they have been flushed from the bypasses prior to 
spawning. Another respondent stated that much of the pesticide loading 
in the Yolo Bypass was due to runoff from upstream sites.
    Our Response: Please see our discussion under threats. In general, 
there are findings that have heightened our concern regarding these 
substances. However, there is little data on the direct affects to 
splittail.
    Comment 27: A respondent felt that we were inconsistent when it was 
stated in the January 12, 2001, reopening of comment period (66 FR 
2828), that wetland rehabilitation could be deleterious to the 
splittail, but that wetland habitat improvements within the species' 
range would be beneficial. The respondent felt we had not ``* * * 
integrated its concepts and concerns in a manner that weighs relative 
risks and concepts.''
    Our Response: We agree with the respondent that wetland restoration 
projects are generally beneficial to splittail.
    Comment 28: A respondent felt that our statement that the present 
operation of Federal, State and private water development projects, 
that entail water storage, diversions, re-diversions, and agricultural 
return flows, destroy splittail habitat was incorrect.
    Our Response: We refer the respondent to the section entitled 
Summary of Factors Affecting the Species.
    Comment 29: A respondent felt that we did not adequately 
acknowledge the positive environmental effects of the CVP and SWP. The 
respondent specifically noted that the inland extent of saltwater 
intrusion into the Delta is currently lower than with the ``without-
project'' condition.

[[Page 55157]]

    Our Response: We do not consider the pre-SWP and CVP extent of 
saltwater intrusion to be detrimental to splittail. Saltwater intrusion 
was defined by the respondent as the location of the chloride 
concentration of 1000 milligrams per liter (mg/L)(1000 parts per 
million (ppm)), measured 90 minutes after high tide. It is not clear if 
the inference is that brackish water such as this is detrimental to the 
splittail. Splittail occupy brackish water at various stages of their 
life and such habitat may actually be essential to the species' life 
history. The 1000 parts per million value is equivalent to 1 part per 
thousand (ppt), which differs little from the 2 ppt standard identified 
as X2. The White Paper (Moyle et al. 2001) includes numerous references 
to the use of brackish water near X2 by splittail, indicating that it 
may actually characterize optimal rearing habitat for fish greater than 
75 mm (3.0 in) in standard length (typically late year 0 or early year 
1 fish). Non-reproductive (rearing juvenile and adult) splittail are 
most abundant in shallow brackish tidal sloughs, such as those found in 
Suisun Marsh. Growth of splittail in brackish sloughs is rapid in the 
first year of life, with fish reaching a size of 12 to 14 cm ( 4.7 to 
5.5 in) TL. Further, historic, pre-reclamation conditions in the Delta 
would have allowed the ``natural'', non-SWP and CVP manipulated X2 
location to exist within extensive flooded wetlands. Also note that 
splittail have wide salinity tolerance (10 to 18 ppt) (Moyle 1976; 
Moyle and Yoshiyama 1992), with an absolute observed tolerance of 29 
ppt for short periods (Young and Cech 1996). Inland brackish water 
intrusion may have thus been at tolerable or even desirable 
concentrations for the species. We do not consider the changes in 
estuarine hydrology induced by the SWP and CVP to be beneficial to the 
splittail and traditionally the Service and other wildlife agencies 
have accepted as fact the supposition that splittail habitat was 
degraded as a result of the operation of these projects (see the 
section entitled Summary of Factors Affecting the Species).
    Comment 30: The court directed that we respond to the issue that 
splittail have a broader distribution than previously thought, 
including a broader range in the Sacramento and San Joaquin Rivers. 
Another respondent noted that larval, Age 0 and Age 1 splittail have 
all been collected above the Delta.
    Our Response: The greater range of the splittail was acknowledged 
in the January 12, 2001, notice (66 FR 2828). The above Background 
section of this final document contains a discussion of the range of 
the splittail.
    Comment 31: Nearly all respondents felt that we should not classify 
the Yolo and Sutter bypasses as a threat to the splittail, as we did in 
the January 12, 2001, reopening of comment period (66 FR 2828), based 
primarily upon the data found in Sommer et al. (1997) and Sommer 
(2001a). The bypasses have demonstrated the capability of producing 
large numbers of splittail when inundated.
    Our Response: We have determined, based on consideration of 
scientific data and information provided by respondents, that the Yolo 
and Sutter bypasses are not, in and of themselves, a threat to the 
splittail. Our reevaluation of this issue is discussed in Factor E of 
the section entitled Summary of Factors Affecting the Species.
    Comment 32: Some respondents stated that the bypasses, the 
Sacramento River Flood Control System, and other reclamation and flood 
control efforts are beneficial to the splittail because they redirect 
water into the Sacramento River that, prior to the 1920s, would have 
spilled into the Colusa, Yolo, Butte, Sutter, and American basins, thus 
entraining significant numbers of fish.
    Our Response: Splittail evolved in the Central Valley and we 
postulate that the species is likely evolutionarily equipped to exist 
in the presence of natural flood basins inundated during unaltered 
hydrologic conditions. The splittail's high salinity tolerance (see 
Background section, above) also indicates its ability to persist in 
detached, increasingly saline waters. The number of confounding factors 
as well as lack of any historic data severely limits our ability to 
assess with any real authority the ultimate effect of the Sacramento 
River Flood Control System, the CVP and the SWP. Following is our 
assumed scenario regarding the effects on splittail of past reclamation 
and flood control efforts. However, we acknowledge that alternative 
assumptions and conclusions could be drawn from existing information.
    Reclamation activities, including the Sacramento River Flood 
Control Project and similar efforts to prevent flooding of urban and 
agricultural lands, have resulted in the confinement of the Sacramento 
River primarily to a single, leveed or otherwise artificially-confined 
channel, with much of the former American and Colusa basin habitat no 
longer available to fish occupying the mainstem river. The respondent 
claimed this was a benefit in that splittail were no longer subject to 
entrainment in these basins. While it is true that splittail are no 
longer subject to stranding in these basins, no data were provided to 
indicate that these basins, in their unaltered state, were a source of 
mortality sufficient to cause a decline of the species. There were no 
hydrologic data provided to indicate when the historic basins would 
have become connected or isolated from the Sacramento River in a 
typical year. These basins, being situated lower than the adjoining 
river and likely maintaining an alluvial (stream bed sediment) water 
connection, may have existed as perennial marshes wherein splittail 
could persist until inundation was restored. Indeed, the White Paper 
(Moyle et al. 2001) states that splittail historically occurred in 
alkaline lakes on the valley floor. The Butte Basin remains connected 
to the Sacramento River via the Sutter Bypass and Butte Creek; 
splittail are known to spawn in this area (Baxter 1999a).
    It is also possible that, for the American River, Feather River, 
and other eastside streams, pre-European habitat conditions contained 
more complete and/or longer duration surficial (surface water) 
hydrologic connections between rivers and sinks than they did following 
the period of massive hydraulic mining. Hydraulic mining resulted in 
massive deposition of sediments in the beds of many eastside streams. 
The streambeds then became elevated. Rivers began to meander, as 
gradient and sinuosity are inversely related. When hydraulic mining 
ceased, the rivers began to straighten, eroding back through the 
deposits, and leaving elevated banks as effective barriers for the 
basins' receding flood waters. These elevated banks could have 
exacerbated the tendency for the rivers to become disconnected from the 
natural basins.
    Comment 33: Several respondents felt that our determination that 
the Sutter and Yolo bypasses would require inundation for at least 30 
continuous days between March and April in order for them to be 
considered a beneficial splittail spawning habitat was inaccurate and 
could affect water supply and flood management. Another respondent 
indicated that constant flows, related to inundation of the bypasses, 
would favor non-native fish.
    Our Response: We have not proposed inundation of the bypasses for 
any specific interval, duration, or frequency. Rather, we have 
suggested that the bypasses would have their greatest benefits to 
splittail if they became inundated at a frequency and duration that as 
closely as possible mimics the natural, precipitation-driven 
hydrograph. The reference to 30 days is a statement regarding how the

[[Page 55158]]

inundation patterns of the bypasses at times do not meet the life 
history requirements of the splittail. Inundation of bypasses in dry 
years would reduce the effects of drought on the splittail. We also 
speculate that if the bypasses were inundated at a frequency and 
duration that as closely as possible mimics the natural, precipitation-
driven hydrograph, then the numbers of non-native fish would be 
reduced, as non-native fishes favor ponded and continuously inundated 
habitats.
    Comment 34: Certain respondents felt that compensation should be 
provided to land owners when habitat restorations affected land use.
    Our Response: If habitat restorations affect land use, there is a 
separate process available to landowners for redress. While we do not 
anticipate that efforts to restore the habitat will result in 
substantial changes in the land use practices in the bypasses, the 
regulations governing listing [50 CFR Sec.  424.11(b)] state that 
listing of a species as threatened or endangered is made ``* * * solely 
on the basis of the best available scientific and commercial 
information regarding a species' status, without reference to possible 
economic or other impacts of such a determination.'' Accordingly, we do 
not consider or address this issue in our listing decision.
    Comment 35: Several respondents commented that our classification 
of the Yolo Bypass as a threat in the January 12, 2001, notice (66 FR 
2828) would undermine potential ecosystem restoration actions that 
would benefit the splittail.
    Our Response: In this notice, we have determined that the Sutter 
and Yolo bypasses are not in and of themselves threats.
    The bypasses remain important splittail spawning and rearing 
habitat during wet periods. Sommer et al. (1997) and Sommer et al. 
(2001a, 2001b) found that the bypasses as they exist today, and when 
flooded, already provide substantial amounts of habitat.
    Comment 36: A respondent claimed that this determination could not 
be promulgated because it was not likely to include the required 
critical habitat designation or the preparation of a recovery plan.
    Our Response: We have determined that listing as a threatened 
species is not warranted for the splittail, and therefore the 
designation of critical habitat is not warranted.
    Comment 37: A respondent claimed that we must consider the 
cumulative impacts of multiple species listings and critical habitat 
designations.
    Our Response: The ESA does not allow us to consider cumulative 
impacts of multiple species listings and critical habitat designations 
when making a listing determination.
    Comment 38: A respondent stated that sport fishing take of other 
listed species, specifically salmonids, is a significant source of 
mortality of splittail caught unintentionally and asked if the listing 
of splittail would include measures to protect the species from this 
threat.
    Our Response: We concur that sport fisheries can be a source of 
mortality for splittail caught unintentionally. However, since we have 
determined that listing as a threatened species is not warranted for 
the splittail, this notice does not include restrictions on 
sportfishing.
    Comment 39: Several respondents objected to our statements 
regarding the entrainment risks present in the bypasses based upon 
Sommer et al.'s (1997) findings that entrainment is not a significant 
threat within the bypasses. It is thought that the splittail's 
evolutionarily-derived ability to emigrate prior to stranding reduces 
the risk of stranding. Respondents felt that the magnitude of the 
entrainment threats presented by the bypasses was overestimated when we 
cited in the January 12, 2001, notice (66 FR 2828), the death of a 
number of juvenile splittail in an approximately 0.8 hectare (ha) (2 
acre (ac)) borrow pit as statistically-significant and that the 
classification of ``natural sinks'' as a threat was in error.
    Our Response: We have considered these data and now agree that 
entrainment in the Yolo Bypass is less than was originally thought. 
Information presented at the January 29, 2001, CALFED Splittail Science 
Conference indicates that a modest degree of topographic variability 
within an inundated area may be beneficial, as it may create a 
diversity of flow patterns and velocities which in turn may allow 
juvenile splittail to evade predation and forage more effectively 
during egress.
    Comment 40: A respondent described that many of the non-native 
species of the Delta have arrived via the discharge of ballast water 
from seagoing vessels and asked if the listing of the splittail would 
result in the regulation of maritime trade.
    Our Response: As we have determined that listing as a threatened 
species is not warranted for the splittail, this notice does not 
include restrictions on maritime trade.
    Comment 41: A respondent stated that we should consider only 
project-induced effects associated with existing projects and their 
associated operations. The respondent discouraged assessments of 
effects to splittail that would occur based upon implementation of 
projects that will be constructed and/or operated in manners that 
cannot be substantially verified at present, such as those in CALFED 
and the CVPIA.
    Our Response: We agree and have revised and reevaluated the threats 
presented by existing conditions and projects (see Summary of Factors 
Affecting the Species section).
    Comment 42: Several respondents believed that full implementation 
of the CALFED Program would preclude the need to list the splittail and 
indicated that over $10 million had been spent on actions that could 
improve conditions for splittail.
    Our Response: We agree that actions taken under the CALFED program 
have contributed to the current improvements in habitat that affects 
the splittail and anticipate that other actions of that type are 
forseeably likely to occur. ( We refer the respondent to the sections 
entitled Summary of Factors Affecting the Species.)
    Comment 43: Various respondents informed us of the contents of an 
April 24, 2001, Sacramento Bee article wherein Dr. Peter B. Moyle, a 
recognized expert in aquatic ecology, fisheries science, and the 
splittail, discussed the February 8, 1999, listing of the splittail as 
threatened. Respondents related Dr. Moyle's statement that ``Things 
were getting better'' and argued that it constituted an opinion that 
the species should not have been, and by inference, should not now be 
listed.
    Our Response: We have read the article in question. We cannot 
conclude that Dr. Moyle was making a statement on the listing status of 
splittail. However, we do note that ecosystem improvements are a 
primary reason why we are removing the listing. We have cited several 
of Dr. Moyle's scientific publications and conclusions within this 
document.
Summary of Factors Affecting the Species
    After a thorough review and consideration of all the best 
scientific and commercial information available, we have determined 
that the listing of the Sacramento splittail as a threatened species 
should be removed. We followed procedures found at section 4(a)(1) of 
the Act and regulations (50 CFR part 424) implementing the listing 
provisions of the Act. A species may be determined to be endangered or 
threatened due to one or more of the five factors described in section 
4(a)(1).

[[Page 55159]]

These factors, and their application to our decision to remove from the 
list the Sacramento splittail as threatened, are as follows:
    A. The present or threatened destruction, modification, or 
curtailment of its habitat or range. We have identified, as threats to 
the splittail, the present operation of Federal, State, and private 
water development projects entailing water storage, diversions and re-
diversions, releases, flood control, and export and agricultural return 
flows, which destroyed splittail habitat (59 FR 682, 64 FR 5963, 66 FR 
2828). Each is discussed briefly below as are the beneficial effects of 
CALFED and the CVPIA, which offset some of these threats.
    Habitat Loss: The Bay Institute (1998) has estimated that 
intertidal wetlands in the Delta have been diked and leveed so 
extensively that only approximately 3,237 ha (8,000 ac) remain of the 
161,875 ha (400,000 ac) that existed in 1850, and that 90 percent of 
the riparian forest and riparian wetlands of the Sacramento Valley have 
been cleared, filled, or otherwise eliminated. Diking, dredging, 
filling of wetlands, and reduction of freshwater flows through more 
than half of the rivers, distributary sloughs, and the estuary for 
irrigated agriculture and urban use have widely reduced fish habitat 
and resulted in extensive fish losses (Moyle et al., 1995; Nichols et 
al., 1986).
    There has been loss and degradation of the near-shore habitat 
required by splittail. Riparian and natural bank habitats are features 
that historically provided natural function to the stream banks and 
flood plains for splittail by providing spawning substrate, organic 
material, food supply, and cover from predators. Vast stretches of the 
Sacramento and San Joaquin Rivers, their tributaries, and distributary 
sloughs in the Delta have been channelized and the habitat converted or 
destroyed.
    Delta water diversions and exports currently total 1.1 hectare-
meters (ha-m) (9 million acre-feet (MAF)) per year. These diversions 
and exports also harm the splittail. The Federal and State water 
projects presently export as much as approximately 740,000 ha-m (6 MAF) 
per year from the Delta when sufficient water is available. 
Agricultural diversions for lands within the Delta range from 7,400 to 
160,000 ha-m (60,000 acre-feet to 1.3 MAF); approximately 123,000 ha-m 
(1.0 MAF) per year in the long term period, 136,000 ha-m (1.1 MAF) in 
critical and dry years (CALFED 2000b). The draft White Paper entitled 
Factors Relating to Salvage of Splittail at South Delta Pumping Plants 
(Cannon 2001 in prep.) states that ``* * * lower population levels 
occurring as a consequence of salvage-entrainment related mortality may 
be reducing population resilience (e.g., less dependence on a single 
age class) and jeopardizing the long-term viability and ecological role 
of splittail in the estuary.'' If entrainment mortality increases 
further, it could be expected to have even greater adverse effects on 
the splittail. In addition, reservoir operations and ramping rates for 
flood control inadvertently drain shallow water spawning habitat along 
river corridors and exacerbate stranding of splittail.
Beneficial Actions Offsetting Adverse Affects
    A number of beneficial actions offset the above described adverse 
affects. Below are some of the specific actions or programs describing 
the beneficial actions.
    CALFED Habitat Restoration: The CALFED Bay-Delta Program (CALFED) 
exists as a multi-purpose (water supply, flood protection, and 
conservation) program with significant ecosystem restoration and 
enhancement elements, and is well into its implementation phase (CALFED 
2000a, 2000b). The stated mission of CALFED is to develop a long-term 
comprehensive plan that will restore ecological health and improve 
water management for all beneficial uses of the Bay-Delta system 
(CALFED 2000a, 2000b). The plan specifically addresses ecosystem 
quality, water quality, water supply, and levee system integrity 
(CALFED 2000a, 2000b). CALFED encompasses eight separate program 
elements; each having disparate potential effects to the splittail 
(CALFED 2000a, 2000b).
    CALFED is a cooperative effort of the U.S. Department of the 
Interior, the U.S. Department of Commerce, the Environmental Protection 
Agency, the California Environmental Protection Agency, and the 
California Resources Agency, as well as other State and Federal 
agencies, with the involved public formally participating originally 
through the Bay-Delta Advisory Council, and currently through the Bay-
Delta Public Advisory Committee (CALFED 2000a, 2000b). CALFED is a long 
term effort with an initial, shorter term implementation strategy 
(CALFED 2000a, 2000b). The Record of Decision (ROD) for CALFED was 
signed in August, 2000.
    CALFED has has received sufficient funding (approximately 80 
percent of funding required from the State of California, from CVP and 
SWP water project users and local entities, and from Federal funding), 
to make progress toward achieving its goals which include restoration 
and enhancement of splittail habitat (CALFED 2000a, 2000b). While 
CALFED is not meeting the expected schedules, the individual actions 
are occurring generally within the scope of their own schedules (CALFED 
2000a, 2000b). With respect to splittail actions, CALFED has identified 
the plan to be implemented, as well as the funding level, funding 
sources, and other resources necessary to implement it (CALFED 2000a, 
2000b). In addition, CALFED has identified the appropriate authorities 
as well as the legal, regulatory, and procedural requirements necessary 
to implement the conservation effort. Importantly, CALFED has completed 
the environmental reviews and consultations necessary to proceed with 
its proposed actions. CALFED describes the nature and extent of threats 
being addressed, and addresses the threats to the splittail through its 
tidal and riparian habitat restoration projects, fish screen projects, 
environmental water program, water quality program and numerous other 
programs (CALFED 2000a, 2000b). CALFED defines its conservation 
objectives in terms of recovery of targeted species, including the 
splittail, and has identified the steps necessary to implement the 
program (CALFED 2000a, 2000b). The goal of CALFED to recover the 
splittail will remain whether the splittail is listed or not (CALFED 
2000a, 2000b). CALFED has identified and employed quantifiable, 
scientifically valid parameters to demonstrate achievement of 
objectives and the standards by which progress is to be measured 
(CALFED 2000a, 2000b). CALFED monitors and reports on progress towards 
implementation (based on compliance with the implementation schedule) 
and effectiveness (based on evaluation of quantifiable parameters) of 
the conservation effort (CALFED 2000a, 2000b). Adaptive management has 
been incorporated into CALFED (CALFED 2000a, 2000b).
    Although the splittail reared in the Sacramento River and/or Yolo 
Bypass are likely to largely avoid the CVP and SWP pumps, in the 
absence of any consideration of the splittail in the CALFED process, 
the splittail's status could be adversely affected by program elements 
to increase water storage in the Central Valley upstream of the Delta; 
modify Delta hydrologic patterns to convey additional water south, and 
upgrade and maintain Delta levees. However, as noted previously CALFED 
has an explicit goal to balance the water

[[Page 55160]]

supply program elements with these the restoration of the Bay-Delta and 
tributary ecosystems and recovery of the splittail and other species. 
Because achieving the diverse goals of the program is iterative and 
subject to annual funding by diverse agencies, CALFED has committed to 
maintaining balanced implementation of the program within an adaptive 
management framework (CALFED 2000a, 2000b). Within this framework of 
implementation, it is intended that the storage, conveyance, and levee 
program elements would only be implemented in such a way that the 
splittail's status would be maintained and eventually improved (CALFED 
2000a, 2000b). The restorative components of CALFED will positively 
influence the status of the splittail; these are the Ecosystem 
Restoration Program (ERP), the Multi-Species Conservation Strategy 
(MSCS,) and the Environmental Water Account (EWA) (CALFED 2000a, 
2000b). CALFED has identified 29 species enhancement conservation 
measures for splittail (CALFED 2000a, 2000b). These measures include a 
variety of actions consistent with our conservation strategy.
    CALFED's Ecosystem Restoration Program includes the development and 
implementation of a program to address flows resulting from the present 
operation of Federal, State, and private water development projects, 
entailing water storage, diversions and re-diversions, releases, export 
and agricultural return flows (CALFED 2000a, 2000b). This includes the 
development of a methodology for evaluating Delta flow and hydrodynamic 
patterns and implementation of an ecologically based plan to restore 
conditions in the rivers and sloughs of the Delta sufficient to support 
targets for the restoration of aquatic resources, including splittail 
(CALFED 2000a, 2000b).
    The EWA's stated purpose is to provide benefits to threatened or 
endangered fish without causing additional adverse impacts on water 
deliveries from diversions and the export facilities (CALFED 2000a, 
2000b). The EWA, not analyzed in the February 1, 1999, final rule (64 
FR 5963), or in the January 12, 2001, notice (66 FR 2828), purchases 
water from willing sellers, then banks, stores, transfers and releases 
it as needed to protect fish and compensate water users (CALFED 2000a, 
2000b). The EWA has set a goal of acquiring at least 23,400 ha-m 
(190,000 acre-feet) of water each year through purchases, but also 
expects to obtain additional 23,400 ha-m (190,000 acre-feet) of water 
on average each year through additional pumping at times safe for fish 
(CALFED 2000a, 2000b). Already the EWA has demonstrated some success. 
In its first year, the account provided 35,400 ha-m (287,000 acre-feet) 
of water for environmental purposes without reducing allocations to 
agricultural and urban users. The EWA thus has functioned as a 
mechanism for providing for improved Delta conditions for splittail.
    A review of the CALFED ERP projects shows that as of June 2002, the 
ERP has funded: 58,300 acres of habitat proposed for protection, 
including 12,000 acres dedicated to wildlife friendly agriculture and 
16,000 acres of floodplain; 39,000 acres of habitat proposed for 
restoration, including 9,500 acres of shallow water tidal and marsh 
habitat; 63 miles of upstream habitat proposed for protection and/or 
restoration; 93 miles of riparian corridor proposed for protection and/
or restoration; 72 fish screens accounting for an additional 2,565 cfs 
of diversion capacity screened; 15 fish ladders and 10 dam removals to 
provide better upstream passage; 31 projects involving analysis of 
environmental water and sediment quality; 18 projects intended to 
specifically address nonnative invasive species; and 75 projects 
supporting local watershed stewardship and environmental education 
(CALFED 2002). Clearly substantial efforts are underway to continue to 
restore and develop optimum splittail habitat.
    Full implementation of the 30 year program will require both State 
and Federal funding and is expected to require both annual 
appropriations by Congress and continued funding by the State of 
California. To date, the federal government has spent over $700 million 
on CALFED, and the overall expenditures for the first 3 years of the 
program exceeds $2 billion; all of which has been spent for 
environmental restoration.
    CVPIA Habitat Restoration: The Central Valley Project Improvement 
Act (CVPIA) (Public Law 102-575) signed October 30, 1992, amends 
previous authorizations of the Central Valley Project (CVP) (16 U.S.C 
695d-695j) to include fish and wildlife protection, restoration, and 
mitigation as project purposes having equal priority with irrigation 
and domestic water supply, and fish and wildlife enhancement having 
equal priority with power generation. Two of the stated purposes of the 
CVPIA are to ``protect, restore, and enhance fish, wildlife, and 
associated habitats in the Central Valley * * * of California'' and 
``to contribute to the State of California's interim and long-term 
efforts to protect the San Francisco Bay-Sacramento-San Joaquin Delta 
Estuary.'' We also note that the CVPIA is a mitigative effort for past 
impacts of the CVP, and like CALFED, is a multi-purpose program that, 
at full implementation, will include both beneficial ecosystem 
restoration elements as well as water supply, water conveyance, and 
flood control projects, all of which are required to be implemented in 
a manner that considers the needs of the environment, rather than just 
maximizing flood control and water supply and delivery which was the 
case in the past.
    The CVPIA exists as a multi-purpose (water supply, flood 
protection, and conservation) program with significant ecosystem 
restoration and enhancement elements and has been approved by all the 
affected parties including the FWS. It is well into its implementation 
phase and is fully funded. While the CVPIA is not meeting the expected 
schedules, the individual actions are occurring generally within the 
scope of their schedules. The CVPIA has identified the plan to be 
implemented, as well as the funding level, funding source, and other 
resources necessary to implement it. In addition, the authorities, and 
the legal, regulatory and procedural requirements necessary to 
implement the conservation effort have been identified. Finally the 
necessary environmental reviews and consultations have been completed. 
The CVPIA describes the nature and extent of threats being addressed, 
and addresses the threats to the splittail through its tidal and 
riparian habitat restoration projects, fish screen projects, 
environmental water programs and numerous other programs. The CVPIA's 
conservation objectives are defined in terms of recovery of targeted 
species, of which the splittail is one, and has identified the steps 
necessary to implement the program. The program has identified and 
employed quantifiable, scientifically valid parameters to demonstrate 
achievement of its objectives and the standards by which progress is to 
be measured. The CVPIA monitors and reports on progress towards 
implementation (based on compliance with the implementation schedule) 
and effectiveness (based on evaluation of quantifiable parameters) of 
the conservation effort.
    Provisions of the CVPIA to benefit fish and wildlife habitat 
include protection and restoration of natural channel, riparian, and 
wetland habitats (sections 3406(b)(1) and 3406(d)), dedication and 
management of 98,680 ha-m (800,000 ac-ft) of CVP yield (section 
3406(b)(2)), acquisition of additional water supplies to supplement the 
amount dedicated (section

[[Page 55161]]

3406(b)(3)), modification of CVP operations (sections 3406(b)(1) and 
3406 (b)(19)), removal of fish migration barriers (sections 3406(b)(10) 
and 3406(b)(17)), screening of water diversions (section 3406(b)(21)), 
and acquisition of land and associated water rights (section 3408(h)), 
among others. Funding sources for CVPIA mitigation and restoration 
actions include the CVPIA Restoration Fund; State funds provided to 
meet CVPIA cost share requirements; and additional Federal funds 
appropriated by Congress.
    Two programs, the CVP Conservation Program, and the CVPIA Habitat 
Restoration Program, were created to proactively restore and improve 
the Central Valley environment that was or is being impacted by the 
operations of the CVP. These two programs have provided funding to a 
number of projects which collectively would double the acres of 
riparian forest on the Sacramento River (from approximately 8,093 ha 
(20,000 ac) to 16,188 ha (40,000 ac)) and to contribute to the recovery 
of threatened and endangered species (Carlton 2003 in prep.). Combined 
efforts of Federal, state, and nonprofit partnerships have reforested 
almost 1,619 ha (4000 ac) between Red Bluff and Colusa during the last 
15 years (Carlton 2003 in prep.). Riparian forest restoration would, 
over time, also increase the amount of large woody debris habitat 
available to splittail.
    Section 3406(b)(2) of the CVPIA dedicates 98,680 ha-m (800,000 ac-
ft) of CVP yield annually to implement fish, wildlife, and habitat 
restoration, and to help federally listed species. A portion of the 
98,680 ha-m (800,000 ac-ft) identified in the CVPIA may be used to meet 
the Department of the Interior's obligations under the Bay-Delta Accord 
(discussed below). The rest of the water can be used for instream 
flows, additional Delta outflow, and the other purposes of the CVPIA. 
Management of dedicated, supplemental, and reoperated CVP yield will 
benefit splittail when water releases are made at times and locations 
that coincide with splittail spawning and rearing, and in such a manner 
that the releases are adequate to flood vegetated areas adjacent to 
stream channels. The provisions of section 3406(b)(2) are to be 
implemented for five years and involve not only upstream actions but 
also actions in the Delta which may benefit splittail.
    Other Habitat Restoration Projects: Ecosystem restoration efforts 
have been undertaken within the splittail's range. USACE began 
implementation of an ecosystem restoration project on Prospect Island 
in the northwestern Delta in 2001 (Coastal America 2000). The project 
is likely to result in the restoration of approximately 243 ha (600 ac) 
of open water, 134 ha (330 ac) of tidal emergent marsh, and 95 ha (235 
ac) of mud flat within Prospect Island's approximately 486 ha (1,200 
ac) interior. These may represent habitat enhancements for splittail.
    Restoration efforts have been undertaken at the Cosumnes River 
Reserve under management by the Bureau of Land Management (BLM), The 
Nature Conservancy, and a number of other agencies and private 
organizations (The Nature Conservancy 2002a). Restoration activities 
that benefit splittail include riparian enhancement and intentional 
breaching of levees to restore floodplain function. Restoration is 
ongoing and splittail are likely to benefit from any efforts, as the 
area has also been described as among the most important floodplain 
habitats still available to the species (Moyle et al. 2001).
    CDWR has also completed an ecosystem restoration on Decker Island, 
located on the Sacramento River, adjoining Sherman Island near the 
confluence with the San Joaquin River (CDWR 1998). The project has 
restored approximately 4.45 ha (11 ac) of shallow water habitat that is 
likely to be utilized by the splittail. The California Department of 
Transportation has committed to restore 190 ha (470 ac) of tidal 
marshes within the range of splittail for the benefit of splittail as 
compensation for impacts resulting from the construction of the Benicia 
Martinez New Bridge (USFWS 2003a).
    USACE and CDFG are currently in the final stages of planning the 
Napa River Salt Marsh Restoration Project (USFWS 2003b). Approximately 
1,262 ha (3,120 ac) of diked salt ponds would be restored to tidal 
marshes usable by splittail.
    The 44 ha (109 ac) Kimball Island Mitigation Bank reestablished 
riverine aquatic bed, riparian forest, shaded riverine aquatic, and 
tidal marsh habitat at the mouth of the Delta usable by splittail 
(Wildlands, Inc. 2002).
    In early 2002, our Sacramento River National Wildlife Refuge 
Complex (SNWRC) began implementation of the Environmental Assessment 
for Proposed Restoration Activities on the Sacramento River National 
Wildlife Refuge. The restoration activities will result in the 
reestablishment or enhancement of approximately 960 ha (2,372 ac) of 
land on 11 units or subunits of the SNWRC. Restoration and enhancement 
will involve the removal of crops, orchards, and related infrastructure 
(pumping units, barns, sheds, etc.) followed by replacement with native 
vegetation appropriate to each site (USFWS 2002a). A portion of these 
actions are expected to benefit splittail through the improvement of 
vegetative conditions on floodplains and the eventual creation of large 
woody debris (via riparian tree mortality and entrainment).
    The Vic Fazio Yolo Bypass Wildlife Area (Wildlife Area), located 
within the Yolo Bypass, will increase in size from its current 
approximately 1,497 ha (3,700 ac) to approximately 5,261 ha (13,000 ac) 
(The Nature Conservancy 2002b). This increase was not analyzed in the 
February 1, 1999, final rule (64 FR 5963), or in the January 12, 2001, 
notice (66 FR 2828). Though the Wildlife Area does contain entrainment 
hazards, and is located along the slightly less infrequently inundated 
western edge of the Yolo Bypass, it will incorporate opportunities to 
restore the lower reaches of Putah Creek. The added area may allow 
restorations to proceed that benefit splittail to a greater degree than 
possible with the current shorebird and waterfowl-intensive management 
regime.
    Other State efforts may contain actions beneficial to the splittail 
which were not analyzed in the February 1, 1999, final rule (64 FR 
5963), or in the January 12, 2001, notice (66 FR 2828). Assembly Bill 
(AB) 360, the State Delta Flood Protection Act, has a primary purpose 
of strengthening Delta levees with various ``hard'' measures, including 
riprap. Habitat restoration components of AB 360, more properly 
considered mitigation for concurrent State projects' impacts to aquatic 
and terrestrial ecosystems in the Delta do require improvement rather 
than a strict mitigation approach which results in an increased habitat 
benefit and a net increase in habitat. The State Senate Bill (SB) 1086-
funded Sacramento River Conservation Area is an interagency group 
chartered to promote and guide protection and enhancement of riparian 
resources and fluvial function the reach of the lower Sacramento River 
between Red Bluff and Colusa. The Nature Conservancy, working with the 
Sacramento River Conservation Area and local stakeholders, has acquired 
appreciable amounts of land for restoration. This and other future 
Sacramento River Conservation Area actions may be beneficial to 
splittail.
    Conclusion: The loss of spawning and rearing habitat remains a 
potential threat the splittail. However, the implementation and 
magnitude of the CALFED, and CVPIA programs, and other habitat 
restoration activities, which focus on the restoration of

[[Page 55162]]

habitats which directly and indirectly benefit splittail go far beyond 
any forseeable habitat losses (particularly in the context of the 
state's Environmental Quality Act (CEQA) which explicitly requires 
mitigation for habitat loss. The overall effect of such habitat 
restoration activities is also expected to continue to be beneficial 
for splittail at present and into the foreseeable future.
    B. Overutilization for commercial, recreational, scientific, or 
educational purposes. We believe that overutilization (i.e., 
recreational and commercial harvest) is not a factor affecting the 
splittail. As noted in the January 6, 1994, proposed rule (59 FR 862) 
and the 1999 final rule (64 FR 5963), some scientific collecting is 
conducted for splittail, but these activities do not adversely affect 
the species. In addition, striped bass anglers report occasional use of 
splittail as bait, but we think this usage has little affect on the 
species.
    In the January 6, 1994, proposed rule, and the 1999 final rule, we 
also noted that the small splittail fishery (Daniels and Moyle 1983; 
Caywood 1974) was poorly documented and that no evidence suggested it 
was a threat to splittail. At present, we do not consider the threat of 
recreational fishing to be significant. Baxter (2001b) analyzed 1999 
and 2000 creel census data from the Sacramento River from Garcia Bend 
to Redding. Monthly catch amounted to 103 and 232 splittail, 
respectively. However, no abundance indices were calculated by any 
agency, organization, or individual from these data, as they fail to 
meet the criteria established by Meng and Moyle (1995) and are 
generally considered inadequate to the task of quantifying splittail 
abundance.
    The largest splittail are the first to engage in the spawning 
migration (Caywood 1974; Moyle et al. 2001). The early season fishery 
thus targets and removes females with high reproductive potential. The 
effect of this fishery in the Sacramento River may be relatively 
greater in dry years, when splittail spawning is largely confined to 
river margins. However, at present, there is no evidence of any trend 
in the available data suggesting that larger fish are being removed 
from the population or that the size structure of the population have 
been altered by this or other fisheries.
    C. Disease or predation. In our 1994 proposed rule we indicated 
that this factor was not applicable to splittail (59 FR 862). Since 
that time, we have questioned whether that disease may be a threat due 
to high incidences of adult splittail in poor health being captured in 
the State and Federal water project facilities in the south Delta. The 
south Delta is dominated by water from the San Joaquin River, where 
pesticides (e.g., chlorpyrifos, carbofuran, and diazinon), salts (e.g., 
sodium sulfates), trace elements (boron and selenium), and high levels 
of total dissolved solids are prevalent in agricultural runoff (59 FR 
862, 64 FR 5963). We are unwilling to dismiss the potential that 
disease is related to the presence of environmental contaminants. Of 
specific concern are the threats posed by metals, mercury, selenium, 
and pesticides. We speculate that there is some possibility that 
disease in splittail could be a function of increased contaminant 
loading and subsequent immune system depression. However, offsetting 
this concern is information found in the White Paper (Moyle et al. 
2001) indicating that disease and parasite infestation may be a natural 
function related to the heavy cost of migration and spawning. Post-
spawn adult splittail, and male fish in particular, are substantially 
weakened when outmigrating. We have considered whether selenium 
exposure can reasonably be expected to exacerbate this condition. No 
research is known to be conducted on disease occurrence in splittail; 
the only information we found on disease in splittail was in the White 
Paper (Moyle et al. 2001). Therefore, given the lack of available 
information, we are unable to determine that splittail are impacted by 
disease.
    In the past, we have considered threats of predation to be minor 
because striped bass had coexisted with splittail for decades and 
because CDFG had forgone hatchery rearing and release of striped bass 
(59 FR 862, 64 FR 5963). We have determined that predation may be a 
minor factor in the decline of the splittail. Additionally, CALFED 
includes numerous studies on the threats posed by predators (CALFED 
2000a, 2000b) (see Factor A for a discussion of CALFED).
    D. The inadequacy of existing regulatory mechanisms. In the past 
(59 FR 682, 64 FR 5963), we did not consider the suite of available 
regulatory mechanisms to be adequate to protect the splittail. Our 
primary concerns involved the likelihood that the CVPIA, the Bay-Delta 
Accord and CALFED, though not regulatory programs, would be sufficient 
to control water movement in a way that would protect splittail. At 
that time, the funding and implementation of the Bay-Delta Accord and 
CALFED had just begun, and it was too early to know if their funding 
and implementation would continue. We now believe that progress to date 
indicates that these mechanisms are likely to allow effective 
management of water for the benefit of splittail. In addition, we 
believe that some benefits will accrue from efforts associated with 
these programs (see Factor A above for a discussion on CALFED and the 
CVPIA).
    We also note that splittail's habitat, the loss of which 
constitutes the single largest threat to the species, is protected by 
the State under CEQA and by state statutes specific to Delta levees 
which protect levee habitat. Finally, plittail are listed as a Species 
of Special Concern requiring special considerations for mitigation and 
protection under CEQA.
    To the extent that projects may sometimes be constructed without 
proper authorization under section 10 of the Rivers and Harbors Act and 
section 404 of the Clean Water Act, this could result in threats to the 
splittail. Implementation of the unpermitted projects could have 
negative effects on near-shore splittail habitat similar to those 
described under Factor A , and would not necessarily include mitigative 
features.
    In summary, there is a slight potential that some residual threats 
still face splittail due to of inadequate application or enforcement of 
RHA and CWA regulatory mechanisms. However, we have been unable to 
document these threats in other than the most nebulous and anecdotal 
manner. Notwithstanding this potential, as the CALFED program is 
designed to improve habitat for the splittail as well as offset any 
adverse effects of its own actions and provide for recovery of a number 
of species including splittail, we believe it ameliorates the bulk of 
the minor threats associated with this factor.
    E. Other natural or manmade factors affecting its continued 
existence. In our past rules and notices concerning the splittail (59 
FR 682, 64 FR 5963, 66 FR 2828), we identified the risk of drought, 
invasive species (including interference in CVP and SWP salvage 
operations by the introduced Chinese mitten crab (Eriocheir sinensis)), 
detrimental flood bypass operations, the lack of screened water 
diversions, poor water quality and environmental contaminants including 
mercury, selenium and pesticides, bioaccumulation of selenium in the 
introduced Asiatic clam (Potamocorbula amurensis) as threatening the 
splittail. These topics and our current viewpoint of their affect on 
the splittail are further discussed below.
    Drought: The variability of California's Mediterranean climate is 
not a threat to the species; it represents a baseline condition. This 
climate, however, may exacerbate the effects of the threats discussed 
above. Since the proposal to list the splittail, California

[[Page 55163]]

has had relatively wet hydrologic conditions that benefit fish species, 
though water year 2001 was below normal. Because the splittail is a 
floodplain adapted species, a dramatic decline in abundance was 
observed during the 1987 to 1992 drought. Similarly, abundance peaks 
during years when there is extensive floodplain inundations, and of the 
Yolo and Sutter bypasses in particular (Sommer et al. 1997) (see below 
for a discussion of Yolo and Sutter bypasses). When another drought 
occurs, splittail indices will again invariably drop. We have 
speculated the drought cycle may at some point stress the species to 
extinction if populations are too depressed. However, we have no direct 
evidence this is the case, and in the context of the significant 
habitat improvements being undertaken, are far less concerned that 
populations will fall to levels that makes this a concern.
    Invasive species: Chinese mitten crabs (Eriocheir sinensis) could 
reach concentrations sufficient to intermittently impede the operation 
of fish screens and salvage facilities, thus reducing the effectiveness 
of splittail salvage and repatriation efforts. Since the January 12, 
2001, notice (66 FR 2828), USBR has installed a device, known as 
Crabzilla, to remove the Chinese mitten crab from their CVP fish 
salvage facilities. In addition, Chinese mitten crabs have not appeared 
in large numbers at either of the fish salvage facilities in recent 
years. Therefore, the Chinese mitten crab does not appear to be a 
current threat to splittail, as they have not appeared in large numbers 
at the fish salvage facilities and those that do are efficiently 
removed and destroyed before they are able to clog the pipes and 
intakes at the fish salvage facilities.
    Of some concern is the presence of Brazilian pondweed (Egeria 
densa) and water hyacinth (Eichhornia crassipes), both of which tend to 
form dense near-shore and slough-wide mats of vegetation which serves 
as a retreat, foraging, and ambush site for splittail predators and 
which may divert upstream- and downstream-migrating splittail into 
channels rather than the more-productive bankside habitat (Moyle et al. 
2001 in prep). The California Department of Boating and Waterways 
(CDBW) and the United States Department of Agriculture (USDA) 
Agricultural Research Service (ARS) are presently and have been for at 
least 10 years, engaged in a program to control these invasive plant 
species. To date, the control effort has not had a measureable effect 
on splittail.
    CALFED includes numerous studies on the threats of non-native 
competitors (CALFED 2000a, 2000b) (see Factor A for a discussion of 
CALFED).
    Detrimental flood bypass operations: It has been documented that 
splittail make use of the Sutter Bypass, and particularly heavy use of 
the Yolo Bypass for spawning under certain hydrologic conditions and 
that the shallow, vegetated waters provide excellent rearing conditions 
for juvenile fish (Sommer et al. 1997, 2001a, 2001b). The bypasses are 
primarily flood control facilities and secondarily agricultural lands, 
and are passively operated as such. Splittail using the bypasses are 
subject to many of the same threats found elsewhere, such as habitat 
loss, environmental contamination, harmful reservoir operations, 
pesticide loading, competition with and predation by non-native fish, 
etc.
    The flood bypasses are only flooded when flows in the Sacramento 
River reach a certain level. This inundation tends to occur at the 
correct time of year for splittail spawning, but may be reduced in 
frequency and duration (Yates 2001), with direct implications for 
splittail spawning. This constitutes a threat in that adult fish, 
having migrated to suitable spawning habitats on a floodplain, could be 
denied the opportunity to spawn. In those cases where adult splittail 
have successfully spawned, the resulting eggs or larvae could become 
trapped and killed. Insufficient floodplain inundation could also force 
egress of juvenile splittail before they have attained a size and 
swimming ability sufficient to avoid predation.
    Since the publication of our January 12, 2001, notice (66 FR 2828), 
we have determined, based on consideration of scientific data and 
information provided by the public, that the Yolo and Sutter bypasses 
are not, in and of themselves, a threat to the splittail. A threat is 
that which, if removed, will result in improvements in a species' 
status. The removal of the Yolo and Sutter bypasses would be highly 
detrimental to the splittail, as the bypasses constitute a substantial 
portion of the species available spawning habitat. We agree that the 
bypasses are presently important to the splittail when inundated and 
that they produce more fish than they harm. The bypasses likely have 
helped this resilient species to persist through over a century of 
largely unmitigated habitat destruction.
    CALFED's ERP includes the development of a program to eliminate 
fish stranding in the Sacramento, Feather, and Yuba rivers and the 
Colusa Basin Drain and Sutter Bypass in the active stream channels, 
floodplains, shallow ponds, and borrow areas (CALFED 2000a, 2000b) (see 
Factor A for a discussion of CALFED). In addition, the program will 
conduct instream flow studies to determine the flows necessary to 
support all life stages of anadromous and estuarine fish species, 
including splittail (CALFED 2000a, 2000b).
    Entrainment as a result of water diversions: We conclude that 
diversion of water from any river or stream or other water course that 
results in the entrainment, injury or death of Sacramento splittail, 
including stranding of eggs, larvae, juveniles or adults; or diversions 
and subsequent runoff that results in the degradation of waters 
containing splittail is no longer a threat to splittail. Entrainment of 
splittail at diversions is reduced if fish screens are installed at 
diversions in splittail habitat areas. Two programs implemented under 
CVPIA, particularly the Anadromous Fish Restoration Program (AFRP) and 
allied Anadromous Fish Screen Program (AFSP), which were not analyzed 
in the January 12, 2001, notice (66 FR 2828), have had a net benefit to 
the splittail. Removal of migration barriers and placement of fish 
screens on water diversions is ongoing under the AFRP and AFSP, and 
several actions with adjunct benefits to splittail have been completed. 
Removal of migration barriers can provide additional splittail habitat 
where potential habitat is blocked, and entrainment of splittail at 
diversions can be reduced if fish screens are installed in splittail 
habitat areas. Though many small diversions remain unscreened, 
approximately 95 percent of water annually diverted has been or is in 
the process of being screened, including all water diversions greater 
than 40 cubic feet per second, and many of the remaining unscreened 
diversions are small and intermittently operated (O'Leary 2003 pers. 
comm.). CALFED's Ecosystem Restoration Program includes a program to 
consolidate and screen the remaining small agricultural diversions in 
the Delta, and the Sacramento and San Joaquin rivers. The NOAA 
Fisheries Restoration Center has also begun to fund small fish screen 
projects in the Sacramento River within the range of the splittail. 
This represents a near-total reduction in the threat of entrainment in 
unscreened diversions to the splittail, and thus removal of the threat.
    Water quality and environmental contaminants: Metals such as 
copper, zinc and cadmium (Environmental Protection Agency (EPA) 1976) 
can be directly toxic to fish, and presumably to splittail, especially 
in their sensitive

[[Page 55164]]

larval stages, with the effects particularly deleterious near inputs of 
acid mine drainage within the Sacramento River watershed and in the 
vicinity of highly industrialized near-shore areas of the lower San 
Francisco Bay Estuary. These metals damage gills and alter liver and 
nervous system functions causing death, behavioral changes, and reduced 
growth and reproduction (EPA 1976). These metals can have the same 
effects on food items of the splittail, reducing their prey base and 
placing additional stress on the splittail (EPA 1976). However, we are 
not aware of any evidence suggesting that splittail are at any higher 
risk of suffering direct or indirect adverse effects from metals 
exposure than other fish species within the Sacramento River and San 
Francisco Bay estuary systems. For all such species, the potential for 
at least periodic adverse impacts from exposure to metals is of 
substantive concern, but poorly understood.
    Three other potential contaminant threats are of concern 
specifically with respect to the splittail: (1) mercury; (2) selenium; 
and (3) pesticides (persistent organochlorines and currently used 
organophosphates). In part, these contaminant threats are of concern 
because they may be focused, to varying degrees, on habitat features 
and biological characteristics tentatively identified as particularly 
relevant to splittail conservation (Moyle et al. 2001).
    Recent analytical data indicate that mercury concentrations in 
aquatic biota in the San Joaquin River are exceeding screening 
thresholds and may pose ecological and human health risks (Davis et 
al., 2000). A benthic-foraging, longer-lived fish such as splittail 
would be likely to acquire higher and more toxic levels of whole body 
mercury concentration. We are concerned the combined data from these 
monitoring and research efforts may indicate that mercury in the San 
Joaquin River poses a threat to ecological health in general, and the 
splittail, as a benthic forager, in particular. Some findings have 
linked elevated mercury to the Consumnes and Yolo Bypass (Slotten et 
al. 2000), which are both primary spawning areas for splittail (Moyle 
et al. 2001). Furthermore, the Yolo Bypass may be hydrologically 
connected to Suisun Marsh, the likely core rearing area for splittail 
(Moyle et al. 2001). Suchanek et al. (2000) is investigating the role 
of wetland restoration involving re-flooding of mercury-contaminated 
soils.
    Significant exposure to selenium could potentially pose a threat to 
splittail throughout much of its range, including the Yolo Bypass. 
Recent samples of splittail from Montezuma Slough collected by USGS 
scientists (Stewart et al. 2000, Stewart et al. unpubl. data) have 
revealed elevated muscle selenium concentrations ranging as high as 4 
to 5 mg/kg (5 ppm), and liver concentrations ranging as high as 20 mg/
kg (20 ppm). The relationship between the bioaccumulation of selenium 
in the Asiatic clam and its predation by splittail could become 
significant in the near-term future because the clam, via its predation 
on typical splittail prey items such as estuarine copepods (Eurytemora 
affinis, and Acartia spp.) (Kimmerer and Pe[ncaron]alva 2000), is 
creating conditions that promotes increasing reliance of splittail on 
the clam as an alternate food source (Feyrer and Matern 2000). Thus, a 
potential scenario for the future is greater reliance of splittail on 
Asiatic clams as a food supply and possibly further increases of 
selenium concentrations in both Asiatic clams and splittail. Selenium 
threats to splittail are not confined to the Yolo Bypass/Suisun Marsh 
systems. We speculate that when splittail are exposed to this level of 
selenium, there is potential that a reduction in reproductive 
performance will occur, which would then result in poor post-hatch 
survivorship. This means that less splittail young would be able to 
recruit to adulthood. There are 1998 splittail data which confirm that 
these fish are being exposed to harmful levels of selenium in their 
range along the San Joaquin River.
    Splittail apparently experience substantial post-spawning stress, 
and are subject to substantial stress during salvage operations at the 
State and Federal pumping facilities. In addition to weakening the 
immune defenses of fish and wildlife, excessive environmental selenium 
can also trigger pathogen and toxin challenges that would not otherwise 
have occurred. At this point, we have no direct information on the 
potential effects of selenium with respect to splittail. However we 
have considered the selenium-mediated vulnerability to non-chemical 
stressors when assessing the threats presented by exposure of splittail 
to selenium.
    Several of the pesticides present in the rivers of the Central 
Valley have been documented to have adverse effects on animal life. 
However, we have no direct evidence that pesticides are a pervasive 
threat to the splittail throughout its range. If there is a threat it 
may be relatively greater in the bypasses due to the large amount of 
spawning and early rearing that occurs there in wet years. All major 
rivers that are tributary to the Estuary are exposed to large volumes 
of agricultural and industrial chemicals that are applied in the 
Central Valley watershed (Nichols et al. 1986) as agricultural 
chemicals and their residues, as well as chemicals originating in urban 
runoff find their way into the rivers and estuary.
    In addition, re-flooding of the Sutter and Yolo Bypasses and the 
use of other flooded agricultural lands by splittail for spawning can 
result in agricultural-related chemical exposures depending on the 
circumstances.
    Toxicology studies of rice field irrigation drain water of the 
Colusa Basin Drainage Canal have documented significant toxicity of 
drain water to striped bass (Morone saxatilis) embryos and larvae, 
Oryzias latipes larvae (in the Cyprinodontidae family), and opossum 
shrimp, which is the major food organism of striped bass larvae and 
juveniles (Bailey et al. 1991), as well as all age classes of 
splittail. This drainage canal flows into the Sacramento River just 
north of the City of Sacramento. The majority of drain water samples 
collected during April and May 1990 were acutely toxic to striped bass 
larvae (96 hour exposures); this was the third consecutive year rice 
irrigation drain water from the Colusa Basin was acutely toxic (Bailey 
et al. 1991). Splittail may be similarly affected by agricultural and 
industrial chemical runoff, particularly, because like striped bass, 
adults migrate upriver to spawn and young rear upriver until waters 
recede in late spring.
    While we have considered these contaminants as possible threats to 
the splittail, it must also be noted that we have no information on the 
splittail's thresholds for metals and pesticides. We are unwilling to 
accept the use of a surrogate species to determine acceptable 
thresholds for splittail. While there are abundant non-native cyprinids 
available (fathead minnows [Pimephales promelas] and golden shiners 
[Notemigonus crysoleucas]), we assert the splittail is behaviorally 
unlike these non-native fishes and most likely physiologically distinct 
from them as well. Further, potential surrogate native cyprinids 
(hardhead [Mylopharodon conocephalus], blackfish [Orthodon 
microlepidotus], pikeminnow [Ptychocheilus grandis]) are piscivorous 
(fish-eating) when adults, and therefore likely distinct from 
splittail. Splittail may have its closest relative in the Rhinichthys 
complex (speckled dace [Rhinichthys osculus] and others) but use of 
these diminutive, short-lived, small-stream species would be similarly 
unadvisable. Lastly, we would have serious concerns with results 
obtained

[[Page 55165]]

from non-cyprinids surrogate species, such as white sturgeon, bluegill, 
inland silverside, mosquito fish, and lake trout, as they would 
certainly be both physiologically and behaviorally distinct from 
splittail and therefore useless in determining thresholds for the 
splittail. We therefore have determined that the above mentioned 
thresholds for other fish species are not indicative of the thresholds 
of the splittail. For all fish species, the potential for at least 
periodic adverse impacts from exposure to metals and pesticides is of 
potentially substantive concern, but poorly understood and poorly 
documented. Thus we have no real basis for concluding that these 
substances represent a particular threat to the splittail.
    Finally, Moyle et al. (2001) hypothesize that success of juvenile 
downstream migration is strongly linked to the size that juvenile 
splittail achieve prior to exiting the spawning areas. It was suggested 
that a minimum size of 25 mm (1 in) greatly enhances success of 
downstream migration. Moyle et al. (2001) have already presented data 
demonstrating statistically-significant declining growth rates in 
Suisun Marsh splittail between 1980 and 1995. The apparent declines in 
growth rate appear to correlate to the invasion of the estuary by the 
Asiatic clam, and the subsequent shift of splittail to an Asiatic clam-
dominated diet. Moyle et al. (2001) suggested that this trend might 
reflect poorer energetics of a non-mysid shrimp-dominated diet, but it 
can just as plausibly be suggested that it reflects the cachexia 
(contaminant-induced weight loss despite calorically sufficient dietary 
intake) that is a classic symptom of non-lethal selenium poisoning. 
However we have no particular basis for finding the growth rates are 
the result of any contaminent induced mechanism.
    CALFED's Water Quality Program, which was not analyzed in the 
January 12, 2001, notice (66 FR 2828), will have a net benefit for the 
splittail when implemented (see Factor A for a discussion of CALFED). 
The Water Quality Program includes the following actions: (1) Reduce 
the impacts of pesticides through development and implementation of 
Best Management Practices (BMPs) for both urban and agricultural uses, 
through support of pesticide studies for regulatory agencies, and 
through providing education and assistance in implementation of control 
strategies for the regulated pesticide users; (2) reduce the load of 
organochlorine pesticides in the system by reducing runoff and erosion 
from agricultural lands through BMPs; (3) reduce the impacts of trace 
metals, such as copper, cadmium, and zinc, through source control at 
inactive and abandoned mine sites, urban storm water programs and 
agricultural BMPs; (4) reduce mercury levels in rivers and the estuary 
by source control at inactive and abandoned mine sites; (5) reduce 
selenium impacts through reduction of loads at their sources and 
through appropriate land fallowing and land retirement programs; (6) 
reduce salt sources in urban and industrial wastewater and facilitate 
development of successful water recycling, source water blending, and 
groundwater storage programs; (7) manage Delta salinity by limiting 
salt loadings from its tributaries and through managing seawater 
intrusion by such means as using storage capacity to maintain Delta 
outflow and adjust timing of outflow, and by export management; (8) 
reduce turbidity and sedimentation; (9) reduce the impairment of rivers 
and the estuary from substances that exert excessive demand on 
dissolved oxygen; and, (10) through research and monitoring, to 
identify parameters of concern in the water and sediment and impairment 
actions, to reduce their impacts to aquatic resources.
    Conclusion: Splittail are no longer threatened by interference in 
CVP and SWP salvage operations by the introduced Chinese mitten crab 
and unscreened diversions. The Yolo and Sutter Bypasses are a net 
benefit to the splittail. CALFED's Ecosystem Restoration Program 
(discussed in Factor A above) will conduct instream flow studies to 
determine the flows necessary to support all life stages of anadromous 
and estuarine fish species, including splittail, which will offset the 
threat of drought and flow regime changes resulting from water project 
operations. The threats of poor water quality from contaminants 
including mercury, selenium and pesticides, and bioaccumulation of 
selenium in the introduced Asiatic clam, appear to be reduced by 
CALFED's Water Quality Program (discussed in Factor E above). At 
present, although environmental contaminants are pervasive throughout 
the range of the splittail, and many contaminants have the potential to 
pose a significant threat to splittail, there is insufficient 
scientific evidence at this time to indicate that environmental 
contaminants impair splittail growth and reproduction at all; much less 
to a magnitude that would warrant listing splittail due to that threat 
alone or in combination with others.

Finding

    We have carefully assessed the best scientific and commercial 
information available regarding the abundance and distribution of; and 
the past, present, and future threats faced by the splittail in this 
listing determination. The following narrative will summarize the 
pertinent data regarding abundance and threats.
    Based upon our statistical analysis using a relaxed standard for 
significance, we conclude that splittail populations may have declined 
over the period of analysis. We recognize that other agencies, 
including USBR and CDFG, believe that the available data do not 
indicate a population decline. However, the magnitude, certainty, and 
ecological significance of the apparent population decline remain 
unclear.
    We believe that above all else, the primary threat to splittail is 
the loss of spawning and rearing habitat. Past habitat losses are 
offset by the implementation programs of CALFED and the CVPIA which are 
restoring significant amounts of habitat previously lost. In addition, 
those programs ensure that future water operations and development will 
protect and improve existing habitats. The many additional ongoing and 
future habitat restoration projects throughout the range of the 
splittail include, either as direct or indirect effects, spawning and 
rearing habitat for the splittail, or enhancement of such habitat. The 
restoration of splittail habitat enables greater spawning and rearing 
opportunities and thus increases the population size, ameliorating all 
of the remaining threats to a level below the point at which the 
splittail would meet the definition of a threatened species.
    We therefore have determined that the splittail is not in danger of 
extinction through all or a significant portion of its range either now 
or in the foreseeable future. It therefore does not meet the definition 
of an endangered or threatened species. As a result, we have determined 
that listing the splittail as endangered or threatened under the Act is 
not warranted.
    In making this finding, we recognize that the Sacramento splittail 
may be experiencing a decline in population size based upon our 
conservative statistical analysis, and that the species continues to 
face potential threats from habitat loss. We also recognize that the 
full implementation of CALFED and the CVPIA restoration programs are 
not 100 percent certain. Finally, we recognize other threats to the 
species, its habitat, and its prey exist, including effects of drought 
and climate change on habitat; non-native competitors and predators; 
and possible threats of disease and environmental contaminants. We will 
continue to monitor the status and

[[Page 55166]]

management of the species. We will continue to accept additional 
information and comments from all concerned governmental agencies, the 
scientific community, industry, or any other interested party 
concerning this finding. If we find that circumstances change to the 
point that any of these threats change significantly, we will reexamine 
the status of the splittail.

Coordination With the State of California

    The State of California administers, via CDFG, the California 
Endangered Species Act (CESA) (Fish and Game Code sections 2050 to 
2116, et seq.). The purposes of the CESA are to conserve, protect, 
restore, and enhance any bird, mammal, fish, amphibian, reptile, or 
plant meeting CESA criteria for threatened or endangered status, and to 
acquire lands for habitat for these species.
    Procedures governing the submission and review of petitions for 
listing, uplisting, downlisting, and delisting of CESA endangered and 
CESA threatened species of plants and animals are described in section 
670.1, Title 14, California Code of Regulations.
    Under CESA, a State ``threatened'' species is a California native 
species that, although not presently threatened with extinction, is 
likely to become an endangered species in the foreseeable future in the 
absence of special protection and management efforts (Fish and Game 
Code section 2067). A State ``endangered'' species is that which is in 
serious danger of becoming extinct throughout all, or a significant 
portion, of its range due to one or more causes, including loss of 
habitat, change in habitat, overexploitation, predation, competition, 
or disease (Fish and Game Code section 2062). The splittail is not 
listed as threatened or endangered by the State of California under the 
authority of CESA. There appears to be substantive similarity between 
the Federal requirement under section 4(a)(1) of the Act and the State 
requirement under section 14(i)(1)(A) of the of the California Code of 
Regulations to consider all factors affecting a species. There also 
appears to be a high degree of similarity between the definition of a 
``threatened species'' under both section 3(20) of the Act and CESA 
(Fish and Game Code section 2067).
    CDFG submitted comments regarding the status of the splittail 
during the January 12, 2001, May 8, 2001, and August 17, 2001, comment 
periods (66 FR 2828, 66 FR 23181, and 66 FR 43145, respectively) 
subsequent to the court's June 23, 2000, summary judgement. Further, 
CDFG staff were involved in an interagency peer review effort 
undertaken concurrent with the August 17, 2001, comment period. CDFG 
comments were limited only to alternate analyses of species abundance 
(see the Summary of Comments and Recommendations section).
    We are actively coordinating with California Environmental 
Protection Agency (CalEPA), the State Water Resources Control Board 
(SWRCB), and the Regional Water Quality Control Boards (RWQCBs) through 
public comment periods on their regulatory program actions (USFWS 
2002b). The CalEPA, SWRCB, and OEHHA provided no comments regarding the 
listing, however. The CDWR and the Reclamation Board did comment to a 
certain degree regarding the factors affecting the splittail (see the 
Summary of Comments and Recommendations section).
    We have given full consideration to CDFG as well as CDWR 
recommendations to employ an alternate abundance analysis (see 
Abundance and our response to Comment 1). Indeed, we used the CDFG/USBR 
MRF model, the result of a joint State and Federal scientific 
undertaking, to determine if a trend exists for the species. Based on 
our evaluation of conservation efforts completed, currently underway, 
and likely to stem from CALFED and the CVPIA, we now agree with the 
State that listing of the splittail as a threatened species is not 
warranted at this time.

National Environmental Policy Act

    We have determined that we do not need to prepare an Environmental 
Assessment and/or an Environmental Impact Statement as defined by the 
National Environmental Policy Act of 1969 in connection with 
regulations adopted pursuant to section 4(a) of the Endangered Species 
Act. We published a notice outlining our reason for this determination 
in the Federal Register on October 25, 1983 (48 FR 49244).

Paperwork Reduction Act

    This rule does not contain any information collection requirements 
for which OMB approval under the Paperwork Reduction Act is required. 
An agency may not conduct or sponsor, and a person is not required to 
respond to, a collection of information unless it displays a valid OMB 
control number. For additional information concerning permits and 
associated requirements for threatened wildlife species, see 50 CFR 
17.21 and 17.22.

References Cited

    A complete list of all references cited in this final rule is 
available upon request from the Sacramento Fish and Wildlife Office 
(see ADDRESSES).

Authors

    The primary authors of this document are staff of the Sacramento 
Fish and Wildlife Office.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
record-keeping requirements, Transportation.

Regulation Promulgation

0
For the reasons given in the preamble, we amend part 17, subchapter B 
of chapter I, title 50 of the Code of Federal Regulations, as set forth 
below:

PART 17--(AMENDED)

0
1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. 99-625, 100 Stat. 3500; unless otherwise noted.

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2. Amend Sec.  17.11(h) by removing the entry ``Sacramento splittail'' 
under ``FISHES'' from the List of Endangered and Threatened Wildlife 
and Plants.

    Dated: September 15, 2003.
Marshall P. Jones, Jr.,
Acting Director, Fish and Wildlife Service.
[FR Doc. 03-23919 Filed 9-18-03; 12:01 pm]
BILLING CODE 4310-55-P