[Federal Register Volume 66, Number 75 (Wednesday, April 18, 2001)]
[Proposed Rules]
[Pages 19910-19914]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-9443]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17


Endangered and Threatened Wildlife and Plants; 12-month Finding 
for a Petition To List the Sicklefin Chub (Macrhybopsis meeki) and the 
Sturgeon Chub (Macrhybopsis gelida) as Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 12-month petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service, announce a 12-month 
finding for a petition to list the sicklefin chub (Macrhybopsis meeki) 
and the sturgeon chub (Macrhybopsis gelida) as endangered under the 
Endangered Species Act of 1973, as amended. After review of all 
available scientific and commercial information, we find that listing 
either of these two species is not warranted at this time.

DATES: The finding announced in this document was made on April 10, 
2001.

ADDRESSES: Data, information, comments, or questions regarding this 
notice should be sent to Mr. Allyn Sapa, Field Supervisor, 3425 Miriam 
Avenue, Bismarck, North Dakota, 58501. The complete administrative file 
for this finding is available for inspection during normal business 
hours, by appointment, at the above address. The status review document 
for the sicklefin chub and the sturgeon chub also may be obtained at 
that address, or at our Internet web site at http://mountain-prairie.fws.gov/endspp/chubs>.

FOR FURTHER INFORMATION CONTACT: William Bicknell at the above address, 
telephone (701) 250-4414, or e-mail [email protected]>.

SUPPLEMENTARY INFORMATION:

Background

    The sicklefin and sturgeon chub are members of the Cyprinidae or 
minnow family. They are native to the Missouri River basin and the 
Mississippi River downstream from the confluence with the Missouri 
River. Both species are highly adapted for conditions found in large 
free-flowing rivers with relatively high levels of turbidity.
    The sicklefin chub is usually yellowish or tan colored on the back 
and silvery-white on the belly with a snout protruding slightly beyond 
the mouth. A single pair of maxillary barbels is located at the corners 
of the mouth. Average adult length ranges from 3.6 to 10.1 centimeters 
(1.4 to 4.0 inches) with the average adult weight ranging from 0.6 to 
6.2 grams (0.02 to 0.2 ounce). The sicklefin is a relatively short-
lived species with a small percentage of the population reaching age 4. 
The sicklefin chub can be most readily distinguished by its elongated 
pectoral fins and a sickle-shaped dorsal fin.
    The sturgeon chub is tan to pale green on the back and cream to 
white on the belly. A few black speckles occasionally are present on 
the sides and back. It has a long, fleshy snout with a single pair of 
maxillary barbels located at the corners of the mouth. Average adult 
length ranges from 3.8 to 9.6 centimeters (1.5 to 3.8 inches) and 
average adult weight ranges from 0.3 to 9.3 grams (0.01 to 0.3 ounces). 
The sturgeon chub is relatively short-lived species with a maximum 
life-span of about 4 years. Sturgeon chub can be identified by the 
unique longitudinally-arranged ridges or keels on most scales.
    Section 4(b)(3)(B) of the Endangered Species Act of 1973 (Act), as 
amended (16 U.S.C. 1531 et seq.), requires that within 90 days of 
receipt of the petition, to the maximum extent practicable, we make a 
finding on whether a petition to list, delist, or reclassify a species 
presents substantial scientific or commercial information indicating 
that the requested action may be warranted. If the petition contains 
substantial information, the Act requires that we initiate a status 
review of the species and publish a 12-month finding indicating whether 
the petitioned action is (a) not warranted, (b) warranted, or (c) 
warranted but precluded from immediate listing proposal by other 
pending proposals of higher priority. Such 12-month findings are to be 
published promptly in the Federal Register.
    In 1993, we issued status reports for the sicklefin chub and 
sturgeon chub (U.S. Fish and Wildlife Service 1993a, b). The reports 
indicated the range and populations of sicklefin and sturgeon chubs had 
been substantially reduced. On June 29, 1994, we received a petition 
from a coalition of groups to list the

[[Page 19911]]

sicklefin and sturgeon chubs as endangered throughout their range in 
accordance with the provisions of the Act. The petitioners include 
American Rivers, Environmental Defense Fund, Mni Sose Intertribal Water 
Rights Coalition, National Audubon Society, and the Nebraska Audubon 
Council.
    The petitioners assert that, historically, sicklefin chub and 
sturgeon chub populations inhabited a substantial portion of the 
Missouri River, its larger tributaries, and the Mississippi River 
downstream from the confluence with the Missouri River. They indicate 
that the historic range of sicklefin and sturgeon chubs included waters 
in or bordering 13 and 14 States, respectively.
    The petitioners indicate that sicklefin and sturgeon chubs have 
physically adapted through evolution to inhabit turbid, swift-flowing 
rivers. The petitioners assert that the impoundment and channelization 
of the Missouri River have drastically altered the natural habitat of 
the chubs by altering the natural hydrograph and reducing water 
temperature and turbidity levels. The petitioners also contend that 
aquatic insect larvae are the primary food source for these species. 
They believe the removal of snags from the Missouri River and dam 
construction have affected the range and abundance of aquatic insect 
larvae.
    The petitioners conclude that the reduction of sicklefin chub and 
sturgeon chub habitat has severely impacted the species ability to 
survive. Transformation of the Missouri River has created colder, less 
turbid conditions which favor other Missouri River fish. The 
petitioners assert that the existing programs are not adequate to 
protect sicklefin and sturgeon chub populations. They believe listing 
these species as endangered will ensure consultation under section 7 of 
the Act for actions authorized, funded, or carried out by Federal 
agencies. The petitioners also indicate that scientists desperately 
need more information about both species and listing will place a 
higher priority on funding sicklefin and sturgeon chub research needs.

Status Review

    On January 18, 1995, we published a positive 90-day finding for 
both species in the Federal Register indicating that the petitioned 
action may be warranted. At that time, we requested public comments on 
the 90-day finding and any available information on the status of the 
species. We established a status assessment team, consisting of 
biologists from Service Regions 3, 4, and 6, to gather information 
documenting sicklefin chub and sturgeon chub populations and to 
determine whether listing these species as threatened or endangered 
under the Act was warranted. A draft 12-month finding was completed in 
August 1995 and subsequently revised in 1997, 1999, and 2000, to 
include substantial new information. The Montana Rivers Coalition filed 
a 60-day notice of intent to sue the Secretary of the Interior on April 
6, 2000, for the Service's alleged failure to act on the petition in 
the timeframes established by the Act. The Montana Rivers Coalition's 
action resulted in a settlement agreement in which we agreed to submit 
the 12-month finding for the sicklefin and sturgeon chubs for 
publication in the Federal Register on or before April 12, 2001.
    We received information concerning the status of sicklefin and 
sturgeon chub populations from State game and fish departments, the 
U.S. Bureau of Reclamation, U.S. Geological Survey, tribal 
representatives, universities, and other organizations and individuals. 
We also reviewed information on the sicklefin and sturgeon chub from 
peer-reviewed journal articles, agency reports and file documents, 
telephone interviews, and written correspondence with fisheries 
biologists familiar with these species.
    Around the time the petition to list the sicklefin and sturgeon 
chubs as endangered was filed, fishery biologists modified the gear 
used to sample cyprinid populations. Until 1993, researchers primarily 
relied on seines to collect small fish in the Missouri and Mississippi 
Rivers. Seines allowed sampling in shallow water, usually not exceeding 
1.5 meters (4.9 feet) in depth, in sandbar and border channel habitats. 
Grisak (1996) was the first to use a benthic trawl, modified to catch 
small fish, to characterize the fish population in a portion of the 
Missouri River. Grisak's work above Fort Peck Reservoir in Montana 
during 1994 and 1995 and the results of subsequent field investigations 
using benthic trawls have provided new information on the range and 
relative abundance of the sicklefin and sturgeon chubs.

Sicklefin Chub Status Summary

    Based on our current understanding of this species, we believe that 
the sicklefin chub historically occurred in approximately 85 miles of 
the Lower Yellowstone River, approximately 1,950 miles of the main stem 
Missouri River, and about 1,150 miles of the Mississippi River, below 
the mouth of the Missouri River.
    Since 1993, when we completed a Sicklefin Chub Status Report (U.S. 
Fish and Wildlife Service 1993a), additional surveys have been 
conducted throughout most of this species' historical range. These 
studies indicate that sicklefin chub are more widely distributed and 
more common than previously believed. The effectiveness of sampling 
techniques has dramatically improved with the use of benthic trawls 
that have been modified to collect small fish. Benthic trawls have 
permitted sampling in deep-water habitats where seines, the traditional 
cyprinid collection method, are ineffective or cannot be used.
    Recent studies using benthic trawls indicate that sicklefin chub 
comprise a significant part of the fish population at three locations 
in the Missouri River drainage--above Fort Peck Reservoir in Montana; 
the Yellowstone/Missouri River confluence area in North Dakota and 
Montana; and the lower Missouri River in Missouri. Grisak (1996) used 
both seines and a benthic trawl to sample the fish population in the 
Missouri River above Fort Peck Reservoir in 1994 and 1995. He found 
sicklefin chubs comprised 21.9 percent of the benthic trawl catch and 
only 0.08 percent of the catch with seines. Sicklefin chubs were the 
second most common species collected in benthic trawl tows. In 1999 and 
2000, Gardner (2000a,b) sampled the same general area as Grisak. The 
sicklefin chub was the most common species collected in 1999 (41.5 
percent of the catch) and the third most common species collected in 
2000 (5.1 percent of the catch). Welker (2000) used both seines to 
sample shallow border channel habitat and a benthic trawl to sample 
deep-water habitat in the Yellowstone/Missouri River confluence area in 
1997 and 1998. Sicklefin chubs were the most common species collected 
in benthic trawl tows, comprising 33.2 percent of the trawl catch. By 
contrast, only 12 sicklefin chub were collected in seine hauls (0.005 
percent of the catch using seines). Liebelt (in litt. 1999) sampled the 
Missouri River above the headwaters of Lake Sakakawea in 1999. 
Sicklefin chubs were the third most common species collected, making up 
8.6 percent of the catch. Grady and Milligan (1998) sampled the 
Missouri River in Missouri in 1997. They collected 3,934 fish in seine 
hauls, including 1 sicklefin chub. By contrast, sicklefin chubs were 
the second most common species collected with a benthic trawl (8.4 
percent of the catch).
    In addition to the Missouri River populations, field studies 
conducted by the Missouri Department of

[[Page 19912]]

Conservation since 1997 have documented viable populations of sicklefin 
chub in the Middle Mississippi River and in the Wolf Island area of the 
Lower Mississippi River. Prior to these studies, collections of 
sicklefin chub in the Lower Mississippi River were rare and generally 
document the presence of an individual fish.
    Based on the information provided by these surveys, we now estimate 
that sicklefin chub currently occupy approximately 1,110 miles or about 
54 percent of the species' historic range in the Missouri River 
drainage.

Sturgeon Chub Status Summary

    We believe that the sturgeon chub historically occurred in 
approximately 2,100 miles of the main stem Missouri River and about 
1,150 miles of the main stem Mississippi River. The species also was 
found in the Yellowstone River in Montana and North Dakota and 30 
tributaries to the Yellowstone and Missouri Rivers. The sturgeon chub 
occurred in portions of four tributaries in Wyoming, nine in Montana, 
five in North Dakota, six in South Dakota, six in Nebraska, and four in 
Kansas. Tributaries such as the Powder River, which provides sturgeon 
chub habitat in both Wyoming and Montana, are included in the tallies 
for both States. Other tributaries that historically provided sturgeon 
chub habitat in two states include the Big Horn, Little Missouri, and 
Republican Rivers.
    Studies conducted since 1994 using benthic trawls designed to 
collect small fish from deep-water areas of the border and main channel 
have provided new information about the distribution and relative 
abundance of sturgeon chub. Grisak (1996) conducted the first studies 
using a benthic trawl with small mesh netting to specifically collect 
cyprinids and other small fish in the Missouri River. He sampled the 
Missouri River above Fort Peck Reservoir in 1994 and 1995 and found 
that sturgeon chub comprised 18.9 percent of the benthic trawl catch 
compared to only 0.16 percent of the catch with seines. In Grisak's 
study, sturgeon chub were the third most common species collected in 
benthic trawl tows. In 1999 and 2000, Gardner (1999, 2000) sampled the 
same general area as Grisak. Gardner collected 218 sturgeon chub (16.1 
percent of the catch) in August 1999 and 145 sturgeon chub (32.0 
percent of the catch) in August 2000 using a benthic trawl. Welker 
(2000) used both seines and a benthic trawl to sample the fish 
population in the Yellowstone/Missouri River confluence area in North 
Dakota. Sturgeon chub were the second most common species collected 
(32.3 percent of the catch) in benthic trawl samples taken in the main 
channel. Shallow border channel areas also were sampled with seines. 
Sturgeon chubs were rare in seine samples, representing less than 0.01 
percent of the catch. Liebelt (in litt. 1999) sampled a reach of the 
Missouri River from Williston, North Dakota, downstream to the 
headwaters of Lake Sakakawea in August 1999. Sturgeon chubs were the 
second most common species collected, representing 11.1 percent of the 
catch in benthic trawl tows. In Missouri, Grady and Milligan (1998) 
sampled the Lower Missouri River with seines and benthic trawls in 
1997. They collected 3,934 fish with seines; however, no sturgeon chub 
were captured. Sturgeon chub ranked fourth in abundance for fish 
collected in benthic trawl tows (4.1 percent of the catch).
    Since 1997, field studies conducted by the Missouri Department of 
Conservation indicate a viable population of sturgeon chub exists in 
the Middle Mississippi River and in the Wolf Island area of the Lower 
Mississippi River (Hrabik and Herzog, in litt. 2000 a,b). Historic 
collections of sturgeon chub in the Lower Mississippi River below Wolf 
Island are rare and do not provide adequate information to assess if 
this area historically provided important sturgeon chub habitat.
    Using these studies we believe the distribution of sturgeon chub in 
the main stem Missouri and Mississippi Rivers is similar to that of the 
sicklefin chub. Like the sicklefin chub, sturgeon chub comprise a 
significant portion of the Missouri River fish community above Fort 
Peck Reservoir in Montana, in the Yellowstone/Missouri River confluence 
area in Montana and North Dakota, and in the Lower Missouri River in 
Missouri.
    In total, we estimate that sturgeon chub currently occupy 
approximately 1,155 miles or about 55 percent of the species, historic 
range in the Missouri River. The species also continues to be found in 
11 of 30 tributaries to the Yellowstone and Missouri Rivers that have 
been documented as providing sturgeon chub habitat. Viable populations 
of sturgeon chub are also present in the Middle Mississippi River and 
in the Wolf Island area of the Lower Mississippi River. As with the 
sicklefin chub, information documenting sturgeon chub populations in 
the Mississippi River is limited by comparison to the Missouri River 
data set.
    The Act defines a ``threatened species'' as any species which is 
likely to become an endangered species within the foreseeable future 
throughout all or a significant portion of its range. An ``endangered 
species'' is defined as any species which is in danger of extinction 
throughout all or a significant portion of its range.
    Section 4(a) of the Act describes five threat factors that we must 
consider to determine whether any species is a threatened or endangered 
species for purposes of the Act. Any one or combination of the five 
threat factors may indicate the appropriateness of a warranted 12-month 
administrative finding. Section 4(b) of the Act requires that we also 
give consideration in our determination of a species' status to efforts 
being made by any State or foreign nation to protect such species. We 
considered the five threat factors established by the Act and any 
ongoing conservation measures for sicklefin and sturgeon chubs in our 
determination. A full discussion of the threats appears in the current 
status review (U.S. Fish and Wildlife 2001) for these species, and is 
summarized as follows:
    1. The present or threatened destruction, modification, or 
curtailment of the species habitat or range.
    Water development projects on the Missouri and Middle and Lower 
Mississippi Rivers and tributaries have impacted sicklefin and sturgeon 
chub populations. Reservoirs flooded river habitat, altered temperature 
and flow regimes, and reduced sediment transport and turbidity. Dams 
fragmented populations and restricted movement. Channelization 
straightened and narrowed river habitat, reduced habitat diversity, and 
reduced overbank flooding. These impacts have resulted in a reduction 
in the range of these species by approximately one half.
    There are potential impacts associated with coalbed methane 
production in Wyoming and Montana, and future water impoundment and 
depletion projects on the Yellowstone River, its tributaries, and 
tributaries to the Missouri River. Information documenting how coalbed 
methane products will affect water quality in tributaries such as the 
Powder River is not known at this time. The amount of water involved 
with the potential depletions is not of a sufficient magnitude to 
suggest major impacts to the chubs. The impact of these projects on 
aquatic ecosystems will be investigated further during the planning and 
permitting process.
    Although the chubs have suffered reductions in range, our status 
survey determined that both species currently have a wider distribution 
than previously thought, and there are numerous populations that appear 
to be

[[Page 19913]]

viable throughout the range of both species. Channelization projects 
continue to be implemented in the Missouri River Basin, but at a pace 
much reduced from the levels experienced in the first half of the 20th 
century. The construction of new large reservoirs is not anticipated. 
The fact that these short-lived fish are clearly reproducing where 
stream habitat conditions are adequate leads us to conclude that 
neither species will become threatened or endangered in the foreseeable 
future due to habitat loss.
    2. Overutilization for commercial, recreational, scientific, or 
educational purposes.
    We are not aware of any significant threats to either species in 
this category. However, removal of individuals from the wild could have 
occurred and may continue to occur from harvest of bait fish. We find 
no evidence of significant impacts to the chub species from 
overutilization for commercial, recreational, scientific, or 
educational purposes.
    3. Disease or predation.
    No diseases are currently known to threaten the species. Predation 
has likely increased over historic levels due to stocking of 
piscivorous fish into the reservoirs and remaining riverine sections. 
Reduced turbidity levels in chub habitat also may have resulted in 
increased predation rates. However, we find no evidence to indicate 
that current levels of predation threaten the continued existence of 
either chub species. Sampling of chub habitats in recent years strongly 
suggests that these short-lived species are reproducing in adequate 
numbers to sustain viable populations for the foreseeable future.
    4. The inadequacy of existing regulatory mechanisms.
    Currently there is no Federal legal protection for the sicklefin 
and sturgeon chubs. In addition, few States provide any legal 
protection to these species. Within their historical range, both chubs 
receive legal protection in the State of Kansas where the sturgeon chub 
and sicklefin chub are classified officially as threatened and 
endangered, respectively. Take of either species is prohibited, and 
provisions allow for habitat protection and designation of critical 
habitat (Kansas Department of Wildlife and Parks 1992). In South 
Dakota, both chubs officially are listed as State threatened. The State 
of Illinois prohibits the take of the sturgeon chub and provides some 
habitat protection (Sue Lauzon, pers. comm. 1995). Kentucky has 
restrictions on collections of both chubs (Wayne Davis, Kentucky 
Department of Fish and Wildlife Resources, pers. comm. 1995), and 
Tennessee prohibits the take or possession of either chub, or the 
knowing destruction of habitats from Federal actions (Bob Hatcher, 
Tennessee Wildlife Resource Commission, pers. comm. 1995).
    Several national and State professional conservation societies and 
environmental departments within various State governments unofficially 
have classified the sturgeon chub and sicklefin chub as either 
threatened or endangered, a species of special concern, rare, on a 
watch list, deemed in need of management, or transient. However, these 
designations do not provide any legal protection to either chub 
species.
    5. Other natural or manmade factors affecting its continued 
existence.
    Severe drought in the early 1990's may have eliminated sturgeon 
chub from some Missouri River tributaries and may reoccur and impact 
additional tributary populations. Sturgeon chub populations have been 
eliminated from approximately 800 miles of the Missouri River that has 
been converted to reservoir habitat. Tributaries that now flow into 
reservoirs may never naturally recolonize. However, our status review 
found that there are numerous viable populations of both species 
currently extant throughout about half of the species' historic range, 
which indicates that these species persist through drought cycles.
    Our status review examined the impact of entrainment of sturgeon 
chubs by irrigation structures and potential water quality impacts. We 
have entered formal consultation under section 7 of the Act concerning 
impacts to pallid sturgeon (Scaphirhynchus albus) associated with the 
Intake Diversion Structure and lowhead dam, and Reclamation's plans to 
privatize and transfer the facilities to the Lower Yellowstone 
Irrigation District. Studies conducted at this structure projected that 
over 2,000,000 fish were entrained in the irrigation canal system 
during the 1996, 1997, and 1998 irrigation seasons. Reclamation 
estimated that over 289,000  113,000 sturgeon chub were 
entrained during the 3-year study period. Reclamation is working with 
the Service and others to develop a design that allows for fish passage 
over the lowhead dam and minimizes entrainment losses. Implementation 
of ``fish friendly'' measures will benefit the sturgeon chub population 
in the Yellowstone River. Conservation measures developed for the 
Intake Diversion Structure and lowhead dam may be applicable at other 
water diversion sites on the Yellowstone River.
    Another potential threat to sicklefin and sturgeon chub populations 
is the presence of four species of Asian carp in the Mississippi River 
and the Missouri River below Gavins Point Dam. There are no data 
currently available to document that chubs are being impacted by 
invasive species. However, if Asian carp populations continue to 
expand, the diversity of species supported by the Missouri and 
Mississippi River ecosystems, including chubs, may be negatively 
impacted.

Conservation Measures

    We also have evaluated ongoing and proposed conservation measures 
that will have a beneficial impact on sicklefin and sturgeon chub 
populations when fully implemented. We have identified two conservation 
actions, one that is being implemented and one that is currently in the 
planning stage, that will benefit both sicklefin and sturgeon chubs. 
Implementation and monitoring of the Missouri River Bank Stabilization 
and Navigation Project (BSNP) fish and wildlife mitigation plan is 
ongoing. The BSNP was established to create a navigable channel from 
Sioux City, Iowa, to the mouth of the Missouri River near St. Louis 
(735 river miles). Originally authorized by the Rivers and Harbors Act 
of 1912 and officially completed in 1981, the project created one 
stabilized, self-sustaining channel from numerous small channels using 
revetments and transverse dikes. In 1986, Congress authorized 
mitigation for fish and wildlife habitat losses associated with the 
construction, operation, and maintenance of the BSNP in Nebraska, Iowa, 
Kansas, and Missouri. The project mitigation plan authorized the 
acquisition of 29,900 acres (12,109 hectares) and the development of an 
additional 18,200 acres (7,371 hectares) of existing public land. 
Recently, the mitigation plan was reauthorized as part of the Water 
Resources Development Act of 1999, and the acquisition ceiling was 
increased by 118,650 acres (48,053 hectares). Based on the conceptual 
plans that have been developed, State and Federal agencies anticipate 
the rehabilitation of aquatic and terrestrial habitats will benefit 
fish and wildlife resources, including the sicklefin and sturgeon chub.
    In November 2000, we completed a biological opinion under Section 7 
of the Act on the Corps of Engineers' Operation of the Missouri River 
Main Stem System, the related operation of the Kansas River Tributary 
Reservoirs, and the Operation and Maintenance of the Missouri River 
Bank Stabilization and Navigation Projects (U.S. Fish and

[[Page 19914]]

Wildlife Service 2000). We found that, to avoid jeopardizing the 
continued existence of the pallid sturgeon, least tern, and piping 
plover, conservation measures to restore riverine and aquatic habitat 
and hydrologic conditions on segments of the Missouri River between 
Fort Peck Dam and the headwaters of Lake Sakakawea and below Gavins 
Point Dam are necessary. The emphasis of the Biological Opinion is to 
restore or rehabilitate enough of the Missouri River ecosystem to avoid 
jeopardizing the pallid sturgeon and other listed species. 
Implementation of the identified conservation measures are expected to 
have a significant beneficial effect on sicklefin and sturgeon chub 
through habitat restoration and creation projects, improved water 
temperature regimes, and flow modifications designed to mimic the 
natural hydrograph. The Corps of Engineers is currently seeking public 
input on the Implementation Plan for the Reasonable and Prudent 
Alternative identified in the Biological Opinion.

Conclusions

    The principal factors impacting sicklefin and sturgeon chub 
populations are the construction and continuing operation of the dams 
on the main stem Missouri River and channelization of the Middle and 
Lower Missouri and Mississippi Rivers. Water depletion projects, 
impoundments, entrainment, and drought have impacted sturgeon chub 
populations in the Yellowstone River and tributaries to the Yellowstone 
and Missouri Rivers. The threats posed by the dams and reservoirs have 
been in place for over 35 years. Despite the loss of over 1,000 miles 
of suitable habitat in the Missouri River, viable, self-sustaining 
populations of sicklefin and sturgeon chubs occur where habitat 
conditions, flow patterns, and turbidity levels resemble conditions 
prior to the construction of the main stem dams.
    Field studies conducted since the 1993 status reports were issued 
indicate that sicklefin chub and sturgeon chub are more widespread and 
occur in greater numbers than previously believed. Researchers in 
Montana (Grisak 1996, Gardner 2000a, b), North Dakota (Liebelt, in 
litt. 1999, Everett 1999, Welker 2000), and Missouri (Grady and 
Milligan 1998, Hrabik and Herzog, in litt. 2000a, b) have collected 
substantially greater numbers of sicklefin and sturgeon chub using 
trawling techniques. Recently, new locations supporting sicklefin and 
sturgeon chub populations, such as the Wolf Island area of the Lower 
Mississippi River, have also been identified.
    While major information gaps remain concerning feeding habits, 
reproduction, seasonal habitat use, and other aspects of sicklefin and 
sturgeon chub biology, substantially greater emphasis has been placed 
on documenting chub populations and their habitats during the past 7 
years. Therefore, on the basis of the best available information, we 
conclude that neither the sicklefin chub nor the sturgeon chub is 
likely to become threatened or endangered in the foreseeable future 
throughout all or a significant portion of their range. Therefore, 
listing either the sicklefin chub or the sturgeon chub is not warranted 
at this time.
    This finding is based on our analysis of the current status and 
potential threats to these two cyprinids. In addition we are encouraged 
by proposed modifications in the operation of the Federal projects on 
the main stem Missouri River, which when fully implemented will improve 
native fish habitat and benefit sicklefin and sturgeon chub 
populations.

References Cited

    Everett, S.R. 1999. Life history and ecology of three native 
benthic fishes in the Missouri and Yellowstone Rivers. M.S. Thesis. 
University of Idaho, Moscow.
    Gardner, W.M. 2000a. Upper Missouri River Pallid Sturgeon 
Recovery Studies--1999 Progress Report. Montana Department of Fish, 
Wildlife, and Parks. Lewistown.
    Gardner, W.M. 2000b. Upper Missouri River Pallid Sturgeon 
Recovery Studies--2000 Progress Report. Montana Department of Fish, 
Wildlife, and Parks. Lewistown.
    Grady, J.M., and J. Milligan. 1998. Status of selected cyprinid 
species at historic Lower Missouri River sampling sites. U.S. Fish 
and Wildlife Service, Columbia, Missouri. 49 pp.
    Grisak, G.G. 1996. The status and distribution of the sicklefin 
chub in the Middle Missouri River, Montana. M.S. Thesis, Montana 
State University, Bozeman. 77 pp.
    Hrabik, R., and D. Herzog, in litt. 2000a. Missouri Department 
of Conservation, Open River Field Station, Jackson.
    Hrabik, R., and D. Herzog, in litt. 2000b. Missouri Department 
of Conservation, Open River Field Station, Jackson.
    Liebelt, J., in litt. 1999. Fisheries Biologist, Montana 
Department of Fish, Wildlife and Parks, Fort Peck.
    U.S. Fish and Wildlife Service. 1993a. Status report on 
sicklefin chub (Macrhybopsis meeki), a candidate endangered species. 
U.S. Fish and Wildlife Service, Bismarck, North Dakota. 41 pp.
    U.S. Fish and Wildlife Service. 1993b. Status report on sturgeon 
chub (Macrhybopsis gelida), a candidate endangered species. U.S. 
Fish and Wildlife Service, Bismarck, North Dakota. 58 pp.
    U.S. Fish and Wildlife Service. 2000. Missouri River Biological 
Opinion. Denver, Colorado and Fort Snelling, Minnesota. 286 pp.
    U.S. Fish and Wildlife Service. 2001. Updated status review of 
sicklefin and sturgeon in the United States. USFWS Denver, Colorado 
74 pp.
    Welker, T.L. 2000. Ecology and structure of fish communities in 
the Missouri and Lower Yellowstone Rivers. PhD. Thesis, University 
of Idaho, Moscow. 232 pp.

Author

    The primary author of this document is William Bicknell (see 
ADDRESSES above).

Authority

    The authority for this action is the Endangered Species Act of 
1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: April 10, 2001.
Marshall P. Jones, Jr.,
Acting Director, Fish and Wildlife Service.
[FR Doc. 01-9443 Filed 4-17-01; 8:45 am]
BILLING CODE 4310-55-P