Endangered and Threatened Wildlife and Plants; Withdrawal of
Proposed Rule To List the Pecos Pupfish (Cyprinodon pecosensis) as
Endangered
[Federal Register: March 17, 2000 (Volume 65, Number 53)]
[Proposed Rules]
[Page 14513-14518]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17mr00-39]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AE56
Endangered and Threatened Wildlife and Plants; Withdrawal of
Proposed Rule To List the Pecos Pupfish (Cyprinodon pecosensis) as
Endangered
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule; withdrawal.
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SUMMARY: We, the Fish and Wildlife Service (Service), withdraw the
proposal to list the Pecos pupfish (Cyprinodon pecosensis) as an
endangered species under the Endangered Species Act of 1973, as amended
(Act). The Pecos pupfish is native to the Pecos River and its
tributaries, and nearby lakes, sinkholes, and saline springs in New
Mexico and Texas. The species now occurs in some reaches of the Pecos
River in New Mexico, on lands administered by us, the New Mexico
Division of State Parks (NMDSP), and the Bureau of Land Management
(BLM); and on private lands in Texas. This withdrawal is based on
actions taken by us and other Federal and State resource and management
agencies to remove immediate threats to the species and also on
commitments by us and those agencies to actively protect and enhance
existing populations and habitats and to repatriate the species to
appropriate habitats within its native range. In cooperation with the
New Mexico Department of Game and Fish (NMDGF), New Mexico Department
of Agriculture, NMDSP, Texas Parks and Wildlife Department (TPWD), and
BLM, we have executed a Conservation Agreement that addresses the
threats to the survival of the species. These protections will
sufficiently assure the viability of the Pecos pupfish within its
historical range.
ADDRESSES: The complete file for this notice is available for public
inspection, by appointment, during normal business hours at our New
Mexico Ecological Services Field Office, 2105 Osuna NE, Albuquerque,
New Mexico 87113.
FOR FURTHER INFORMATION CONTACT: Joy Nicholopoulos, Field Supervisor,
New Mexico Ecological Services Field Office, at the above address (505-
346-2525).
SUPPLEMENTARY INFORMATION:
Background
The Pecos pupfish, described by Echelle and Echelle (1978), is a
member of the family Cyprinodontidae. The taxonomic status of the Pecos
pupfish had been uncertain for more than 30 years because of a previous
description of a pupfish (Cyprinodon bovinus) from the Pecos River
(Baird and Girard 1853). Type specimens from the Pecos River in the
original series were lost or in poor condition but were assumed to be
the same as the Pecos pupfish until an extant population of C. bovinus
was found at Leon Springs, Texas, and confirmed as different from the
form in the Pecos River proper (Echelle and Miller 1974).
The Pecos pupfish is a small, deep-bodied (2.8 to 4.6 centimeters
(cm) (1.1 to 1.8 inches (in) average length) gray-to-brown fish. Male
dorsal (back) and anal fins are black almost to the margin with no
yellow on the dorsal, anal, or caudal (tail) fins. The lateral (side)
bars on the female are typically broken into blotches ventrolaterally
(along the sides near the bottom). The abdomen is generally without
scales, except for a few scales in front of the pelvic fins and a patch
just behind the gill membrane isthmus (a narrow strip of tissue). There
are 20 to 21 gill rakers and usually 3 or 4 preorbital (behind the eye
socket) pores on each side of the head (Echelle and Echelle 1978).
The Pecos pupfish is native to the Pecos River and its tributaries,
and nearby lakes, sinkholes, and saline springs in New Mexico and
Texas. The historical range of the species included the Pecos River
from Bitter Lake National Wildlife Refuge and Bottomless Lakes State
Park near Roswell, Chaves County, New Mexico, downstream approximately
650 kilometers (km) (404 miles (mi)) to the mouth of Independence
Creek, southeast of Sheffield, Pecos County, Texas (Wilde and Echelle
1992). The species was also found in gypsum sinkholes and saline
springs at Bitter Lake National Wildlife Refuge; sinkholes and springs
at Bottomless Lakes State Park (Brooks and Woods 1988); and in Salt
Creek, Reeves County, Texas.
In Texas, genetically pure populations of the Pecos pupfish are now
thought to occur only in the upper reaches of Salt Creek, Culberson and
Reeves Counties, Texas (G. Garrett, TPWD, pers. comm. 1998). In New
Mexico, the species still occurs in the Pecos River from north of
Malaga upstream to Bitter Lake National Wildlife Refuge. The species is
also found at Bottomless Lakes State Park and the BLM's Overflow
Wetlands Wildlife Habitat Area/Area of Critical Environmental Concern.
This range reduction represents a loss of more than two-thirds of the
species' former range (Echelle and Connor 1989; Echelle et al. 1997;
Hoagstrom and Brooks 1998).
Since the Pecos pupfish was proposed for listing on January 30,
1998 (63 FR 4608), the most significant threats to its continued
existence have been ameliorated. The main threats to the Pecos pupfish
were habitat loss caused by damming and dewatering of the Pecos River,
excessive pumping of groundwater, and, since the early 1980s,
hybridization with the sheepshead minnow (Cyprinodon variegatus).
Genetically pure populations have been made more secure--a fish barrier
constructed at the Bitter Lake National Wildlife Refuge has protected
the population that exists there; a fish barrier constructed at Dexter
National Fish Hatchery and Technical Center has created a managed
wetland for establishing a refugial population; and the BLM has placed
the population on the BLM's Overflow Wetlands Area of
[[Page 14514]]
Critical Environmental Concern under active protection through BLM's
Resource Management Plan. Through this plan, the BLM has prohibited
surface occupancy in future oil and gas leases within a buffer zone of
the Area, restricted future oil and gas surface occupancy in other
areas, excluded rights-of-way in certain portions of the Area, limited
use of off-highway vehicles, and retired a grazing lease. These
actions, which are discussed in the Conservation Agreement, have
already been implemented. Habitat for the populations at Bottomless
Lakes State Park and Bitter Lake National Wildlife Refuge is being
renovated. Moreover, the States of Texas and New Mexico have begun
managing the introduction of the nonnative sheepshead minnow, which has
hybridized and displaced the Pecos pupfish in much of the historical
pupfish habitat. Both States have approved modification of existing
fishing regulations to ban the use of sheepshead minnow as a bait fish
in the Pecos River.
In addition to these already implemented actions, the Conservation
Agreement includes commitments for long-term protective and enhancement
actions for the species. For instance, various agencies in both New
Mexico and Texas have committed to--(1) removing nonnative predators
from sinkholes with a pupfish population, (2) replacing sheepshead
minnow x Pecos pupfish hybrids with pure pupfish whenever feasible, (3)
identifying additional habitats under State control for expansion of
populations of Pecos pupfish, and (4) working with willing private
landowners to identify potential repatriation sites on private lands. A
more complete discussion is found below.
Summary of Comments and Recommendations
We proposed the Pecos pupfish for listing as an endangered species
on January 30, 1998 (63 FR 4608). We published notices inviting public
comment in seven newspapers of general circulation in the area of the
Pecos River valley in both New Mexico and Texas--the Albuquerque
Journal, the Fort Stockton Pioneer, the Pecos Enterprise, the Roswell
Daily Record, the Carlsbad Current Argus, the Midland Reporter-
Telegram, and the Odessa American. We also published notices of a
public hearing in these same newspapers. We held the hearing on the
proposal in Carlsbad, New Mexico on April 9, 1998.
During this extended public comment period (January 30 to November
20, 1998), we contacted State and Federal land and resource management
agencies in New Mexico and Texas to determine if adequate protections
could be implemented through a Conservation Agreement. We made the
Conservation Agreement developed by these agencies available for public
review through a notice of availability in the Federal Register (63 FR
71424) on December 28, 1998. The comment period was reopened and
extended to January 27, 1999, in order to receive additional comments
on the proposal and on the draft Conservation Agreement. We sent
approximately 200 copies of the draft Conservation Agreement to
agencies and individuals on the mailing list maintained by our New
Mexico Ecological Services Field Office. The mailing included a request
to the interested entities for review and comments. Finally, we
reopened the comment period from February 24, 1999, to March 26, 1999
(64 FR 9119).
In accordance with our peer review policy published in the Federal
Register on July 1, 1994 (59 FR 34270), we drafted the Conservation
Agreement with the expert input of researchers who have spent decades
investigating the Pecos pupfish and its habitats in Texas and New
Mexico. In addition to the input received during the development of the
document, we also sought peer review during periods of public comment.
We presented the draft conservation agreement to the Rio Grande Fishes
Recovery Team for review at the annual meeting of the team in November
1998. During the reopened public comment period, we provided the draft
document for peer review to Recovery Team members in addition to other
experts on the species at the University of Texas Pan-American, the
University of New Mexico, Oklahoma State University, Arizona State
University, and the University of Michigan. We did not receive any
comments from the peer review of the draft Conservation Agreement.
We received 15 comments on the proposal to list the Pecos pupfish.
We received one letter of support from a scientist working on the
species. Three commenters--the NMDGF; the New Mexico Energy, Minerals &
Natural Resources Department; and the Texas Commissioner to the Pecos
River Compact-- recommended the use of alternative methods, such as a
Conservation Agreement, to protect the species. One Federal agency
provided comments concerning editorial corrections to the proposal but
with no position regarding the listing of the species. Ten comment
letters opposed the listing.
We received a total of 11 comments on the draft Conservation
Agreement: from 1 municipality, 2 private organizations, 1 county
agency, 1 water power and control district, and 6 State agencies.
Below we address issues raised concerning the proposal, followed by
the issues and our responses to the comments on the Conservation
Agreement. We grouped comments of a similar nature into general issues
delineated below for purposes of response.
Comments and Responses on the Proposed Rule
Issue 1: The Service should attempt proactive management to address
the threats to the pupfish posed by the sheepshead minnow. Given that
the primary threat to the Pecos pupfish is introgressive hybridization
with the sheepshead minnow and that hybrids are common in the Pecos
River, the prudent course at this point seem to be the establishment of
secure off-channel refugia until the hybrid swarm can be eliminated, if
that is possible.
Our Response: We concur that management of the sheepshead minnow to
reduce or remove the threat of hybrids replacing pure Pecos pupfish in
this ecosystem is important for conservation of the pupfish. Under the
Conservation Agreement, fish barriers have been installed to protect
off-channel refugia for remaining populations of pure Pecos pupfish. In
addition, the States of Texas and New Mexico have approved regulations
banning the use of sheepshead minnows as bait.
Issue 2: The Service should propose critical habitat.
Our Response: When we list a species as threatened or endangered,
the Act requires that the listing rule specify, ``to the maximum extent
prudent and determinable,'' the species' critical habitat. However,
this issue is now irrelevant because we are not listing the Pecos
pupfish.
Comments and Responses on the Conservation Agreement
Based on the comments received during the first public comment
period, particularly from the NMDGF, the TPWD, and the Texas
Commissioner to the Pecos River Compact, we initiated efforts in
February 1998 to develop an agreement among the management entities to
address the identified threats to the Pecos pupfish. The Conservation
Agreement that resulted from the meetings set forth the commitments of
[[Page 14515]]
State and Federal agencies to control nonnative competing species and
to protect and manage the Pecos pupfish and its habitat to ensure its
survival and promote its conservation.
Significant threats to the species include problems associated with
small, isolated populations and the potential for hybridization with
the sheepshead minnow. The signatory agencies to the Conservation
Agreement made commitments to protect known extant populations of pure
Pecos pupfish, to expand the distribution of the species within its
native range by establishing new populations, and to prohibit the use
of sheepshead minnow through revision of baitfish regulations in New
Mexico and Texas. As discussed above, several of the provisions of the
Conservation Agreement have been implemented.
Below is a description of comments received on the Conservation
Agreement provided for public review on December 28, 1998. Some
commenters raised issues on the proposal to list the Pecos pupfish in
their comments on the Conservation Agreement. For the issues concerning
the data upon which the biological status of the Pecos pupfish was
determined, please refer to the above discussion of comments.
Issue 3: What set of circumstances would create a situation where
reintroduction of the Pecos pupfish into the mainstream of the Pecos
would be appropriate? To what extent would the signatories attempt to
modify the environment of the mainstream of the Pecos River in order to
create circumstances appropriate for reintroduction?
Our Response: The primary factor to be addressed in any
consideration of repatriation of the Pecos pupfish to its historical
habitat in the mainstream of the Pecos River is the presence or
absence, or relative dominance within the fish community, of the
sheepshead minnow. Should a significant fishkill occur naturally, such
as that observed in 1985-86 in the Pecos River in Texas as a result of
an algal bloom, sheepshead minnow and other nonnatives may be removed
or significantly reduced. At that time, the Conservation Agreement
participants would determine whether the biological conditions support
the repatriation of the Pecos pupfish to the river. The signatory
agencies may undertake other efforts, quite likely on a much more
localized level, to eradicate the sheepshead minnow if the conditions
are favorable.
We and other species experts recognize that major efforts to
repatriate the pupfish to large reaches of its historical habitat in
the Pecos River will not likely occur either in the near future or
without significant events, either natural or induced, affecting the
existing fish community. However, we believe that the potential for
restoration of the species to its historical habitat should be included
in any plan or agreement for its conservation. It should be noted that
one of the major purposes of this Conservation Agreement is to protect
and enhance habitat conditions to facilitate population expansion.
Issue 4: Several commenters requested the clarification of goals
and objectives of the Conservation Agreement, particularly with respect
to those objectives considered essential to the continued conservation
of the Pecos pupfish and, thus, the removal of the need to protect the
species by listing it under the Act.
Our Response: We modified the Conservation Agreement to include
quantifiable and time-certain standards by which the agreement and its
applicability to the conservation of the Pecos pupfish will be
measured. However, the Conservation Agreement partners have already
implemented a number of protective measures (see Background section of
this rule) that, combined with measures to be implemented in the future
as part of the Conservation Agreement, have reduced the threats so that
the species is no longer in danger of extinction, nor likely to become
so, in the foreseeable future throughout all or a significant portion
of its range.
Issue 5: Some commenters objected to section V.F.8 of the draft
Conservation Agreement, in which the agencies participating in the
Conservation Agreement agreed to support the listing of the Pecos
pupfish should the measures and actions be found insufficient to remove
the threats to the species.
Our Response: We amended this section by removing the sentence
regarding the support of listing by the Conservation Agreement entities
should we determine that listing the species is necessary.
Issue 6: One commenter requested that we extend the time for the
decision on the proposal to list by six months, in part, to better
assess or gather additional biological information. The commenter felt
that the biological information was not adequate to proceed with the
withdrawal of the proposed rule.
Our Response: In accordance with section 4(b)(6) of the Act and the
implementing regulations at 50 CFR 424.17, within one year of the
publication of a proposed listing action, we generally must publish a
final determination or a notice withdrawing the proposed action if we
find that the available evidence does not justify the action. When
there is ``substantial disagreement among scientists knowledgeable
about the species concerned regarding the sufficiency or accuracy of
the available data relevant to the determination concerned,'' the Act
and regulations allow for a 6-month extension of a proposed listing
action.
We cannot use an extension to obtain more information or to provide
more time before making a decision. We can only use this provision if
there is a legitimate disagreement among scientific experts and a
definitive resolution is expected that will clarify the subject of the
disagreement. We do not agree with the assessment of the adequacy of
the biological information presented by the commenter. We consulted
experts on the Pecos pupfish (see the discussion in the paragraph on
peer review, above), including scientists who performed the original
research and reported the results that formed the basis of the
commenter's review. No disagreement exits among these species experts
concerning the status and distribution of the species to support the 6-
month delay.
Issue 7: Four commenters raised concerns regarding the proposed
actions of the BLM within the Conservation Agreement, including changes
in grazing leases. We requested that the BLM respond to those comments.
Their response is summarized as follows:
The BLM's Roswell Field Office is responsible for managing all uses
of about 602,973 hectares (1,490,000 acres) where both the surface and
subsurface estates are in Federal ownership. The land use plan
governing management of these public lands addressed all proposed
actions included in the Conservation Agreement and was, after public
review and comment, signed by the Bureau's State Director on October
10, 1998. In addition, the Roswell Field Office prepared the Overflow
Wetlands Habitat Management Plan and Environmental Assessment for the
Overflow Wetlands Wildlife Habitat Area in 1992. The adjustment of
grazing leases for Allotments 65060, 65062, and 65069, and the
cancellation of the grazing lease on Allotment 65041 were presented
during the development of the Roswell Resource Management Plan, as were
the oil and gas lease stipulations, mineral entry closure, and rights-
of-way exclusion. Socio-economic impacts of implementing the Plan were
analyzed in Chapter 4 of the Proposed Plan and Final Environmental
Impact Statement.
The BLM disclosed the adjustment of grazing leases for the above
allotments
[[Page 14516]]
in the Plan to inform the public of this possible action. The types of
adjustments were listed as changes in stocking rate and seasons of use,
but a reduction in the number of livestock was not listed in the
Resource Management Plan. Reductions could occur based on range
monitoring studies for the entire allotment and not necessarily for the
Pecos pupfish Conservation Agreement. The specific adjustments, if
necessary, would be made by the BLM at the grazing lease/permit level
with an accompanying environmental analysis, not at the Conservation
Agreement level. Therefore, no specific adjustments are presented in
the Conservation Agreement.
The grazing lease for Allotment 65041 was canceled. In 1991, the
BLM acquired the private lands within this allotment from a willing
seller (who also held the grazing lease) for the protection of the
Overflow Wetlands Wildlife Habitat Area, which is now designated an
Area of Critical Environmental Concern. Allotment 65041 is no longer an
active grazing allotment.
Summary of Factors Affecting the Species
Section 4(a)(1) of the Act and the regulations (50 CFR part 424)
that implement the listing provisions of the Act set forth the
procedures for adding species to the Federal lists. We must consider
the five factors described in section 4(a)(1) of the Act when
determining whether to list a species. These factors and their
application to our decision to withdraw the proposal to list the Pecos
pupfish are as follows:
A. The present or threatened destruction, modification, or
curtailment of its habitat or range. Historical habitat of the Pecos
pupfish in New Mexico has been drastically altered or destroyed by
human uses of the Pecos River and activities in its watershed. These
alterations include conversion of flowing waters into slack waters by
impoundment; alteration of flow regimes (including conversion of
perennial flow to intermittent or no flow, and the reduction,
elimination, or modification of natural flooding patterns); alteration
of silt and bed loads; loss of marshes and backwaters; increases or
decreases in water temperatures; and alteration of stream channel
characteristics from well-defined, surface-level, heavily vegetated
channels with a diversity of substrates and habitats to deeply cut,
unstable arroyos with little riparian vegetation, uniform substrate,
and little habitat diversity.
Causes of such alterations include water diversion, damming,
channelization, channel down-cutting, excessive groundwater pumping
with resultant lowering of water tables, destruction of riparian
vegetation, and other watershed disturbances. These changes in habitat
conditions, along with displacement of the species by hybrids,
threatened the survival of the Pecos pupfish throughout its entire
range (Wilde and Echelle 1992; Echelle et al. 1997).
Low-velocity floodplain habitats adjacent to the main channel of
the Pecos River provide refugia for the small Pecos pupfish from high
flows in the main channel. These habitats are also characterized by
higher levels of productivity and more stable food sources for the
omnivorous pupfish. However, channelization and stream incision of the
Pecos River, exacerbated by encroachment and channel armoring by salt
cedar, have eliminated extensive floodplain habitat along the Pecos
River. Wetlands and marshes adjacent to the river, once regularly
flooded by peak river flows, are now dry or are only sporadically
wetted. Base flows were also reduced by dam construction and reservoir
operation, greatly reducing the number and extent of these habitats
linked to the main river channel.
Pecos pupfish living in sinkholes and springs are threatened by
groundwater depletion. In southeastern New Mexico, groundwater is the
primary water source for a variety of uses, including drinking water
and irrigation. This dependence on groundwater has lowered the water
tables, resulting in a decline in water levels in sinkholes and springs
where Pecos pupfish live. When the water table was higher, water flowed
between sinkholes but because the water table has been lowered, these
sinkholes are no longer interconnected (Lee Marlatt, Service, Bitter
Lake National Wildlife Refuge, pers. comm. 1987). Because they are
isolated from the river that is inhabited by sheepshead minnow,
sinkhole populations of Pecos pupfish are more protected from the
threat of hybridization than are river populations. Therefore, the loss
of these populations would seriously affect the survival of the
species.
The Conservation Agreement executed by the State and Federal
agencies specifically addresses the protection of all known off-
channel, pure populations of Pecos pupfish. As discussed in the
Background section of this rule, a number of protective actions have
already been implemented. Further, both State and Federal land
management entities will ensure that the management of the species is
incorporated into resource management plans. Additionally, each has
committed to identifying additional habitats under its control for
expansion of populations of Pecos pupfish. Resource management agencies
in both New Mexico and Texas are committed to working with willing
private landowners to identify potential repatriation sites on private
lands and establish populations of the species on those lands.
In summary, while the Pecos pupfish has been eliminated from a
significant portion of its historical range, we believe that the
measures provided in the Conservation Agreement have significantly
reduced threats to the species and will ensure its continued existence.
B. Overutilization for commercial, recreational, scientific, or
educational purposes. We are unaware of threats to the species from
these factors. Anglers may occasionally collect Pecos pupfish as bait
and scientists may collect specimens for scientific study, but these
uses probably have a negligible effect on total population numbers.
C. Disease or predation. We are unaware of threats to the species
from disease. Sinkholes that support introduced game fish have lower
numbers of pupfish than sinkholes without game fish (Echelle and
Echelle 1978). As the Pecos pupfish population is impacted by habitat
loss and degradation and refugia become scarce, predation could become
a more important threat. However, the measures through the Conservation
Agreement to remove nonnative predators from sinkholes will reduce this
threat.
D. The inadequacy of existing regulatory mechanisms. New Mexico
State law provides limited protection for the Pecos pupfish. The State
of New Mexico lists the Pecos pupfish as a threatened species.
Threatened species, as defined by the State of New Mexico, are those
species ``* * * whose prospects of survival or recruitment within the
State are likely to be in jeopardy within the foreseeable future.''
This designation provides the protection of the New Mexico Wildlife
Conservation Act (sections 17-2-37 through 17-2-46) and prohibits
taking of such species except under the issuance of a scientific
collecting permit. The State also has a limited ability to protect the
habitat of the species through the Habitat Protection Act (sections 17-
6-1 through 17-6-11) and through water quality statutes and
regulations. The species' habitat is also somewhat protected through a
provision of the Habitat Protection Act (section 17-4-14) that
[[Page 14517]]
makes it illegal to de-water areas used by game fish.
The State of Texas listed the Pecos pupfish as threatened by on
March 1, 1987. The State prohibits taking, possessing, and transporting
State-listed species or goods made from such species (Texas Parks and
Wildlife Code, section 68.015 (1975)). However, State-listing in Texas
provides no protection for the habitat of listed species.
State regulations in New Mexico and Texas allow for the use of live
bait in the Pecos River in areas containing the Pecos pupfish. This
situation has encouraged the spread of detrimental species,
specifically the sheepshead minnow, which replaces and/or hybridizes
with the Pecos pupfish (see Factor E). However, the NMDGF and the TPWD
modified fishing regulations to ban the use of sheepshead minnow as a
bait fish. Additionally, all signatories of the Conservation Agreement
have committed to, when and where feasible, replacing the sheepshead
minnow x Pecos pupfish hybrids within the Pecos River and at other
sites with pure Pecos pupfish.
E. Other natural or manmade factors affecting its continued
existence. The primary cause for the recent (post 1980) range reduction
of Pecos pupfish is the introduction of the sheepshead minnow, a
species once confined to shallow, brackish, coastal waters of the Gulf
and Atlantic coasts of the continental United States. The two
Cyprinodon species appear to have little in the way of premating
isolating mechanisms and readily hybridize (Cokendolpher 1980).
Hybridization with and/or replacement by the sheepshead minnow poses a
major threat to the Pecos pupfish. The sheepshead minnow was introduced
into the Pecos River, probably in the vicinity of Pecos, Texas,
sometime between 1980 and 1984. Sheepshead minnow x Pecos pupfish
hybrids have since moved upstream and downstream at a rapid pace
despite the presence of six irrigation diversion dams. The spread of
hybrids has occurred both naturally and presumably through ``bait
bucket'' introductions.
The purity of the pupfish populations in Salt Creek, Texas, and in
the abandoned gravel pits near Grandfalls, Texas, were unknown at the
time of the proposal. Both populations occur on privately owned lands,
and surveys had not been conducted on these lands since 1989. Because
the gravel pits are close to the Pecos River and because hybrids occur
in that portion of the river, the gravel pit populations were
considered extremely vulnerable to introgression. Research conducted
during the proposal period confirmed that the gravel pit populations
are hybrid.
The northward expansion of sheepshead minnow x Pecos pupfish
hybrids reduced the range of the Pecos pupfish by approximately 60
percent by the late 1980s (Wilde and Echelle 1992). Subsequent
expansion of the hybrids into the Pecos River upstream from Red Bluff
Reservoir has further constricted the range of the pupfish. Genetically
pure populations of Pecos pupfish may now occur only in off-channel
habitats. While the river populations are most susceptible to
replacement by and/or hybridization with sheepshead minnow, the
sinkhole populations are also considered vulnerable to hybridization
due to the possibility of anglers releasing sheepshead minnows into
sinkholes. However, actions by the States of New Mexico and Texas to
restrict the use of sheepshead minnows for bait, plus the construction
of a fish barrier at Bitter Lake National Wildlife Refuge, have
enhanced the security of the off-channel pupfish populations.
Additionally, all signatories of the Conservation Agreement have
committed to, when and where feasible, replacing the sheepshead minnow
x Pecos pupfish hybrids within the Pecos River and other sites with
pure Pecos pupfish.
Large-scale fish kills caused by algal blooms occurred in the Pecos
River, Texas, in 1985 and 1986 (Rhodes and Hubbs 1992). Such algal
blooms may affect the Pecos pupfish (Rhodes and Hubbs 1992).
Other threats to the Pecos pupfish include nonnative fish
introductions and piscicide applications. Anglers interested in
developing sport fisheries in sinkholes apply piscicides to remove
unwanted fish species prior to introducing sport fish. Such
manipulation, conducted exclusively on private lands and without the
knowledge by the landowner of the presence of the Pecos pupfish, can
adversely affect or eliminate Pecos pupfish populations. Enforcement by
either State of its prohibitions against take of protected species on
private lands is not considered an effective bar to these activities.
However, we do not consider such applications of piscicides a
significant threat to the species and do not specifically address
piscicide application in the Conservation Agreement.
Oil spills from pipelines into Salt Creek in Texas are a threat
because they have occurred in the past and represent an ongoing threat
to water quality and Pecos pupfish habitats. However, Salt Creek is
believed to be the only population clearly vulnerable to such a
catastrophe, and the Salt Creek population, although the only known
naturally occurring pure population in Texas, represents only about
one-tenth of the species' population throughout its range. Catastrophic
spills of oil or other contaminants into pupfish-occupied privately
owned habitats are not considered controllable by the Conservation
Agreement. However, establishment of more populations, as delineated in
the agreement, would act as a buffer against such losses.
We consider the latter two threats, the introduction of nonnative
fish and use of piscicides on private land and uncontrolled oil spills
or other contamination of isolated habitats, far less significant
threats to the Pecos pupfish than hybridization. Thus, we do not
specifically address them in the Conservation Agreement. However, both
the States of New Mexico and Texas have committed to conducting public
outreach and education to inform private landowners of the occurrence
of the Pecos pupfish and to increasing the numbers and security of
populations of the Pecos pupfish. Hence, the increased numbers of fish
diminish the potential impacts of isolated losses arising from the
latter two threats.
Finding and Withdrawal
The Conservation Agreement signed by the NMDGF, New Mexico
Department of Agriculture, NMSPD, TPWD, the BLM, and us was
specifically developed to address and alleviate the known threats to
the Pecos pupfish.
The two most significant threats, security of existing populations
and loss of genetic purity of Pecos pupfish populations through
hybridization with the sheepshead minnow, have received immediate
action--physical barriers now prohibit access by the sheepshead minnow
to occupied Pecos pupfish habitat; the resource entities have included
the conservation of the Pecos pupfish as a specific management goal in
planning documents; and the NMDGF and the TPWD approved revision of
State regulations to ban the use of sheepshead minnow as a bait fish in
the Pecos River. Additionally, signatories of the Conservation
Agreement committed to establishing and protecting additional
populations on lands they administer and, with the cooperation of
willing landowners, on private lands within the historical range of the
species. Based on these commitments, we determine that listing the
Pecos pupfish as endangered or threatened under the Act is not
warranted. Therefore, we withdraw our January 30, 1998, proposed rule
(63 FR
[[Page 14518]]
4608) to list the Pecos pupfish as endangered.
References Cited
A complete list of all references we cited, as well as others, is
available upon request from our New Mexico Ecological Services Field
Office (see ADDRESSES section).
Author
The primary author of this document is Jennifer Fowler-Propst, New
Mexico Ecological Services Field Office (see ADDRESSES section).
Authority: The authority for this action is section
4(b)(6)(B)(ii) of the Endangered Species Act (16 U.S.C. 1532 et
seq.).
Dated: February 25, 2000.
Jamie Rappaport Clark,
Director, Fish and Wildlife Service.
[FR Doc. 00-6602 Filed 3-16-00; 8:45 am]
BILLING CODE 4310-55-P
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