[Federal Register Volume 65, Number 53 (Friday, March 17, 2000)]
[Proposed Rules]
[Pages 14513-14518]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-6602]


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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