[Federal Register Volume 64, Number 147 (Monday, August 2, 1999)]
[Proposed Rules]
[Pages 41903-41905]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-19711]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Notice of 90-Day
Finding on Petition To Delist the Concho Water Snake
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of 90-day petition finding.
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SUMMARY: We, the Fish and Wildlife Service (Service) announce a 90-day
finding for a petition to delist the Concho water snake (Nerodia
paucimaculata) under the Endangered Species Act of 1973, as amended. We
find that the petitioner did not present substantial information
indicating that delisting this species may be warranted.
DATES: The finding announced in this document was made on July 13,
1999.
ADDRESSES: Comments, material, information, or questions should be sent
to the Supervisor, U.S. Fish and Wildlife Service, Ecological Services,
10711 Burnet Road, Suite 200, Austin, Texas 78758. The petition and
supporting data are available for public inspection by appointment
during normal business hours at the above address. A copy of the
finding announced in this notice may be obtained by writing to the
above address.
FOR FURTHER INFORMATION CONTACT: Patrick Connor, Fish & Wildlife
Biologist, at the above address (telephone 512-490-0057 ext. 227).
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(A) of the Endangered Species Act of 1973, as
amended (16 U.S.C. 1531 et seq.) (Act), requires that we make a finding
on whether a petition to list, delist, or reclassify a species presents
substantial scientific or commercial information to demonstrate that
the petitioned action may be warranted. To the maximum extent
practicable, we must make this finding within 90 days of the date the
petition is received, and this finding must be published promptly in
the Federal Register. If the finding is that the petitioner has
presented substantial information we must then promptly commence a
status review of the species.
When evaluating whether the substantial information standard is
met, we use the definition provided in the implementing regulations at
50 CFR 424.14(b). Substantial information is defined as ``that amount
of information that would lead a reasonable person to believe that the
measure proposed in the petition may be warranted.'' The factors for
listing, delisting or reclassifying species are described in 50 CFR
424.11. We may delist a species only if the best scientific and
commercial data available substantiate that it is neither endangered
nor threatened. Delisting may be based on one of the following
reasons--(1) extinction, (2) recovery, or (3) original data for
classification were in error.
On June 29, 1998, we received a petition by John W. Grant on behalf
of the Colorado River Municipal Water District (CRMWD) dated June 24,
1998, to delist the Concho water snake (CRMWD 1998). The petition
asserts that--(1) the status of the Concho water snake was stable at
the time of listing and continues to be stable, (2) all putative
threats are insubstantial, and (3) the determination that the Service
made to list the snake as threatened was in error. After careful
review, we find that the snake should remain classified as threatened
under the Act.
The Concho water snake is endemic to the Concho and Colorado rivers
in Runnels, Tom Green, Concho, McCulloch, Coleman, Brown, Mills, San
Saba, Irion, Lampasas, and Coke counties, Texas. We listed the Concho
water snake as threatened on September 3, 1986, due in part, to its
limited geographic range, limited population sizes, and loss of
important habitats and prey base resulting from water development
projects (past, ongoing, and future) (51 FR 31412). We designated
critical habitat for the species on June 29, 1989 (54 FR 27377).
[[Page 41904]]
Information presented in the petition indicates that, in the 15
areas monitored by CRMWD and in certain reaches of O.H. Ivie
Reservoir's shoreline, Concho water snake populations persist. The
voluminous data on the snake and its fish preybase submitted by the
petitioner provides a detailed picture of snake's status at the CRMWD
and Texas A&M University monitoring sites. However, as discussed in the
petition, due to limitations in site visits and resultant low number of
recaptures, CRMWD biologist were unable to make precise local Concho
water snake population size estimates.
The current range of the Concho water snake is similar to when the
species was listed 13 years ago. The snake's primary habitat remains
riverine (located on or inhabiting the bank of a river). This habitat
is threatened by inadequate instream flows to support the fish preybase
for the snake. Each of the three major riverine sections (Concho River,
Colorado River from Spence Reservoir to O.H. Ivie Reservoir, and
Colorado River downstream of O.H. Ivie Reservoir) of the snake's range
are downstream of reservoirs. Operations at these reservoirs (O.C.
Fisher, Lake Nasworthy, Twin Buttes, E.V. Spence, and O.H. Ivie) can
affect instream flows for snakes and their prey for significant periods
of time.
In a biological opinion for the U.S. Army Corps of Engineers we
identified instream flows (including flushing flows for channel
maintenance) below Spence and Ivie reservoirs in our reasonable and
prudent alternatives. If we delist the Concho water snake, the
requirements of the biological opinion would no longer be in effect.
CRMWD biologists made multiple preybase surveys using seines at the
15 required monitoring sites, as well as other sites. The small fishes
in these surveys, upon which snakes are known to feed, are variable in
numbers from year to year but generally do not appear to have been a
limiting factor for local populations during this period. However, if
instream flows are inadequate there will be a decrease in Concho water
snake prey.
We do not agree with statements made in the petition that
reductions in stream flow are not (and will not be) a problem. Low flow
conditions exacerbate any significant pollution problems (i.e.
increases in nutrients and/or toxic compounds). If those conditions
persist long enough (perhaps for as little as three years), water
snakes in those reaches will be at risk of extirpation. The demise of
the Concho water snake population below E.V. Spence Reservoir following
its construction is likely related to inadequate instream flows
(reservoir releases). Scott et al. (1989) found certain reaches of the
Colorado River ``too dry for too long to support water snake
populations.''
Since the early 1930s, at least five major droughts occurred State-
wide in Texas lasting multiple years and disrupting normal use of the
State's water resources (U.S. Geological Service 1991). An inadequate
instream flow regime remains one of the most serious threats to the
snake due to the prevalence of droughts in Texas.
According to information presented in the petition, in the years
following the inundation of riverine habitat by O.H. Ivie Reservoir,
Concho water snakes survived and reproduced in the reservoir. However,
blockage to Concho water snake movement by Freese Dam and the
discontinuous nature of some of the reservoir habitat remain as
potential barriers to gene flow between populations. In addition,
available information does not enable precise estimates on the size or
health of the snake population on O.H. Ivie Reservoir. Despite
indications that Concho water snakes have been able to survive for a
decade, the mid-term and long-term fate of the Concho water snake in
O.H. Ivie Reservoir remains uncertain. Examination of the data
presented suggests that the abundance of snakes is variable among
reservoirs and in general less than the abundance of snakes in suitable
riverine habitat. Information presented and available to us indicates
that habitat loss from water development and diversion projects remains
a threat.
The information presented in the petition indicates that, at least
in the early successional stages of O.H. Ivie Reservoir, snakes have
been able to survive. However, in the course of the life of reservoirs
such as O.H. Ivie, sediment will deposit in the upper reaches of the
reservoir. Over time and depending on various conditions in the
watershed, upper O.H. Ivie will likely become less suitable snake
habitat. Furthermore, changes to the reservoir's fishery due to
stockings of game fish and degradation of cover and structure may
adversely affect Concho water snake prey availability. While Concho
water snakes are somewhat flexible in their response to changes in prey
items, an event that would result in the reduction of preferred size
food items (e.g, small minnows for juvenile snakes) could affect the
species' ability to sustain current population levels. If such an event
lasted multiple years, we would expect the snake population to decline.
Recruitment would be reduced and populations would decline.
Another factor that threatens the Concho water snake is the
fragmentation and isolation of populations resulting from habitat
disturbance and from physical barriers such as the Freese Dam. The
petition discusses fragmentation citing the Concho water snake genetics
study of Sites and Densmore (1991). There is general agreement on
several issues--(1) the distribution of the Concho water snake is a
linear array of demes (a series of local populations) connected with
occasional gene flow and associated with specific habitat features such
as riffles (a section of a river characterized by swifter currents,
shallow depths and broken water with turbulence or waves at the
surface); (2) the Freese Dam poses a barrier to water snake movement
both upstream and downstream; (3) mitigation against fragmented
habitats and conservation of the Concho water snake require the
artificial movement of Concho water snakes between (a) the Colorado
River below Freese Dam and the Concho River and (b) the Colorado River
below Freese Dam and the Colorado River above Ivie Reservoir; and (4)
water snakes (Nerodia spp.) in general and Concho water snakes
specifically have very low levels of genetic variation.
The petition states that the Ivie Reservoir population effectively
connects the Concho and upper Colorado River populations. However, two
issues remain that indicate the reservoir itself may be a barrier--(1)
the current discontinuity of habitat patches along the reservoir
shoreline along with the variability with which Concho water snakes
occupy those patches and (2) more importantly, the ultimate fate of (a)
the reservoir's physical habitats in the upper reaches and (b) the
Concho water snake reservoir populations.
One significant point not addressed by the petition is the wide
variability in the health of Concho water snake reservoir populations.
Concho water snakes are probably absent from the lakes of the San
Angelo area. Available information dating to Martin Whiting's thesis
(1993) indicates that the Spence Reservoir population is limited with
probably less than 200 individual snakes total (n < 200="" total)="" for="" his="" two="" study="" sites.="" additionally,="" whiting="" found="" no="" evidence="" that="" the="" two="" spence="" concho="" water="" snake="" populations="" (pecan="" creek="" and="" pump="" station="" populations)="" exchanged="" individuals="" even="" though="" they="" were="" in="" the="" same="" general="" area="" of="" the="" reservoir="" separated="" by="" about="" 2,000="" meters="" (m)="" or="" (6,562="" feet="" (ft)).="" [[page="" 41905]]="" the="" likelihood="" of="" survival="" of="" concho="" water="" snakes="" in="" specific="" reservoirs="" is="" likely="" to="" be="" dependent="" upon="" a="" variety="" of="" factors="" such="" as--(1)="" reservoir="" hydrology="" (inflows="" to="" and="" outflows/diversions="" from="" the="" lake);="" (2)="" the="" time="" scale="" chosen="" (changes="" to="" water="" snake="" habitats="" found="" along="" the="" shoreline="" and="" the="" shallow="" parts="" of="" a="" lake="" may="" occur="" over="" several="" decades="" as="" opposed="" to="" years);="" limnology="" (study="" of="" freshwater="" systems="" such="" as="" lakes="" ponds="" and="" rivers="" and="" their="" plant="" and="" animal="" communities="" as="" they="" are="" affected="" by="" their="" physical,="" chemical,="" and="" biotic="" environment);="" and="" (4)="" continuity="" and="" connectivity="" with="" other="" concho="" water="" snake="" populations.="" the="" persistence="" of="" the="" concho="" water="" snake="" in="" spence="" reservoir="" does="" not="" assure="" us="" that="" the="" snake="" will="" persist="" in="" ivie="" reservoir.="" the="" two="" reservoirs="" differ="" in="" their="" hydrology,="" and="" we="" believe="" more="" data="" are="" needed="" to="" understand="" the="" fate="" of="" the="" concho="" water="" snake="" in="" ivie="" reservoir="" area.="" finding="" in="" addition="" to="" the="" analysis="" discussed="" above,="" we="" evaluated="" the="" petition="" in="" the="" context="" of="" the="" snake's="" recovery="" criteria="" as="" set="" forth="" in="" the="" species'="" recovery="" plan="" (service="" 1993).="" we="" will="" consider="" the="" concho="" water="" snake="" for="" delisting="" when--(1)="" adequate="" instream="" flows="" are="" assured;="" (2)="" viable="" populations="" are="" present="" in="" each="" of="" the="" three="" major="" reaches="" *="" *="" *;="" and="" (3)="" movement="" of="" an="" adequate="" number="" of="" snakes="" is="" assured="" to="" counteract="" the="" adverse="" effects="" of="" population="" fragmentation.="" importantly,="" the="" petition="" does="" not="" address="" criterion="" one.="" in="" regards="" to="" criterion="" two,="" while="" concho="" water="" snake="" population="" in="" each="" of="" the="" three="" major="" reaches="" are="" stable,="" there="" is="" no="" reliable="" data="" available="" to="" indicate="" that="" these="" populations="" remain="" viable.="" viable="" populations="" are="" self-sustaining="" and="" can="" persist="" for="" the="" long-term="" (soule="" 1987).="" we="" believe="" the="" information="" provided="" by="" the="" petitioner="" has="" added="" to="" our="" knowledge="" of="" the="" distribution="" and="" abundance="" of="" the="" concho="" water="" snake.="" however,="" the="" petition="" lacks="" adequate="" information="" upon="" which="" to="" evaluate="" the="" long-term="" viability="" of="" individual="" populations.="" further="" investigations="" are="" needed="" to="" understand="" the="" various="" factors="" important="" to="" the="" snake's="" long-term="" viability,="" including="" range="" wide="" monitoring,="" and="" the="" future="" distribution="" of="" habitat="" patches,="" whether="" occupied="" and="" unoccupied,="" including="" those="" at="" the="" o.h.="" ivie="" reservoir.="" in="" summary,="" the="" petition="" fails="" to="" provide="" information="" indicating="" that="" any="" of="" the="" three="" criteria="" for="" delisting="" (from="" the="" recovery="" plan)="" are="" met.="" further,="" the="" impact="" of="" declining="" instream="" flows="" (due="" to="" drought="" and/or="" water="" diversions),="" long="" term="" changes="" to="" lake="" habitats,="" pollution,="" and="" other="" habitat="" threats="" on="" the="" riffle-dwelling="" fish="" in="" the="" concho="" and="" colorado="" rivers="" are="" not="" addressed="" in="" the="" petition.="" references="" cited="" colorado="" river="" municipal="" water="" district.="" 1998.="" petition="" to="" delist="" the="" concho="" water="" snake.="" submitted="" to="" united="" states="" department="" of="" the="" interior="" and="" texas="" parks="" and="" wildlife="" department.="" pp.="" 33="" +="" appendices="" a-c.="" scott,="" n.j.,="" jr.,="" t.c.="" maxwell,="" o.="" w.="" thornton,="" jr.,="" l.a.="" fitzgerald,="" and="" j.w.="" flury.="" 1989.="" distribution,="" habitat,="" and="" future="" of="" harter's="" water="" snake,="" nerodia="" harteri,="" in="" texas.="" journal="" of="" herpetology="" 23(4):="" 373-389.="" soule,="" m.e.="" 1987.="" introduction.="" in:="" viable="" populations="" for="" conservation.="" m.e.="" soule,="" editor.="" cambridge="" univ.="" press.="" new="" york.="" 189="" pp.="" u.s.="" fish="" and="" wildlife="" service.="" 1993.="" concho="" water="" snake="" recovery="" plan.="" albuquerque,="" new="" mexico="" vii+66="" pp.="" whiting,="" m.j.="" 1993.="" population="" ecology="" of="" the="" concho="" water="" snake,="" nerodia="" harteri="" paucimaculata,="" in="" artificial="" habitats.="" unpublished="" m.s.="" thesis.="" texas="" a&m="" university.="" xvi+137="" pp.="" author:="" the="" author="" of="" this="" document="" is="" patrick="" connor,="" austin="" ecological="" services="" field="" office="" (see="" addresses="" section).="" authority="" the="" authority="" for="" this="" action="" is="" the="" endangered="" species="" act="" of="" 1973,="" as="" amended="" (16="" u.s.c.="" 1531="" et="" seq.).="" dated:="" july="" 13,="" 1999.="" john="" g.="" rogers,="" acting="" director,="" fish="" and="" wildlife="" service.="" [fr="" doc.="" 99-19711="" filed="" 7-30-99;="" 8:45="" am]="" billing="" code="" 4310-55-u="">