7163

• UCREFRP Catalog Number: 7163
• Author: Haynes, C. M. and J. R. Bennett.
• Title: Relationship between the Preservation of Wilderness Values and Endangered Species
• USFW Year: 1985.
• USFW - Doc Type: A Case-Study from the Upper Colorado River Basin, U.S.A.
• Copyright Material: YES

Research, to date, has revealed a number of basic
aspects of the life history and limiting factors
for the Colorado squawfish. Unfortunately. much
vital knowledge relating to the biology of this
unique fish is incompletely understood and will
be essential to the future management and
recovery of the species. A number of deficient
areas await resolution. The following list of
questions suggests future research objectives.
The list is not intended to be exhaustive nor are
topics ranked according to priorities.

1. How will we recognize when the Colorado
squawfish is "recovered"? If recovery is
to be defined in terms of a specified
number of self-sustaining subpopulations,
we must develop methods which allow us to
recognize "self-sustaining". Is it
necessary that the species be self-
sustaining every year throughout its range
for recovery to be achieved?

2. How can we recognize when "good" or "bad"
things are happening to the species?
Relative abundance indices (e.g., C/E) are
promising but require close scrutiny
relative to sources and magnitudes of
error. It must be recognized that C/E
methodologies do not lend themselves well
to application in an open system like the
Colorado River and their results can be
misleading.

3. Is there a measurable relationship between
flows (assuming comparable thermal
regimes) and larval production on the
spawning grounds? Hypothetically, high
flows such as those observed in 1983 fit
well into Tyus's (1985) hypothesis of
evolutionary adaptation for wet years.
High flows could serve to flush spawning
bars and, if flows do not recede too
rapidly, provide greater substrate area
for spawning.

4. Do high spring flows suppress spawning of
exotic species while enhancing squawfish
spawning? Evidence from the Yampa in 1983
suggests that this maY,be the case,
however, observations from the main stem
Colorado suggest that exotic species may
actively avoid currents and not be caught
by drift sampling techniques (R. Valdez,
pers. comm.). Should future studies
demonstrate that exotic species are in
fact suppressed by high spring flows, this
knowledge could conceivably be incor-
porated into a basin-wide water budget.

5. How do we monitor (census) the species in
the upper basin? At what life stage? Can
carefully timed drift collections be used
as economically efficient monitors of
larval production?

6. Are squawfish larvae truly aperiodic?
Evidence from the Soviet Union suggests
thnt cyprlnlds may exhibIt dIurnnl
periodicity in clear rivers but that the
same species may drift around the clock in
rivers of low transparency (Pavlov and
others 1977). If this is the case for the
Colorado squawfish, it would require
alterations in drift monitoring methods
depending on the flow year in question.

7. What effects, if any, do contaminants such
as agrichemicals, heavy metals, etc. have
on the species' decline and prospects for
its recovery? To date, knowledge of
specific contaminant levels is insuf-
ficient. It should not be tacitly assumed
that, as the chemical nature of the river
changes, this will have no effect on the
overall fitness of Colorado squawfish (and
other native species).

8. Is physical habitat enhancement possible?
For what life stages? Can we measure
future deleterious changes in essential
habitat features such as the spawning
areas in lower Yampa Canyon? If recog-
nized, can remedial action be meaningfully
implemented? Can the relatively unaltered
lower Yampa River be used as a model for
corrective efforts elsewhere?

9. Are effective methods available for exotic

species management?

10. Can migrational barriers be altered to
permit bi-directional passage of migratory
adults?

11. Is artificial propagation a meaningful
tool for enhancing populations?
Experience by Toney (1974) and Hamman
(1981) suggests that culture is relatively
easy; however, experience with an
experimental release of juveniles in small
ponds connected to the mainstem Colorado
River (Moffat County, Colo.) resulted in
heavy predation by exotics (L. Kaeding,
CRFP, pers. comm.). Would it be better to
release larger individuals to reduce
predation mortality? Is it necessary to
be concerned with maintaining the
heterozygosity of genetic subpopulations
under cultural conditions?

12. Unquestionably, further research on the
homing hypothesis should be conducted.
Experience gained with salmonid homing
experimentation could be considered. If
migrating adults are in fact homing to an
olfactory cue, the release of artifi-
cially propagated "naive" individuals
could be problematical. Further, if
homing is a reality, the preservation of
the chemical integrity of Yampa River
seeps is critical.

194