7775

• UCREFRP Catalog Number: 7775
• Author: Carlson, C. A. and R. T. Muth.
• Title: Inland Fisheries Management in North America, Chapter 15
• USFW Year: 1993.
• USFW - Doc Type: Endangered Species Management.
• Copyright Material: YES

,
. .

ENDANGERED SPECIES

375

-......"'" .-. -.

Figure 15.5 Ponds at Horsethief Canyon State Wildlife Area, Colorado, are used as
refugia for endangered fishes of the upper Colorado River basin. (Photograph courtesy of
D. Gates.)

of average genic heterozygosity in refugium populations of desert pupfish; he
considered use of refugia to be a valid practice for endangered fish management
and conservation (Figure 15.5). Similarly, Ammerman and Morizot (1989) found
that captive Colorado squawfish did not differ significantly from wild populations
in allele frequencies at loci that affect overall individual fitness. Nonetheless,
there is general agreement that fishes should be transplanted to refugia only when
their extinction is imminent and they should be reintroduced to native habitats as
soon as possible.
Allendorf and Leary (1988) stated that the primary goal of any conservation
program must be to ensure maintenance of existing genetic variation. Loss of
genetic variation is generally expected to increase the probability of extinction by
adversely affecting such survival-related characteristics as growth, fertility,
longevity, normal development, disease resistance, and ability to adapt to
changing environmental conditions. Long-term conservation of a large range of
species is possible only in natural communities, and we may have a responsibility
to keep evolutionary options open. To conserve our genetic estate (biological
heritage), Frankel (1974) urged that geneticists playa role in planning ecological
reserves for conservation of such communities and that the genetic principles of
conservation be explored and clarified. Smith and Chesser (1981) emphasized the
importance of genetic variability in maintaining stable, complex ecosystems and
species. Since management practices may reduce that variability below normal
levels, they called for conservation efforts to maintain existing levels of genetic
variability in natural fish populations. Meffe (1986) reviewed the nature of
potential genetic problems in management of endangered fishes and suggested
means to minimize genetic deterioration of endangered stocks. Management of

~