7023

• UCREFRP Catalog Number: 7023
• Author: Meffe, G. K.
• Title: Conservation Genetics and the Management of Endangered Fishes
• USFW Year: 1986
• USFW - Doc Type: Fisheries
• Copyright Material: YES

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Conservation Genetics and the Management
of Endangered Fishes
Gary K. Meffe
... wild species must have available a pool of genetic diversity if they are to survive environmental pressures exceeding
the limits of developmental plasticity. If this is not the case, extinction would appear inevitable." (Frankel 1983,
p. 3).
ABSTRACT
The emerging field of endangered fishes management has yet to'fully incorporate conservation genetics into recovery
programs. Genetic aspects of small populations must be considered at the outset of management programs in order to
maximize probability of their long-term survival and continued adaptability. Total genetic variance of a species consists
of within population genetic diversity, and the differences found among populations; both types of variance should be
maintained to maximize adaptive flexibility of endangered fishes. Forces that erode genetic variation include small
population size, population bottlenecks, genetic drift, inbreeding depression, artificial selection in captivity, and mixing
of distinct genetic stocks. These can lead to increased homozygosity, loss of quantitative variation, and exposure of
deleterious recessive alleles, all of which may reduce fitness. Suggestions for genetically sound management of endan-
gered fishes include genetic monitoring of natural and captive populations, use of large numbers for captive breeding
where feasible, selective mating to avoid.)nbreeding where necessary, minimization of time in captivity, and separate
maintenance of distinct stocks.
ince passage of the En-
dangered Species Act in
1973, fisheries scientists have
dealt with the problem of
maintaining declining popu-
lations of rare fishes. These or-
ganisms have been intensively
studied under natural condi-
tigns (Minckley 1973, 1983;
Naiman and Soltz 1981; Meffe
et al. 1983), have been reared
extensively in captivity for re-
stocking in native habitats (To-
ney 1974; Hamman 1981, Gary K. Meffe
1982a, 1982b; Johnson and Rinne 1982), and are the objects
of large investments of money and manpower. However,
the field of endangered fishes management is new and still
largely experimental. For example, there is only one hatch-
ery facility for endangered fishes, located at the Dexter Na-
tional Fish Hatchery (DNFH), New Mexico, established in
1974. Extensive experience in recovery work is generally
lacking, and many conservation efforts are by necessity trial-
and-error attempts at saving a species from immediate ex-
tinction, without full regard for long-term prospects of sur-
vival.
As experience in conservation of rare fishes accrues and
recovery plans are devised and implemented, it is appro-
priate to address genetics in the welfare of endangered fishes.
Until now little attention has been paid to long-term genetic
health of rare fishes. This is understandable since some re-
covery efforts have been eleventh hour, unplanned attempts
at avoiding extinction (e.g., Hubbs and Brodrick 1963; Miller
and Pister 1971). As the science of endangered fish conser-
vation matures it is imperative that a genetic foundation
underpins recovery efforts, since long-term conservation of
any endangered species will likely fail if genetic aspects are
ignored at the outset (Frankel and Sou16 1981).
My purposes here are two-fold. First, in a primarily the-
oretical treatise, I call to the attention of endangered fishes
managers the nature of potential genetic problems in man-
agement programs. Second, I suggest courses of action as
first approximations toward minimization of genetic dete-
rioration of an endangered stock. Detailed plans should
eventually be based upon experience gained with early re-
covery programs, with collaborative input from population
geneticists, aquaculturists, and others with pertinent ex-
pertise.
Several caveats must be made at the outset. First, the
literature on genetics of endangered fishes is very small.
Consequently, basic principles were derived from other taxa
and from a variety of fields including aquaculture, sport
fisheries, animal husbandry, zoo care, and population ge-
netics. Second, there is a decided bias in this work toward
southwestern fishes, due to both my own familiarity with
that region, and the fact that 61% of U.S. fishes originally
listed as endangered are endemic to the southwest (Johnson
and Rinne 1982). Third, this paper is concerned only with
genetic aspects of conservation, with no comment on other
factors that will have strong bearing on management deci-
sions such as economic, political, or social constraints. I fully
recognize that budgetary and facility limitations may se-
verely restrict the extent to which theoretical genetic con-
Gary K. Meffe is a fish ecologist on the senior staff at the
University of Georgia's Savannah River Ecology Lab, Aiken, South
Carolina. His research interests include ecology and conservation
of desert fishes, fish life history patterns, community ecology of
stream fishes, and impacts of introduced species on natural com-
munities.
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Fisheries, Vol. 11, No. 1