8121

• UCREFRP Catalog Number: 8121
• Author: Williamson, J. H. and R. S. Wydoski.
• Title: Genetics Management Guidelines.
• USFW Year: 1994.
• USFW - Doc Type: Denver, CO.
• Copyright Material: NO

If conducted in a scientifically sound manner, captive propagation of
' endangered fish will prevent: (1) extinction of the species; (2) loss of
genetic diversity within a species, stock, or population; (3) loss of
genetic diversity among stocks or populations; and (4) inadvertent
' artificial selection that may lead to directional succession from
inbreeding or genetic swamping of wild stocks (Busak 1990; Kapuscinski et
al. 1993). The genetic processes that may be affected by these risks and
the hatchery activities that may cause the risks are summarized in Box 4.
' The extinction of indigenous fish stocks can be caused by stocking
captive-reared fish but is generally preceded by the loss of genetic
diversity within and between populations.
' C. Guidelines for Stocking Captive-Reared Endangered Fishes. Suitable
habitat must be available in river reaches that are proposed for stocking
' to increase the likelihood of successful stocking. The reasons for
holding, rearing, and stocking endangered fishes are summarized in Box 5.
Criteria for holding, rearing, or stocking captive-reared endangered
fish, criteria for when to stock, and action required are provided in Box
' 6. Guidelines for preparation of stocking plans for release of captive-
reared endangered fish into the Upper Colorado River Basin are summarized
in Box 7.
' D. Reasons for Maintaining Genetic Diversity in Captive Propagation
Programs. The major objective in captive propagation of threatened and
endangered fish species is (1) to develop broodstocks and to produce
' offspring that have genetic characteristics similar to those of the
founding population. Two additional objectives for captive propagation
of endangered fishes are (2) to use captive propagation and stocking when
' necessary as temporary fishery management tools to facilitate recovery
(i.e., development of self-sustaining populations) of endangered fishes
in their natural habitats in the upper basin while preserving the genetic
diversity of wild endangered fish stocks and (3) to maintain artificial
genetic refugia for endangered fish species or stocks that may be
susceptible to extinction from declining numbers and from catastrophic
risk in the wild, until such risks are removed. Breeding, rearing, and
' maintaining captive stocks such that genetic diversity similar to wild
stocks is maintained from generation to generation is important in
achieving this objective. Managing captive populations to maintain
existing natural genetic diversity preserves future options for effective
management and recovery of the taxon by fish and wildlife managers (Ralls
and Ballou 1992; Thomas 1990).
' The natural genetic diversity within a population is associated with its
evolutionary history and is important for adaptation, long-term survival,
and maximum production in the wild. Protecting genetic diversity within
a hatchery broodstock prevents artificial selection, inbreeding, and
genetic drift which frequently occurs in hatchery programs (Allendorf
1993). The concept of "maximally protecting genetic diversity" within a
hatchery stock assumes that a sufficient number of randomly sampled
individuals from the appropriate donor stock or population were used such
that the broodstock truly reflects the genetic characteristics of the
donor population. Proper broodstock development during the founding
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