8123

• UCREFRP Catalog Number: 8123
• Author: Wydoski, R. S.
• Title: Coordinated Hatchery Facility Plan
• USFW Year: 1994.
• USFW - Doc Type: Need for Captive-Reared Endangered Fish and Propagation Facilities.
• Copyright Material: NO

offspring that are sterile or inviable after several generations (Lande
1988). The 1% maximum inbreeding rate recommended by Simberloff (1988)
for wild populations should be used as a target for an effective
population size in developing broodstocks of the endangered Colorado
River fishes.
Allendorf (1993) recommended stocking equal numbers of offspring of
family lots from pedigreed matings. This practice will eliminate or
minimize the potential for loss of genetic diversity. Philipp et al.
(1993) recommended that genetic characterization of captive-reared fish
be compared with wild stocks to ensure that the genetic diversity is
similar.
F. Ideal Number of Founders for Broodstock Development. The designation of
"endangered" to any organism under the Endangered Species Act implies
that the numbers of wild organisms are limited. The basic goal in an
captive propagation program is to maintain the genetic diversity of
captive broodstocks that is similar to the parent wild stock. Simberloff
(1988) emphasized that general agreement does not exist about the
absolute numbers of animals needed to maintain genetic diversity in
captive propagation programs.
To achieve Simberloff's recommendation of keeping the maximum rate of
inbreeding at 1% or lower, an effective population size of fifty parents
(25 males and 25 females) is needed for development of a broodstock.
Mating of one male with one female is desirable to maximize the genetic
contribution from all fish used as parents (Allendorf 1993). This
strategy of 25 paired matings is recommended as a target for an effective
population size in the captive propagation of endangered Colorado River
fishes. This strategy was designated as "Priority 1" in Box 10 for the
maximization of genetic diversity in broodstock development. The
fertilized eggs from mating one male and one female (i.e., 1 family lot)
should be divided and reared in separate facilities to avoid the total
loss of the genetic contribution from those two parents through an
accident or catastrophe.
It is desirable to mate the 25 pairs of endangered fish in one year
because broodstocks would mature at the same time so that equal numbers
of all family lots could be produced and stocked from parents of the same
age. This procedure would eliminate many variables that could influence
genetic diversity and stocking success.
If sufficient numbers of endangered fish are in the wild, the goal would
be to increase wild recruitment until self-sustaining populations are
realized to meet the carrying capacity of available habitat. However,
for declining endangered fish stocks with little or no recruitment,
captive propagation may be necessary to augment wild stocks since a
critical level of abundance of adults or threshold density (Allee Effect)
may be needed for successful natural spawning (Lande 1988). In river
reaches where the endangered fish have been extirpated, restoration
stocking may be necessary, provided that suitable habitat is available
for all life stages. If an effective population size of 50 adults cannot
be obtained in one year, broodstock development can be accomplished over
a number of years by mating one male with one female (Item 2 in Box 10).
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