9314

• UCREFRP Catalog Number: 9314
• Author: Wick, E. J. and J. A. Hawkins.
• Title: Colorado Squawfish Winter Habitat Study.
• USFW Year: 1989.
• USFW - Doc Type: Fort Collins.
• Copyright Material: NO

Box 5. Reasons for holding, rearing, or stocking endangered and candidate
fishes
1. Place fish in refuges to protect genetic diversity when the stock
may become extinct in the near future from population declines or
catastrophic risk.
2. Produce of fishe for experimental stocking to obtain biological,
ecological, or environmental information from field experiments
that are essential to the recovery effort.
3. Produce fishe for augmentation stocking to enhance severely
depleted stocks.
4. Produce fishe for restoration stocking of extirpated populations or
stocks.
extirpated or is extremely low, then founders should be obtained that would be
the nearest neighbor from an evolutionary (not necessarily geographic)
standpoint. Fish from nearest neighbor stock should exhibit life history
patterns similar to the extirpated population and be taken from a similar
environment.
It is especially important to obtain a random sample of fish that
represents the donor population by sampling adults within and among
spawning times throughout the spawning range. The number of wild fish
removed at any one time should be limited so the remaining population is
not adversely affected, unless the species is in immediate danger of
extinction.
F. Estimating the Number of Fish Required to Develop Broodstocks. The
number of broodfish needed at the end of each growing season is dependent
upon the attrition (i.e., mortality) rates of the fish at the end of each
growing season. Conservative attrition rates must be estimated. These
rates will be refined from empirical data from captive propagation of the
fish in different facilities. More fish may be produced than are needed
for broodstock development. Disposition of surplus fish will follow the
guidelines provided in Section VI of this document.
G. Important Considerations in Captive Propagation The following
considerations must be taken when establishing broodstocks: (1) Equal sex
ratios among breeding adults (Kapuscinski et al. 1993; Lacava and Hughes
1989; Tave 1984), (2) equal numbers of offspring among family lots from
pedigreed matings (Allendorf 1993: Kapuscinski et al. 1993), and (3)
avoidance of selection (Frankham et al. 1992; Kapuscinski et al. 1993).
Ignoring these factors can resulted in rapid loss of genetic diversity in
broodstocks (Allendorf 1993: Kapuscinski et al. 1993). Equal numbers of
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