9585

• UCREFRP Catalog Number: 9585
• Author: U.S. Fish and Wildlife Service.
• Title: Inland Salmonid Broodstock Handbook.
• USFW Year: n.d.
• Copyright Material: NO

2. Plan Management Practices
All practices that involve intentional selection should be
avoided. It must be remembered that traits that relate to
performance in the wild cannot be selected for in the hatchery
environment. Unintentional selection may at times be
unavoidable, but it should be eliminated to whatever extent
possible. New, innovative practices may be required
to maintain as much genetic variation as possible in "wild"
broodfish populations. Dependent upon results of genetic
evaluation, there may be a need to go back to the original
founder population for an infusion of genetic material.
Allendorf and Leary, 1988 (2), have suggested that a 10~
infusion of genetic material from the founding population
every 10 years may be sufficient to effectively minimize
domestication. There is no substitute for long range planning
in an effort to conserve genetic variability. All management
practices should be evaluated based on their genetic impact
prior to adoption as part of hatchery procedure.
3. Methods to Minimize Loss of Variability `in Future Brood
Pot~ulatlons
A. Mating Ratio
The optimal procedure to prevent loss of variability
is to use paired matings between one female and one
male. Paired matings function to increase the
effective population size. If paired matings are
not possible,- every attempt should be made to
include a genetic contribution from all individuals
in the population.
B. Avoid Inbreeding
The closer the relationship between the parents, the
less variability in the genetic make-up of the
offspring. One method to reduce the degree of
inbreeding is to use matings between males and
females of different year classes. This methodology
will reduce loss of variability as well as prevent
the reproductive isolation of year classes.
C. Number of Matings
The recommended number of paired matings to maintain
a broodstock is 250 (Leary, personal commumication).
The minimum number of paired matings to maintain an
acceptable level of variability is 100 (3). These
numbers refer to the number of fish pairs required
to contribute gametes to the next generation. In
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