9585

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

F. Number of Spawning Takes.
Time of spawning has been shown to be highly
heritable. Fish that spawn at or near the same time
stand a good chance of being related. To avoid
possible inbreeding and loss of heterozygosity,
future brood should be represented by eggs obtained
from at least 60~ of the individual spawning takes.
Egg takes that include the beginning, middle, and
end of the spawning season should all be
represented. As stated above, actual number of eggs
retained from each take.. should be relative to the
number of fish spawned on that occasion.
G. Crossbreeding (outcrosses)
As stated previously, a 10$ infusion of genetic
material from the founding population every 10 years
will help to minimize domestication. Outcrosses
with related "strains" may also be considered as a
method to preserve or increase variability.
However, before such measures are- initiated,
documentation of need should be supported by
electrophoretic data, as well as consultation with
trained geneticists.
H. Selection
The best methodology to minimize selection is to
not select at all during spawning operations. With
the possible exception of fish that suffer obvious
deformities, all fish .should be spawned. Fish
should never be selected based on size, coloration,
body condition, etc.
I. Mating Regimen
Individuals to be mated should always be selected at
random. To avoid selection for early maturity, mate
individuals only at the time when 90~ of the
population becomes sexually mature. If there is any
doubt about the quality of a particular male, use
another male to fertilize the eggs of a given
female. Only fish with obvious deformities should
be excluded from contributing to future generations.
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