Disadvantages
When broodstocks are used to supplement natural populations they face different selective pressures to normal. Thus they may not have adequate fitness to survive the natural environment, or can alter and decrease natural genetic diversity due to the bottleneck nature of breeding from a smaller population.
Broodstocks require supplementation from outside sources regularly to prevent negative effects of closed populations. Domestication of broodstocks in hatcheries can reduce reproductive capabilities and alter other genetic characteristics. For example, a trout stock maintained as a closed population for 20 generations showed reduced number and size of egg production.
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