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Rapid evolution of egg size in captive salmon
Daniel D Heath1, John W Heath, Colleen A Bryden
1Great Lakes Institute for Environmental Research and Department of Biological Sciences, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada. dheath@uwindsor.ca
Science (New York, N.Y.)
|March 15, 2003
Summary
Captive breeding programs can unintentionally select for smaller egg sizes in chinook salmon, potentially reducing the success of conservation efforts. This rapid evolution in hatchery-raised fish may not be adaptive in the wild.
Area of Science:
- Evolutionary biology
- Conservation genetics
- Aquaculture science
Background:
- Captive breeding and release programs aim to boost declining populations by reducing juvenile mortality.
- Benign captive environments may inadvertently select for traits maladaptive in natural settings.
Purpose of the Study:
- To investigate how hatchery rearing influences egg size evolution in chinook salmon.
- To assess the impact of relaxed natural selection and fecundity selection on life-history traits.
Main Methods:
- Comparative analysis of egg size in chinook salmon from hatchery and natural populations.
- Examining trends in egg size related to the intensity of hatchery supplementation.
Main Results:
- Hatchery rearing in chinook salmon relaxes selection for large eggs, leading to rapid evolution of smaller egg sizes.
- Populations with high hatchery supplementation show trends toward smaller eggs, unlike minimally supplemented populations.
Conclusions:
- Unintentional selection in captivity can drive rapid, potentially detrimental, changes in critical life-history traits.
- These evolutionary shifts may compromise the effectiveness of conservation and reintroduction programs.
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