Differences in juvenile phenotypes and survival between hatchery stocks and a natural population provide evidence for modified selection due to captive breeding
K.E.
Kostow-2004
Can. J. Fish. Aquat. Sci., 61(4): 577-589
Abstract:
Juvenile phenotypes and fitness as indicated by
survival were compared for naturally produced steelhead (Oncorhynchus
mykiss), a new local hatchery stock, and an old nonlocal hatchery stock
on the Hood River, Oregon, U.S.A. Although the new hatchery stock and the
naturally produced fish came from the same parent gene pool, they differed
significantly at every phenotype measured except saltwater age. The
characteristics of the new hatchery stock were similar to those of the old
hatchery stock. Most of the phenotypic differences were probably
environmentally caused. Although such character changes would not be
inherited, they may influence the relative fitness of the hatchery and
natural fish when they are in the same environment, as selection responds to
phenotypic distributions. A difference in fitness between the new hatchery
stock and naturally produced fish was indicated by significant survival
differences. Acclimation of the new hatchery stock in a “seminatural”
pond before release was associated with a further decrease in relative
smolt-to-adult survival with little increase in phenotypic similarity
between the natural and hatchery fish. These results suggest that modified
selection begins immediately in the first generation of a new hatchery stock
and may provide a mechanism for genetic change.
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