Reproductive Success of Artificially Hybridized Golden Trout (Salmo aguabonita) and Rainbow Trout (Salmo gairdneri)

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Abstract
Golden trout (Salmo aguabonita) were artificially crossed to hatchery rainbow trout (S. gairdneri). Interspecific matings were as fertile as intraspecific matings, and hatchability and survival to 35 d were not significantly different among the mating types. Embryos derived from golden trout eggs hatched sooner than those derived from rainbow eggs, and G♂ × R♀ hybrids were significantly larger than golden trout or rainbow trout at 165 d. Hybrid males were significantly more fertile than golden trout or rainbow trout males, and hatchability of the eggs from hybrid females was significantly higher than that of eggs from golden trout females. However, this apparent hybrid superiority may not be genetic. The results suggest that postzygotic reproductive isolating mechanisms between the two species are very weak or nonexistent, at least through the F1 generation.