Survival traits of naturalized, hatchery, and hybrid strains of anadromous rainbow trout during egg and fry stages

摘要

Two strains of anadromous rainbow trout Oncorhynchus mykiss, naturalized steelhead and "kamloops" (not the pure Kamloops strain from British Columbia, hence not capitalized) currently inhabit the Minnesota waters of Lake Superior and may have the potential to hybridize. Ova viability and fry behaviour experiments were undertaken to evaluate the potential for hybridization and to provide information for future management of the 2 strains. The kamloops ova were slightly smaller but sizes overlapped substantially with steelhead ova sizes. Mortality of kamloops ova from spawning to hatching was greater than for steelhead ova. Steelhead fry exhibited a greater fright response (wariness) than kamloops fry when startled by movement over their tanks. Hybrid ovum survival and wariness traits were intermediate to those of the pure strains but more closely resembled those of the maternal strain. The traits appeared to be heritable.