Genotypic and Phenotypic Divergence of Sockeye Salmon in New Zealand from Their Ancestral British Columbia Populations

Abstract
Embryos of sockeye salmon Oncorhynchus nerka were transplanted from Shuswap Lake, British Columbia (BC), to tributaries of Lake Ohau in the South Island of New Zealand (NZ) in 1901. This single shipment gave rise to a self-sustaining freshwater resident population that spawns primarily in Larch Stream north of Lake Ohau. We compared the genotypic (using protein electrophoresis) and phenotypic traits of the NZ O. nerka with anadromous (sockeye salmon) and nonanadromous (kokanee) populations of the species in the Shuswap Lake system. Genetic analysis confirmed that the transplanted fish had been sockeye salmon, not kokanee, and allele frequencies in the current NZ population were not significantly different from those in anadromous sockeye salmon from Scotch Creek, BC. The NZ O. nerka developed two life history patterns: some spent their entire rearing period in Lake Ohau, whereas others migrated downstream from Lake Ohau after 1 year to mature in Lake Benmore. These latter “migrants” grew faster a...