Long-Term Changes in Brown Trout and Rainbow Trout Populations in Great Lake, Tasmania

Abstract

Abstract Great Lake, central Tasmania, was first stocked with brown trout Salmo trutta in 1870 and with rainbow trout Oncorhynchus mykiss (formerly Salmo gairdnert) in 1910; both species established self-supporting populations. Angling statistics revealed a general decline in mean weight of both species from 1892 (brown trout) and 1912 (rainbow trout) to 1950. During 1950–1985, the annual mean size of trout in anglers' catch and spawning migrations stabilized; overall mean weights of brown trout and rainbow trout were, respectively, 1.2 and 1.0 kg in anglers' catch, and 1.4 and 1.5 kg in spawning migrations. Four stages were evident in the fishery: initial dominance of brown trout prior to 1920, rainbow trout dominance in anglers' catch and spawning migrations during 1920–1940, declining numbers of rainbow trout and mean weight in catch from 1940 to 1950, and equal representation of both species in angler catches with a predominance of brown trout in spawning migrations from 1950 to 1985. Various correlat...