Maturity, fecundity, growth, and sustained yield of coastal cutthroat trout at Florence Lake, Southeast Alaska

Abstract

The resident coastal cutthroat trout Oncorhynchus clarki clarki population in Florence Lake, Southeast Alaska was sampled from July through October, 1997 to assess its maturity, fecundity, growth and sustained yield. Maturing female cutthroat have significant gonad development between mid September and late October. A gonadosomatic index threshold was established for female cutthroat trout. A logistic model for maturity estimated asymptotic percentages by age and length: 92% and 100% for males and 86% and 80% for females, indicating presence of skip spawning. Male cutthroat trout matured earlier and at smaller length than females, but females matured more rapidly. An allometric model fitted fecundity data well. Schnute's growth model indicated that growth was relatively slow. An ll-inch (279 mm) minimum size limit allows a high proportion of trout at Florence Lake to spawn at least once. Age-based and length-based per recruit analyses performed comparably and established sustainable fishing mortality estimates.