Relations of Fecundity, Maturation, and Body Size of Lake Trout, and Implications for Management in Northwestern Ontario Lakes

Abstract

The life history traits of lake trout Salvelinus namaycush in six lakes that vary in conductivity are described, and an adaptive management strategy that is based on differences in lake trout growth, fecundity, and maturity schedule is recommended. Lake trout in low-conductivity lakes exhibited slower somatic growth, matured at an older age, attained maturity at similar or smaller body sizes, and were less fecund than lake trout in high-conductivity lakes. To prevent overfishing of fecund components of lake trout populations, managers may need to restrict the harvest of females larger than 550 mm in fork length from low-conductivity lakes, whereas in high-conductivity lakes, regulations should limit removal of females that are 600 mm or larger in fork length. Extreme interpopulation differences in adult size structures support a change in management strategy, a change from a single regionwide regulation to lake-by-lake regulations that reflect lake conductivity and prey type base.