Growth, Maturity and Mortality in the Relatively Unexploited Lake Trout, Cristivomer namaycush, of Great Slave Lake

Abstract

Ages of 9,215 lake trout were determined. Length-weight and time-maturity relationships are shown. Sex ratio is 1:1. Only half the females of mature size spawn each year. There is no growth except during June to September, inclusive. There is a tremendous difference in size at a given age. Growth is much faster in one half of the lake than in the other, it is the same as or slightly slower than in lakes farther south and considerably faster than in Great Bear Lake. Seven years of commercial fishing did not increase total annual mortality by much. Mortality rate increases with age among all fish of catchable size. A given year-class probably attains maximum biomass well before most of its members reach commercial size. No significant variation in year-class strength was found.