Coastal populations of brook trout, Salvelinus fontinalis, in Lac Guillaume-Delisle (Richmond Gulf) Québec

Abstract

Brook trout grow slowly in coastal streams and resident fish average only 15.6 cm during their fourth summer. Anadromous fish move into brackish water at approximately 20 cm fork length. In the gulf, the modal age is 4+ and age groups 3+ to 6+ account for 80–90% of the catch. Fish rapidly attain lengths of 35–40 cm, instantaneous growth in weight decreases from 1.27 for 2- to 3-year-old fish to 0.35 for 5- to 6-year-old fish. Dispersal from river mouths may be restricted to a distance of only 5–6 km. Late in July and throughout August, maturing fish of both sexes enter fresh water where ripening occurs. Movements at sea and duration of residence are controlled by salinity and temperature as influenced by maturation.