The Effect of Impoundment on the Population and Movement of Atlantic Salmon in Ellerslie Brook, Prince Edward Island

During autumn spates Atlantic salmon (Salmo salar) commonly enter the small spring-fed streams of Prince Edward Island and spawn. Annual variations in freshwater discharge from Ellerslie Brook were found to determine the number of salmon and time of ascent. A pond formed on the brook created a habitat that exercised a strong retaining influence on the movements of spawners, kelts, parr, and migrating smolts. Smolts which stayed in the pond suffered heavy mortalities.Movements by sexually mature male parr, within and between fresh and salt water, occurred in the fall. Some parr remained in the estuary (0–27‰ salinity) throughout the year. The pond provided a habitat for parr.Smolt transformation at ages II and III occurred in the stream, pond, and estuary in the spring. Pond and stream smolts of the same age group were similar in size when they migrated.