IN-SEASON MANAGEMENT OF ATLANTIC SALMON (SALMO-SALAR) - AN EXAMPLE USING SOUTHERN GULF OF ST-LAWRENCE RIVERS

Adjusting harvest allocations on the basis of in-season forecasts woul d have improved management of summer returning Atlantic salmon (Salmo salar) compared with preseason methods at 12 stock assessment sites in southern Gulf of St. Lawrence rivers. Allocation changes based on imp roved in-season forecasts did not always improve management performanc e as the season progressed. The relative effectiveness of making a sin gle in-season allocation change or updating allocations once a week de pended on the penalty associated with overharvesting. Weekly updated a llocations were always better when penalties for overharvesting and un derharvesting were equal. When the penalty for overharvesting was grea ter than for underharvesting, the management performance of single ver sus weekly updated allocations was site dependent. Sites with shorter migrations were better managed by single allocations than those with l onger migrations, but the timing of these allocation changes was criti cal for effective results. Sites with mean returns three times higher than spawning escapement targets were not improved by in-season manage ment. Increased harvest variation was also an important effect of in-s eason management. Defining the relative penalty to place on overharves ting is the most important factor in determining how in-season managem ent is implemented.