Rr. Claytor, IN-SEASON MANAGEMENT OF ATLANTIC SALMON (SALMO-SALAR) - AN EXAMPLE USING SOUTHERN GULF OF ST-LAWRENCE RIVERS, Canadian journal of fisheries and aquatic sciences, 53(6), 1996, pp. 1345-1359
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.