Abstract
A 16‐year time series of research trawl catches, commercial landings, and effort data were used to evaluate two areas protected from mobile gear fishing off Cape Cod, Massachusetts, and assess effects of the spring otter trawl fishery for longfin squid Loligo pealeii on local abundance of finfish frequently caught as bycatch. Catch rates were compared between a seasonal closure, a permanent closure, and adjacent waters open to mobile gear fishing. Winter flounder Pleuronecles americanus and scup Stenotomus chrysops were more abundant in the two protected areas. Black sea bass Centropristis striata and windowpane Scophthalmus aquosus were more abundant in the seasonal closure but not in the permanent closure. Abundance indices of summer flounder Paralichthys dentatus and longfin squid were not significantly different between the seasonal closure and the exploited area but both species were less abundant in the permanent closure. Little skate Raja erinacea were more abundant in areas open to trawling. Significantly lower catch rates of the latter four species in the permanent closure indicated that habitat differences were important in determining local abundance. Decreased local density of finfish in open areas was not related to inshore spring squid trawling effort or landings. Regional trawl effort on Georges Bank and in southern New England did have significantly negative effects on local finfish density. Inferences of causal relationships between the inshore squid fishery and decreased local abundance of finfish were not supported. These results suggest that inshore abundance of these species is more related to total regional trawl effort.