Consumption of important pelagic fish and squid by predatory fish in the northeastern USA shelf ecosystem with some fishery comparisons

The fish biomass on the continental shelf off the eastern USA and Southeast ern Canada has shifted towards a higher proportion of pelagic fishes in the 1990s. This study provides estimates of consumption by 12 piscivorous fish es on Atlantic mackerel (Scomber scombrus), Atlantic herring (Clupea hareng us), butterfish (Peprilus triacanthus), sand lance (Ammodytes sp.), short-f inned squid (Illex illecebrosus), and long-finned squid (Loligo pealei duri ng 1977-1997. Results suggest that total consumption tall prey) by the 12 p redatory fish species is probably large relative to standing stocks of the above prey. Total consumption by these piscivores (all prey) ranged from 1. 5-3.0 million tonnes during this period. The flow of fish biomass from thes e prey pelagic species to these 12 predators is an important and large frac tion of the overall energy budget of the Northeast USA shelf ecosystem. The abundance of prey fishes and squids was reflected in the diets of individu al predators; for example several prey species, such as sand lance and Atla ntic herring, were very prominent at specific times during the period 1977- 1997. Consumption of pelagic fish and squid by predatory fish appears to eq ual or exceed landings in most years from 1977-1997. In several cases, nota bly for long-finned squid, Atlantic herring and butterfish, consumption by piscivores may approach or exceed the current estimates of maximum sustaina ble yield, suggesting that changes in predator abundance may have important implications for long-term fishery yields of pelagic species. (C) 2000 Int ernational Council for the Exploration of the Sea.