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

Abstract

The fish biomass on the continental shelf off the eastern USA and Southeastern Canada has shifted towards a higher proportion of pelagic fishes in the 1990s. This study provides estimates of consumption by 12 piscivorous fishes on Atlantic mackerel (Scomber scombrus), Atlantic herring (Clupea harengus), butterfish (Peprilus triacanthus), sand lance (Ammodytes sp.), short-finned squid (Illex illecebrosus), and long-finned squid (Loligo pealei) during 1977–1997. Results suggest that total consumption (all prey) by the 12 predatory 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 these prey pelagic species to these 12 predators is an important and large fraction of the overall energy budget of the Northeast USA shelf ecosystem. The abundance of prey fishes and squids was reflected in the diets of individual predators; for example several prey species, such as sand lance and Atlantic herring, were very prominent at specific times during the period 1977–1997. Consumption of pelagic fish and squid by predatory fish appears to equal or exceed landings in most years from 1977–1997. In several cases, notably for long-finned squid, Atlantic herring and butterfish, consumption by piscivores may approach or exceed the current estimates of maximum sustainable yield, suggesting that changes in predator abundance may have important implications for long-term fishery yields of pelagic species.