Stomach contents of immature lobsters (Homarus americanus) from Placentia Bay, Newfoundland

Abstract

Stomachs of immature lobsters (Homarus americanus) from Placentia Bay, Newfoundland, were examined to determine natural diet. The most frequently occurring prey were sea urchins, mussels, rock crabs, polynoid and nereid polychaetes, and brittlestars. There was high incidence of lobster exuviae during the moulting period in late summer. Rock crabs, brittlestars, and mussels were dominant (in terms of relative volumes of hard parts in each stomach) more often than other food items. Sea urchins, periwinkles, chitons, rock crabs, and polynoids were consumed more frequently in late summer compared with other seasons. Stomach contents constituted approximately 1% of the wet weight of individual lobsters. There were no significant seasonal differences in stomach fullness during the period June to November.The residencies of natural prey hard parts in immature lobster stomachs were estimated. Some items remained in stomachs for up to 180 days. Measures of stomach fullness of lobsters 3 days after ad libitum feeding on rock crabs, mussels, and sea urchins were similar. Linear selection indices indicated relatively high selection by immature lobsters for hard parts of rock crabs and mussels and positive selection for nereids, polynoids, and brittlestars. Immature lobsters showed negative selection for hard parts of sea urchins, starfish, and periwinkles.