Stomach contents of snow crab (Chionoecetes opilio, Decapoda, Brachyura) from the Northeast Newfoundland Shelf

Abstract

A sample of about 1000 snow crabs (Chionoecetes opilio) from NAFO (Northwest Atlantic Fisheries Organization) Division 3K (Northeast Newfoundland Shelf), taken by bottom trawl for studies of their stomach contents, indicated that about 12 benthic or demersal prey types occurred in their diet from that area. The most frequently occurring prey types were sabellid polychaetes, crustaceans (shrimp, crabs and smaller crustaceans) and infaunal clams (Macoma calcarea). Shrimps (especially pink shrimp, Pandalus borealis) and fishes (especially capelin, Mallotus villosus) were the most important prey types with respect to their percentage contribution to the total food mass. Brittle stars (Ophiuroidea) were regularly preyed upon by males but were virtually absent from the stomach contents of mature females. Males preyed more heavily upon fish and infaunal prey types (polychaetes and clams) whereas females preyed more heavily on shrimp and readily-accessible epibenthic prey types (gastropods, crabs and sea urchins). Males appeared to be more capable predators than were mature females. Predation on fish was related to predator size for both sexes but was most commonly practiced by males that were larger than the maximum size of mature females. However predation on fish was also more commonly practiced by males than by mature females at comparable sizes. There were no other effects of predator size in the predation by males whereas predation by mature females on clams, shrimp, gastropods, sea urchins, and possibly polychaetes increased with predator size. Cannibalism was most frequently practiced by intermediate-sized crabs and more frequently by females than males. Cannibalism was more common in our study than in others reported to date and may represent an important density-dependent source of mortality that could affect recruitment levels and patterns.