Seasonal Food Habits of Highlands Ground Haddock

Abstract

Stomach contents of 941 juvenile and adult haddock collected at monthly intervals at the Highlands Ground off Cape Cod, Massachusetts, from February 1958 to January 1959 were analyzed. Approximately equal numbers of both sexes were represented. Weight of stomach contents from individual fish ranged from 0 to 48.2 grams; average weight was 2.2 grams. There were no indications of important differences between males and females in species of animals preyed upon or quantities of food ingested. Mean stomach content weight increased as haddock size increased from 25 to 70 centimeters in length, but specimens longer than 70 centimeters contained unexpectedly small quantities of food. There was a marked seasonal variation in the quantity of food in the stomachs. A low feeding rate prevailed during late summer, fall, winter, and early spring, followed by heavy feeding in June. Water temperature appeared to be relatively unimportant in affecting the feeding rate. A wide variety of small benthic organisms were represented in the diet. The more important species are listed. The principal food groups, in order of decreasing importance were: Crustacea, Annelida, Pisces, Echinodermata, and Mollusca. Some differences in diet were associated with haddock size. Small organisms (amphipods, cumaceans, brittlestars) were more common in small haddock. Relatively large foods (decapod crustaceans, fish) were prevalent in large haddock only. Distinct seasonal changes in diet composition were detected. Crustacea and Pisces varied substantially and quite sharply, as opposed to Echinodermata which exhibited smaller, more gradual changes. The proportion of Annelida in the diet was quite uniform throughout the year.