Parasites, diet and stable isotopes of shorthorn sculpin (Myoxocephalus scorpius) from Frobisher bay, Canada

Abstract

Shorthorn sculpin (Myoxocephalus scorpius) from Frobisher Bay, Baffin island, is a slow growing long-lived species. A wide range of diet items were present in the stomachs of the shorthorn sculpins sampled but 2-3 diet items (amphipod species) comprised 99.5% of total food consumed. These amphipods were present in the stomachs in similar proportions among all age classes of shorthorn sculpin. Several new host records for parasites were reported and mean numbers of parasite species increased with shorthorn sculpin age. The increased diversity of parasite species and higher delta15N values in older/larger individuals suggest that their diets were more diverse and the prey items consumed had higher delta15N values. By contrast, the value of delta13C in dominant diet items masked the delta13C values of minor diet items. We conclude that parasites and stable isotope values provide complementary data on feeding patterns of the shorthorn sculpin. The ubiquitous marine acanthocephalan, Echinorhynchus gadi, was found at high prevalences (87-100%) and mean intensities (28-35), and were localized in the midgut. In contrast to other studies on acanthocephalans, E. gadi did not influence fish condition as measured by condition factor, liver somatic and gonado-somatic indices.