Research Document - 2013/056
Feeding habits and trophic niche differentiation in three species of wolffish (Anarhichas sp.) inhabiting Newfoundland and Labrador waters
By M.R. Simpson, G.D. Sherwood, L.G.S. Mello, C.M. Miri, and D.W. Kulka
Abstract
The food and feeding habits of Northern Wolffish (Anarhichas denticulatus), Spotted Wolffish (A. minor), and Atlantic Wolffish (A. lupus) in Newfoundland and Labrador continental shelf waters were examined. A total of 1,451 stomachs were analysed for contents: 152 for Northern Wolffish; 262 for Spotted Wolffish; and 1,037 for Atlantic Wolffish. No particular prey item dominated the diet of any species. The two most important prey groups were pelagic fish and benthic fish (52 % of total fullness) for Northern Wolffish, shrimp and echinoderms (68 %) for Spotted Wolffish, and crabs and echinoderms (57 %) for Atlantic Wolffish. Diet overlap was highest between Spotted and Atlantic Wolffish (Schoener’s Index; a = 0.52), and lowest among Northern and Atlantic Wolffish (a = 0.21). Ontogenetic shifts in dietary proportions of nine major prey groups were described for each species. Discriminant function analysis correctly classified species based on mean feeding habits (partial fullness index), with a 93-100 % success rate. Species differed significantly with respect to the relative proportions of nine major prey groups (mean PFI) in the diet (MANOVA; p < 0.0001), and percent contribution of benthic and piscivorous diet (MANOVA; p < 0.01). Based on all analyses, Northern Wolffish were described as “fish specialists” (piscivores), Spotted Wolffish as “echinoderm specialists” (benthivores), and Atlantic Wolffish as “mollusc specialists” (benthivores).
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