The Feeding Ecology of Flatfish in the Northwest Atlantic

Source - Journal of Northwest Atlantic Fishery Science, Volume 30: 1-17
ISSN-0250-6408

Abstract

Flatfish are an economically and ecologically important component of continental shelf ecosystems worldwide. These species are impacted from fishing activities, both as direct targets and through indirect effects on habitat and food supply. We examined 25 years of diet data for juveniles and adults of nine species of flatfish in the Northwest Atlantic on the continental shelf off of the USA and parts of Canada in order to understand how flatfish feeding ecology may have changed after decades of fishing and related impacts on the ocean bottom. Atlantic halibut (Hippoglossus hippoglossus), summer flounder (Paralichthys dentatus) and fourspot flounder (P. oblongus) were generally piscivorous. American plaice (Hippoglossoides platessoides) ate primarily ophiuroids. Yellowtail flounder (Limanda ferruginea), winter flounder (Pseudopleuronectes americanus), windowpane (Scophthalmus aquosus), witch flounder (Glyptocephalus cynoglossus) and gulfstream flounder (Citharichthys arctifrons) ate primarily polychaetes, gammarids and other benthic invertebrates. American plaice, summer flounder and fourspot flounder exhibited significant ontogenetic shifts in diet, consuming fewer polychaetes with increasing size. Summer and fourspot flounder also exhibited significant shifts in diet across the time series. None of the benthivorous flatfish exhibited significant changes in diet composition across the time series. The mean weight of stomach contents declined in all species over the past 20 years. The role of flatfish trophic dynamics is discussed in the context of major changes that have occurred in this continental shelf ecosystem.

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