MEPS 464:221-235 (2012)  -  DOI: https://doi.org/10.3354/meps09878

ABSTRACT: Interspecific and intraspecific variation in the distributions and diets of congeneric sculpins, Myoxocephalus jaok, M. polyacanthocephalus, and M. scorpius, were described from data collected during summer trawl surveys of the eastern Bering Sea (EBS) continental shelf between 2000 and 2010 by the Alaska Fisheries Science Center (AFSC). Generalized additive models (GAMs) of abundance (count) and presence-absence data were applied separately for each species to examine the influence of selected factors (depth, bottom temperature, substrate type and location) on distribution and abundance. The final models indicated strong predictive relationships, suggesting habitat partitioning between species. Ontogenetic distributions were observed as larger individuals of each species tended to be associated with deeper depths and lower latitudes. Analysis of stomach contents indicated that these species consume a wide variety of prey and that the diet composition also shifted ontogenetically. Multivariate analyses of the mean percent weight (%W) of 23 diet categories indicated that the diets differed among and within species. The diet of M. jaok consisted primarily of mysids, shrimps, and flatfish, with larger sculpins feeding on a greater amount of flatfish prey and less benthic infauna. Both M. polyacanthocephalus and M. scorpius fed considerably on commercially important Chionoecetes crabs, particularly C. opilio; however, similar-sized M. polyacanthocephalus consumed larger Chionoecetes prey than M. scorpius. Diets were more variable among smaller sculpins of these 2 species, and piscivory was more common among M. polyacanthocephalus. Habitat and diet partitioning were evident among species within this genus, as each species exhibited distinct spatial boundaries and diets, possibly avoiding inter- and intraspecific competition in this environment.

KEY WORDS: Resource partitioning · Distribution · Diet · Ontogeny · Myoxocephalus · Chionoecetes · Eastern Bering Sea