Seasonal habitat use and community structure of rockfishes in the Gulf of Alaska

Abstract

Research is needed to determine the seasonal importance of high-relief habitats, particularly those containing biotic structures to rockfishes within the Gulf of Alaska. We examined the density and community structure of commercially important rockfishes in low-relief, high-relief, and biotic habitats in the spring, summer, and winter seasons at three sites in the central Gulf of Alaska using stereo drop cameras and bottom trawls. The fish community structure within all three sites was dominated by dusky rockfish (Sebastes variabilis), northern rockfish (S. polyspinis), Pacific ocean perch (S. alutus), and harlequin rockfish (S. variegatus). There was no effect of season on community structure and density of rockfish in the study area. While there were local differences in fish density and community structure, rockfish densities throughout the study areas were higher in complex than bare habitats. Significant differences in densities between high-relief and biotic habitats were not found and the additional value of structure- forming invertebrates was not proven. Juvenile rockfish were also associated with high-relief habitat, particularly complex boulder habitat. This study advances our knowledge of seasonal habitat preferences of commercially important rockfish species with the Gulf of Alaska and emphasizes the need to consider these preferences in surveying and managing these species.