Describing Summer Pelagic Habitat Over the Continental Shelf in the Eastern Bering Sea, 1982-2006

The continental shelf of the eastern Bering Sea (EBS) is highly productive, supporting some of the most valuable finand shellfish fisheries in the United States as well as large, local and migratory, populations of seabirds and marine mammals. Temperature and hydrographic structure are important components to the pelagic and epibenthic habitat that influence the distribution, behavior and inter-specific interactions of larger commercially and ecologically important species in the EBS. Since 1982, the Alaska Fisheries Science Center has collected depth-temperature data during their annual standardized bottom trawl survey (BTS) of the EBS. We describe the origination and post-survey processing of the data, and the procedures used to calculate statistics describing nominal temperature, mixed and transition layers, and stratification characteristics. We discuss the potential use of this data to identify larger scale domains and fronts and to calculate indices describing overall conditions encountered by the BTS. Changes in BTS timing and duration over the years are important to consider when interpreting any patterns. The statistics and indices resulting from the depth-temperature data provide a means to examine relationships between pelagic habitat characteristics and biological characteristics such as species composition, abundance and feeding habits.