Southeast Bering Sea Carrying Capacity

Ric Brodeur and Ned Cokelet

Southeast Bering Sea Carrying Capacity (SEBSCC) is one of the newer projects sponsored by NOAA's Coastal Ocean Program. Begun in fall of 1996, SEBSCC is a five-year, interdisciplinary, regional ecosystem study. The southeast Bering Sea is a major ecosystem and economic resource, supporting an abundance of marine life and some of the most productive fishing grounds in the world. This ecosystem responds to changing conditions in ways that we observe as fluctuations in abundance of commercial fish and shellfish, seabirds and marine mammals. To manage the economic resource we need to understand what processes perturb the ecosystem and how it responds.

In its present condition, the southeast Bering Sea ecosystem has a dominant species: the pelagic, commercially-fished walleye pollock. Because of its prevalence, pollock is a nodal species, constituting an integral part of the region's food chain as both prey and predator. SEBSCC researchers are studying the ecosystem in that context. Research topics concern the role of the physical environment, the sources and fates of nutrients, and the food chain from phytoplankton through zooplankton to pollock and other fish, seabirds, and marine mammals. Techniques include retrospective analyses, ecosystem monitoring, process studies, and modeling, with an emphasis on developing annual indices of pollock juvenile abundance. Further details are available in the SEBSCC Home Page (

In February 1997, SEBSCC began an eight-month field season investigating the southeastern Bering Sea ecosystem. Using ships from the NOAA and UNOLS fleet and cooperative cruises with foreign research vessels, investigators deployed ocean measuring equipment on instrumented buoys and collected physical data and many types of biological and acoustical data. A dominant factor in spring-time Bering Sea production is the extent of the seasonal ice pack. In cold years like 1995, ice covers much of the operating area on the continental shelf until the middle of April. This winter began with extensive ice development, but southerly winds slowed the advance, and spring 1997 appeared to have been a normal ice season. The summer conditions were extremely mild leading to a shallow mixed layer, warm ocean conditions, and low productivity.

SEBSCC engages agencies, groups, and investigators with broad ecological interest in the southeast Bering Sea. The project is managed by a unique NOAA-academic partnership, with research performed by two NOAA laboratories and five universities. Results from SEBSCC research relating to short-term forecast of pollock recruitment will be incorporated into stock assessments used by NOAA's Alaska Fisheries Science Center to recommend allowable biological catch to the Pacific Fisheries Management Council. Other research results pertaining to the availability of juvenile pollock to upper-food-chain predators will assist Council decisions regarding restriction of fishing around marine mammal rookery areas. The Council incorporates ecosystem factors into its management decisions, and information provided by SEBSCC will expedite this effort by improving knowledge of the role of pollock in the southeast Bering Sea. The project's focus on the response of the ecosystem, and in particular juvenile pollock, to changes in environmental conditions will provide a context for resource management in a changing environment.