I. Introduction

The Bering Sea ecosystem is among the most productive of high-latitude seas and as such produces large biomasses of fishes, birds and mammals. The Bering Sea is important to the U.S. economy. Fish and shellfish constitute almost 10% of the world and 40% of the U.S. fisheries harvest. Pollock, salmon, halibut, and crab generate over 2 billion dollars each year in fisheries revenue and provide a major source of protein. At present, some Bering Sea fisheries, such as pollock, appear not to be overexploited, although there have been major changes in abundance over the last thirty years. Populations of several species, such as king crab and greenland turbot, however, are at near historical lows. We do not know the fragility of the present ecosystem in which pollock plays a singularly important role, yet whose population historically has varied over a wide range.

The relative importance of natural cycles and exploitation in explaining variability in abundance is a key management issue for the Bering Sea. In addition to perturbations created by human activities, environmental factors are seldom stable and are subject to large scale fluctuations, at times of a regular nature. It is clear that the production of new organic matter, which provides the basis for exploitable fish populations and all other higher trophic level animals, is greatly affected by environmental factors. Questions remain, however, concerning the ecosystem dynamics of the vast Bering Sea shelf that supports this high productivity.

This concept paper presents a Coastal Ocean Program Regional Ecosystem Study in the southeastern Bering Sea (Figure 1). Our conceptual model proposes that juvenile pollock are a nodal species in the ecosystem in utilizing the high primary and secondary productivity and providing food for the pelagic upper trophic level species, including adult pollock. By nodal, we imply that a large fraction of the system energy flow passes through this species population. We plan to examine pollock in terms of their linkages to other species: to understand interspecific overlaps in feeding habits through various stages of life history, including energy flow into the pollock population and outward flow via predation by other species; to understand synchronized increases or decreases in biomass at different trophic levels that may indicate the co-influence of factors; to study changes in distribution and intensity of secondary productivity as one of the bases for change in year-class strength; and to examine pollock as a key to the large scale changes in productivity of the Bering Sea over the last three decades. As an abundant resource under stress, pollock provides an important measure of the health of the ecosystem.

Figure 1. Habitats of the eastern Bering Sea: 1a and 1b) SE and NW outer shelf, 2a and 2b) SE and NW middle shelf, 3) Pribilof Islands, 4) Unimak Island, 5) shelf break.

Goal Statement - The goal of SE Bering Sea Carrying Capacity (SEBSCC) is to document the role of juvenile pollock in the eastern Bering Sea ecosystem, to examine the factors which affect their survival, and to develop and test annual indices of pre-recruit (age-1) abundance.

Relation to Bering Sea FOCI - Bering Sea FOCI has been a part of the Coastal Ocean Program from 1991-1995, with a one-year extension through FY1996. At the start of the project, the spatial distribution of pollock stock structure between the basin, and western and eastern shelves was uncertain. This uncertainty led to concern about conducting recruitment studies without the ability to distinguish between spawning populations. There is now sufficient evidence that the southeastern Bering Sea shelf is central and critical to the productivity of pollock. This motivates a SE Bering Sea Carrying Capacity project. Our goal statement is in accord with the recommendations of the National Research Council review of BS FOCI, and also with those emerging from the PICES-GLOBEC workshop held in April 1995.

By using the Coastal Ocean Program to support core projects, we plan an inclusive approach to implementing SEBSCC through engaging other agencies, groups, and investigators with broad ecological interest in the southeast Bering Sea. We plan to use the World Wide Web to exchange project information, preliminary results and data. With the advice and experience of the Technical Advisory Committee, we will assemble a core research team selected based on proposals solicited from the University of Alaska, other universities and agencies, the Alaska Fisheries Science Center, and the Pacific Marine Environmental Laboratory. The following concept paper is organized in accordance with COP guidelines, with sections: I) Project Management, II) Conceptual Model and Scientific Approach, III) Application to Management, and IV) Budget.

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