Introduction to processes controlling variability in productivity and ecosystem structure of the Aleutian Archipelago

FISHERIES OCEANOGRAPHY Fish. Oceanogr. 14 (Suppl. 1), 1–2, 2005 Introduction to processes controlling variability in productivity and ecosystem structure of the Aleutian Archipelago PHYLLIS J. STABENO, 1, * GEORGE L. HUNT, JR 2, AND S. ALLEN MACKLIN 1 National Oceanic and Atmospheric Administration, Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115-6349, USA Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA Key words: Aleutian Islands, ecosystem dynamics, ecosystem structure, marine ecosystems, marine resource management, Steller sea lion PURPOSE This special issue provides the first comprehensive, interdisciplinary examination of the marine ecosystem of the eastern and central Aleutian Archipelago – an area that is susceptible to climate shifts, anthropogenic influences and ecosystem change. Relatively little focused research had been conducted in this region before the studies presented here. The earlier founda- tion of knowledge was largely from efforts of the National Marine Fisheries Service and the Outer Continental Shelf Environmental Assessment Program. Present investigations of the ecosystem of the Aleutian Islands were instigated by a marked decline in the western stock of Steller sea lions (Eumetopias jubatus) from more than 250 000 in the 1970s to less than 50 000 in the early 1990s. This decline resulted in the western stock of Steller sea lions being declared threatened in April 1990. The cause of their decline was not known, but the most likely mechanisms included: climate shifts, direct or indirect effects of fisheries, diseases, and top-down control through pre- dation by killer whales. As part of the effort to evaluate these competing hypotheses and to under- stand why sea lion numbers continued to decline, *Correspondence. e-mail: phyllis.stabeno@noaa.gov Present address: School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195-5020, USA. Received 22 July 2005 Revised version accepted 27 July 2005 O 2005 Blackwell Publishing Ltd. Congress enacted legislation in 2001. That legislation funded investigations of the possible causes of the decline in abundance of the western stock of Steller sea lions that live from Kodiak Island in the Gulf of Alaska westward to and including the Aleutian Islands. The focus of this supplementary volume is the eastern and central Aleutian Archipelago (162– 177°W), which is a critical habitat for the western stock of the Steller sea lion population and also where their decline has been the greatest. Many papers in this volume present results from just two cruises on the R/V Alpha Helix, one in 2001 and the second in 2002. These cruises were funded by the Steller Sea Lion Program, directly and through NOAA’s Coastal Ocean Program. While the original focus of the vol- ume was on Steller sea lions and the findings of these cruises, the volume soon extended beyond just sea lions and resulted in the first integrated ecosystem study of the waters surrounding the Aleutian Islands. Drs J. Schumacher and G. Kruse consented to contribute their time and expertise as guest editors. While both of them are knowledgeable of regional issues, they were not part of any Aleutian research team. Thus, they could be objective in judging the quality and content of manuscripts submitted for publication in this supplement. Rather than delivering the more typical editorial discussing the impact of this supplement on marine science, they elected to con- tribute a unique editorial on the importance of sus- taining the ecosystem services of the Aleutian Archipelago. In their article, they call for develop- ment of an integrated ecosystem management plan that would involve the major agencies and stake- holders that are active in the region. This valuable addition thus recognizes and amplifies the important and timely theme of adopting an ecosystem approach to resource management. IMPORTANCE AND IMPACT While there have been a number of isolated, historical studies of the marine ecosystem of the eastern and