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Resource Ecology & Ecosystem Modeling Program

Aleutian Islands Ecosystem Assessment Workshop

The Aleutian Islands Ecosystem Assessment Team met in September 2011 to begin developing a structuring theme and key indicators for the Aleutian Islands ecosystem to be included in a new ecosystem assessment. The team includes AFSC scientists Stephani Zador, Kerim Aydin, Steve Barbeaux, Libby Logerwell, Ivonne Ortiz, Sandra Lowe, Lowell Fritz, Paul Wade, and Chris Rooper; Nick Bond from the University of Washington's Joint Institute for the Study of Atmosphere and Ocean; Jim Estes from University of California, Santa Cruz; Diana Evans from the North Pacific Fishery Management Council (NPFMC); Dave Fraser from Port Townsend, Washington; Stephen Jewett from University of Alaska Fairbanks; Carol Ladd from NOAA's Pacific Marine Environmental Laboratory; John Olson NMFS Alaska Regional Office; John Piatt from U.S. Geological Survey; Jon Warrenchuk from Oceana; Francis Weise from the North Pacific Research Board; and Jeff Williams from U.S. Fish and Wildlife Service.

Following presentations and review of existing physical and biological data, the team concluded that the significant variability in the island chain ecosystem warranted structuring the Aleutian Islands ecosystem assessment by three ecoregions: western, central, and eastern. The ecoregions were chosen based upon evidence of significant ecosystem distinction from the neighboring ecoregions. The team also concluded that developing an assessment of the ecosystem at this regional level would emphasize the variability inherent in this large area, which stretches 1,900 km from the Alaska Peninsula in the east to the Commander Islands in the west.

The three Aleutian Islands ecoregions used in this assessment are defined from west to east as follows. The Western Aleutian Islands ecoregion spans 170° to 177°E. These are the same boundaries as the North Pacific Fishery Council fishery management unit 543. The Central Aleutian Islands ecoregion spans 177°E to 170°W. This area encompasses the North Pacific Fishery Council fishery management units 542 and 541. There was consensus among the group that the eastern boundary of this ecoregion occurs at Samalga Pass, which is at 169.5°W, but for easier translation to fishery management area, it was agreed that 170°W was a close approximation. The Eastern Aleutian Islands ecoregion spans 170°W to False Pass at 164°W.

The team was tasked with choosing a suite of indicators that together provide a comprehensive view of the Aleutian Island ecosystem reflecting across trophic levels from the physical environment to top predators and humans, as well as both the nearshore and offshore. In addition to providing the "vital signs" for the Aleutian Islands, the preliminarily chosen indicators needed to be updatable on a regular basis, preferably annually; however, the team recognized that many of the surveys that collect data for some indicators do not occur every year. Numerous gaps in available time series were noted and discussed. Although a single suite of indicators was chosen for the entire ecosystem, not all indicators are available or applicable in each of the three ecoregions.

The following indicators were selected for the Aleutian Island ecosystem assessment: 1) the Winter North Pacific Index; 2) reproductive anomalies of least auklet and crested auklets; 3) proportions of hexagrammids, gadids, and Ammodytes in tufted puffin chick diets; 4) apex predator and pelagic forager fish biomass indices; 5) sea otter counts; 6) Steller sea lion non pup counts; 7) the percent of shelf <500 m trawled; and 8) school enrollment.

The Ecosystem Assessment will be presented to the NPFMC's joint plan teams for the groundfish fisheries of the Gulf of Alaska and Bering Sea Aleutian Islands in November 2011 and to the NPFMC in December 2011 as part of the annual catch specification process. The final report will be available on the AFSC website at access.afsc.noaa.gov/reem/ecoweb

By Stephani Zador
 

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