Resource Ecology & Ecosystem Modeling (REEM) Program
Ecosystem Indicators
The Ecosystem Considerations report of the Stock Assessment and Fishery Evaluation (SAFE) Report was updated and finalized during fall 2007 and presented to the North Pacific Fishery Management Council (NPFMC). In September 2007, 22 contributions were updated and 6 new contributions were added to the report. In November and December 2007, 28 contributions were updated and 3 new contributions were added to the final report. New contributions include information on marine mammals, the Aleutian Islands, fishing effort, and human demographics. All of this updated and new information can be accessed on the Ecosystem Considerations web site at http://access.afsc.noaa.gov/reem/ecoweb/index.php.
Major trends in the climate included a relatively cold winter and spring in the Bering Sea, resulting in a large cold pool, with pronounced warming in late spring. The amount of ice and the extent of the cold pool can affect production and distribution of marine organisms. Westerly wind conditions in the Aleutian Islands region suppressed poleward flow of warm Pacific water through the Aleutian passes, thereby contributing to the anomalously cold conditions in the southern Bering Sea from winter into early spring. These winds reversed in the spring, enhancing northward flow, likely contributing to the warming of the southern Bering Sea from spring into summer. During spring, anomalously low sea level pressure was present in the central Gulf of Alaska, which promotes anomalous downwelling in the coastal zone, and a relatively strong Alaska Coastal Current. Gulf of Alaska (GOA) summer survey temperatures indicate cooling of surface waters and warming of deeper waters, supporting the idea that there was anomalous mixing on the GOA shelf.
A major conclusion from the analysis of other indices and information regarding fishing effects on ecosystems and ecosystem trends is that no apparent adverse effects of fishing on the ecosystems have been documented to date. Concerns about high bycatch of Pacific salmon in the Bering Sea pollock fishery, however, remain, and these are being addressed by the Council.
By Jennifer Boldt
Multispecies and Ecosystem Modeling
Food habits data and ecosystem modeling results from the Resource Ecology & Ecosystem Modeling (REEM) Program contributed directly to 18 stock assessments included in the 2007 SAFE documents for the NPFMC. Assessments for Bering Sea-Aleutian Islands (BSAI) arrowtooth flounder, eastern Bering Sea (EBS) flathead sole, EBS walleye pollock, AI walleye pollock, BSAI cod, and AI Atka mackerel incorporated results from the EBS and AI ecosystem models. Ecosystem model results were also included in the BSAI squid and "other species" assessments for squids, skates, sculpins, and octopus. Linkages between BSAI arrowtooth and EBS pollock were reviewed again this year, and recent data indicate that arrowtooth are an increasingly important predator of pollock in the EBS (although not at the scale observed in the GOA).
Seven stock assessments incorporated information from the GOA ecosystem model: GOA walleye pollock, thornyhead rockfish, and skates have since 2005, and this year the GOA rex sole, flathead sole, Dover sole, and arrowtooth flounder assessments incorporated model results. All seven GOA assessments reported diet composition and total consumption of prey species, and the GOA arrowtooth assessment included annual estimates of prey consumption for GOA survey years between 1984 and 2005. In addition, the Alaska sablefish assessment incorporated recent diet data from the Gulf of Alaska and may incorporate further diet information and possibly ecosystem model results in future assessments.
By Sarah Gaichas
APEC Workshop on Proposal for Establishment of Deep-Sea Resources and Fisheries Network
Dr. Sarah Gaichas of the REEM Program was invited to travel to Lima, Peru, 2-5 October 2007 to participate in the Asia-Pacific Economic Cooperation (APEC) International Workshop on the Proposal for the Establishment of a Network for Deep-Sea Resources and Fisheries. The workshop's goal was to link knowledge and experiences in deep-sea resources and fisheries by applying a comparative approach to studying deep-sea ecosystems and fisheries. Dr. Gaichas presented an overview of Alaskan fisheries, including current research on grenadiers, thornyheads, sablefish, elasmobranchs, Greenland turbot, and corals, as well as ecosystem structure and function.
The knowledge and experience of the participants from other Pacific Rim nations shared at the workshop may provide information for fisheries management actions before the NPFMC (e.g., fishery management plan considerations for grenadiers; developing interest in deep-sea fisheries resources). Since many Alaskan fisheries currently export to Asian and other international markets, the AFSC's involvement in an APEC network discussing developing deep-sea fisheries may also provide advance notice of economic changes which may affect fishery development in Alaska.
