Resource Ecology & Fisheries Management (cont.)

AFSC Database Workshop

The AFSC hosted a workshop in February 2002 to familiarize offsite data users with databases stored at the AFSC.  The idea for the workshop evolved from several discussions between participants in Seattle and Anchorage involved in updating essential fish habitat (EFH) descriptions for the EFH Environmental Impact Statement (EIS).  As the AFSC becomes more involved with the various National Enviromental Protection Act (NEPA) and ESA documents, more outside users will seek permission to utilize our data. As a result of the workshop, it was recommended that an AFSC database users guide be created which would include information such as who to contact with specific database questions.   Another consideration at the workshop was to begin discussion among geographic information systems (GIS) users to obtain a consensus on which coverages to use on a regional or Alaska-wide GIS analysis.  With several coverages available for Alaskan waters, there is potential for one document to contain maps using different coverages to describe similar features (a caveat to this is each bathymetric coverage, for instance, gives a different resultant map).  Thus, analyses using these different coverages for the same document will have results that are different or not comparable.  Further discussion of this workshop will be presented in a poster at the GeoHab conference in Moss Landing, California, on 1-3 May 2002.

By Rebecca Reuter.
 

Categorizing Habitat

Preliminary results from a cluster analysis of research survey hauls where rockfish occurred  were  presented at the Western Groundfish Conference held 12-14 February 2002 at Ocean Shores, Washington.  The analysis showed that in the Aleutian Islands at least three habitat categories can be described using rockfish assemblages.  The species composition of those hauls that clustered together and the depth range of those hauls determined the three habitat categories: shelf (100-200 m); outer shelf (200-300 m); and upper-slope (300+ m).  Species associated with those categories were S. alutus, S. polyspinus and S. ciliatus (shelf); S. alutus (outer shelf) and S. aleutianus; S. borealis and Sebastolobus alascanus (upper slope).  To understand the spatial distribution of these assemblages, the haul clusters were mapped to indicate if any associations were due to geographic location.  The next steps in this research are to refine the category definitions by using different size classes by species and to contrast categories between the Gulf of Alaska and Aleutian Islands region.  Habitat use along environmental gradients, such as temperature and depth, will be investigated to further analyze habitat associations and species co-occurrence.  Results from this study may aid in describing essential rockfish habitat and identify areas potentially suitable for spatial management of rockfish fisheries.

By Rebecca Reuter and Paul Spencer.
 

NCEAS Working Group

Kerim Aydin and Sarah Gaichas participated in the ongoing working group “Models of alternative management strategies for marine ecosystems” at the National Center for Ecological Analysis and Synthesis (NCEAS).  The working group includes collaborators from the University of Washington, University of Wisconsin, Duke University, University of British Columbia, the Inter-American Tropical Tuna Commission, and the Pacific Marine Environmental Laboratory.  Other collaborators representing management, industry and environmental interests will participate in future meetings.

The goal of the working group is to attempt to identify robust approaches to the exploitation of large marine ecosystems.  The group intends to achieve this by employing the comparative approach to identify similarities and differences between five large marine ecosystems in the North Pacific Ocean.  The five systems include the eastern Bering Sea, the Gulf of Alaska, the Northern California Current, the Eastern Tropical Pacific, and the Central North Pacific, spanning continental shelf ecosystems and open ocean pelagic ecosystems from subarctic to tropical regions.  Each of these ecosystems has served as the focus of controversy over the ecological consequences of fishery management practices, protection for threatened or endangered species, and the relative importance of large-scale environmental variability, and each has been the focus of model development effort using the common framework of an Ecopath/Ecosim approach.  By defining a common set of objective criteria for evaluating conservation strategies, economic goals, and ecosystem management objectives, the group will employ these five models as the basis for evaluating policy outcomes, clarify the conflict of alternatives, and provide guidance to realistic expectation from management actions.

The group had its initial meeting 13-15 December 2001  and a second meeting 17-20 March 2002.  In the interim, a team of graduate students worked in residence at NCEAS on developing models and making initial model comparisons.  A third meeting is scheduled for December 2002, and the project will continue through 2004.

By Sarah Gaichas.

OSCURS Model

REFM’s Ocean Surface Current Simulator (OSCURS) is used to find indexes of year-to-year changes in ocean circulation that may affect fish stocks in the North Pacific Ocean.  In a recent experiment, changes in surface mixed layer drift currents between Japan and the Washington coast in the westerly (from the west) drift channel between lat. 40EN and 50EN were computed in a time series every 10 days from 1967 to 1998.  The average drift takes about 18 months, thus providing an integrated index of currents all along the track for that time period.  The effects of seasonal signals so prevalent on both sides of the Pacific are averaged out.

Looking at a plot of the end points versus time shows more extreme east-west changes in longitudes of the end points, speed of the long drift, than north-south changes in latitude of the end points.  Major features include greater speeds in the early 1970s, prior to the regime shift, slower speeds through the early 1980s, a return to normal in the late1980s after the 1983 El Niño, and a recent return to faster speeds in the late 1990s.  The recent increase in speed may have contributed to a greater supply of more productive Subarctic Water to the west coast coincident with enhanced salmon runs.

By Jim Ingraham.

AFSC Quarterly
Research Reports
Jan-March 2002