Resource Ecology & Fisheries Management (REFM) Division

Status of Stocks & Multispecies Assessment Program

Essential Fish Habitat Environmental Impact Statement

The Final Environmental Impact Statement for Essential Fish Habitat Identification and Conservation in Alaska (EFH EIS) is nearing completion. Status of Stocks & Multispecies Assessment (SSMA) staff and analysts from the AFSC’s Auke Bay Laboratory and RACE Division completed substantial revisions and additions to Appendix B: Evaluation of Fishing Activities That May Adversely Affect Essential Fish Habitat.

A new and innovative quantitative fishing effects model served as the basis for evaluating potential adverse effects of fishing on EFH. This model and the subsequent assessment methodology were the subject of an independent peer review by the Center for Independent Experts (CIE) in June 2004. The North Pacific Fishery Management Council’s Scientific and Statistical Committee (SSC) also provided extensive comments on various technical aspects of Appendix B.

Appendix B was greatly expanded to address the comments and recommendations by the CIE review panel, the SSC, and the public. The analysts considered habitat effects with respect to species distribution, spawning/breeding, growth, condition (e.g., weight at length), feeding, and stock trends. Although the Appendix B analyses concluded that fisheries do have long-term effects on habitat, these impacts were considered minimal and would not have detrimental effects on fish populations or their habitats. Nevertheless, continuing with its long history of precautionary, ecosystem-based management policy, the Council adopted several new and significant measures to conserve EFH at its February 2005 meeting. The specifics of these measures can be found on the Council’s web site at www.fakr.noaa.gov/npfmc/current_issues/efh/efh.htm.

By Dan Ito

Cod Local Depletion Study Completes Successful Field Season

Peter Munro of the Fisheries Interaction Team (FIT) during the winter FIT survey inspects as Pacific cod dump from the pot onto the sorting table.  Photo by Sandi Neidetcher.

REFM’s Fishery Interaction Team has completed a third year of winter cruises for the Pacific cod local depletion study near Unimak Pass in the southeast Bering Sea. This year’s cruises were conducted 8-28 January 2005 (before the start of the cod trawl fishery) and 12-31 March 2005 (after the main portion of the winter trawl season). The experiment, developed in 2002-03 under the Steller Sea Lion Research Initiative, is designed to test for the presence of local depletion effects from the winter trawl fishery on seasonal aggregations of Pacific cod. At issue is whether commercial fisheries affect food availability for endangered Steller sea lions by creating a localized depletion of sea lion prey.

Both winter 2005 cruises were highly successful, achieving good replication over the full array of 80 experimental stations. Auxiliary studies of cod spawning biology, temporal patterns in pot catch rate, and effects of depth and physical oceanography on catch rate were also completed. Project scientists M. Elizabeth Conners, Peter Munro, Yunbing Shi, and Sandi Neidetcher will present results of the experiment to the North Pacific Fishery Management Council at its June meeting in Girdwood, Alaska, and at the September meetings of the American Fisheries Society in Anchorage, Alaska.

This year is the third replication of the local depletion study. The experiment uses the 10-nautical mile (nmi) no-trawl boundary zone around Cape Sarichef on Unimak Island to define "treatment" (subject to heavy trawl fishing) and "control" areas (open to fixed gear, but closed to trawling). Both zones intersect a shelf area at 40-50 fathoms that has historically been a popular cod trawling ground. The experiment uses modified pot gear to measure an index of local cod abundance. The goal of the experiment is a statistical test of whether cod local abundance in the trawled area declines relative to the control area.

Results of the experiment in 2003 and 2004 showed no differences in cod local abundance or in the seasonal rate of change in abundance between the treatment and control areas. While 2003 results were considered inconclusive due to a small sample size, 2004 results were based on a full sample of three to five fishing days at each experimental station in each cruise and had good statistical power.

Analysis of auxiliary biological and tagging data collected during the experiments indicated that cod in the study area were highly mobile over short time scales. The experiment is designed to look for a local depletion effect that covers a small area (5-10 nmi) and persists in time over several weeks. The negative results of the 2004 experiment suggest that fishing effects may be dispersed over a wider spatial scale or may not persist long enough to be measured. The experiment is being repeated to see if these results are consistent over year-to-year changes in ocean conditions and timing of cod spawning migrations.

By M. Elizabeth Conners

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AFSC Quarterly Research Reports Jan-Mar 2005