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News from the National Academies
Date: Jan. 7, 1998
Contacts: Ellen Bailey Pippenger, Media Relations Associate
Dumi Ndlovu, Media Relations Assistant
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Scientific Review Supports
Federal Assessments of Northeast Fish Stocks

WASHINGTON -- Scientific data from federal assessments of Northeast fish populations indicate that fishing restrictions have been necessary to improve the numbers of several depleted fish stocks, says a new report* from a National Research Council committee. There are initial signs of recovery for some stocks, but population numbers are still dangerously low. Any relaxation of management measures may jeopardize the sustained recovery of these commercial fisheries, which are vital to New England's economy. And although the stock-assessment process generally is considered sufficient, some improvements will be necessary to further enhance the quality of the scientific data and advice used for management decisions.

"The committee's review of the assessment data indicates that although some Northeast fish stocks appear to be increasing, caution is warranted because there are substantial uncertainties in the information available," said committee chair Terrance Quinn, professor of fish populations dynamics, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Juneau. "Without strong regulations similar to current ones that limit fish harvesting, some of our analyses predicting future stock size show a real chance of irrevocable population declines."

The Research Council was asked by Congress in 1997 to review U.S. and Canadian fish stock assessment methods. The fish population numbers derived from these methods were used as the basis for fishing restrictions implemented by the New England Fishery Management Council and the National Marine Fisheries Service (NMFS) in 1995 and 1996. Vast coastal areas of the Gulf of Maine and Georges Bank fishing grounds have been closed since then, and the region's fish catch has been limited by various restrictions on fishing.

Many New England coastal communities depend on ocean fisheries for their economic livelihood. In the past 10 years, important Northeast stocks -- including cod, haddock, and yellowtail flounder -- have fallen to their lowest levels in recorded history. In the early 1990s, assessments indicated that numbers of fish spawning were low compared to levels 20 years before, and that 50 percent to 80 percent of the fish population was being harvested every year. Stocks of Georges Bank haddock and southern New England yellowtail flounder appear to have already collapsed, the committee said. Based on its review of historical estimates of fish population data, the committee said that these species have experienced little or none of the population increases essential for their survival.

The report concentrates on the 1997 stock assessment for cod, haddock, and yellowtail flounder, conducted collaboratively by the U.S. and Canadian governments. The committee noted that while forecasts by NMFS incorporate substantial uncertainty -- an important factor in developing accurate forecasts and simulation models -- some of the main sources of uncertainty have been left out from the assessment.

Different hypotheses about the relationship between stock abundance and subsequent population increases are consistent with the data at hand. Under some of these hypotheses, the probability of the stock not having recovered to thresholds set by the New England Fishery Management Council within 10 years is larger than suggested by NMFS assessments. Estimating such probabilities quantitatively is not easy, so basing management decisions directly on predictions from stock assessments is difficult without adopting a precautionary approach in fishery management strategies.

Northeast Fish Stocks Still at Risk

Little by little, existing management measures appear to be working to decrease fishing mortality in four of the five stocks reviewed by the committee -- the Georges Bank cod, Georges Bank haddock, and southern New England and Georges Bank yellowtail flounder. Stock estimates have increased somewhat as evidenced by older and larger fish appearing in the survey and in catches. Nevertheless, the most recent information from stock assessments generally tends to be the most uncertain, so the apparent increases cannot be confirmed until future assessments are completed.

The numbers of Gulf of Maine cod, however, continue to decline. Present regulations have not controlled its mortality rate, but new interim measures that further restrict harvesting may prove effective.

It is difficult to evaluate the degree to which factors such as fish harvesting, climate changes, or pollution affect the abundance or decline of fish stocks, the committee noted. Even so, fish mortality caused by harvesting is known to have played a major role in reducing stocks in the 1980s and early 1990s, and continues to do so for the Gulf of Maine cod stock.

Recommended Actions

Although the committee found the 1997 Northeast fish stock assessment sufficient for providing sound scientific input for management decisions, it recommended the following actions to enhance the quality of data and advice:

> Fishery surveys should include evaluations of sample size, design, and data collection. Alternative methods for data analysis and more assessment models should be used.

> The relationship between the National Marine Fisheries Service and the fishing community should be strengthened. For example, the agency could provide opportunities for the community to better understand the federal assessment process and could involve fishermen in collecting and assessing certain types of data.

> Personnel exchanges of limited duration between NMFS regional centers could help scientists at each office keep abreast of the latest improvements in stock assessment technologies.

> Greater numbers of independent scientists from academia and elsewhere should participate in peer reviews of federal stock assessments. When necessary, the government should pay competitive rates for outside participation.

> As the New England Fishery Management Council intensifies its management of the region's fisheries, NMFS should perform stock assessments more frequently than the current practice of every three years.

Other recommendations included considering more scenarios for how fish populations may increase over time and investigating whether the results of management measures can be predicted. The committee also suggested working toward a comprehensive management model that would consider stock assessment predictions, as well as ecological and socioeconomic results of long-term management strategies. Only with a far-reaching management approach drawing upon social sciences and a wider range of natural sciences -- including ecology, genetics, and oceanography -- can fisheries management provide for sustainable fish populations while considering the needs of people who rely on fisheries.

In addition to reviewing and replicating some aspects of the 1997 Northeast stock assessment, the committee found the 1997 assessment process mostly consistent with new recommendations recently published in a National Research Council report, Improving Fish Stock Assessments. The assessment process, while needing some improvements, appears to provide valid scientific information for management decisions. Furthermore, the process for that assessment is similar to those used elsewhere in the United States and by other nations.

The study was funded by the National Oceanic and Atmospheric Administration. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. It is a private, non-profit institution that provides science and technology advice under a congressional charter. A committee roster follows.

Read the full text of Review of Northeast Fishery Stock Assessmentsfor free on the Web, as well as more than 1,800 other publications from the National Academies. Printed copies are available for purchase from the National Academy Press Web siteor at the mailing address in the letterhead; tel. (202) 334-3313 or 1-800-624-6242. Reporters may obtain a pre-publication copy from the Office of News and Public Information at the letterhead address (contacts listed above).

      NATIONAL RESEARCH COUNCIL
      Commission on Geosciences, Environment, and Resources
      Ocean Studies Board

      Committee to Review Northeast Fishery Stock Assessments

      Terrance Quinn (chair)
      Associate Professor
      School of Fisheries and Ocean Sciences
      University of Alaska Fairbanks
      Juneau

      Wyatt Anderson*
      Distinguished Professor of Genetics, and
      Dean of Arts and Sciences
      University of Georgia
      Athens

      Wayne M. Getz
      Chair, Division of Insect Biology
      Department of Environmental Science, Policy,
      and Management
      University of California
      Berkeley

      Ray Hilborn
      Professor
      School of Fisheries
      University of Washington
      Seattle

      Cynthia Jones
      Associate Professor
      Department of Biology
      Old Dominion University
      Norfolk, Va.

      Jean-Jacques Maguire
      Consultant
      Halieutikos Inc.
      Sillery, Quebec

      Ana Parma
      Population Dynamicist
      International Pacific Halibut Commission
      Seattle

      Tore Schweder
      Professor of Statistics
      Department of Economics
      University of Oslo
      Norway

      Gunnar Stefansson
      Manager
      Modeling Division
      Marine Research Institute
      Reykjavik, Iceland

      RESEARCH COUNCIL STAFF

      M. Elizabeth Clarke
      Study Director

      (*) Member, National Academy of Sciences