Improving Fish Stock Assessments (1998) / Chapter Skim
Currently Skimming:
6 Findings and Recommendations
6 Findings and Recommendations
Pages 111-118
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From page 111... ...
Diminishing the quality of fishery-independent data by failing to modernize NOAA fishery research vessels or changing sampling methods and gear without proper calibration could imperil existing and future data sets (ASMFC, 1997~. The committee did not evaluate the proficiency with which fishery managers communicate stock assessment results and methods to the public.
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From page 112... ...
Obtain Auxiliary Information Finding: The committee' s simulation study demonstrated that assessments are sensitive to underlying structural features of fish stocks and associated fisheries, such as natural mortality, age selectivity, catch reporting, and variations in these and other quantities. For accurate estimation in stock assessment models, it has long been known that auxiliary information in the form of indices or survey estimates of abundance, model structure information, and information about other population parameters (e.g., natural or fishing mortality)
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From page 113... ...
that was applied to the simulated data provide a natural way to incorporate independent information about M into the assessment while allowing for the existing uncertainty. A natural mortality index could be included easily in existing assessment models or used in an approach such as multispecies virtual population analysis (MSVPA)
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From page 114... ...
The committee's simulation study demonstrated that small, but realistic, departures from standard assumptions of stock assessment models can result in substantial assessment errors. All too frequently, stock assessments provide only point estimates of key population and management parameters without standard errors or confidence intervals.
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From page 115... ...
With this method, if the estimated natural mortality rate is too high, F40%, the estimated exploitable biomass, and TAC will all be too high (Table 5.3, compare data sets 1 and 2~. Even if the correct natural mortality rate is known, biases in the stock assessment, uncertainty, or correlated errors in the biomass projection can degrade management performance.
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From page 116... ...
PEER REVIEW OF ASSESSMENTS AND ASSESSMENT METHODS Finding: External peer review of scientific procedures and results is standard practice throughout much of the scientific community. When applied properly to stock assessments, such reviews would yield an impartial evaluation of the quality of assessments as well as constructive suggestions for improvement.
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From page 117... ...
10~. Recommendations: NMFS and other bodies that conduct fish stock assessments should ensure a steady supply of well-trained stock assessment scientists to conduct actual assessments and to carry out associated research.
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