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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 30 (1991), S. 253-271 
    ISSN: 1573-5133
    Keywords: Rockfish ; Longevity ; Reproductive value ; Fisheries ; Scorpaenidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The characteristics of lightly and heavily exploited Pacific ocean perch,Sebastes alutus, stocks are evaluated relative to the predictions of life history theory. These long-lived species (50–100 year lifespan) show limited phenotypic plasticity and have little buffering against the effects of reduced lifespan. Reduced stock abundance has generated some compensatory increase in growth rate. Length at first maturity varies only slightly with increased growth rate, although age at maturity may decrease by 1–4 years. Grooth increases yield larger (15–20%) size at age and increased reproductive effort at younger ages, but lower size-specific fecundity for these faster-growing fish. This suggests an energy allocation protocol favouring growth over reproduction in these long-lived animals. Rockfishes have late recruitment to fisheries (ages 10–15), and the detection time for results of management actions is equally long. Their vulnerability to overfishing means that indices of population changes, more representative of fishing effects than the catch rate index presently used, are required. Reproductive value indices are shown to be extremely sensitive and continuous with population abundance changes. Their incorporation into monitoring programs would permit more timely evaluation of management actions. Management policies developed for shorter-lived species are shown to be inappropriate for rockfishes. The need for an improved match in the time frame of the species' life history, and that of management strategies, is stressed.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 1991-01-01
    Print ISSN: 0378-1909
    Electronic ISSN: 1573-5133
    Topics: Biology
    Published by Springer
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  • 3
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    In:  http://aquaticcommons.org/id/eprint/9725 | 403 | 2012-08-15 17:52:05 | 9725 | United States National Marine Fisheries Service
    Publication Date: 2021-07-08
    Description: ABSTRACT—Bycatch mortality of Pacific halibut, Hippoglossus stenolepis, in nontarget fisheries is composed primarily ofimmature fish, and substantial reductions in yield to directed halibut fisheries result from this bycatch. Distant-water bottomtrawl fleets operating off the North American coast, beginning in the mid 1960’s, experienced bycatch mortality of over 12,000 t annually. Substantial progress on reducing this bycatch was not achieved until the of extension fisheries jurisdictions by the United States and Canada in 1977. Bycatch began to increase again during the expansion of domestic catching capacity forgroundfish, and by the early 1990’s it had returned to levels seen during the period of foreign fishing. Collaborative action by Canada and the United States through the International Pacific Halibut Commission has resulted in substantial reductions in bycatch mortality in some areas. Methods of control have operated at global, fleet, and individual vessel levels. We evaluate thehierarchy of effectiveness for these control measures and identify regulatory needs for optimum effects. New monitoring technologies offer the promise of more cost-effective approaches to bycatch reduction.
    Keywords: Fisheries ; Management
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 31-37
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