Sustaining Marine Fisheries (1999) / Chapter Skim
Currently Skimming:
4 Diagnosing the Problems
4 Diagnosing the Problems
Pages 64-76
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From page 64... ...
Assessments of Stocks and of Fishing Mortality A fundamental premise of fishery management is that the productive potential of a stock and a fishery on it is a function of the abundance and biomass of the animals present in the stock and their life-history characteristics. These characteristics include the age distribution, natural mortality rate, age at maturity, and fecundity as a function of age.
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From page 65... ...
identified this problem as one that led to inaccurate stock assessments of northern cod, and indeed it is a reason that fishery-independent surveys are preferred in stock assessments. Estimating fishing and natural mortality rates is also difficult, in large part because there is no perfect way to estimate abundance.
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From page 66... ...
The natural variability of many marine stock sizes interacts with uncertainties in current stock assessments to make precise planning impossible. Landing Statistics In some fisheries, landing statistics (the number, kind, and size of fish landed)
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From page 67... ...
For example, the connection of Seattle to the east coast of the United States by the transcontinental railroad in the late nineteenth century provided a market for Pacific halibut, which resulted in an enormous increase in fishing pressure (Thompson and Freeman 1930)
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From page 68... ...
The uncertainty does not always work against the fishers. Recently, the International Pacific Halibut Commission increased the allowable catch of Pacific halibut because it learned that its stock assessments had been too pessimistic: apparently, there are really more halibut than the stock assessments had indicated (Ana Parma, IPHC, personal communication, 1997)
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From page 69... ...
suggested that maintaining the structure of a community unchanged might not be compatible with any catch rate. As another example, Pacific halibut are managed by the International Pacific Halibut Commission, but approximately one-quarter of halibut landings in 1990 were taken as bycatch in other groundfish fisheries (Thompson 1993)
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From page 70... ...
In the United States, the Sustainable Fisheries Act of 1996 requires fishery impact statements that assess the likely effects of management measures on fishing communities. The difficulty of dealing with goals that are not made explicit -- much less agreed on by most of the parties involved -- is common to many resource agencies, not only fishery agencies.
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From page 71... ...
. To date, most of the world's baleen whales have been found in the retail market, including humpback whales, blue whales, fin whales, Bryde's whales, and northern minke whales (legal only since 1994)
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From page 72... ...
A key factor in investment decisions is the rate at which the investor discounts future economic returns as compared with current returns. The lower the discount rate, other things being equal, the greater will be the incentive to invest; higher discount rates lead to a lower incentive to invest.
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From page 73... ...
in formulating his concept of the economically optimal fishing effort that results in maximum economic yield. Gordon implicitly assumed that the appropriate social discount rate is zero, i.e., that future economic returns from the resource should be given the same weight as current returns (Clark and Munro 1982)
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From page 74... ...
The OECD publication in particular contains many recent references and ample examples of fishery management in practice. In theory, the imposition of conservation measures strong enough to be effective, either through input controls such as gear limitations or seasonal and areal closures, or through output controls such as catch limits (usually total allowable catches or TACs)
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From page 75... ...
Vessel and factory owners usually have debts, such as mortgages, to be serviced. As the excess capacity dissipates economic returns from the fishery, the incentive for fishers and processors to press for liberal catch quotas increases as does the political influence of the users: if their catches are significantly reduced, they often face bankruptcy.
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From page 76... ...
Creating more appropriate incentive systems and developing management institutions that can accept and deal with variability and uncertainty are crucial to establishing sustainable fisheries. Without them, populations of individual species and the structure and functioning of marine ecosystems are likely to continue to decline.
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