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Optimal harvest policies in salmon gauntlet fisheries : terminal versus mixed stock fishery harvestLuedke, Wilfred Harold January 1990 (has links)
A case study of the chum salmon (Oncorhynchus keta) gauntlet fisheries in Southern British
Columbia is described. Acrimony between industry and government managers has been
commonplace in the management of this fishery. In an attempt to alleviate this acrimony, a
management system call the "clockwork" has been implemented, which provides all fishermen
an opportunity for greater understanding of the management rationale and greater input into
the decision-making process. The clockwork has been generally successful; the stocks are
rebuilding and the fishermen are involved in the management of the fishery.
However, two problems are identified in the clockwork. First, the success of the clockwork
in alleviating the aaimony associated with the chum fishery depends on the ability of
fishery managers to provide sound and scientifically defensible in-season stock assessments.
If the assessments have no better track record than the intuition of managers and fishermen
then the clockwork will not be successful.
Second, there is a nagging problem of allocation of harvests between the mixed stock
fishery in Johnstone Strait and the terminal fishery in the Fraser River. The main factor is the
difference in price behveen the two fisheries; the price in the terminal fishery is only about
one-third of the price paid in the mixed stock fishery, Dynamic programming techniques are
used to determine the optimal harvest strategies for this gauntlet fishery. Generally, the optimal
strategy is similar to a fixed escapement strategy when both stocks are equally abundant.
But when one stock is much more abundant the optimal strategy is to harvest harder in the
mixed stock fishery. With the current difference in value per fish between the two fisheries,
the optimal exploitation rates in the terminal area are zero, all the catch is taken in the mixed
stock fishery. The minimum price at which terminal fisheries provide long term economic
benefit is the threshold price. For the parameters used to describe the current fishery, the
threshold price is approximately 40% of the mixed stock fishery price. Furthermore, the
threshold price differs with stock recruitment parameters, especially stock productivity
and recruitment variability. Generally the more similar the stocks are, with respect to stock
and recruitment characteristics, the lower the threshold value for fishing in the terminal areas.
The results provide a basis for discussion of the utility of terminal fisheries, and by
adjusting the relative value of the terminal fishery in relation to the mixed stock fishery can
incorporate additional social and aesthetic values, as well as costs such as harvesting costs and
fisheries management costs. / Science, Faculty of / Zoology, Department of / Graduate
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An assessment of area licence configurations in the B.C. salmon fisherySakata, Tommy Taira January 1985 (has links)
There has been much discussion of the merits and limitations of area licensing, i.e., a fishery management tool which restricts fishermen to certain geographic areas, in the British Columbia," Canada, salmon fishery. To date there has been little formal evaluation of the implications of this policy tool for salmon fishery management. In the reports by Pearse (1982), Sinclair (1978) and Fleet Rationalization Committee (1982) some insights on the subject are provided, but an evaluation in terms of specific criteria is lacking.
This study evaluates five area licence configurations in the context of the B.C. salmon fishery. They are assessed based on evaluative criteria that cover the following subject areas: management operations; socio-economic effects; biological effectiveness; and economic efficiency. Each of these broad subjects are factored into specific elements, in which the emphasis is on the nature of the fishery and the resource. From the analysis it was found that the area licence configurations that factored the coast into two large harvest areas or the configuration that alienated small area(s) as test area(s) are most appropriate for the fishery. These configurations facilitated the attainment of management operations, socio-economic and biological goals, but not the economic efficiency goals. The other configurations, in particular those that factor the coast into a number of smaller harvest areas, result in exacerbating the problems with all criteria except economic efficiency and some biological factors. The appropriate area configurations for the B.C. salmon fishery would be the configurations that factors the coast into two large harvest areas; or the configuration where two or three small harvest areas are alienated from the existing harvest area. There are three fundamental reasons for this: (1) they are least disruptive (i.e., minimum impact on present harvest patterns, least politically sensitive, and minimum distributional effects); (2) they offer greatest flexibility to address political, economic, biological and social uncertainties; and (3) these area configurations provide the greatest ease of implementation and incremental adjustment of the status quo. Acceptance of these configurations will depend on the time horizon and the objectives of the decision makers. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate
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Analysis of stock-recruitment dynamics of British Columbia salmonWong, Fred Yuen Churk January 1982 (has links)
An overview of stock-recruitment dynamics for major B.C. salmon (Oncorhynchus spp.) stocks is presented. Stock-recruitment patterns range from linear relationships to "Ricker" type relationships to no relationship at all. However, stocks for which there are accurate escapement estimates generally show patterns expected from stock-recruitment theory. It is concluded that errors in stock definition, mixed catch allocation, and spawning counts bias optimum escapement estimates downward so that poorly monitored stocks may become severely overexploited without being noticed. Because of poor escapement counts and/or difficulties in separating mixed catches, optimum escapements for many B.C. salmon stocks, which account for about half of the total B.C. production, cannot be estimated. Most stocks for which optimum escapement can be estimated are now being severely depleted. Restoration of these stocks by increasing escapement to optimum levels would increase the total catch by at least 40% of the current yield. Further, experimental management by increasing escapement appears to be the best policy for most of the other stocks. / Science, Faculty of / Zoology, Department of / Graduate
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