Research Document 1998/48

Decision rules for the 4Vn overwintering herring fishery

By R. Claytor and C. LeBlanc

Abstract

Biological information concerning timing and locations of herring concentrations in 4Vn are presented to assist in the development of a decision rule on where to fish in 4Vn (Decision Rule 4). A computer simulation model is used to examine the consequences of catching various amounts of fish (Decision Rule 1).

These analyses determined that for Decision Rule 4: the general principle of fishing in areas where stocks are randomly mixed is most likely to be met in northern areas of 4Vn. Risk of fishing in areas where small vulnerable local stocks are concentrated is greater between Cape Smoky and Cape Dauphin, than north of Cape Smoky. Fishing below Cape Smoky increases the proportion of spring spawners in the catch. Therefore, given the declining situation in the Bras d'Or Lakes, the Cape Smoky line is appropriate at this time.

Similarly, for Decision Rule 1 it was determined that: the rule previously established, that the overwinter catch is not to exceed recent average landings, is still appropriate and would limit exploitation rates on local stocks within conservation target levels

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