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DEFINITION
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In general, the extent to which a stock is susceptible to fishing.
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In fisheries models, the factor (q) relating abundance to stock size (x = q.N) and fishing mortality to fishing effort (F = qf.). Following the latter, (q) is a measure of fishing mortality generated on a stock by one unit of effort.
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Other Definitions
(q). The fraction of a fish stock which is caught by a defined unit of the fishing effort. When the unit is small enough that it catches only a small part of the stock - 0.01 or less -it can be used as an instantaneous rate in computing population change. . Also called: catchability coefficient. |
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Ricker W.E. (1975): Computation and interpretation of biological statistics of fish populations. Bulletin of the Fisheries Research Board of Canada, 191: 2-6
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COMMENT
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Catchability often increases with developments in fishing technology, and so needs to be monitored. It depends on the habits of the fish as well as on the type and deployment of fishing gear. It may also depend on the abundance of the fish (e.g. less abundant fish may be more catchable due to less saturation of gear or to concentration in schools). Specific climatic conditions may result in increased or decreased availability of the fish. This would lead to increased (decreased) catchability and, thus, increased (decreased) fishing mortality rate with the same fishing effort.
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