The effect of hook size on the size-specific selectivity of hottentotPachymetopon blochii(Val.) and on yield per recruit

Abstract

A model for the relationship between hook size and length distribution of catches for a line fishery was applied to experimental data for hottentot Pachymetopon blochii. Hook size influenced the length frequency of catches. The selectivity function was modelled to an adequate approximation by a gamma distribution. Exploitation rates at various fishing centres off the Western Cape, South Africa, were investigated in the context of an observed variation in the mean mass of the individual fish caught. When allowance was made for the various hook sizes used at different locations, only the resource at Gans Bay appeared to be overexploited in yield-per-recruit terms. If hook size affects the length distribution of the catch, it is important to incorporate this aspect into assessments of resource status.