ANALYSIS OF SPATIAL STRUCTURE IN FISH DISTRIBUTION USING COMMERCIAL CATCH AND EFFORT DATA FROM THE NEW-ZEALAND HOKI FISHERY

A linear model was fitted to commercial catch per unit effort data in the spawning hoki trawl fishery off the west coast of the South Island of New Zealand. Correlations in the residuals from this model extend out to 11 nautical miles and persist for periods of up to 14 days, sug gesting that there is patchiness in the fish distribution on this spat ial and temporal scale. Simulation studies show that this method can d etect patchiness in the density distribution even when the trawl shots are comparable in length with the size of the patches, and that the e xtent of the correlations correctly estimates the size of the patches.