Effect of otter prawn trawling on the macrobenthos of a sandy substratum in a New South Wales estuary

Abstract

The effect of the use of otter trawling gear (of the type commonly employed for prawn fishing in New South Wales estuaries) on the macrobenthos of a sandy substratum was studied. The effect was assessed by direct quantitative sampling of the macrobenthos at three treatment sites and one control site on three occasions: before and after intensive trawling, prior to the opening of the commercial prawning season. and again at the close of the commercial season. Underwater observations of otter trawl nets were also made. The similarity of sites was examined using numerical clustering techniques as a preliminary step to statistical comparisons of epifaunal, infaunal and 'whole' faunal community indices (No. of individuals. No. of species and Shannon species diversity) by analysis of variance. From both the quantitative sampling and underwater observations, it was shown that the otter praazn trawling gear used did not cause any detectable changes in the macrobenthic fauna of the trawl grounds.