The influence of depth, latitude and width of the continental slope on the size distribution and availability of spiny lobster Palinurus delagoae off the east coast of South Africa

Abstract

The influence of depth, latitude and width of the continental slope on the size distribution and catch per unit effort of Palinurus delagoae captured in longline traps off the east coast of South Africa was examined by means of generalized linear models. Depth had the strongest influence on size distribution. As depth increased from 150 to 400 m, average carapace length decreased and, based on this, a long-term inshore migration pattern during the benthic phase of the life cycle of P. delagoae is suggested. Catch per unit effort increased at depths from 150 to 250 m, but it remained uniform between 250 and 400 m. In the latitude functions, average carapace length increased from 27 to 28°S, reaching a maximum at 28–29°40′S, but decreasing thereafter towards 32°S. Width of slope had little influence on size distribution along the coast, but catch per unit effort increased moderately with increasing width of slope.