Sampling juvenile Penaeus latisulcatus Kishinouye with a water-jet net compared with a beam-trawl: spatial and temporal variation and nursery areas in Gulf St Vincent, South Australia

Abstract

This study demonstrates that the water-jet net is more effective than a beam trawl in capturing juvenile Penaeus latisulcatus. In contrast with the beam trawl, which is maximally effective only at night when prawns are active, the jet net captures high numbers of prawns in daylight. This, combined with its ability to minimize catchability effects, makes the jet net very suitable for sampling juvenile P. latisulcatus. For sampling prawns of widely varying size, perpendicular trawls were more effective than parallel trawls because larger individuals are distributed in deeper waters. Nursery areas for P. latisulcatus are intertidal sand/mudflats and there is little daily variation of prawn abundance and distribution within one site. Large differences in abundance of juvenile prawns were observed throughout Gulf St Vincent with highest concentrations in the northern part of the gulf.