Effects of lunar periodicity on catches of Penaeus plebejus (Hess) in an Australian coastal lagoon

Abstract

Eastern king prawns, Penaeus plebejus, were quantitatively sampled in a small, intermittently open, coastal lagoon over three consecutive lunar cycles to determine if abundance of prawns differed with respect to lunar period, and obtain an indication of the catch per unit effort (CPUE) of recreational fishers and size distributions of prawns that comprise their catches in a temperate intermittently open coastal lagoon. Bare-sand substrata were sampled along transects every two weeks for three months using a standard recreational scoop net. CPUE was significantly higher during the new moon across all months sampled. Mean carapace length of prawns did not differ with respect to lunar period, but differed with respect to month sampled, presumably due to rapid growth. The abundance and large size of prawns caught suggests that intermittently open lagoons are productive habitats for prawns, where they may attain a large size due to protection from large predators and inhibited seaward migrations due to intermittent closure of the lagoon entrance.