Cannibalism Reduction in Juvenile Barramundi Lates calcarifer by Providing Refuges and Low Light

Abstract

Cannibalism is a special form of predation to kill and consume the whole of an individual of the same species. Cannibalism has been found in 36 of 410 fish families and can take place at various sizes or ages depending on species and environments (Hecht and Pienaar 1993). The occurrence of cannibalism in larval and juvenile fish is of considerable concern for aquaculture (Smith and Reay 1991). Intracohort cannibalism is one of the most important issues to address in intensive fish aquaculture. Among commonly aquacultured fish species, cannibalism has been reported in catfish Clarias gariepinus (Hecht and Appelbaum 1988). walleye Stizostedion vitreum (Cuff 1980), common carp Cyprinus carpi0 (Damme et al. 1989), Atlantic cod Gadus morhua (Folkvord 199 I) , Perca Jluviatilis (Melard et al. 1996), and many others. Since cannibalistic behavior has been widely found in fish culture, determination of factors influencing cannibalism is important in order to reduce its impact. Factors causing cannibalism fall into two primary categories: genetic and behavioral factors. Within the genetic category the principal cause of cannibalism is size variation within a cohort (Valerio and Barlow 1986). The behavioral category of causative factors is obviously linked to the genome, but environmental factors are closely linked to agonistic behaviors (Fox 1975; Hecht and Appelbaum 1988). Barramundi Lates calcarifer is an important species for aquaculture in Australia and