Occurrence and intensity of intercohort cannibalism of post-hatching stages in the broad-nosed pipefish,Syngnathus typhle

Abstract

In the broad-nosed pipefish, Syngnathus typhle, males brood their offspring in a ventral brood pouch, providing them with nutrients and oxygen. The pregnancy is costly to the males as they feed less and grow more slowly than females during the breeding season (Svensson, 1988). The juvenile fish, once completely developed, leave the pouch to lead independent lives. At this stage, the juvenile fish can be in risk of predation, even by conspecific adults according to field results obtained in other related Syngnathus species (Franzoi et al., 1993; Teixeira and Musick, 1995). This form of cannibalism has been defined as intercohort cannibalism of juvenile stages by Smith and Reay (1991). In this study, incidence and intensity of intercohort cannibalism have been assessed in a sampling of a broadnosed pipefish population inhabiting the Venice Lagoon, at the peak of the breeding season.