Reproduction of chondrichthyans

Abstract

Species of the class Chondrichthyes (sharks, rays, and chimaeras) exhibit diverse reproductive modes ranging from strictly lecithotrophic oviparity to viviparity with varying matrotrophic nutritional supplement (histotrophy, ovatrophy, adelphotrophy, and placentatrophy). Compared with invertebrate and bony fish taxa, chondrichthyan fishes are long-lived and produce small numbers of large offspring. These characteristics underlie their high vulnerability to harvest as only a small proportion of their populations can be taken annually to ensure sustainable catches and to avoid population depletion. These characteristics also produce challenges for their conservation in the wild and their husbandry associated with commercial fish farming in sea cages and display in aquaria. There is a growing need to address these issues through improved facilities for scientific study and breeding of animals in captivity. Improved conservation of wild stocks and husbandry of captive chondrichthyan animals require a quantitative approach to investigating their maturity, maternity, fecundity, and productivity.