Teleosts versus Elasmobranchs

This chapter looks into the differences and similarities between the two groups of fish: the teleosts and the elasmobranchs. In the data analyses done so far in this volume, the fish most considered were the teleosts (Teleostei), which represent by far the dominant group, in terms of both biomass and living number of species. Second in line comes the cartilaginous fishes—the elasmobranchs (sharks, rays, skates, and sawfish). This chapter describes the differences between teleosts and elasmobranchs from a population dynamics perspective. It shows that the main difference between the two groups is in their offspring size strategy: teleosts make small offspring; elasmobranchs make large offspring. The chapter uses this difference to quantify the sensitivity of elasmobranchs to fishing relative to teleosts. It also develops an evolutionary explanation for why the offspring size strategy differs between teleosts and elasmobranchs.