Title of Dissertation: BIOLOGY, LIFE HISTORY AND CONSERVATION OF ELASMOBRANCHS WITH AN EMPHASIS ON WESTERN ATLANTIC SKATES

In this dissertation two approaches were used to increase the knowledge of elasmobranch population dynamics and life history: (1), the comparative approach and (2), the species-specific approach. In the comparative approach I constructed standardized three-stage matrix models for 55 species of sharks and rays. Using these models I (1) conducted elasticity analyses to determine how the vital rates of mortality (M) and fertility (f) influence elasmobranch population growth rate r, (2) estimated sensitivity of elasticity to perturbation in vital rates, and (3) examined the taxonomic distribution of model inputs and species vital rates, such as size at maturity (Lmat), and total length (Lmax). I found positive relationships between the elasticity of λ (population growth rate) to changes in juvenile and adult stages to longevity and age at maturity; however, the age at maturity and the elasticity of λ to changes in the adult stage relationship appeared to be invariant. Combining vital rates and elasticities, I found similar suites of life histories and demographics within taxonomic groups at various levels. Further I examined where (or if) elasmobranchs fall in the evolved triangula