Oral Presentation Australian Society for Fish Biology Conference 2017

Sharks, rays and abortion: the prevalence of capture-induced parturition in elasmobranchs (#109)

Kye R Adams 1 , Lachlan C Fetterplace 1 , Andy R Davis 1 , Matt D Taylor 2 , Nathan A Knott 3
  1. Biological Sciences, The University of Wollongong, Wollongong, NSW, Australia
  2. Port Stephens Fisheries Institute, New South Wales Department of Primary Industries, Taylors Beach, NSW, Australia
  3. Marine Ecosystems Unit, Department of Primary Industries, Huskisson, NSW, Australia

The direct impacts of fishing on chondrichthyans (sharks, rays and chimeras) are well established. Here we review a largely unreported, often misinterpreted and poorly understood indirect impact of fishing on these animals — stress-induced parturition (either premature birth or abortion). Although direct mortality of discarded sharks and rays has been estimated, the prevalence of abortion/premature birth and subsequent generational mortality remains largely unstudied. We synthesise a diffuse body of literature to reveal that a conservative estimate of > 10% of live bearing elasmobranch species show stress-induced parturition in response to capture. For the 23 species with available data, we estimate capture stress-induced parturition events for 2 – 64% of pregnant females (average 20%). Stress-induced parturition was only observed in live-bearing species. We compile data on threat-levels, method of capture, reproductive mode and gestation extent of premature/aborted embryos. We also utilise social media to identify 42 social-media links depicting a stress-induced parturition events which provide supplementary visual evidence for the phenomenon. The mortality of embryos will have implications for elasmobranch populations, and there are limited options to deal with this problem. This review is the first to synthesize available data on stress-induced parturition in sharks and rays, and highlights an important ethical and management issue for fishers and managers deserving of much greater attention.