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1 Nominal Dasyatis sp. 1 (White et al., 2006) specimens from Indonesia and northern Australia. A, ANFC specimen H 5286-01 caught in the Kamora River estuary, Papua; B, NTM specimen S.14424-011 caught at Pocock's Beach in the Kakadu National Park; C, NTM S.15930-008 caught in the Keep River estuary, western Northern Territory.
Source publication
Thirteen elasmobranch species were collected during a four year seine-net survey of the intertidal margins of Moreton Bay, a large subtropical embayment in southeast Queensland, Australia. The inshore elasmobranch fauna of Moreton Bay is relatively species rich in comparison to sites elsewhere in Australia, emphasising the regional importance of th...
Citations
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 — capture-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 synthesize a diffuse body of literature to reveal that a conservative estimate of > 12% of live bearing elasmobranchs (n = 88 species) show capture-induced parturition. For those species with adequate data, we estimate capture-induced parturition events ranging from 2 to 85% of pregnant females (average 24%). To date, capture-induced parturition has only been 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 41 social-media links depicting a capture-induced parturition event 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 capture-induced parturition in sharks and rays, and highlights an important ethical and management issue for fishers and managers deserving of much greater attention. ### Note: This is the accepted peer-reviewed green open access version of the paper before typesetting.###
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 — capture-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 synthesize a diffuse body of literature to reveal that a conservative estimate of > 12% of live bearing elasmobranchs (n = 88 species) show capture-induced parturition. For those species with adequate data, we estimate capture-induced parturition events ranging from 2 to 85% of pregnant females (average 24%). To date, capture-induced parturition has only been 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 41 social-media links depicting a capture-induced parturition event 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 capture-induced parturition in sharks and rays, and highlights an important ethical and management issue for fishers and managers deserving of much greater attention.
Evaluating the extinction risk of poorly known fishes is one of the key problems in marine conservation biology. Elasmobranchs are widely recognised to be highly susceptible to anthropogenic impacts, with ecological specialists being particularly at risk. The estuary stingray Dasyatis fluviorum is endemic to near-shore, estuarine and riverine habitats along the eastern coast of Australia. The present study aimed to obtain basic data on the biology and demography of D. fluviorum to inform conservation evaluation of the species. Age and growth data were collected from rays caught in Moreton Bay, Queensland. Maturity occurred at 630mm disc width (W-D) (13.4 years) in females and 412mm W-D (7.0 years) in males, with maximum age estimates of 21 and 16 years from females and males, respectively. These parameters produced a positive population growth of 1.02 year(-1) in a stochastic demographic model based on indirect estimates of mortality. The life history parameters of D. fluviorum confer a high to very high vulnerability to population decline, emphasising the need for directed conservation efforts for the species. Without management intervention, even minor levels of additive anthropogenic mortality are likely to lead to the species' conservation status declining further to Endangered based on IUCN classification criteria.
