On the Exploitation of Elasmobranchs, with Emphasis on Cowtail Stingray Pastinachus Sephen (Family Dasyatidae)

D. Pauly, S. Booth, V. Christensen, W. L. Cheung, C. Close, A. Kitchingman, M. L. D. Palomares, R. Watson, D. Zeller, (2005). “On the Exploitation of Elasmobranchs, with Emphasis on Cowtail Stingray Pastinachus Sephen (Family Dasyatidae),” Fisheries Centre Working Paper (Fisheries Centre, University of British Columbia, Vancouver, B.C., Canada

Characterized by over-exploitation of many of the commercial stocks, the fisheries of the world are in a crisis. In particular, pressure is extremely strong on predators at the top of marine food webs. Typically, the fisheries for these predators, once initiated, last about 10-15 years, i.e., from the time the fisheries start developing and catches are minimal to the time catches have peaked, and then collapsed. This is particularly true for elasmobranchs (mainly sharks, rays and skates), which are characterized by high longevity and low fecundity. Among the elasmobranchs, large rays are particularly susceptible to trawl fishing, although in most countries, they are not targeted, but form part of the by-catch. In fact, one of the first documented extirpations (i.e., local extinctions) of marine fish was of a ray in the Irish Sea. As a large long-lived elasmobranch, the Cowtail stingray (Pastinachus sephen) is extremely susceptible to overfishing, and is widely caught as by-catch of the shrimp trawl fisheries throughout its Indo-Pacific range. The development of targeted fisheries for this stingray, driven by the luxury leather market demand for its skin for processing into pens, wallets, boots, etc., will accelerate the depletion to which this and allied species are already subjected. None of the countries in which the Cowtail stingray is abundant have fisheries management systems in place for this or any other species of rays. It can be expected that the directed fisheries will expand geographically from their center in Southeast Asia, as the original stocks are depleted (as has been the case for fisheries elsewhere), leaving devastated stocks behind. The fisheries science community has no way of ensuring that this exploitation can be made sustainable. It is questionable, therefore, that a demand for luxury products should be allowed to expand that may devastate this and related species, and the ecosystems of which they are a part.

1198-6727, http://www.fisheries.ubc.ca/publications/working/2005/series7.pdf