The Dusky Shark (Carcharhinus obscurus) is a highly migratory coastal and occasionally pelagic shark species of tropical, sub-tropical and temperate seas. It is found along continental shorelines and the shelf, where it can range from shallow waters to the outer reaches of the continental shelf and adjacent oceanic waters. It is very large and fairly slender, and can be identified by its bluish grey colour, fin shape and markings. Its snout is slightly shorter than or as long as the width of the mouth. Such species undergo seasonal transboundary migrations to remain in the warmth.
The Dusky Shark is an apex predator with a high trophic level (4.2) and diverse diet. It preys on a wide array of bony and cartilaginous fishes as well as a variety of invertebrates and occasionally marine mammals. Juveniles primarily consume pelagic teleosts and cephalopods, with an increase in the consumption of elasmobranch prey as their body size increases.
However, the Dusky Shark is one of the least productive and most vulnerable of all shark species, giving birth to pups only every two or three years. Its populations therefore have very low intrinsic growth rates, making them highly susceptible to over-fishing and other anthropogenic threats. Unsustainable fishing is the greatest threat to this species worldwide, whether by target fisheries supplying demand for Dusky Shark meat and the international fin trade, or utilized bycatch in fisheries for other species. Its abundance has declined markedly from historic levels. For example, declines are reported ranging from 62 per cent up to 99 per cent in the Atlantic Ocean and up to 75 per cent in the Indo-Pacific Ocean.
Due to severe, continued declines in their population around the world, the Dusky Shark is listed by the IUCN on its Red List of Threatened Species as Vulnerable to Extinction globally. To protect this species, Australia, South Africa and the United States have implemented a variety of species-specific management measures at national level, ranging from recreational bag limits to strict legal protection. If the declines of Dusky Sharks are to be reversed and fisheries become sustainable, a more precautionary multilateral approach to this species’ management at international level is urgently needed. Currently, the Dusky Shark is listed in Appendix II of CMS.
|Date of entry in Appendix II||2017|