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Environmental Status: Sharks and rays

Summary

  • Some 125 species of sharks, rays, skates and chimeras are found in the Great Barrier Reef, and inhabit a wide variety of habitats.
  • Sharks have very conservative life history traits and are generally unable to withstand the levels of fishing most bony (teleost) fishes are able to sustain. Many shark fisheries around the world have collapsed.
  • As sharks are apex predators, they help to control populations of prey species. Consequently, reducing the number of sharks may have significant and unpredictable impacts on other parts of the ecosystem.
  • There is very little information available about the sharks in the Great Barrier Reef, and their status is unknown. The basic biological characteristics of most species in the Great Barrier Reef have yet to be studied.
  • Some sharks found in the Great Barrier Reef are listed as threatened species. Some of these sharks are protected under GBRMP legislation, state legislation and the Environmental Protection and Biodiversity Conservation Act 1999. Recovery plans have also been developed for the great white shark and grey nurse shark, while recovery plans for the Bizant River shark and whale shark are in various stages of completion.
  • The main pressure on sharks in the Great Barrier Reef is fishing, and this pressure is increasing. More than 90% of the Great Barrier Reef commercial shark harvest is taken by the gillnet fishery with the remainder taken by the line and trawl fisheries. However recreational fishers catch and retain a significant number of sharks.
  • The commercial harvest of shark has increased four fold between 1994 and 2003. It is unknown whether this level of fishing is sustainable.
  • There is inadequate reporting of shark catch and there are no species specific catch and effort data. Further, bycatch and shark finning are significant issues but are poorly documented. The practice of removing shark fins and discarding the body at sea is now banned in the Great Barrier Reef, and measures have been introduced to reduce bycatch in non-target fisheries.
  • Some sharks are highly migratory and travel large distances. As a result, they are also subject to pressures from fisheries outside the Great Barrier Reef such as the Northern Shark Fishery, Eastern Tuna and Billfish Fishery, and fisheries throughout Australia and the wider Pacific.
  • The existing fisheries research, stock assessment and management regimes for sharks in the Great Barrier Reef need to be improved if the shark fishery is to be managed sustainably. Research is currently underway to collect more robust data on the Great Barrier Reef shark catch, and these data will form the basis of future stock and species risk assessments.
  • International and national initiatives such as the National Plan of Action for the Conservation and Management of Sharks, and assessments under the Environment Protection and Biodiversity Conservation Act (1999) are also driving new research and efforts to improve the sustainability of fisheries impacting sharks. Public education and awareness raising programs have also been implemented.
  • Other pressures include the degradation of habitats such as seagrass meadows and estuarine systems from terrestrial runoff and coastal development. This is being addressed through coastal zone management initiatives and the Reef Water Quality Protection Plan.
  • The rezoning of the Great Barrier Reef Marine Park has improved the level of protection of the biodiversity and ecological functions that support the various habitats of the Great Barrier Reef. The new Great Barrier Reef Marine Park Zoning Plan came into effect on 1 July 2004, and will increase the resilience of the Great Barrier Reef ecosystem in the face of multiple pressures, as well as helping to sustain the ecological processes and habitats that support shark populations.

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