In two years, scientists with CSIRO’s Wealth From Oceans National Research Flagship, have named a third of Australia’s – and about a tenth of the world’s – shark and ray species.
Team member, Dr William White, said the project timing coincides with the second edition of Sharks and Rays of Australia (CSIRO Publishing,forthcoming 2009), by Peter R. Last and John D. Stevens, so that every species has a formal name.
Many new species had been listed, but with sketchy details, in the first edition (1994) edited by Dr Peter Last, the current project's team leader.
International Project to Identify Fish at Risk
Although Australians led the research project, they were not alone.
“Most of the major shark and ray taxonomists had some involvement in this project,” Dr White said.
“Co-authors of the 50 separate papers included nine Australian scientists, with others from Brazil, Germany, Malaysia, South Africa, New Zealand, France, Japan and the USA.”
This work contributes to the international taxonomic initiative, SHARK-BOL, in the Fish Barcode of Life project by molecular biologists at CSIRO and Canada’s University of Guelph.
Rare and Endangered Fish Identified
Found all around Australia from freshwater rivers in northern Australia to depths of over 1000 metres off the Continental slope, the new species include several endangered or critically endangered animals.
- The endangered Maugean Skate - Has an extremely narrow distribution, and barely survives off the south-western tip of Tasmania. It’s little changed from its Gondwanan ancestor of 80 million years ago.
- The critically endangered gulper shark, the Southern Dogfish - Endemic to the Continental slope off southern Australia, its population has severely declined in the past few decades.
- Two of the largest freshwater animals in Australia: the Northern Freshwater Whipray and the Northern River Shark, both which grow to over two metres in length
DNA Fingerprinting Separates Species
Dr White said analysis of DNA sequences was one technique used to separate closely related species.
“Specimens of the new species were minutely compared to closely-related species, and we used detailed morphological, meristic (tooth counts and vertebral counts), and molecular information to confirm that they are in fact new species.”
The Ecological Importance of Sharks and Rays
Sharks are top-level predators, and Australians are particularly aware of the dangers of sharks near beaches. Why protect them?
“Sharks and rays are important in the ecosystem as they are typically apex predators at the top of the food chain. Their removal has serious cascade effects which will influence the whole ecosystem,” Dr White said.
“Take them away and what does it mean for the rest of the ecosystem? We can’t understand possible implications unless we know what species we’re dealing with.”
Rays are sometimes considered “flat-sharks” because they are also apex predators.
Rays are generally smaller, but one new species, the Freshwater Whipray (Himantura dalyensis) from Northern Australia, grows to over 1.2 metres wide, maybe larger, a very large animal for river systems.
Why Sharks and Rays are Endangered
“Sharks and rays have k-selected life histories, meaning that they are slow growing, long-lived animals that produce relatively few young,” Dr White explained.
Many of them have very restricted ranges, including a narrow depth range, and are often in areas subjected to over-fishing.
“This makes them vulnerable to intensive pressures and once depleted, populations can take decades to recover,” he said.
“Their populations are also sensitive to small-scale events and can be an indicator of environmental change.”
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