Empty Seas: Oceanic Shark Populations Dropped 71% Since 1970 | heatlh & science , science

A hammerhead shark. Half of the world’s 31 oceanic shark species are now listed as either endangered or critically endangered by the International Union for Conservation of Nature

"The authors (of the study) attribute this decline to an 18-fold increase in relative fishing pressure - a measure of the proportion of sharks and rays caught relative to their global population - over the period", the research read.

"You drop a fishing line in the open ocean, and often it's sharks that are there first-whether or not they're the primary target", marine biologist Stuart Sandin of the Scripps Institution of Oceanography who was not involved with the research tells the Associated Press. Zoological Society of London manages the LPI and the International Union for Conservation of Nature looks at the RLI.

Mr Chlebeck said Australia was "doing pretty well compared to the rest of the world in shark conservation", but more could be done to ensure the flake sold in our fish and chip shops was from the two approved species of shark (gummy and rig) rather than endangered varieties.

Prof Simpfendorfer stressed today's global study tracked the decline of deep ocean animals, which may only occasionally visit Australian coastal waters, but declines had been noted in many species that frequented our coasts.

The study marks the first global analysis of its kind, the authors say.

Scientists from the Simon Fraser University, Canada, and the University of Exeter in the United Kingdom have revealed that since 1970, there has been a shocking 71 percent decline in shark and ray populations. "Combined with their increasing rarity, that means relative fishing pressure on sharks and rays is now 18 times greater".

The new study, among many others, is a reminder for the worldwide communities to take action to reverse the detrimental effects of human activities while there's still time. The system assesses how threatened species are based on their rate of population decline and geographic range.

"The data revealed a gaping, growing hole in ocean life", Pacoureau said.

Sharks are sought out for their meat and liver oil. Plus, they're not very well protected. "And we know they work", he added, pointing to the recovery of great white sharks around the USA after new regulations.

Dr Richard Sherley, of the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall, said: "The species that we studied are some of the ocean's apex predators. Governments should adopt, implement, and enforce - at domestic and regional levels - science-based catch limits and other protective measures", professor Simpfendorfer said. To protect them, the researchers urge governments to immediately implement stricter regulations on fishing for them in the world's oceans. They usually take several years to achieve sexual maturity, in comparison to most other forms of fish, and they have fewer offspring. The study notes white sharks saw a 70% decline over the past 50 years, but bans in some regions are helping populations recover.

Even taste tests were insufficient, Mr Chlebeck said, as most shark and ray flesh tasted similar. Those in the depths of the ocean are often neglected, but the study indicates that in fact, elasmobranchii may be some of the most threatened animals on Earth.

Sharks and rays are especially vulnerable to population collapse because they grow slowly and reproduce comparatively infrequently.

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