New Study Shows Overfishing Threatens Ocean Sharks And Rays With Extinction

A new study released today by scientists has revealed that three quarters of ocean shark and ray species are in danger of extinction. An alarming 71% decline in shark and ray populations was found over the last 50 years with the primary threat being that of overfishing. Since 1970, “relative fishing pressure” (which can be defined as the exploitation of fish stocks relative to the number of fish left in oceans), has increased 18-fold.

The team of researchers, led by Simon Fraser University and including the University of Exeter warn that extinctions among these species could jeopardise the health of our ocean ecosystems and food security in poorer developing nations.  

"The species that we studied are some of the ocean’s apex predators," said Dr Richard Sherley, of the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall.

"They roam far from land and so might seem immune to the direct impacts of humans on our planet. Not so. Our global analysis points to some staggering declines.”

"It highlights the very real risks these species face if we do not act now – and act decisively – to limit the pressures fishing exerts on their populations. But there is hope. A few bright spots in the data demonstrate that even these long-lived animals can recover when science-based fishing restrictions are enacted and enforced."

The study found that species in tropical areas are declining more steeply than those elsewhere. In the Indian Ocean, shark and ray abundance has declined continually since 1970 – falling by 84.7% in total. 

However, the paper does highlight some positive changes, including the recovery of White sharks in several regions. These improvements appear to have been the result of strictly enforced fishing rules – and the researchers say further science-based catch limits and landing bans are needed immediately. 

The paper, published in the journal Nature is entitled “Half a century of global decline in oceanic sharks and rays” and when published will be available to read at: https://www.nature.com/articles/s41586-020-03173-9 

Words by Kristian Parton

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