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Sharks and rays threatened worldwide – overfishing to blame

Sawfish are the most endangered members of the shark family. Flickr/Kaptain Kobold

We have heard a lot of about sharks recently. In particular Western Australia’s plan to cull threatened white sharks has stirred up plenty of protest from the community, and a frenzy of media coverage and commentary (see Conversation articles here and here and here).

But new research is showing that there are hundreds of species of sharks and rays that face an increased risk of extinction, not just the couple of species that grab the media spotlight.

A new study published today in the journal eLife has for the first time estimated the risk of extinction across all 1041 species of sharks and rays that make up an entire class of vertebrates. This first-ever study undertaken by the International Union for Conservation of Nature (IUCN) Shark Specialist Group took the expertise of over 300 scientists around the world to complete.

Bleak picture

The results paint a bleak picture of the status of this important group of ocean predators. Approximately one quarter of the known species are estimated to be threatened according IUCN Red List categories and criteria, mostly as a result of overfishing.

Possibly even more concerning is the result that 47% of species were assessed as Data Deficient, meaning that we don’t have enough information to properly assess their status. Clearly there is a need for a lot more science to help manage a group that is obviously under threat.

Many people who hear these grim statistics will think of shark finning (where the fins of sharks are cut off at sea and the bodies dumped) as the likely reason for the declines. While finning is a major factor in the decline of some populations it is far from the main reason that many of these species are threatened with higher chances of extinction.

We don’t know nearly enough about thresher sharks. All three species are listed as Endangered on the IUCN Red List. Flickr/Raven_Denmark

Why? Because more of species that are globally threatened are rays (107 species vs 74 species of sharks), most of which do not have fins suitable for the fin trade. Incredibly, five of the seven families that are most threatened are rays. One of the shark families is the angel sharks, which also have flat, ray-like bodies.

Warning signs

That there is such a crisis for rays has come as a shock, even to many involved in the study. Could we have predicted such a perilous status for rays? Possibly.

It turns out that since the mid-1970s the landings of rays reported to the UN Food and Agriculture Organisation has consistently been higher than sharks. So now the challenge will be to get the rays the attention that they need so that we can start to address these declining populations.

The benefit of the global analysis is also that we can identify geographic regions where the threats are greatest. The three areas where humans have had the greatest effects on shark and ray populations are western Indonesia/Thailand, the Red Sea and the Mediterranean Sea.

While these three areas are the hotspots of concern, there is nowhere that sharks and rays have not been affected – this is truly a global problem. So while some countries have worked hard to secure the future for many of their shark and ray populations (such as Australia, New Zealand and the US) by having science-based catch limits, many others have little or no regulation.

Reversing the trend

Given the diversity of the species, and differing capacity of countries, reversing the declines of sharks and rays will not be simple. Some countries have well developed science-based management while others lack the resources for comprehensive or even basic fisheries management.

Angel sharks might not have valuable fins, but they are still targeted. They’re the second most threatened group of sharks. Flickr/Philippe Guillaume

Few situations, however, would not benefit from improved data collection, particularly with respect to prompt and accurate reporting of species-specific catches.

Through the International Plan of Action for Sharks, the UN Food and Agricultural Organisation provides not only directives for completing valuable national and regional plans, but also technical guidance and the promise of more tailored assistance toward conservation for developing countries.

Globally, completion and full implementation of these key plans remains patchy. Their development, however, should not stand in the way of the urgent need to control – and in most cases – reduce fishing mortality of sharks and rays (from targeted and incidental catches). While these challenges may seem daunting, key steps can make a difference.

The real take home message from this new study is best summed up by Sonja Fordham, IUCN SSG Deputy Chair and president of the Washington, DC-based Shark Advocates International, a project of The Ocean Foundation:

Significant policy strides have been made over the last two decades, but effective conservation requires a dramatic acceleration in pace as well as an expansion of scope – to include all shapes and sizes of these exceptional species. Our analysis clearly demonstrates that the need for such action is urgent.

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