By Tonya Wiley
The world’s sawfishes are rightfully once again in the global conservation spotlight as a new analysis published in the journal Current Biology highlights the mounting threats facing the world’s sharks, rays, and chimaeras (chondrichthyan fishes). The study finds that a third of these species are now threatened with extinction, due primarily to overfishing, and that depletion is most severe in tropical and subtropical regions.
The authors assessed nearly 1,200 shark, ray, and chimaera species against International Union for Conservation of Nature (IUCN) Red List criteria and found that 391 (32%) qualify as Critically Endangered, Endangered, or Vulnerable. Species classified in these three IUCN categories are considered threatened with extinction. This second global chondrichthyan assessment finds twice as many species threatened as the first such analysis in 2014. Chondrichthyans now rank second among vertebrates (after amphibians) in terms of extinction threat.
Extinction risk is shown to be greatest for large-bodied, warm-water, coastal elasmobranchs, such as sawfishes. More than three-quarters of tropical and subtropical chondrichthyans are threatened. Rays are the most imperiled of the three chondrichthyan fish groups, with 41% of species threatened, compared to 36% of sharks and 9% of chimaeras. The sawfishes remain among the top five most threatened chondrichthyan families, along with wedgefishes, giant guitarfishes, devil rays, and pelagic eagle rays.
Head Out of Water by Tonya Wiley 
Tagged swimming to credit Beau Yeiser 
Bowmouth GuitarShark Southern Mozambique
Overfishing is main risk for all of the 391 chondrichthyans classified as threatened. About one-third of these species are also imperiled by habitat degradation. Climate change currently affects about 10% of threatened chondrichthyans but is a rapidly emerging concern.
The authors review the importance of chondrichthyans to marine ecosystems and the species’ inherent vulnerability to overfishing (due to slow growth and relatively low numbers of offspring). In noting how overfishing has outpaced effective management, they flag governments’ poor overall performance in fulfilling conservation obligations under treaties such as the Convention on International Trade of Endangered Species and the Convention on Migratory Species. (Sawfishes received the highest level of protection under these two treaties many years ago but implementation of basic safeguards has been seriously lacking.)
The paper includes an urgent call for chondrichthyan conservation action, particularly limits on fishing. As a general rule, retention of Endangered and Critically Endangered species should be prohibited. Most chondrichthyans would benefit from programs to minimize incidental catch and associated mortality. Area closures to further restrict fishing and protect habitats can improve chances for recovery while rebuilt populations are best positioned to withstand climate change. Immediate remedies outlined in the paper that would help sawfish in particular include strict retention bans, protections for key habitats (such as mangroves), and full implementation of various international commitments to ban trade, pursue regional conservation initiatives for shared populations, etc.
Overfishing drives over one-third of all sharks and rays toward a global extinction crisis, is available online as an open access publication.
This piece was prepared online by Panuruji Kenta, Publisher, SEVENSEAS Media