A team of researchers with members from the AZTI, Marine Research, Basque Research and Technology Alliance, the International Seafood Sustainability Foundation and Simon Fraser University's, Earth to Ocean Research Group has found that while tuna and billfish are responding positively to conservation efforts, sharks are not and their numbers continue to drop.
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Tuna and billfishes are large species that have long been targeted by fisheries, whereas sharks, which are also large fishes, have tended to be considered as by-catch or nontarget species.
After almost three decades of decline, tuna and billfishes have begun to recover because of proactive fisheries management approaches.
Sharks, however, which have received much less conservation attention, have continued to decline.
These results both reinforce the value of conservation and management and emphasize the need for immediate implementation of these approaches for sharks.
"We find that since 1950, the global extinction risk of oceanic predatory fishes has continuously worsened as a result of rising and excessive fishing pressure, up until the late 2000s when management actions reduced fishing mortality, allowing for recovery of tunas and billfishes.
"However, sharks remain undermanaged and their extinction risk continues to rise.
"Our findings reveal a core problem and ongoing challenge in the management of oceanic multigear and multispecies fisheries.
"Whereas target species are increasingly sustainably managed to ensure maximum yields, the functionally important shark species being captured incidentally by the same fisheries continue to decline as a result of insufficient management actions.
"Furthermore, our study also connects annual changes in global extinction risk with changes in fishing mortality over the last 70 years, demonstrating how the global RLI trajectory of oceanic predatory fishes is highly sensitive and responsive to fishing mortality.
"Although halting biodiversity loss by rebuilding highly valuable commercial tuna and billfish species has been achieved, the next challenge is to halt declines in shark species by setting clear biodiversity goals and targets as well as implementing science-based conservation and fishery management measures and international trade regulations.
"Unless an effective mitigation hierarchy of management actions to reduce shark mortality is urgently implemented (and adapted to the complexity of each fishery and shark species), their risk of extinction will continue to increase.
"Furthermore, we demonstrate a high alignment and complementarity between the current population-level Red List status and fishery exploitation status of tunas, billfishes, and sharks, when applied at the same scale.
"Although we do not propose that the RLI be used to manage fish populations, this strong alignment eliminates any technical barrier for use of the RLI by policy-makers for tracking CBD and SDG targets." ■