To save an endangered shark, Atlantic Ocean fisheries managers must act now
In November, regional fisheries managers are again faced with the decision to unite to support the recovery of the North Atlantic porbeagle, a population not commercially targeted but on the verge of collapse due to decades of collateral damage to longline fisheries targeting blue shark and swordfish.
The adoption of the mako stimulus package is long overdue
In 2019, scientists from the International Commission for the Conservation of Atlantic Tunas (ICCAT) recommended a total ban on the retention of North Atlantic porbeagle sharks by fishing vessels. Scientists also noted the need for additional management measures, such as fishing restrictions for specific times and locations – called space-time closures – modifications to longline gear, and the requirement that all shortfin mako sharks captured are released alive and handled in a way that improves their likelihood. survival. Despite recommendations from ICCAT scientists, governments have repeatedly delayed taking necessary action, including at a meeting in July to address this management failure. The commission will hold its virtual annual meeting from November 15 to 23.
Rebuilding the endangered mako population will now require a multi-pronged approach, with science highlighting the need for a drastic reduction in catches. Among the measures needed are measures to control bycatch, such as a ban on retaining makos and gear changes to reduce the likelihood of bycatch. In addition, new research is also providing more support for space-time closures as another tool to help this species recover.
Why space-time closures work
Space-time closures prohibit fishing activities in certain areas at certain times of the year in order to protect vulnerable species or habitats. While the use of modified longline gear would reduce mako mortality if caught, space-time closures prevent many blue-finned makos from being hooked in the first place. Arguments in favor of spatio-temporal closures for sharks are growing, including a forthcoming paper which, using publicly available ICCAT data, concludes that it is possible to identify areas where catches of shortfin mako shark can be reduced more substantially and faster than the capture of the target species. swordfish and blue sharks in the North Atlantic.
Although the data is not detailed enough to serve as a single basis for specific spatiotemporal closures for the benefit of makos, the paper identifies some areas where the benefits could outweigh the decline in targeted catches. And when these areas overlap with possible nursery areas (for example, the waters around the Canary Islands and the northwest coast of Africa), the potential benefits of conservation would be magnified. Closing these areas to all longline fishing would provide additional protection to juveniles and larger breeding females, both present in the nursery areas. Used with no retention measures, space-time closures can clearly help rebuild the shortfin mako shark population.
Comprehensive measures needed
Managers should only consider space-time closures in addition to a non-retention measure, not instead of one. Increased data sharing and transparency, as well as more research, are needed to identify and design effective closures that maximize catches of target populations while minimizing mako bycatch.
One thing is clear: as governments prepare for the ICCAT annual meeting in November, it is essential that they finally reach agreement on the measures needed to sufficiently reduce mako shark mortality in the fisheries of the United States. ‘Atlantic. A multi-pronged management approach that does not include any retention and mitigation measures, such as space-time closures, is needed to first slow the ongoing decline of makos and, at some point, help to rebuild the population of the North Atlantic.
KerriLynn Miller is Associate Director and Grantly Galland is Senior Executive of The Pew Charitable Trusts International Fisheries Project.