Sharks and rays are in devastating decline a global solution is needed – chinadialogue ocean

The study attributes these declines to overfishing. The researchers documented a greater than twofold increase in fishing pressure from longline fisheries, for instance, which use lines stretching up to 100km and bearing 1,200 baited hooks. These lines are deployed each day by any one of the thousands of longlining vessels worldwide, snaring sharks in the open ocean either intentionally or as bycatch while targeting other marine life.

The study also found increases in the proportion of sharks being fished beyond sustainable levels. Its particularly worrying that unreported catches werent included in the studys analyses. This means the number of sharks and rays killed by fishing boats is likely to be an underestimate and the actual declines of these species may be even worse. Unlike most species of bony fish, sharks and rays produce few offspring and grow slowly. The rate at which they reproduce is clearly no match for current levels of industrialised fishing.

Immediate and far-reaching action is needed to rebuild these populations. Its clear that the rate of overfishing has outstripped the implementation of fisheries management measures and trade regulations. Since most oceanic sharks and rays are caught in the high seas areas beyond national jurisdictions agreements between fishing nations within management organisations are needed for conservation measures to work.

But, as this new study details, fishery limits imposed by management organisations of regional tuna fisheries bodies tasked with managing oceanic sharks and ray populations have largely failed to follow scientific advice. As recently as November 2020, the EU and US blocked a catch retention ban for North Atlantic shortfin mako sharks, despite scientific evidenceclearly indicating that it was the first rung on a ladder to restoring this population of an endangered species.

To begin the recovery of oceanic shark and ray populations, strict measures to prohibit landings of these species and to minimise their bycatch in other fisheries are needed immediately. This must be coupled with strict enforcement. Reducing the number of sharks and rays caught accidentally will be crucial but challenging, especially for longline fishing, which inadvertently catches lots of different species. This means bans on intentional fishing are unlikely to be effective on their own. One solution would include modifying fishing gear and improving how fishers release sharks and rays after capture, to give them a better chance of survival.

An equally important measure, noted in the current study, would be banning fishing fleets from hotspots of oceanic sharks and rays.Research published in 2019 highlighted where these areas overlap most with fishing vessels. Led by the UN, negotiations are underway for a high seas treaty which would create no-take marine reserves to protect threatened species in the open ocean. This new study should urge the international community to take such action while theres still time.

This article was first published in The Conversation.

The rest is here:

Sharks and rays are in devastating decline a global solution is needed - chinadialogue ocean