Overfishing has killed populations of sharks and rays by more than 70 percent in the last 50 years, leaving a “gaping, growing hole” in ocean life, according to a new study. Among the worst-affected is the oceanic whitetip shark.
The animal is almost extinct because of human activity. The sharks are targeted for their fins. Their global population has dropped 98 percent in the last half-century.
“That’s a worse decline than most large terrestrial mammal populations,” Nick Dulvy, a professor at Simon Fraser University’s department of biological sciences, told AFP.
Dulvy and a team of scientists spent years collecting and analyzing information from scientific studies and fisheries data to build up a picture of the global state of 31 species of sharks and rays.
They found three-quarters of the species examined have been killed so much by humans, that they are threatened with extinction. “The data revealed a gaping, growing hole in ocean life,” the study’s lead author Nathan Pacoureau told AFP.
Three sharks were found to be critically endangered, with their populations declining by more than 80 percent: the oceanic whitetip shark, scalloped hammerhead and great hammerhead.
Sharks and rays are especially vulnerable to population collapse because they grow slowly and reproduce comparatively infrequently.
The study, published Wednesday in the journal Nature, blames overfishing and weak protection, and calls for tighter restrictions and better implementation of existing rules.
Pressure governments to care for sharks
The study notes an increase in the use of fishing with longlines and seine nets — methods that can kill all marine life, including endangered animals.
Regional governments that manage international fisheries “have not prioritized shark and ray protection,” Pacoureau said. “Proactive measures can prevent population collapses. And we know they work,” he added, pointing to the recovery of great white sharks around the US after new regulations.
Dulvy said that citizens had a role to play by pressing governments to meet their national and international commitments: “Wherever you can, urge your government to care for sharks.”