URI Shark Researcher Worries Fishermen May Capture His Research Subjects

By ecoRI News staff

Mako sharks have a worldwide distribution, so they are among the most commonly captured shark in the finning trade. (istock)

Mako sharks have a worldwide distribution, so they are among the most commonly captured shark in the finning trade. (istock)

KINGSTON, R.I. — It’s the peak of shark fishing season, when hundreds of fishermen enter tournaments throughout southern New England and Long Island to catch the biggest shark. It has Bradley Wetherbee worried.

The University of Rhode Island shark researcher knows that one mako shark he tagged off the coast of Maryland last year — which a sponsor named Charlotte — arrived in Rhode Island waters last week after a yearlong, 6,500-mile journey. And given his track record of having his tagged sharks captured and killed by commercial and recreational fishermen, Wetherbee has his fingers crossed that Charlotte survives the month.

“Makos are caught in all kinds of fisheries all around the world,” he said. “They’re the shark everyone wants to catch because they’re good to eat — like a shark version of swordfish — and they fight and jump and put up a big battle.

“But it takes a great deal of effort and money to catch and track sharks, and we don’t want to see our research subjects captured and killed and lose their contribution to science.”

Wetherbee doesn’t object to shark fishing. In fact, his research is aimed at collecting information about the animals so they can be better managed. He just hopes that any fisherman who catches Charlotte or any other shark with a satellite tracking tag on its fin will release the shark unharmed.

Little is known about the health of mako shark populations, the migratory routes they travel, or their preferred feeding grounds. Wetherbee hopes his research will help to answer some of those questions. Makos are especially difficult to manage because they travel through the waters of dozens of countries, thereby requiring significant international cooperation to protect them from overfishing.

Fishing isn’t the only threat to mako shark populations, however. The demand in China for shark fin soup is causing 70 million sharks to be killed annually for their fins. And while little shark finning takes place in New England waters, mako sharks have a worldwide distribution, so they are among the most commonly captured shark in the finning trade.

Wetherbee and his colleagues at the Guy Harvey Research Institute at Nova Southeastern University have tagged more mako sharks in the Atlantic Ocean than any other scientists. The satellite tags they attach to the sharks’ fins enable the researchers to track the animals’ movements daily, which is how Wetherbee knew exactly when Charlotte arrived back in Rhode Island waters. It’s also how he knows that nearly a third of the 50 mako sharks he has tagged in recent years have been caught and killed by fishermen.

“It’s easy to see the track lead right to a port somewhere and the tag just ends up sitting on a dock,” he said.

The data Wetherbee is collecting from his tagged sharks is providing estimates of mako shark mortality that are far higher than scientists once believed.

“So it’s possible that they are being overfished much more than previously thought,” Wetherbee said.

His tagged sharks have moved through the waters of 27 countries. One shark traveled 14,000 miles in one year, and many have traveled more than 10,000 miles. Charlotte’s route took her from Maryland to Virginia, then north to Rhode Island and Long Island, where she spent several months last fall. She then returned south to North Carolina, before going on a two-month loop far out into the Atlantic in April and May. She returned to south coastal waters in June, and then traveled to Rhode Island, where she arrived last week.

“It’s information that no one had any idea about — their movements, how much time they spend in the north in winter, the countries they visit,” Wetherbee said. “It’s generating a lot of great information that is useful for managing shark populations.”