Great hammerhead shark washes up on Jacksonville Beach

Experts say shark likely died from catch and release stress

By Elizabeth Campbell - Reporter

JACKSONVILLE BEACH, Fla. - An endangered species of shark was found dead in Jacksonville Beach about two weeks ago.

A 10 foot great hammerhead shark, a protected species in Florida, and globally endangered, was found dead, washed along the shore in Jacksonville Beach.

Experts believed it likely died from the stress of being caught and released.

News4Jax spoke with shark experts about why hammerhead sharks are more susceptible to stress from being caught, even if they're put back in the water.

University of North Florida shark biology graduate student John Whalen got a picture from a friend a couple of weeks ago of a 10 foot great hammerhead shark. Whalen and other UNF researchers believe this mature female shark died as a result of stress from capture by a recreational or commercial fisher.

“There's a high mortality rate because of fishery related stress for hammerheads, something with their physiology, but as the fight time increases with the hammerhead on the line, the cortisol levels increase as well. Cortisol is a stress hormone, so when these hormones increase subsequently the shark will have a higher likelihood of dying,” Whalen said.

Even off of the Jacksonville Beach pier, it's not uncommon to catch a shark. Hearing the way this hammerhead shark likely died makes fishermen, like Jamie Strongosky, even more vigilant when catching and releasing a fish.

“Like any other fish, you have to revive it,” Stongosky said. “I think the only thing you can do is try to drag it into deep water and try to get it out into the open water -- kind of push it back out there to get the water circulating to the gills again.”

Many types of hammerhead sharks, including the great hammerhead, are protected in Florida, meaning if someone catches one, by law, they have to release it. Whalen's professor, Jim Gelsleichter, said fishermen can't control what they catch on their lines, but they can be more aware.

“Once they identify (the shark), they should really not be continuing the fight, so to speak,” Gelsleichter said. “They should be trying to cut the line as close to the hook as possible and release the animal while still in the water.”

The next step for UNF biologists with the 10-foot shark is to age it, which they said they can do by counting vertebral rings on its spine -- similar to counting rings on a tree. They said they may possibly use the skeleton for educational outreach.

“We took it back to our necropsy lab, and the hammerhead took up almost a whole table,” Whalen said. “We ended up dissecting, and we found a hook wound just in the corner of its mouth. It looks to be fresh, so were thinking it was probably caught recently and subsequently died after that.” 

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