Researchers looked at how sharks respond to stress imposed by catch-and-release fishing.
The team found a variety of responses across different shark species; but found hammerheads were the most vulnerable to human-caused stress, a University of Miami Rosenstiel School of Marine & Atmospheric Science news release reported.
The team simulated catch-and-release fishing in "hammerhead, blacktip, bull, lemon and tiger sharks," the news release reported.
The researchers conducted reflex tests on the sharks and looked at "stress, including pH, carbon dioxide and lactate levels." They also used satellite tags to keep track of the shark's movement and survival rates.
"Our results show that while some species, like tiger sharks, can sustain and even recover from minimal catch and release fishing, other sharks, such as hammerheads are more sensitive" lead author and Abess Center Ph.D candidate Austin Gallagher, said in the news release. "Our study also revealed that just because a shark swims away after it is released, doesn't mean that it will survive the encounter. This has serious conservation implications because those fragile species might need to be managed separately, especially if we are striving for sustainability in catch and release fishing and even in bycatch scenarios."
The team observed a change in lactate levels in the sharks that had been forced to fight on a fishing line; these levels are similar to what can be seen in humans when they participate in exhausting physical activity. This has been linked to an increase in mortality in fish.Hammerheads showed the greates signs of this phenomenon.
"Many shark populations globally are declining due to overfishing. Shark anglers are some of the biggest advocates for shark conservation. Most have been making the switch from catch and kill to all catch and release. Our study helps concerned fisherman make informed decisions on which sharks make good candidates for catch and release fishing, and which do not, such as hammerheads," study co-author Dr. Neil Hammerschlag, a Research Assistant Professor at UM, said.
