Ten sharks tagged in conservation project

Feared for their reputation as the deadliest fish in the water and ruthlessly hunted for their large fins, oceanic whitetip sharks are disappearing from the western Atlantic at an alarming rate.  

Now researchers in Cayman are doing their part to save the species by tagging and tracking sharks caught in Cayman’s waters. 

Nine oceanic whitetip sharks were caught and fitted with satellite tags by experts from the Guy Harvey Research Institute during a fishing competition last month. 

The tags will help scientists monitor their movements for up to three years to help establish basic information about the lives of the mysterious ocean hunters. 

Alexandrea Prebble, director of operations at the Guy Harvey Ocean Foundation, said oceanic white tips were once among the most abundant pelagic shark species in the world.  

But they have been hit hard by overfishing to fuel the shark fin soup trade and numbers have declined by 98 percent in the last 30 years, according to the International Union for Conservation of Nature, which lists the species as critically endangered in this region. 

Cayman, because of its proximity to deep ocean trenches, is one of a few places where oceanic whitetips come close to land, making it an ideal spot for tagging. 

The tagging expedition last month was timed to coincide with the Kirk Slam fishing tournament, with anglers supporting the effort. 

“As soon as an oceanic whitetip was hooked, one of three boats raced to take the shark of their hands tag it and let it go as fast as possible,” said Ms. Prebble. 

Tagging a 10-foot shark is not an easy task, but Ms. Prebble said the researchers have it down to a fine art. 

Once caught, the shark is secured alongside the boat, the researchers drill a hole in its dorsal fin and bolt the satellite receiver to the fish. Measurements and sex data, as well as a DNA sample, are taken. The whole process takes around five minutes and has little effect on the shark, according to Ms. Prebble, 

“All the sharks were in excellent condition and made a rapid departure on release,” she said. 

The Smart Position and Temperature tags send a signal to a satellite every time the shark’s fin breaks the surface. The data allows researchers to keep a track of its movements, which are logged on the website at www.nova.edu/ocean/ghri/tracking. 

The data will be used for scientific papers by the Guy Harvey Research Institute and will be available to other scientists and the public. 

“The baseline knowledge about oceanic whitetips is actually very little. Unless we know what they do and where they go, it is hard to protect them,” said Ms. Prebble. 

Oceanic whitetips, described by diving pioneer Jacques Cousteau as the “most dangerous of all sharks,” are believed to be responsible for several fatal attacks on humans, mostly as a result of predation on survivors of shipwrecks or downed aircraft. Oceanic whitetips were famously blamed for picking off the survivors of the USS Indianapolis, a navy ship that was torpedoed during the Second World War.  

Ellen Cuylaerts, a Cayman Islands-based photographer who has swam with and photographed the species off Cat Island in the Bahamas, said the reputation of sharks as mindless man eaters was unjust and partially responsible for the huge decline in numbers. 

She said by observing some basic precautions and showing mutual respect for the sharks, it was possible to safely swim with them in the wild. 

“Simple rules makes it possible to observe these magnificent animals in the wild. Sharks are the top predators of the ocean and feed on the weakest or sick animals. That keeps the fish population healthy and the reefs clean and healthy. It’s about balance. 

“Photographing them in their peaceful and natural behavior helps me to spread awareness and education about their important role in the food chain,” she said. 

Ms. Cuylaerts is concerned about the decline in shark populations generally, which she says is “devastating for the health of the oceans.” But she is not convinced that tagging is the answer. 

“I have seen lots of tagged sharks and also a lot of sharks wounded and stressed by tagging,” she said. “As a nature photographer, I don’t like it unless the research that follows the tagging is really needed and significant, which I sometimes doubt.  

“Lots of tagging is to track the sharks and their migration patterns, but the same results can be obtained by getting people on the water involved, like fishermen and divers, and start to ID them.” 

Mahmood-Shivji-Bradley-Wetherbee-Tagging-Sharks-S

Mahmood Shivji and Bradley Weatherbee get to work tagging a shark in Cayman.
0
0

NO COMMENTS