KINGSTON, R.I. – January 4, 2012 – University of Rhode Island sophomore Chelsea Stephens spent the last six months testing a new method of catching sharks that reduces the chance the animal will die. The marine biology major from Dover, Del., found that the use of “hook blockers” significantly reduced the number of sand tiger sharks that were hooked in the gut after swallowing the bait.
“Sand tiger sharks are a protected species, and their population has been decreasing rapidly in recent years,” said Stephens. “If fishermen catch them, they have to be released. But the sharks swallow their food whole – they’re kind of like a vacuum cleaner — so they have a tendency to get gut hooked, which can cause them serious damage. So even if they’re released they still might end up dead.”
Working in collaboration with URI lecturer Brad Wetherbee and colleagues at Delaware State University, Stephens spent several weeks last summer testing the use of hook blockers, a 10-inch piece of PVC pipe attached to the fishing line 7 inches above the hook, which gets caught in the corners of a shark’s mouth so the hook cannot go too far down its throat.
In Delaware Bay, the researchers put out 1,200 feet of line with 24 baited hooks attached at 50-foot intervals, half with hook blockers and half without. After two hours, the line was pulled in by hand, which Stephens said felt “like you’re hauling up the bottom of the ocean when you have a big shark on the line. It’s a good workout.”
They caught from 3 to 20 sharks each time, with the largest being about 10 feet long and weighing more than 200 pounds. Only two sharks were gut-hooked using the hook blockers, and those were especially large sharks whose mouths were wider than the length of PVC pipe. About one hundred sharks were gut-hooked on hooks without the blockers.
“The blockers definitely worked, and now we want to let the scientific community know that they work and that they’re inexpensive and easy to use,” said Stephens. “If you’re a scientist doing conservation work tagging and tracking sharks, you should use the blockers because they reduce the mortality rate.”
She encourages recreational shark fishermen to do the same when they are in waters inhabited by sand tiger sharks. “Most other sharks don’t swallow the hook, so it’s only useful on those species that eat the same way sand tigers do.”
Stephens’ research was conducted as part of the URI Coastal Fellows Program, a unique initiative designed to involve undergraduate students in addressing current environmental problems. Now in its 17th year, it is based at URI’s College of the Environment and Life Sciences. Students are paired with a mentor and research staff to help them gain skills relevant to their academic major and future occupations.
The poster Stephens created illustrating her research won first prize among the 50 Coastal Fellows who exhibited their research at the University on Dec. 12.
A member of the URI Marching Band and its Quidditch team, Stephens said that her first research experience taught her a great deal about the research process, as well as how to maintain boats, splice ropes, and other useful skills. She hopes to tackle a different project next summer through the Coastal Fellows Program or as an intern with the National Oceanic and Atmospheric Administration. She ultimately aims to earn a Ph.D. in marine biology and become a college professor.
Photos submitted by Chelsea Stephens