UNE's John Mohan presents at regional marine research conference

Portrait of John Mohan
John Mohan. Ph.D., assistant professor of marine sciences.

John Mohan, Ph.D., assistant professor in the School of Marine and Environmental Programs and principal investigator of the Shark and Fish Ecology Lab at UNE, recently presented his research on novel methods to conserve shark populations at the Blue Ocean Society for Marine Conservation’s 2024 research symposium on March 29.

At the symposium, held at the Star Theater in Kittery, Maine, Mohan gave a talk entitled “Promoting Conservation of Sharks by Developing Innovative Technology and Engaging Stakeholders in Fisheries.” The event was attended by several prominent marine science researchers and educators from Maine and New England.

Among other topics, Mohan’s talk centered around work he and his students have done to pilot a novel method of preventing sharks from ending up caught in the fishing lines of both commercial fishermen and recreational anglers.

According to Mohan, shark populations have experienced significant decline over the past few decades, with a large proportion of losses attributed to overfishing. Increased shark mortality rates can be driven by unintended capture in commercial fisheries, known as bycatch. Recreational fisheries can also contribute to the post-release mortality of sharks.

Few effective methods have been demonstrated to reduce shark bycatch, and post-release mortality rates remain difficult to quantify, Mohan said.

To combat bycatch, preserve shark populations, and promote fisherman safety, Mohan and his students have researched the effectiveness of small devices known as electronic bycatch reduction devices, or BRDs, which emit electrical signals that target the sharks’ electro-sensory systems and deter them from the bait.

Students in the Mohan Lab are researching if the devices can be placed both on commercial fishing lines and recreational rods to ward off sharks and prevent them from becoming mixed up in the fishing haul. Recent lab trials have shown a 50% reduction in bites of a small shark species, known as spiny dogfish, on lines with active BRDs.

These preliminary results are encouraging, Mohan said, adding that he is co-organizing a symposium on shark deterrent technology at the American Fisheries Society symposium this September, where he will gather experts in the field of bycatch research and learn what approaches prove effective or ineffective at protecting sharks.

Mohan completed his Ph.D. in marine science at the University of Texas Marine Science Institute, with a focus on fish ecology and natural chemical tracers. He was a postdoctoral researcher and research scientist at Texas A&M University at Galveston in the Shark Biology and Fisheries Science Lab before relocating to New England. 

Read more about Mohan’s and his students research in the 2023 UNE Magazine, “Faces of Our Future: Empowering Students to Build a Better Tomorrow.”

Mohan (right) and Michael Nguyen inspect a bycatch reduction device.