An international team of researchers, led by the University of Massachusetts at Amherst, has compiled a massive dataset that spans years of information on the position, migration and interaction of sharks and game fish. This research has immediate relevance to anglers, who report increased contact with sharks over the years. The research, recently published in Ecological Applications and which draws on innovative use of acoustic telemetry and machine learning, gives us the clearest window yet into complex ecological relationships and promises to be a tool useful in ongoing conservation efforts.
“It’s so rare to observe multi-species interactions in the ocean,” says Lucas Griffin, co-lead author of the paper and postdoctoral fellow in environmental conservation at UMass Amherst. Indeed, species such as those the researchers focused on – great hammerheads and bull sharks, permit and Atlantic tarpons – can span hundreds of square miles of open ocean. . There has long been anecdotal evidence from the big game fishing community that cases of depredation – when a shark eats a fish that has been hooked – are on the rise, but to date there is no had hard data to back up whether or not such encounters are actually increasing and, if so, why.
For this study, the researchers focused on the coastal regions of the Florida Keys. Over a three-year period, the collaborative team deployed nearly 300 acoustic receivers and tagged 257 fish (including 73 sharks) with transmitters. Each time one of the tagged sharks or fish swam within range of the receiver, its presence was recorded and tagged with the date and time. This approach, called acoustic telemetry, gave the team unprecedented access to the migration, reproduction and feeding patterns of sharks and gamefish. The team then ran their raw data through a state-of-the-art machine learning algorithm to model the incredibly complex interplay of environmental factors, such as time of year, lunar cycle, ocean depth and temperature. water.
“The combination of acoustic telemetry and machine learning has helped us answer a host of questions about predators and prey,” says Grace Casselberry, the paper’s other co-lead author and graduate student at the UMass Amherst Department of Environment Marine Science and Technology program. Preservation. It turns out that tarpon and permit return to the same spawning grounds, at the same times of the year, every year. The sharks know this: “They seem to remember where and when the tarpon and the permit congregate,” Casselberry explains. The same goes for anglers who, after years of word of mouth telling when fish are biting where, end up trying to catch the same fish that sharks feed on. Knowing this, fisheries managers can adapt their management strategies to better protect the interests of sharks, fish and fishermen.
Finally, the team’s research is innovative not only in its methods, but also in its cooperation. A wide range of institutions have shared data on tagged fish, including research institutes, like the University of Miami and Bimini Biological Field Station in the Bahamas, with state agencies, like Florida Fish and Wildlife. Conservation Commission, and non-profit environmental groups, Bonefish & Tarpon Trust. “We also worked extensively with the local fishing guide community to help tag fish and sharks and determine where to place receivers,” says Griffin. “Our lab embraces a spirit of collaboration and cooperation,” says Andy Danylchuk, professor of fish conservation at UMass Amherst and one of the paper’s lead authors. “We are grateful to our research partners and hope that our science will help refine conservation and management strategies for fish and sharks.”