Sarasota Dolphin Research Program

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Assessment of interactions between bottlenose dolphins and sport fishing in northwest Florida and Alabama
By Steve Shippee, PhD Candidate, University of Central Florida

Locations of reported human-dolphin interactions in the Southeast Region.

Sport anglers in the North Central Gulf Coast frequently complain to fisheries managers that interactions with bottlenose dolphins are on the rise. Charter operators and private anglers regularly report negative encounters with aggressive dolphins during deep-sea fishing trips. Gulf pier fishermen also commonly report problems with dolphins taking their catch. Fisheries interactions consist of three types: depredation (dolphin removes catch from fishing gear); scavenging (dolphin takes fish that have been discarded by an angler); and incidental encounters (dolphin becomes snared due to proximity to fishing activity). To better understand these issues, last summer I began to observe deep-sea and pier fishing over a two-year period. The primary study locations are the sport fishing ports of Destin, FL and Orange Beach, AL, plus shore fishing piers at Fort Walton Beach and Pensacola, FL (see map). This work also ties together with long-term dolphin photographic identification projects underway in both areas. The project goals are: 1) to assess the frequency and characteristics of these fishery interactions; 2) to estimate the size of the subpopulations of dolphins involved; 3) to identify dolphin movement patterns around the region and between sites; 4) to investigate methods to mitigate adverse interactions; and 5) to conduct outreach aimed at public education about this problem. I am using photo-identification to develop a catalog of individual dolphins in the areas to compare to those seen on fishing observations.

Dolphin scavenging on discarded fish.

Since summer of 2008, I have observed over 48 deep-sea fishing trips and made over 64 visits to piers. Dolphins have been observed nearby on 55% of deep-sea trips and 48% of pier visits, and fishery interactions have been observed 35% and 16% of the time, respectively. The preliminary findings show that most incidences of depredation on deep-sea fishing trips are in conjunction with scavenging of discarded fish. Because fisheries management regulations require anglers to release numerous species of regulated sport fish, there is a steady supply of discards for dolphins to scavenge. Although many dolphins seen interacting on deep-sea trips appeared to only engage in scavenging, I occasionally observed animals that aggressively stripped caught fish off lines. This happens at less than half the rate of scavenging but is a more worrisome behavior due to the potential for injury to the dolphin. In addition, there have been several dolphins identified so far that were observed on more than one deep-sea trip, one of which was identified at reef sites 60 km apart. At the piers, most interactions involve depredation since pier anglers typically do not discard many fish. Most of the dolphins identified at the fishing piers are known residents of the nearby bays, and many have been seen repeatedly at each pier. Several dolphins have been seen at both fishing piers, which are 53 km apart, and at least two have been seen in both Pensacola and Choctawhatchee Bays, which are 70 km apart. It is not yet possible to tell if the inshore dolphins also frequent the offshore reefs, as the analysis is incomplete.

I am working with several sport charter operators to explore means of reducing dolphin depredation of fishing lines and ways to effectively release fish so that dolphins are less likely to scavenge them. This includes modifying fishing tackle using tickler wires and use of fish release devices such as descender weights and baskets. We will continue to explore the practicality of these ideas in the coming year. I have also engaged local community organizations to conduct public education at outdoor events, seminars, and schools in order to bring attention to the potential harm to dolphins and other marine wildlife from entanglement, incidental human provisioning, and aggressive encounters with anglers. The eventual result of this project will be to foster an appreciation of dolphin-friendly sport fishing practices that also conserve fish and wildlife. This project is funded by the Mississippi-Alabama Sea Grant Consortium under the U.S. Department of Commerce’s National Oceanic and Atmospheric Administration.

Dolphin alongside deep-sea fishing boat.