Quantification of the Interaction between Bottlenose Dolphins and the Atlantic Blue Crab Fishery in Charleston, South Carolina
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Entanglement in commercial fishery equipment is the number one anthropogenic cause of marine mammal death worldwide. The Atlantic blue crab fishery is the number one cause of fishery related incidents for bottlenose dolphins (<italic>Tursiops truncatus</italic>) in South Carolina. It is hypothesized that the dolphins are attracted to the pots either by the bait or possibly the other marine life drawn to the pots. Hydrophones deployed in baited and unbaited crab pots recorded dolphin vocalizations which were used as proxy for dolphin presence. Recorded data were used to quantify the interaction between dolphins and crab pots as well as elucidate the effects of tide, bait presences, and time of day on the interactions. Sonar imaging was deployed to determine if prey species aggregated around the crab pots and whether bait presence affects the fish activity. The hydrophones recorded 1,103 hours of audio data, and 18 hours of visual data were recorded by the dual-frequency identification sonar. The results found that dolphin interactions with the crab pots were not significantly impacted by the presence of bait. Time of day and tidal stage did affect the frequency and duration of interactions. Prey species were observed aggregating around the crab pots and no impact of bait presence on fish activity was observed. Results from this study will aid in the understanding of when and why bottlenose dolphins intearct with the Atlantic blue crab fishery. Such information can then be used in the formulation of preventative measures against entanglement.