AN ANALYSIS OF ENVIRONMENTAL CONDITIONS AND FISHERMEN ACTIVITY POTENTIALLY INFLUENCING THE ENTANGLEMENT OF BOTTLENOSE DOLPHINS (Tursiops truncatus) IN THE SOUTH CAROLINA BLUE CRAB TRAP/POT FISHERY
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McGhaw, Kaiya Rotrice
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In South Carolina, the Atlantic Blue Crab Trap/Pot industry has been responsible for 38 dolphin entanglements from 1999 to 2020, with 20 of these occurring since 2016. The impacts of environmental conditions on dolphin entanglement are not well studied in South Carolina. The objectives of this study are (1) to determine whether past environmental data such as precipitation, salinity, water depth or season of the year significantly impacts dolphin entanglement in the South Carolina blue crab fishery, and (2) to analyze surveys from fishermen to determine where they place their traps, the impacts of dolphin entanglement in their fishing gear, and whether fishermen observed begging behavior or have recently changed their fishing practices. NOAA data of dolphin entanglement from 1999 to 2020, which includes the day, month, year, and location of entanglement, were used for analysis. Precipitation, water depth and salinity were collected using the NOAA Global Summary of the Month program, NOAA Seamless Raster Navigational Chart Services and South Carolina Trammel-Net Surveys respectively. A total of 377 blue crab fishermen were surveyed by mail and email with a response rate of approximately 15% (n=57). Entanglement occurred most when precipitation was moderate (Χ<sup>2</sup> = 6.368, p= 0.0414), in depths below 15 feet (Χ<sup>2</sup> = 17.312, p<0.001) and in the spring season (Χ<sup>2</sup> = 11.263, p= 0.0104). Most of the survey participants reported not observing, hearing, or experiencing an entanglement or begging behavior, said that dolphin entanglement in their fishing gear would be little to no cost or time to repair or replace, and indicated that they had not changed their fishing practices. Factors like the impact of turbidity on dolphin visibility in South Carolina estuaries, the influence of major rain events and droughts, what length of fishing line fishermen can use to optimize their catch, but that also minimizes line bunching and looping, and tactics for motivating fishermen to invest in dolphin safety in this fishery should be considered for future research.