Modeling Response of Target and Nontarget Dolphins to Biopsy Darting

Abstract: Remote biopsy sampling is a valuable technique to collect data on free-ranging cetaceans. Numerous researchers have evaluated effects of biopsy darting on the target animal, but biopsy sampling may also have unintentional effects on nearby nontarget animals. We evaluated reactions of target and nontarget animals during remote biopsy sampling conducted on bottlenose dolphins (Tursiops truncatus) in August 2004 off Folly Beach, South Carolina, and Jekyll Island, Georgia, USA, and in February-March and July-August 2005 off Hilton Head, South Carolina. We examined external factors that might influence response of the target animal as well as other individuals in the group. Target animals reacted to biopsy attempts 90.9% (n = 475) of the time. Of these, 97.5% (n = 432) of reactions were to biopsy hits, and 84.4% (n = 320) of all hits had reactions recorded as low. Nontarget animals reacted 21.9% (n = 1,158) of the time; interanimal distance from target animal, season, sea state, and depth affected reactions of nontarget animals. Overall, however, biopsy effects appear to be minimal. We present a statistical tool for identifying factors that elicit greater reactions. This model could be adapted for species or locations, as needed, to identify factors that could influence effects of biopsy sampling.