External Scarring as an Indicator of Fisheries Interactions with Bottlenose (Tursiops truncatus) and Pantropical Spotted (Stenella attenuata) Dolphins in Maui Nui, Hawai'i

In Maui Nui, Hawai'i, limited information is avail-able regarding the impact of fisheries interactions on two island-associated populations of common bottlenose (Tursiops truncatus) and pantropical spotted (Stenella attenuata) dolphins. To quantify the number of individuals with evidence of fish-eries interactions, this study examined images of bottlenose and spotted dolphins' dorsal fins, mouth-lines, and bodies that were photographically identi-fied during survey efforts from 1996 to 2020. Our results reveal that 27% of the 255 identified bottle-nose dolphins and 13% of the 374 identified spotted dolphins displayed one or more fishery gear-related scars. These data suggest that fisheries interactions may pose a serious threat to the population of bottle-nose dolphins and is a concern for spotted dolphins in Maui Nui, Hawai'i. Our methodology of review-ing above-and underwater footage for mouthline and body images increased scar-detection rates by 51 and 40% for bottlenose and spotted dolphins, respectively. We recommend that future surveys expand dorsal fin photo-identification efforts to col-lect additional above-and underwater images of animals' mouthlines and bodies when in the field. In conjunction with the apparent decline in the Maui Nui bottlenose dolphin population, our find-ings highlight the need for further investigation regarding the level of impact fisheries interactions have on the status of these populations.