Meeting Abstract
36.1 Friday, Jan. 4 Kinematic and Behavioral Analyses of Loggerhead Turtles (Caretta caretta) Interacting with Baited Longline Hooks GUZM�N, A.*; MARSHALL, C.D.; Texas A&M University; Texas A&M University at Galveston asalazarguzman@gmail.com
Interactions between marine turtles and the longline fishing industry are a growing concern. Feeding biomechanics, foraging behavior, and diet preferences are likely candidates for loggerheads� vulnerability to capture in the longline fishery. A motion analysis study on 7 loggerheads (SCL 40-55 cm) was conducted to investigate how these turtles interacted with five barb-less, squid-baited longline hooks (J with 25° offset, 16 circle no offset, 16 circle with 10° offset, 18 circle no offset, and 18 circle with 10° offset). Seven kinematic variables (e.g, maximum gape distance) and three behavioral variables (e.g, hooking location) were assessed in relation to hook treatment. These data were used to test the hypothesis that loggerhead feeding behavior is modulated relative to hook type, hook size and hook offset angle. No difference was detected between hook treatments in all kinematic variables analyzed (p>0.05). Mean frequency of strikes did not vary between hook treatments or hooked and non-hooked interactions. The overall hooking percentage was lowest in the 16 circle hook with no offset (29.6%) and 18 circle hooks with 10° offset (29.8%). The highest overall hooking percentage (45%) occurred when turtles interacted with 16 circle hooks with 10° offset. When comparing with the hook size treatment, the least difference in overall hooking percentage was observed in 18 circle hooks. Specifically looking at hooking location (mouth, throat, or undetermined), the 16 circle hook with 10° offset had the highest percentage of throat hooking (48.3%) while the 18 circle no offset hook resulted in the lowest percentage of throat hooking (21.1%). These investigations of simulated loggerhead-longline fishery interactions will provide data that can be used to develop or modify longline fishery gear that may potentially reduce loggerhead bycatch.
