Measuring recovery of bycatch turtles from hypoxia using RAMP

Midland painted turtle, Harding 2009

Reflex impairment was tested in recovering freshwater painted turtles (Chrysemys picta) that were exposed to hypoxia as bycatch in fyke net fisheries (LeDain et al. 2013).

"Adapting the use of RAMP from fish to gauge the severity of anoxia on painted turtles was effective. All the reflexes used in this study indicated some level of impairment following submergence, with some reflexes being more sensitive than others. The tactile responses to the limbs and head were the most insensitive to submergence: they were often the only remaining reflexes after submergence (Table 1). Thus, the absence of tactile responses could be indicative of turtles requiring assisted recovery the most. Other species of turtles may require different types of reflex responses that suit their morphology better (e.g., loggerhead turtles, Caretta caretta, are too large to use a hand holding ‘‘escape response’’). However, a tactile response is a universal reflex that can be used in all species. Employing a presence/absence scoring reduced subjectivity and will ease the training of commercial fishers, researchers, and government and nongovernment agencies on the use of the RII. In sum, we feel the RII is a very useful tool to assess turtle condition."

The authors suggest that tests for reflex impairment (RII, reflex impairment index) modeled after RAMP methodology can be useful for assessing assisted recovery and potential mortality in turtle bycatch.

"Although reduction of turtle mortality can be achieved through educating fishers on proper handling and recovery methods for turtles, the first course of action should be checking nets frequently and implementing seasonal or area restrictions. Bycatch reduction devices (turtle excluders and escape modifications) are also effective in reducing the number of turtles caught in nets while maintaining fish catch (Guillory and Prejean 1998; Lowry et al. 2005; Fratto et al. 2008; Hart and Crowder 2011; Larocque et al. 2012c). However, since turtle bycatch can still occur despite these conservation measures, albeit at reduced levels, examining reflex impairment is an effective and inexpensive way to discern whether turtles require assisted recovery after incidental capture in submerged nets."