Do colours affect biting behaviour in loggerhead sea turtles?

Sea turtles are considered to be primarily visual predators, but the influence of different colours on the probability of eliciting biting behaviour has not yet been fully investigated. We explored this colour influence in 38 wild loggerhead sea turtles Caretta caretta incidentally caught during fishing activities and rehabilitated in rescue centres. Our results showed for the first time that wild loggerheads tend to bite the same colour first chosen (i.e. each individual has its colour preference) but, considering the whole sample, no clear preference or avoidance for one of the three colours tested (yellow, red and blue) is shown. Such heterogeneity may be related to each subject's history and habits. These results suggest that changing the colour of baits as a mitigation measures may have little impact on sea turtles incidental capture rates. The length of captivity prior to the experiment affected the rate of the turtles' biting behaviour, suggesting that this parameter is a potential confounding factor that should be included in models for sensory behavioural studies.