Behavioral and visual stress-induced proxies in elasmobranchs

Understanding how elasmobranchs respond to stressors is imperative so that effective measures to reduce mortality be employed, whether in commercially captured animals or sharks and rays maintained in human care. Currently, reflex action mortality predictors (RAMPs) are the most reliable proxies to indicate an animal's condition state, commonly employed for both teleost and elasmobranchs. As our understanding of mortality predictors is evolving, is it necessary that traditional indicators be constantly reviewed and new proxies proposed, in order to improve the tools available for the best possible evaluation of a stressed individual. In this context, this review aimed to compile data on behavioral and visual proxies, along with the proposition of new proxies to guide professionals and assist them in identifying signs associated with alarming situations that might potentially result in the death of highly stressed individuals or sub-lethal effects at population level (migration, reproduction) that may seriously compromise the success of release measures.