Sytemic gas embolism in dead and live loggerhead sea turtles (Caretta caretta) due to by-catch

Abstract

Sea turtles are among the longest and deepest diving of the air- breathing vertebrates (marine animals). There are references of osteonecrosis-type surface lesions in marine turtles in the Cretaceous age while very rarely observed in specimens younger than the Miocene age. It has been hypothesized that at present, the minimal susceptibility to the underlying "DCS" is the result of evolution of physiologic and/or behavioral mechanisms for compensation. To the best of the authors' knowledge, no reference of turtles suffering of acute gas embolism, resembling DCS, has been previously reported either in live or dead individuals. Here we report an "in vivo" and "postmortem" diagnosis of systemic gas embolism in 20 loggerhead sea turtles (Caretta caretta) which were recovered dead or still alive from by-catch trawlers and gillnets at different depths from the Valencian coast region (eastern Mediterranean Spanish coast) from 2010 until present. Diagnosis in live animals was made based on different diagnostic techniques including plain dorso-ventral and latero-lateral radiographs; renal, liver and cardiac ultrasound; venipuncture and blood analysis; and CAT scans. Systematic and detailed necropsy and histopathology with additional laboratory analysis was also performed on dead turtles. Based on these observations, a final diagnosis of "acute gas embolism" consistent with "DCS" was confirmed in several specimens after being trapped in fishing gear. We describe a "gas systemic embolism" linked to by-catch as a likely new clinical and pathological entity resembling DCS in marine turtles. The importance of these new findings regarding rehabilitation and releasing of by-catch turtles will be also discussed.