Capture-induced vulnerability in male Shortnose guitarfish during their reproductive period

The assessment of physiological responses to capture provides useful information for elasmobranch conservation. In particular, understanding these impacts in species caught as bycatch that are released after capture can predict their “post-release” fate and aid in management plans. Although well studied in several species, capture-stress is nonetheless frequently assessed without considering putative variability between sexes. Given the high mortality of pregnant Zapteryx brevirostris females reported in the literature, the present study aimed at determining greatest vulnerability period for males. Our results demonstrate that, when caught during the reproductive period, males display higher mortality (68%) than when caught outside the reproductive period (zero mortality). Seven out of 11 markers (i.e. sodium, chloride, potassium, lactate, phosphorus, triglycerides and condition factor) differed significantly following capture-induced stress between males caught during the reproductive period and those caught outside this period. Results demonstrate the need for specific protocols during the reproductive period, also considering the influence of sex on physiological responses to stress for effective management.