Insights into the origin and magnitude of capture and handling-related stress in a coastal elasmobranch Carcharhinus limbatus

A suite of blood chemistry parameters (including acid–base indicators and plasma electrolytes) was serially measured in blacktip sharks (Carcharhinus limbatus), captured via rod-and-reel, to gain a more thorough understanding of the physiological stress response to recreational capture. Sharks were caught both from the shore and from fishing vessels and experienced varying degrees of air exposure during handling. While all captured sharks exhibited a metabolic acidosis during the fight on the line (increasing lactate and decreasing pH and bicarbonate), the observed acidosis was compounded by a respiratory component (increasing pCO2) in sharks removed from the water during handling. Vessel-caught sharks handled in the water exhibited significantly greater increases in lactate and glucose (0.73 ± 0.21 mmoll−1 min−1 and 0.81 ± 1.07 mg dl−1 min−1, respectively) than sharks handled out of water (0.21 ± 0.17 mmoll−1 min−1 and −0.32 ± 1.05 mg dl−1 min−1; p < 0.001 and p < 0.05, respectively). These findings provide insights into how differences in recreational capture methods and air exposure can mediate the origin and magnitude of capture-related stress and highlight the importance of considering both sampling time (time from capture to phlebotomy) and sampling location (in water vs. out) in studies conducted on capture-related stress.