Comparisons of energy metabolism and personality traits before and after angling in crucian carp ( Carassius auratus )

Catch and release has become a very popular fish conservation strategy and fisheries management tool. The physiological and behavioral changes in individuals who experience catch and release may be adaptive. These individuals may exhibit more cautious bait use or hook avoidance behavior when faced with lures again. Here, our study was conducted on crucian carp (Carassius auratus) to compare energy metabolism and personality (e.g. activity) before and after angling for three bouts of repeated angling. Our study showed that the standard metabolic rate, maximum metabolic rate, aerobic scope and factorial aerobic scope were all lower after three bouts of repeated angling, and the metabolic rates were greater before angling than after angling in the first two bouts of angling. In addition, the total magnitude of excess postexercise oxygen consumption after repeated angling also showed a decreasing trend as the number of angled bouts increased. The percentage of time spent moving increased after three bouts of repeated angling, but there were no changes in either individual swimming speed or total distance traveled. Our results suggest that repeated angling causes a high death rate and decreases the aerobic/anaerobic metabolic capacity of crucian carp, which may reduce their metabolic potential for other physiological functions, such as locomotion, growth and digestion. Future studies should continue to focus on the effects of fishing on the physiology, behavior, and population dynamics of fish.