Laboratory captivity can affect scores of metabolic rates and activity in wild brown trout

Phenotypic scoring of wild animals under standardized laboratory conditions is important as it allows field ecologists and evolutionary biologists to understand the development and maintenance of interindividual differences in plastic traits (e.g. behaviour and physiology). However, captivity is associated with a shift from a natural familiar environment to an unfamiliar and artificial environment, which may affect estimates of plastic phenotypic traits. In this study, we tested how previous experience with laboratory environments and time spent in captivity affects behavioural (i.e. activity) and metabolic (i.e. standard and maximum metabolic rates) scoring of our model species, wild brown trout Salmo trutta. We found that individuals with previous experience of laboratory captivity (10.5 months earlier) showed higher activity in an open field test than individuals with no prior experience of laboratory captivity. Previous experience with captivity had no significant effect on metabolic rates. However, metabolic rates seemed to increase with increasing time spent in captivity prior to the collection of measurements. Although there are benefits of keeping wild animals in captivity prior to scoring, our results suggest that while allowing for sufficient acclimatization researchers should aim at minimizing time in captivity of wild animals to increase accuracy and ecological relevance of the scoring of plastic phenotypic traits

Hook Avoidance Induced by Private and Social Learning in Common Carp

It is essential for fish to respond appropriately when faced with a threatening situation. Accordingly, fish are able to reduce predation risk through learning. In addition to privately learned experiences, fish can acquire social information about a threat by observing the response of conspecifics and use such public information to adapt future behavior through learning. It is unclear if social learning can also influence the behavioral response of fish when faced with human-induced threats in the form of angling. Using an experimental approach in the laboratory, we examined the influence of private (i.e., direct experience of hooking) and social information on angling vulnerability in Common Carp Cyprinus carpio—a species regularly exposed to catch-and-release angling. Compared with control groups, individuals with direct or social experience of catch-and-release angling expressed significantly elevated hook avoidance behavior during a short-term vulnerability assessment hours after a catc