Postrelease exploration and diel activity of hatchery, wild, and hybrid strain brown trout in seminatural streams

Abstract

Behaviour that is adaptive in captivity may be maladaptive in the wild and compromise post-release survival of hatchery fish. The understanding of behavioural variation displayed immediately after release could help to improve hatchery protocols and development of behavioural tests for assessing the fitness of fish reared for releases. We characterised the post-release behaviour of common-garden raised offspring of wild resident, captive-bred migratory, and hybrid brown trout (Salmo trutta) in two experiments: in small artificial channels, and in high and low densities in semi-natural streams. The results from semi-natural streams showed that hatchery fish were more likely to disperse downstream from the initial stocking site compared to hybrid and wild-strain fish. The small-scale experiment did not reveal this ecologically pivotal difference in post-release performance among strains, and individual responses were inconsistent between the experiments. Circadian activity patterns did not differ among strains. These detailed observations of post-release behaviour reveal significant intrinsic differences in dispersal traits among brown trout strains and suggest that selective breeding and crossbreeding can significantly affect these traits.

Does parental angling selection affect the behavior or metabolism of brown trout parr?

“…The populations we studied also differed in their life-histories, with the wild population being clearly less migratory than the hatchery population (Lemopoulos et al 2019b). Moreover, juveniles from the wild population show lower tendency for post-release dispersal in a stream environment than juveniles from the hatchery population (Alioravainen et al 2020b). Although we reared offspring under common garden conditions and maximized genetic diversity within each group through a fully factorial breeding matrix, it is possible that differences in the early rearing environments of wild and hatchery parents had contrasting effects on offspring through parental or epigenetic effects (Crews et al 2012;Reddon 2012).…”

Does parental angling selection affect the behavior or metabolism of brown trout parr?

“…The populations we studied also differed in their life histories, with the wild population being clearly less migratory than the hatchery population (Lemopoulos et al., 2019). Moreover, juveniles from the wild population show lower tendency for postrelease dispersal in a stream environment than juveniles from the hatchery population (Alioravainen, Prokkola et al., 2020). Although we reared offspring under common garden conditions and maximized genetic diversity within each group through a fully factorial breeding matrix, it is possible that differences in the early rearing environments of wild and hatchery parents had contrasting effects on offspring through parental or epigenetic effects (Crews et al., 2012; Reddon, 2012).…”

“…The populations we studied also differed in their life histories, with the wild population being clearly less migratory than the hatchery population . Moreover, juveniles from the wild population show lower tendency for postrelease dispersal in a stream environment than juveniles from the hatchery population (Alioravainen, Prokkola et al, 2020 Note: For exploration intensity, the t test was used with Satterthwaite approximations to degrees of freedom and the model was fit with restricted maximum likelihood. For latency, proportional hazard estimates for risk or emergence (±SE) are shown with hazard ratios (e coef ).…”

Life-history genotype explains variation in migration activity in Atlantic salmon ( Salmo salar )

“…The selected timing of the experiment overlaps with the natural smolt migration timing in Atlantic salmon [29,30]. Each stream was equipped with four RFID-antennas, positioned in quadrats of the circular stream [31]. Since the system had the capacity to record data from maximum 32 antennas at a time, streams were monitored periodically in two sets of eight streams: recording was swapped between the two sets of streams every three days until the end of the data collection period.…”