Telemetry reveals how catch and release affects prespawning migration in atlantic salmon (salmo salar)

With the decline of many exploited fish populations, catch and release has become an increasingly used management practice to allow sport fishing while reducing its impact on wild populations. However, survival and reproductive success can vary according to the catch and release technique and environmental conditions, suggesting a potential impact of this practice on prespawning behaviour. Here we evaluate how some critical aspects of salmon freshwater migration are influenced by catch and release and by environmental factors. For this purpose, 40 multi-sea-winter Atlantic salmon (Salmo salar) (20 catch and release and 20 control) were followed by telemetry from June 2011 to March 2012. Temperature was found to influence movements and the daily probability that a fish would cross a fish ladder, while water discharge influenced daily distance travelled during the prespawning migration. Catch and release was found to influence the daily probability of fish to cross a barrier as well as the total distance traveled in the river. Overall, this study suggests that salmon caught and released by fishermen survive and reproduce, but that prespawning exploration behaviours could be altered compared with those of uncaught salmon. Avec le declin de plusieurs populations de poissons exploitees, la remise a l'eau est devenue une approche de gestion populaire afin d'assurer la peche sportive tout en minimisant ses impacts. Neanmoins, comme la survie et le succes reproducteur peuvent varier selon les conditions environnementales et la methode employee, la remise a l'eau pourrait avoir un impact non-negligeable sur le comportement pre-reproducteur. Cette etude evalue comment certains aspects critiques de la migration en eau douce du saumon atlantique (Salmo salar) sont influences par la remise a l'eau et les conditions environnementales. Quarante saumons redibermarins (20 remis a l'eau, 20 controles) ont ete suivis par telemetrie de juin 2011 a mars 2012. Les resultats indiquent que la temperature influence la probabilite de mouvement et de franchissement d'obstacle, alors que le debit influence la distance journaliere parcourue. Par ailleurs, la remise a l'eau influence la probabilite journaliere pour un individu de franchir un obstacle et la distance totale parcourue par celui-ci. Cette etude suggere que meme si les saumons remis a l'eau survivent et se reproduisent, le comportement pre-reproducteur peut en etre altere.
Introduction As is the case with many other fishes worldwide, Atlantic salmon (Salmo salar) has been declining rapidly since the middle of the 20th century and is now near historic [...]