Behavioural and fitness effects of translocation to a novel environment: whole-lake experiments in two aquatic top predators

Translocation into a novel environment through common fisheries-management practices, such as fish stocking, provides opportunities to study behavioural and fitness impacts of translocations at realistic ecological scales. The process of stocking, as well as the unfamiliarity with novel ecological conditions and the interactions with resident fish may affect translocated individuals, leading to alterations of behaviours and causing fitness impacts. Our objectives were to investigate how aquatic top-predators behaviourally establish themselves and compete with resident individuals following introduction in a novel lake environment and to investigate the resulting fitness consequences. Using high-resolution acoustic telemetry, we conducted whole-lake experiments and compared the activity, activity-space size and fate of translocated and resident individuals in two model top predators, northern pike (Esox lucius, n = 160) and European catfish (Silurus glanis, n = 33). Additionally, w...