Personality of sea trout and consequences for survival quantified using detailed movement data from a telemetry study in a southern Norwegian fjord

Abstract

Animal personality may be an important part of the puzzle that is identifying the components affecting survival of an anadromous species in the marine phase. Also of interest is the interplay between individual personality and changing ecological conditions and/or management tools like marine reserves. In the present study, we have monitored more than 100 individuals of sea trout in a southern Norwegian fjord covered by a dense network of acoustic receivers. The resulting dataset provides detailed information on sea trout movement and depth use, in addition to giving information on the sea trout's use of river, fjord and outer fjord and sea habitats. In the present work, I/we will link behavioural movement traits, and herein personality, to survival in order to assess to which degree personalities can affect fate of sea trout in the marine environment. Preliminary analyses revealed that sea trout had a repeatability of behaviour related to both home range size and mean depth, indicating that these aspects of movement behaviour are consistent within the individual. I/we hypothesize that increased space use and activity will result in reduced survival. The reasons for this are likely complex and may include that more active and/or bolder individuals have a higher chance of being exposed to fishing and have a higher natural mortality. Furthermore, it is of interest how individuals with different behaviours and/or personalities respond to management tools like protection through marine reserves or marine protected areas. I/we present potential protection benefits provided by a small fjord reserve to the sea trout population, and more specifically the variation in obtained protection for different behavioural types within the population. Telemetry studies can provide valuable insights into the fate of individuals within a system, but limitations include uncertainties in determining fate of dead individuals in terms of natural or fishery induced mortality and tag excretion.