External Organisations

  • Fisheries and Oceans Canada, Canada
  • Leibniz Institute of Freshwater Ecology and Inland Fisheries, Germany

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The project focuses on establishing new and comprehensive knowledge on behavior of lake dwelling fish and the impact of human activities, which can eventually enhance management of freshwater fish populations. The study is based on a new automatic acoustic telemetry system, which facilitates fine scale 3D positioning of several hundred fish several times a minute with sub meter accuracy. So far the system has been deployed in a small lake for two consecutive years and has generated data sets on pike, perch and roach behavior with unprecedented details, e.g. activity levels and habitat choice on a diel and seasonal basis coupled to environmental factors such as establishment and break of thermoclines.Hitherto, studies on pike winter behavior during ice cover have generated new insights and added to the increased consciousness of the importance of year-round knowledge on lake ecology processes. The remote sensed monitoring of the tagged fish without presence of personal has allowed for comparison of fish behavior in situations with and without human disturbances, e.g. fishery-related activities. This way a distinct and instantaneous impact of boating on fish behavior has been revealed and the impact of catch and release angling has been addressed. Finally, the system has facilitated studies extending laboratory findings to behavior in the field. For instance, findings of physiological (metabolic rates) and behavioral (boldness-shyness) properties of individual fish in the lab have been linked with behavior of the same individuals in nature by subsequent tagging and release in the lake.

Several issues will be studied concurrently the following years:
1) A principal focus area will be striving to establish which factors impact and confine natural pike populations. The majority of larger pike in the study lake have been followed for at least two years, which has provided a detailed picture of pike behavior and individual variation. The interactions between pike size groups and whether the home range of smaller pike is controlled by larger individuals is being studied by marking a large number of smaller pikes. Pike exploitation of various spawning habitats is assessed and a genetic analysis of pike individuals and pike eggs will be explored, possibly facilitating assessment of the individual contribution to the population and thus enabling a cross-discipline approach to explore how behavior and reproductive fitness is related.
2) The studies on pike winter biology will be expanded to incorporate the entire fish community adding further insights to the limited overall knowledge on lake winter ecology.
3) General studies on predator-prey and species interactions, shoaling etc in a natural system will be continued.
4) Finally, the effect and feasibility of stocking trout in lakes, a theme of high relevance to the management of Danish lakes, will be studied.

The project is coordinated by DTU Aqua.


  • Research area: Freshwater Fisheries and Ecology
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ID: 2286204