Voluntary angler logbooks reveal long-term changes in a lentic pike, Esox lucius, population

Authors

  • T. Jansen,

    1. DTU AQUA – National Institute of Aquatic Resources, Technical University of Denmark, Charlottenlund Castle, Charlottenlund, Denmark
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  • R. Arlinghaus,

    1. Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm, Berlin, Germany
    2. Inland Fisheries Laboratory, Department for Crop and Animal Sciences, Humboldt-University of Berlin, Berlin, Germany
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  • T. D. Als,

    1. DTU AQUA – National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark
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  • C. Skov

    Corresponding author
    1. DTU AQUA – National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark
    • DTU AQUA – National Institute of Aquatic Resources, Technical University of Denmark, Charlottenlund Castle, Charlottenlund, Denmark
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Correspondence: Christian Skov, DTU AQUA – National Institute of Aquatic Resources, Technical University of Denmark; Vejlsøvej 39, 8600 Silkeborg, Denmark (e-mail: ck@aqua.dtu.dk)

Abstract

Sixty-two years of voluntarily collected angling logbook data from a large natural Danish lake were used to study variation in pike, Esox lucius L., CPUE (catch per unit effort), expressed as no. of captured pike per boat trip, as an index of stock size. Pike CPUE was positively related to pike release rate by anglers and negatively affected by certain commercial fishers. The stocking of young-of-the-year pike and a fishery-dependent index of perch, Perca fluviatilis L., abundance (which may be pike prey or predator depending on size) did not correlate with pike CPUE. Analyses of the size distribution of pike, based on sizes of annual record trophy pike captured by anglers, confirmed the negative impact of commercial pike fishing and revealed a positive influence of air temperature. It is concluded that high-quality angler logbooks that record effort and catch can be a cost-effective tool to inform lake fisheries management by revealing long-term population trends. Further, state space modelling, a statistical technique not yet seen in recreational fisheries science, is recommended as a tool to model proxies for population dynamics from angler logbook data.

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