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Aggregation in juvenile pike (Esox lucius): interactions between habitat and density in early winter

  1. L. A. HAWKINS1,*,
  2. J. D. ARMSTRONG2,
  3. A. E. MAGURRAN1

Article first published online: 27 SEP 2005

DOI: 10.1111/j.1365-2435.2005.01039.x

Issue

Functional Ecology

Functional Ecology

Volume 19, Issue 5, pages 794–799, October 2005

Additional Information

How to Cite

HAWKINS, L. A., ARMSTRONG, J. D. and MAGURRAN, A. E. (2005), Aggregation in juvenile pike (Esox lucius): interactions between habitat and density in early winter. Functional Ecology, 19: 794–799. doi: 10.1111/j.1365-2435.2005.01039.x

Author Information

  1. 1

    Gatty Marine Laboratory, School of Biology, University of St Andrews, St Andrews KY16 8LB, UK, and

  2. 2

    Fisheries Research Services Freshwater Laboratory, Faskally, Pitlochry PH16 5LB, UK

* †Author to whom correspondence should be addressed. E-mail: lh36@st-andrews.ac.uk

Publication History

  1. Issue published online: 10 OCT 2005
  2. Article first published online: 27 SEP 2005
  3. Received 11 January 2005; revised 4 April 2005; accepted 21 April 2005

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Keywords:

  • Competitive exclusion;
  • dominance;
  • grouping;
  • ideal despotic distribution;
  • intimidation

Summary

  • 1
    Juvenile pike (Esox lucius), a cannibalistic fish species, aggregates within habitat patches. The advantages to cannibals of aggregating in the absence of other predators and food constraints are not immediately obvious. In this study we explore the basis for this grouping by observing how spatial distributions of juvenile pike are mediated by the presence of conspecifics.
  • 2
    Solitary pike preferred shallow-water (0·17 m depth) habitats. When fish density was increased, the average time spent in alternative deep-water habitat (0·33 m) increased, consistent with a despotic type of distribution and suggesting that interference was occurring.
  • 3
    In pairs of fish, one pike, nominally the dominant individual, showed a habitat use similar to that of single fish. The second individual mostly occupied deep water, again consistent with a despotic distribution and apparently mediated by intimidation interference. However, dominant pike did on occasion enter deep water, at which times the subordinate pike remained with the dominant fish, appearing to aggregate in the pool.
  • 4
    We propose that habitat-specific risk could explain aggregations of pike in deep water. Although remaining in close proximity to dominant individuals in deep water would seemingly put subordinate fish at great risk, the alternative of moving to shallow water may increase risk still further by reducing the capacity to perceive and/or evade attacks.
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