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Are fish populations in temperate streams affected by crayfish? - A field survey and prospects

  • E Degerman
  • Anders Nilsson
  • Per Nyström
  • Erika Nilsson
  • Karin Olsson
Publishing year: 2007
Language: English
Pages: 231-239
Publication/Series: Environmental Biology of Fishes
Volume: 78
Issue: 3
Document type: Journal article
Publisher: Springer

Abstract english

Fish populations may be affected by predation and competition from various types of organisms, among which crayfish have been suggested as important actors. We here present results from stream surveys, suggesting that neither native noble, Astacus astacus, nor introduced signal crayfish, Pacifastacus leniusculus, necessarily affect fish population densities in temperate stream communities. Comparisons of fish densities within stream sites between years with absence and presence of crayfish showed no effect of either crayfish species. A further analysis of changes in fish densities between periods without and with crayfish in low, intermediate and high densities revealed that crayfish density did neither have an effect on fish densities. Our study is one of exceptionally few that consider the above aspects in long-term perspectives in natural systems, and we discuss that previously reported divergent results of cray. sh effects on. sh may be highly dependent on specific species and methods used, and that the effects of cray. sh on. sh populations deserve further attention to enable reliable predictions of community processes in streams.


  • Ecology


  • ISSN: 0378-1909
Anders Nilsson
E-mail: anders [dot] nilsson [at] biol [dot] lu [dot] se


Division aquatic ecology

+46 46 222 83 65

+46 70 346 25 66




Aquatic Ecology


Research group

Aquatic Ecology


Doctoral students and postdocs

Main supervisor

Varpu Pärssinen

Assistant supervisor

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