Full Paper

Environmental Biology of Fishes

, Volume 78, Issue 3, pp 231-239

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

  • Erik DegermanAffiliated withInstitute of Freshwater Research, Swedish Board of Fisheries
  • , P. Anders NilssonAffiliated withDepartment of Ecology, Limnology, Ecology Building, Lund University Email author 
  • , Per NyströmAffiliated withDepartment of Ecology, Limnology, Ecology Building, Lund University
  • , Erika NilssonAffiliated withDepartment of Ecology, Limnology, Ecology Building, Lund University
  • , Karin OlssonAffiliated withDepartment of Ecology, Limnology, Ecology Building, Lund University

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Synopsis

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 crayfish effects on fish may be highly dependent on specific species and methods used, and that the effects of crayfish on fish populations deserve further attention to enable reliable predictions of community processes in streams.

Key words:

community competition density exotic species habitat predation