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From introduction to fishery dominance: the initial impacts of the invasive carp Cyprinus carpio in Lake Naivasha, Kenya, 1999 to 2006

Authors

  • J. R. Britton,

    Corresponding author
    1. * Centre for Conservation Ecology & Environmental Change, School of Conservation Sciences, Bournemouth University, Poole, Dorset, BH12 5BB, U.K., School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, U.K., § Department of Biological Sciences, Queen Mary University, Mile End Road, London, E1 4NS, U.K., Environment Agency, Sussex Area, Southern Region, Worthing, West Sussex, BN11 1DH, U.K., Naivasha Fisheries Department, Moi Lake Road South, Naivasha, Kenya and # Department of Biology, University of Leicester, University Road, Leicester, LE1 7RH, U.K.
      †Tel.: +44 (0) 1202 965384; fax: +44 (0) 1202 965530; email: rbritton@bournemouth.ac.uk
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  • R. R. Boar,

    1. * Centre for Conservation Ecology & Environmental Change, School of Conservation Sciences, Bournemouth University, Poole, Dorset, BH12 5BB, U.K., School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, U.K., § Department of Biological Sciences, Queen Mary University, Mile End Road, London, E1 4NS, U.K., Environment Agency, Sussex Area, Southern Region, Worthing, West Sussex, BN11 1DH, U.K., Naivasha Fisheries Department, Moi Lake Road South, Naivasha, Kenya and # Department of Biology, University of Leicester, University Road, Leicester, LE1 7RH, U.K.
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  • J. Grey,

    1. * Centre for Conservation Ecology & Environmental Change, School of Conservation Sciences, Bournemouth University, Poole, Dorset, BH12 5BB, U.K., School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, U.K., § Department of Biological Sciences, Queen Mary University, Mile End Road, London, E1 4NS, U.K., Environment Agency, Sussex Area, Southern Region, Worthing, West Sussex, BN11 1DH, U.K., Naivasha Fisheries Department, Moi Lake Road South, Naivasha, Kenya and # Department of Biology, University of Leicester, University Road, Leicester, LE1 7RH, U.K.
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  • J. Foster,

    1. * Centre for Conservation Ecology & Environmental Change, School of Conservation Sciences, Bournemouth University, Poole, Dorset, BH12 5BB, U.K., School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, U.K., § Department of Biological Sciences, Queen Mary University, Mile End Road, London, E1 4NS, U.K., Environment Agency, Sussex Area, Southern Region, Worthing, West Sussex, BN11 1DH, U.K., Naivasha Fisheries Department, Moi Lake Road South, Naivasha, Kenya and # Department of Biology, University of Leicester, University Road, Leicester, LE1 7RH, U.K.
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  • J. Lugonzo,

    1. * Centre for Conservation Ecology & Environmental Change, School of Conservation Sciences, Bournemouth University, Poole, Dorset, BH12 5BB, U.K., School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, U.K., § Department of Biological Sciences, Queen Mary University, Mile End Road, London, E1 4NS, U.K., Environment Agency, Sussex Area, Southern Region, Worthing, West Sussex, BN11 1DH, U.K., Naivasha Fisheries Department, Moi Lake Road South, Naivasha, Kenya and # Department of Biology, University of Leicester, University Road, Leicester, LE1 7RH, U.K.
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  • D. M. Harper

    1. * Centre for Conservation Ecology & Environmental Change, School of Conservation Sciences, Bournemouth University, Poole, Dorset, BH12 5BB, U.K., School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, U.K., § Department of Biological Sciences, Queen Mary University, Mile End Road, London, E1 4NS, U.K., Environment Agency, Sussex Area, Southern Region, Worthing, West Sussex, BN11 1DH, U.K., Naivasha Fisheries Department, Moi Lake Road South, Naivasha, Kenya and # Department of Biology, University of Leicester, University Road, Leicester, LE1 7RH, U.K.
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†Tel.: +44 (0) 1202 965384; fax: +44 (0) 1202 965530; email: rbritton@bournemouth.ac.uk

Abstract

Following the accidental introduction of the carp Cyprinus carpio into Lake Naivasha during 1999, a sustainable population became rapidly established and in early 2004 became the principal species exploited in the commercial fishery. Over 9000 kg of carp were harvested from the lake between October 2005 and 2006, when fish were captured between fork lengths (LF) 200 and 800 mm (>8 kg). Diet of carp <100 mm LF was dominated by zooplankton, >100 mm LF there was a shift to benthic macro-invertebrates, with these carp feeding principally upon food resources previously unexploited by the fish community. Contrary to predictions and despite the increasing carp abundance, there has been macrophyte regeneration in littoral areas since 2004. There have been substantial increases in areal cover, with coverage in 2006 at levels not observed since the late 1980s, and significant increases in species richness. Possible reasons for this, and the significance of this carp introduction, are discussed.

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