Towards the conservation of crucian carp Carassius carassius: understanding the extent and causes of decline within part of its native English range

Authors

  • C. D. Sayer,

    1. Environmental Change Research Centre, Department of Geography, University College London, London WC1E 6BT, U.K.
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  • G. H. Copp,

    Corresponding author
    1. Centre for Conservation Ecology & Environmental Science, Bournemouth University, Poole, Dorset, BH12 5BB, U.K.
    2. Environmental & Life Sciences Graduate Programme, Trent University, Peterborough, Ontario, K9J 7B8, Canada
    3. Salmon & Freshwater Team, Cefas, Pakefield Road, Lowestoft, Suffolk NR33 0HT, U.K.
      Tel.: +44 01502 527751; email: gordon.copp@cefas.co.uk
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  • D. Emson,

    1. Environmental Change Research Centre, Department of Geography, University College London, London WC1E 6BT, U.K.
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  • M. J. Godard,

    1. Salmon & Freshwater Team, Cefas, Pakefield Road, Lowestoft, Suffolk NR33 0HT, U.K.
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  • G. Zięba,

    1. Salmon & Freshwater Team, Cefas, Pakefield Road, Lowestoft, Suffolk NR33 0HT, U.K.
    2. Department of Ecology and Vertebrate Zoology, University of Łódź, Banacha, Łódź 90-237, Poland
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  • K. J. Wesley

    1. Bedwell Fisheries Services, Welham Green, Hertfordshire AL9 7LP, U.K.
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Tel.: +44 01502 527751; email: gordon.copp@cefas.co.uk

Abstract

The extent and causes of crucian carp Carassius carassius decline were assessed during an initial study of c. 25 ponds in north Norfolk, eastern England, U.K., which was then replicated (a validation study) on another c. 25 ponds in an adjacent area. Of these ponds, c. 40 are known to have contained C. carassius during the 1970s–1980s. In the initial and validation studies, C. carassius were found in only 11 of these ponds, yielding declines of 76% (five of 21 ponds) and 68% (six of 19 ponds), respectively (72% decline overall). Non-native cyprinids, including goldfish Carassius auratus and common carp Cyprinus carpio and their hybrids with C. carassius, were observed in 20% of the ponds. Causes of C. carassius local extinction from 21 ponds were confidently determined as desiccation due to drought, terrestrialization and habitat deterioration, hybridization and competition with non-native cyprinids, agricultural land reclamation and predation (after the introduction of pike Esox lucius). This study led to C. carassius being designated as a Biodiversity Action Plan (BAP) species in the county of Norfolk, the first formal conservation designation for the species in the U.K. The C. carassius BAP plan aims to halt the decline of this much overlooked species through reintroductions and selective stocking of suitable ponds within the native range of the species.

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