, Volume 525, Issue 1–3, pp 245–248 | Cite as

Extensive Aggregations of Wild Fish at Coastal Sea-Cage Fish Farms

  • Tim Dempster
  • Pablo Sanchez-Jerez
  • Just Bayle- Sempere
  • Michael Kingsford


We present evidence of a largely undocumented environmental effect of coastal sea-cage fish farms on wild fish. We estimated the total abundance and biomass of wild fish aggregated in the immediate vicinity of nine fish farms in the Mediterranean Sea and one farm off the east coast of Australia. Estimates of wild fish aggregations ranged from 2000 to 86000 individuals and from 100 kg to 38.5 tons of fish per farm and were always greater than control locations. Particularly large aggregations (>30000 fish, > 12 tons) occurred at half of the farms. Aggregations were temporally stable for weeks to months and most wild fish associated with farms (88%) were of adult size. Potential effects of such large aggregations of wild fish in the immediate vicinity of fish farms include increased vulnerability to fishing and pathogen transfer between caged and wild fish. We suggest specific legislation should be enacted wherever large aggregations of wild fish occur around fish farms to enhance the positive and reduce the negative effects of association.

abundance biomass sea-cage fish farm wild fish 


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Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  • Tim Dempster
    • 1
  • Pablo Sanchez-Jerez
    • 2
  • Just Bayle- Sempere
    • 2
  • Michael Kingsford
    • 3
  1. 1.School of Biological SciencesThe University of SydneyAustralia
  2. 2.Unidad de Biología Marina, Departamento de Ciencias Ambientales y Recursos NaturalesUniversidad de AlicanteAp.C. 99Spain
  3. 3.School of Marine Biology and AquacultureJames Cook UniversityAustralia

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