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Letters to Nature

Nature 426, 661-664 (11 December 2003) | doi:10.1038/nature02164; Received 12 August 2003; Accepted 28 October 2003

Plankton effect on cod recruitment in the North Sea

Grégory Beaugrand1,2, Keith M. Brander3, J. Alistair Lindley2, Sami Souissi1 & Philip C. Reid2

  1. CNRS, UMR 8013 ELICO, Station Marine, Université des Sciences et Technologies de Lille BP 80, 62930 Wimereux, France
  2. Sir Alister Hardy Foundation for Ocean Science, The Laboratory Citadel Hill, Plymouth PL1 2PB, UK
  3. ICES, Palaegade 2–4, 1261 Copenhagen K, Denmark

Correspondence to: Grégory Beaugrand1,2 Email: gbea@mail.pml.ac.uk

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The Atlantic cod (Gadus morhua L.) has been overexploited in the North Sea since the late 1960s and great concern has been expressed about the decline in cod biomass and recruitment1. Here we show that, in addition to the effects of overfishing1, fluctuations in plankton have resulted in long-term changes in cod recruitment in the North Sea (bottom-up control). Survival of larval cod is shown to depend on three key biological parameters of their prey: the mean size of prey, seasonal timing and abundance. We suggest a mechanism, involving the match/mismatch hypothesis2, by which variability in temperature affects larval cod survival and conclude that rising temperature since the mid-1980s has modified the plankton ecosystem in a way that reduces the survival of young cod.