Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Plankton effect on cod recruitment in the North Sea


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.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Long-term monthly changes (1958–1999) in the plankton index (as the first principal component, 33.78% of the total variability), resulting from analysis of the table years–months × biological indicators.
Figure 2: Relationships between plankton fluctuations and cod recruitment (one-year-olds) at lag one.
Figure 3: Plankton changes (1958–1999) and their consequences for larval/juvenile cod survival.


  1. 1

    Cook, R. M., Sinclair, A. & Stefansson, G. Potential collapse of North Sea cod stocks. Nature 385, 521–522 (1997)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Cushing, D. H. Plankton production and year-class strength in fish populations: an update of the match/mismatch hypothesis. Adv. Mar. Biol. 26, 249–292 (1990)

    Article  Google Scholar 

  3. 3

    Pope, J. G. & Macer, C. T. An evaluation of the stock structure of North Sea cod, haddock, and whiting since 1920, together with a consideration of the impacts of fisheries and predation effects on their biomass and recruitment. ICES J. Mar. Sci. 53, 1157–1169 (1996)

    Article  Google Scholar 

  4. 4

    Brander, K. M. Effects of environmental variability on growth and recruitment in cod (Gadus morhua) using a comparative approach. Oceanol. Acta 23, 485–496 (2000)

    Article  Google Scholar 

  5. 5

    Munk, P. Prey size spectra and prey availability of larval and small juvenile cod. J. Fish Biol. 51 (suppl. A), 340–351 (1997)

    Article  Google Scholar 

  6. 6

    Rothschild, B. J. Year class strengths of zooplankton in the North Sea and their relation to cod and herring abundance. J. Plankton Res. 20, 1721–1741 (1998)

    Article  Google Scholar 

  7. 7

    ICES Cooperative Research Report Report of the Workshop on Gadoid Stocks in the North Sea during the 1960s and the 1970s. 4th ICES/GLOBEC Backward-facing Workshop (eds Heath, M. R. & Brander, K. M.) (ICES, Copenhagen, 2001)

    Google Scholar 

  8. 8

    Myers, R. A., Hutchings, J. A. & Barrowman, N. J. Hypotheses for the decline of cod in the North Atlantic. Mar. Ecol. Prog. Ser. 138, 293–308 (1996)

    ADS  Article  Google Scholar 

  9. 9

    Thorisson, K. The food of larvae and pelagic juveniles of cod (Gadus morhua L.) in the coastal waters west of Iceland. Rapp. P.-v. Reun. Cons. Perm. Int. Explor. Mer. 191, 264–272 (1989)

    Google Scholar 

  10. 10

    Warner, A. J. & Hays, G. C. Sampling by the continuous plankton recorder survey. Prog. Oceanogr. 34, 237–256 (1994)

    ADS  Article  Google Scholar 

  11. 11

    Cushing, D. H. The gadoid outburst in the North Sea. J. Cons. Cons. Int. Explor. Mer. 41, 159–166 (1984)

    Article  Google Scholar 

  12. 12

    Letcher, B. H., Rice, J. A., Crowder, J. A. & Rose, K. A. Variability in survival of larval fish: disentangling components with a generalized individual based model. Can. J. Fish. Aquat. Sci. 53, 787–801 (1996)

    Article  Google Scholar 

  13. 13

    Ricker, W. E. Stock and recruitment. J. Fisher. Res. Bd Can. 11, 559–623 (1954)

    Article  Google Scholar 

  14. 14

    ICES Cooperative Research Report. Report of the ICES Advisory Committee on Fish Management (ICES, Copenhagen, 2002)

    Google Scholar 

  15. 15

    Bollens, S. M. et al. Seasonal plankton cycles in a temperate fjord and comments on the match-mismatch hypothesis. J. Plankton Res. 14, 1279–1305 (1992)

    Article  Google Scholar 

  16. 16

    Gotceitas, V., Puvanendran, V., Leader, L. L. & Brown, J. A. An experimental investigation of the match/mismatch hypothesis using larval Atlantic cod. Mar. Ecol. Prog. Ser. 130, 29–37 (1996)

    ADS  Article  Google Scholar 

  17. 17

    Cushing, D. H. Towards a Science of Recruitment in Fish Populations (Ecology Institute, Oldendorf/Luhe, 1997)

    Google Scholar 

  18. 18

    Platt, T., Fuentes-Yaco, C. & Frank, K. T. Spring algal bloom and larval fish survival. Nature 423, 398–399 (2003)

    ADS  CAS  Article  Google Scholar 

  19. 19

    Beaugrand, G., Reid, P. C., Ibañez, F., Lindley, J. A. & Edwards, M. Reorganisation of North Atlantic marine copepod biodiversity and climate. Science 296, 1692–1694 (2002)

    ADS  CAS  Article  Google Scholar 

  20. 20

    Beaugrand, G. & Reid, P. C. Long-term changes in phytoplankton, zooplankton and salmon linked to climate. Glob. Change Biol. 9, 801–817 (2003)

    ADS  Article  Google Scholar 

  21. 21

    Mauchline, J. & Fisher, L. R. The biology of euphausiids. Adv. Mar. Biol. 7, 1–454 (1969)

    Article  Google Scholar 

  22. 22

    Reid, P. C., Borges, M. & Svendsen, E. A regime shift in the North Sea circa 1988 linked to changes in the North Sea horse mackerel fishery. Fish. Res. 50, 163–171 (2001)

    Article  Google Scholar 

  23. 23

    Otterlei, E., Nyhammer, G., Folkword, A. & Stefansson, S. O. Temperature- and size-dependent growth of larval and early juvenile Atlantic cod (Gadus morhua): a comparative study of Norwegian coastal cod and northeast Arctic cod. Can. J. Fish. Aquat. Sci. 56, 2099–2111 (1999)

    Article  Google Scholar 

  24. 24

    Swain, D. P. et al. Density- versus temperature-dependent growth of Atlantic cod (Gadus morhua) in the Gulf of St. Lawrence and on the Scotian Shelf. Fish. Res. 59, 327–341 (2003)

    Article  Google Scholar 

  25. 25

    Pepin, P. An appraisal of the size-dependent mortality hypothesis for larval fish: comparison of a multispecies study with an empirical review. Can. J. Fish. Aquat. Sci. 50, 2166–2174 (1993)

    Article  Google Scholar 

  26. 26

    Gallego, A. & Heath, M. The effect of growth-dependent mortality, external environment and internal dynamics on larval fish otolith growth: an individual-based modelling approach. J. Fish Biol. 51 (suppl. A), 121–134 (1997)

    Article  Google Scholar 

  27. 27

    Mauchline, J. The Biology of Calanoid Copepods (Academic, San Diego, 1998)

    Google Scholar 

  28. 28

    Peters, H. The Biological Implication of Body Size (Cambridge Univ., Cambridge, 1983)

    Google Scholar 

  29. 29

    Shepherd, J. G. Extended survivors analysis: an improved method for the analysis of catch-at-age data and abundance indices. ICES J. Mar. Sci. 56, 584–591 (1996)

    MathSciNet  Article  Google Scholar 

  30. 30

    Vautard, R. P. Y. & Ghil, M. Singular-spectrum analysis: a toolkit for short, noisy chaotic signals. Physica D 58, 95–126 (1992)

    ADS  Article  Google Scholar 

Download references


We are grateful to all past and present members and supporters of the Sir Alister Hardy Foundation for Ocean Science whose sustained help has allowed the establishment and maintenance of the CPR data set in the long term. The main support of this work was from UK DEFRA, and both the French PNEC Art 4 and IFB ‘Biodiversité et changement global’ programmes. Consortium support for the CPR survey is provided by agencies from the following countries: UK, USA, Canada, the Faroe Islands, France, Ireland, the Netherlands, Portugal, the IOC and the European Union. We thank the owners, masters and crews of the ships that tow the CPRs on a voluntary basis.

Author information



Corresponding author

Correspondence to Grégory Beaugrand.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Beaugrand, G., Brander, K., Alistair Lindley, J. et al. Plankton effect on cod recruitment in the North Sea. Nature 426, 661–664 (2003).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing