Body size shifts and early warning signals precede the historic collapse of whale stocks

Abstract

Predicting population declines is a key challenge in the face of global environmental change. Abundance-based early warning signals have been shown to precede population collapses; however, such signals are sensitive to the low reliability of abundance estimates. Here, using historical data on whales harvested during the 20th century, we demonstrate that early warning signals can be present not only in the abundance data, but also in the more reliable body size data of wild populations. We show that during the period of commercial whaling, the mean body size of caught whales declined dramatically (by up to 4 m over a 70-year period), leading to early warning signals being detectable up to 40 years before the global collapse of whale stocks. Combining abundance and body size data can reduce the length of the time series required to predict collapse, and decrease the chances of false positive early warning signals.

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Figure 1: Data from the IWC on the number and body size of whales caught from 1900 to 1985.
Figure 2: Metrics that include body-size-only (orange), catch-only (green) and size–catch (blue) data, which produced early warning signals in each population prior to the inflection point of the fishery.
Figure 3: Early warning signals were detectable with as little as 10 years of data prior to the inflection point.
Figure 4: Consistent early warning signals were present up to 40 years prior to inflection points.

References

  1. 1

    Scheffer, M. et al. Anticipating critical transitions. Science 338, 344–348 (2012).

    CAS  Article  Google Scholar 

  2. 2

    Carpenter, S. R. et al. Early warnings of regime shifts: a whole-ecosystem experiment. Science 332, 1079–1082 (2011).

    CAS  Article  Google Scholar 

  3. 3

    Drake, J. & Griffen, B. Early warning signals of extinction in deteriorating environments. Nature 467, 456–459 (2010).

    CAS  Article  Google Scholar 

  4. 4

    Kéfi, S., Dakos, V., Scheffer, M., Van Nes, E. H. & Rietkerk, M. Early warning signals also precede non-catastrophic transitions. Oikos 122, 641–648 (2013).

    Article  Google Scholar 

  5. 5

    Dakos, V. et al. Methods for detecting early warnings of critical transitions in time series illustrated using simulated ecological data. PLoS ONE 7, e41010 (2012).

    CAS  Article  Google Scholar 

  6. 6

    Clements, C. F., Drake, J. M., Griffiths, J. I. & Ozgul, A. Factors influencing the detectability of early warning signals of population collapse. Am. Nat. 186, 50–58 (2015).

    Article  Google Scholar 

  7. 7

    Burthe, S. J. et al. Do early warning indicators consistently predict nonlinear change in long-term ecological data? J. Appl. Ecol. 53, 666–676 (2015).

    Article  Google Scholar 

  8. 8

    Pauly, D., Hilborn, R. & Branch, T. A. Fisheries: does catch reflect abundance? Nature 494, 303–306 (2013).

    CAS  Article  Google Scholar 

  9. 9

    Clements, C. F. & Ozgul, A. Including trait-based early warning signals helps predict population collapse. Nat. Commun. 7, 10984 (2016).

    CAS  Article  Google Scholar 

  10. 10

    Ozgul, A., Bateman, A. W., English, S., Coulson, T. & Clutton-Brock, T. H. Linking body mass and group dynamics in an obligate cooperative breeder. J. Anim. Ecol. 83, 1357–1366 (2014).

    Article  Google Scholar 

  11. 11

    Ling, S. D., Johnson, C. R., Frusher, S. D. & Ridgway, K. R. Overfishing reduces resilience of kelp beds to climate-driven catastrophic phase shift. Proc. Natl Acad. Sci. USA 106, 22341–22345 (2009).

    CAS  Article  Google Scholar 

  12. 12

    Anderson, C. N. K. et al. Why fishing magnifies fluctuations in fish abundance. Nature 452, 835–839 (2008).

    CAS  Article  Google Scholar 

  13. 13

    Uusi-Heikkilä, S. et al. Altered trait variability in response to size-selective mortality. Biol. Lett. 12(9), 20160584 (2016).

    Article  Google Scholar 

  14. 14

    Hilborn, R. et al. State of the world’s fisheries. Annu. Rev. Envir. Resour. 28, 359–399 (2003).

    Article  Google Scholar 

  15. 15

    Baker, C. S. & Clapham, P. J. Modelling the past and future of whales and whaling. Trends Ecol. Evol. 19, 365–371 (2004).

    Article  Google Scholar 

  16. 16

    Jackson, J. B. et al. Historical overfishing and the recent collapse of coastal ecosystems. Science 293, 629–637 (2001).

    CAS  Article  Google Scholar 

  17. 17

    Gerlach, S. Marine Pollution (Springer, 1981).

    Google Scholar 

  18. 18

    Dierauf, L. & Gulland, F. M. D. CRC Handbook of Marine Mammal Medicine: Health, Disease, and Rehabilitation 2nd edn (CRC, 2001).

    Google Scholar 

  19. 19

    Springer, A. et al. Sequential megafaunal collapse in the North Pacific Ocean: an ongoing legacy of industrial whaling? Proc. Natl Acad. Sci. USA 100, 12223–12228 (2003).

    CAS  Article  Google Scholar 

  20. 20

    Roman, J. & Palumbi, S. R. Whales before whaling in the North Atlantic. Science 301, 508–510 (2003).

    CAS  Article  Google Scholar 

  21. 21

    Basberg, B. L. Technological change in the Norwegian whaling industry. Res. Policy 11, 163–171 (1982).

    Article  Google Scholar 

  22. 22

    Audzijonyte, A. et al. Trends and management implications of human-influenced life-history changes in marine ectotherms. Fish Fish. 17, 1005–1028 (2016).

    Article  Google Scholar 

  23. 23

    Bannister, J. Great Whales (CSIRO, 2008).

    Google Scholar 

  24. 24

    Biggs, R., Carpenter, S. R. & Brock, W. A. Turning back from the brink: detecting an impending regime shift in time to avert it. Proc. Natl Acad. Sci. USA 106, 826–831 (2009).

    CAS  Article  Google Scholar 

  25. 25

    Whitehead, H. Sperm Whales: Social Evolution in the Ocean (Univ. Chicago Press, 2003).

    Google Scholar 

  26. 26

    Rocha, J., Yletyinen, J., Biggs, R., Blenckner, T. & Peterson, G. Marine regime shifts: drivers and impacts on ecosystems services. Phil. Trans. R. Soc. B 370, 20130273 (2014).

    Article  Google Scholar 

  27. 27

    Clarke, S. C. et al. Global estimates of shark catches using trade records from commercial markets. Ecol. Lett. 9, 1115–1126 (2006).

    Article  Google Scholar 

  28. 28

    International Convention for the Regulation of Whaling, 1946 (IWC, 2014).

  29. 29

    Rochet, M. J. et al. Do changes in environmental and fishing pressures impact marine communities? An empirical assessment. J. Appl. Ecol. 47, 741–750 (2010).

    Article  Google Scholar 

  30. 30

    Wood, S. N. mgcv: Mixed GAM Computation Vehicle with GCV/AIC/REML Smoothness Estimation. R package version 1.8-6 (R Foundation for Statistical Computing, 2013).

  31. 31

    R Development Core Team R: A Language and Environment for Statistical Computing (R Foundation for Statistical Computing, 2016).

  32. 32

    Taylor, B. L ., Chivers, S. J ., Larese, J. & Perrin, W. F. Generation Length and Percent Mature Estimates for IUCN Assessments of Cetaceans Administrative Report LJ-07-01 (National Marine Fisheries Service, 2007).

    Google Scholar 

  33. 33

    Pfister, C. A. & Stevens, F. R. The genesis of size variability in plants and animals. Ecology 83, 59–72 (2002).

    Article  Google Scholar 

Download references

Acknowledgements

This work was made possible by an ERC starting grant (no. 337785) to A.O. and an SNF international short visit grant (no. IZK0Z3_166526) to C.F.C. Whale illustrations by K. Askaroff.

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This work was jointly conceived by all the authors. C.F.C. performed the analyses and wrote the first draft of the manuscript. All co-authors contributed substantially to revisions.

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Correspondence to Christopher F. Clements.

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The authors declare no competing financial interests.

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Supplementary Notes 1,2; Supplementary Figures 1–8; Supplementary Table 1; Supplementary References. (PDF 494 kb)

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Clements, C., Blanchard, J., Nash, K. et al. Body size shifts and early warning signals precede the historic collapse of whale stocks. Nat Ecol Evol 1, 0188 (2017). https://doi.org/10.1038/s41559-017-0188

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