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Fishing through marine food webs - PubMed

  • ️Sun Jan 01 2006

Fishing through marine food webs

Timothy E Essington et al. Proc Natl Acad Sci U S A. 2006.

Abstract

A recurring pattern of declining mean trophic level of fisheries landings, termed "fishing down the food web," is thought to be indicative of the serial replacement of high-trophic-level fisheries with less valuable, low-trophic-level fisheries as the former become depleted to economic extinction. An alternative to this view, that declining mean trophic levels indicate the serial addition of low-trophic-level fisheries ("fishing through the food web"), may be equally severe because it ultimately leads to conflicting demands for ecosystem services. By analyzing trends in fishery landings in 48 large marine ecosystems worldwide, we find that fishing down the food web was pervasive (present in 30 ecosystems) but that the sequential addition mechanism was by far the most common one underlying declines in the mean trophic level of landings. Specifically, only 9 ecosystems showed declining catches of upper-trophic-level species, compared with 21 ecosystems that exhibited either no significant change (n = 6) or significant increases (n = 15) in upper-trophic-level catches when fishing down the food web was occurring. Only in the North Atlantic were ecosystems regularly subjected to sequential collapse and replacement of fisheries. We suggest that efforts to promote sustainable use of marine resources will benefit from a fuller consideration of all processes giving rise to fishing down the food web.

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Conflict of interest statement

Conflict of interest statement: No conflicts declared.

Figures

Fig. 1.
Fig. 1.

Illustrative examples of the sequential collapse/replacement (A) and sequential addition (B) mode of fishing down the food web. Total yearly catch for each 0.1 trophic-level increment is indicated by the color bar on the right (104 kg yr−1). The mean trophic level (white line) was smoothed by using a locally weighted regression smoother. (A) The Scotian Shelf ecosystem exhibited a sharp decline in mean trophic level from 1990 to 2001 owing to the collapse of the cod fishery followed by a decline in the herring fishery and then the growth of the northern prawn fishery. (B) The mean trophic level of the Patagonian Shelf declined from 1980 to 2001, during which time catches for upper-trophic-level species (Argentinean hake) grew substantially while new fisheries for shortfin squid developed.

Fig. 2.
Fig. 2.

Estimates of the instantaneous rate of change (% yr−1) in apex predator catches (±SE) during the time period when the mean trophic level was declining in each ecosystem. Parameter estimates that are statistically different from zero (P < 0.05) are indicated by filled circles, and estimates that are not significant are indicated by open circles. Under the sequential collapse/replacement mode ecosystems should show a large decline in apex predator catches, whereas under the sequential addition mode ecosystems should show no change or growth in apex predator catches.

Fig. 3.
Fig. 3.

Comparison of the mean (±SE) instantaneous rate of change in apex predator catches (trophic level > 4; solid bars) and all upper-trophic-level catches (trophic level > mean trophic level; open bars) among ocean regions. An asterisk indicates that the mean is statistically different from zero (P < 0.05).

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References

    1. Jackson J. B. C., Kirby M. X., Berger W. H., Bjorndal K. A., Botsford L. W., Bourque B. J., Bradbury R. H., Cooke R., Erlandson J., Estes J. A., et al. Science. 2001;293:629–638. - PubMed
    1. Botsford L. W., Castilla J. C., Peterson C. H. Science. 1997;277:509–515.
    1. Myers R. A., Worm B. Nature. 2003;423:280–283. - PubMed
    1. Baum J. K., Myers R. A., Kehler D. G., Worm B., Harley S. J., Doherty P. A. Science. 2003;299:389–392. - PubMed
    1. Hilborn R., Branch T. A., Ernst B., Magnusson A., Minte-Vera C. V., Scheuerell M. D., Valero J. L. Annu. Rev. Environ. Resour. 2003;28:359–399.

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