Fishing through Marine Food Webs

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 ext...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2006-02, Vol.103 (9), p.3171-3175
Main Authors: Essington, Timothy E., Beaudreau, Anne H., Wiedenmann, John
Format: Article
Language:English
Subjects:
Animals
Apex predators
Biological Sciences
Biology
Ecology
Ecosystems
Fisheries
Fisheries - methods
Fishery collapse
Fishery economics
Fishes - physiology
Food Chain
Food chains
Food webs
Marine
Marine ecosystems
Ocean fisheries
Oceans and Seas
Pisces
Species
Trophic levels
Tropical regions
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Summary: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.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0510964103