Reading the Bones

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Science  21 Jun 2013:
Vol. 340, Issue 6139, pp. 1377
DOI: 10.1126/science.340.6139.1377-a

Large-scale fishing impacts in the open ocean are recent, mostly occurring during the past half century as industrial fishing technologies were developed. We can quantify these impacts on marine food webs by using current and historical animal tissues to document the temporal signature of human-driven diet change in marine species. Wiley et al. looked at isotopes from bones and flight feathers, collected at modern and historical breeding sites, of Hawaiian petrels. Ranging from current to 4000 years old, specimens represented individuals alive well before the first humans arrived on Hawaii, as well as those from the current depleted system. The percentage of N15 was relatively stable over roughly 3000 years, but rapidly decreased, across all Hawaiian populations, within the past 50 to 100 years, coincident with the onset of industrial fishing. A fisheries-induced decrease in trophic level is the most likely cause of this shift, and the petrel's generalist foraging strategy further suggests the presence of a wider fisheries-driven change in the oceanic food webs of the northeast Pacific Ocean.

Proc. Natl. Acad. Sci. U.S.A. 110, 10.1073/pnas.1300213110 (2013).

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