Back to the Future: A Methodology and Policy Goal for Future Fisheries
By Tony J. Pitcher
ABSTRACT
The ecological effects of fishing on aquatic ecosystems are presented, with examples from the present analysis of trophic levels, from history and archaeology. Overexploitation causes loss of diversity by removing fish with life history characters inimical to harvesting, both within and among species. The loss of keystone species can shift the nature ecosystems. Long-lived, high-value, demersal resources are replaced by pelagic, rapid-turnover, low-value species. Driven by a progression of clever human harvest technologies, three ratchet-like processes, Odum's ratchet, Ludwig's ratchet, and Pauly's ratchet, have brought about episodes of depletion. The present policy goal sustainability will foreclose future options for the generation of food, wealth, and services from ocean resources. Only a policy of rebuilding of ecosystems can reverse this trend. A novel methodology, termed Back To The Future, defines ecosystem policy goals with which to guide this rebuilding process. Ecosystem rebuilding can reduce conflict among resource stakeholders in the long run and encourage the public to act as sentinels. Moreover, the maximum economic value in tomorrow's markets, where supply is likely to vastly outstrip demand, will come from rebuilt ecosystems. In the Back to the Future method, models of past ecosystems are reconstructed using information about the presence and abundance of species derived from derived from historical documents, archaeology, local and traditional environmental knowledge (LEK and TEK). The mass-balance Ecopath and Ecoism suite of ecosystem modeling tools are described together with an example of BTF reconstruction. Economic evaluation of past systems can then be compared with present and alternative ecosystems. Moreover, for almost the first time, the Back to the Future methodology provides the TEK of aboriginal and indigenous peoples with a valuable, direct role in resource management.
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