Fishing Down the Food Web Turns 10!

In 1998, Pauly et al. published their seminal paper in Science on Fishing Down Marine Food Webs (FDFW). The paper has been cited nearly 1000 times and today it turns 10 years old. The paper has been influential, namely in establishing the mean trophic level of fisheries as a tool for measuring the health of the oceans. In 2000, the Convention on Biological Diversity (CBD)--a treaty to sustain biodiversity adopted by every country except the U.S.--mandated that each country report on its the change in mean trophic level over time as an indicator of ocean health.

How did they do the study? The team compiled the trophic levels (position on the food chain based on diet composition) for 220 species of fish. They multiplied that by the fisheries landings for each fish and then summed all the totals. Dividing this number by global catch, Pauly and team found that for all marine areas over the last 45 years there has been in decline in mean trophic level of fisheries landings (from 3.3 in early years to less than 3.1 in 1994). In other words, we're consuming our way down the food web from apex predators (e.g., tuna) to now eating their prey (e.g., mackerel).

As our fisheries change composition and the size decreases, we're still left with what to do about it. Though it's a wonderful paper, The Tragedy of the Commons has become a boring excuse for the demise of fisheries. UBC's Colin Clark showed long ago (in a paper in Science in 1973) that overexploitation of fisheries can occur even under monopoly control. In other words, it's not about ownership. We can't privatize our way out of this trouble. The best-case fisheries scenarios have closed access and immense amounts of regulatory oversights (e.g., Alaska salmon).

Instead of talking about privatization, I prefer Paul Dayton's approach. His article on the Reversal of the Burden of Proof in Fisheries Management was published in the same issue of Science as FDFW. Dayton explains that currently the onus is on scientists and government to prove that fisheries are damaging marine ecosystems (on then can fisheries be curtailed). Dayton argues that fisheries should follow the same model of the U.S. Nuclear Regulatory Commission or the Food & Drug Administration in which the commercial enterprise must prove their activity/product does no harm before it can be approved. In other words, fisheries should be considered guilty until they prove themselves innocent. Fisheries scientist Carl Walters goes one step further saying that rather than viewing the ocean open to fishing with a few exceptions (as we do now), we should view the oceans as close to fishing with a few exceptions.

Maybe in the next ten years...