Perhaps so, especially if it causes us, again and again, to be taken unawares by the magnitude of our own actions: Top-down control can happen in ponds, scientists thought at first, but surely not in the open ocean; but then we converted the greatest of oceanic ecosystems—the Benguela Current—into our own stinking pond. Regime shifts occur, oceanographers found, when the earth's largest system of oceanic circulation exhibit massive rerouting; but then we proved ourselves a force commensurate with Oceanus himself. Top-down control cannot happen in the ocean, an important argument went, because of the high biodiversity on each floor of the food web; but then we cleared out whole stories all at once, and regime shifts ensued.
My students' fishing tale has always struck me, I suppose, because it is a kind of metonymic enactment: little fish is eaten by big fish; big fish is caught by humans; and finally, big fish is replaced by undesirable species—but not without the help of our fishing line. The Canadian shelf and the Benguela current; the North Sea and the Sea of Cortez—they are all, in a way, theatres of a single, overarching regime shift. And the vital question now is whether the species in power will govern wisely. What happens if we do not is depicted, I think, in the image of a ten-ton trawler, pulling itself over, and dumping the crew in among the jellyfish.
© Aaron Hirsh. All rights reserved.