Sea change
Toolbox
Published: April 28, 2007
Mankind is at the end of the era when it could feed itself with the fish from the sea. Fishing as a way of life is on the way out, and the oceans are unraveling as a natural ecosystem.
These were the observations of Jeremy Jackson, a marine ecologist of international stature, who delivered a lecture at Middlebury College on Friday. Jackson described devastation rivaling anything done to the rain forests or other terrestrial habitats, an environmental legacy that has largely gone unnoticed because it is hidden from view. The destruction of ocean habitats is so extreme already that Jackson's mostly hopeful scenario is relatively bleak and his worst scenario depicts the oceans as global dead zones.
The oceans have become "disaster areas," he said, but we aren't even aware of it because of what he called "shifting baseline syndrome." We identify what is natural with "the way it was when you're a kid." Changes that occur later seem like degradation, but often nature as we saw it when we were kids has already been degraded. We suffer from "amnesia about what is natural," he said. "We don't know what we've lost."
He described the coral reef habitats that he encountered as a young man doing research in the Caribbean as a rich and diverse undersea ecosystems. By now he doesn't have the heart to dive because the reefs have been degraded so badly. When vacationers view these nearly destroyed reef habitats, they come away amazed at their beauty, unaware of all that has been lost. "There isn't a Ben & Jerry's ice cream to save the coral reefs," he said.
The culprit is the human species. We have virtually wiped out most of the large species of fish. The fishing industry now is harvesting the last remnants of a vast population of marine animals. Ninety percent of all the big fish are gone. He said that at one time the green turtles of the Caribbean, which grow to 1,000 pounds, constituted a larger biomass than the bison herds of North America. There were 50 million to 100 million of them; now there are fewer than 300,000.
Trawling along the ocean floors has scraped all the life away, turning vast areas of the continental shelf around the world to parking lots. Shrimping is particularly destructive to the oceans. He said an area of the sea floor equal to all the forests ever cut down has been destroyed.
We have also poisoned the oceans with mercury and other toxins. Inuit breast milk qualifies as a toxic waste because of the mercury Inuit women ingest in the animals they eat.
Oysters used to filter the entire Chesapeake Bay every three to five days, he said, but now with most of the oysters gone, the great estuary is polluted with chicken manure and other runoff and is subject to algae blooms and eutrophication — the kind of degradation that is happening to Lake Champlain.
Three human activities are largely responsible for these changes — overfishing and destructive fishing practices; pollution; and warming temperatures caused by global warming.
He was not hopeful that these mistakes could be rectified. But as marine scientists learn more of what is happening in the ocean, we are getting a better idea of what we are in for.
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