A new study concludes centuries of overfishing - not pollution, global warming, and water quality triggered the current collapse of marine ecosystems around the globe.
Jeremy Jackson with the Scripps Institution of Oceanography in California says that over the course of his 30 year career, every marine ecosystem he has ever studied has become unrecognizably different from the way it used to be, and he wanted to know why. So, working with a team of marine scientists from around the globe, he spent two years searching for some answers.
"When we started out we thought we would be looking at the whole range of factors that affect the marine community due to human activity. Fishing is certainly one of them, but pollution, runoff from the land, climate change and all sorts of things," Mr. Jackson explained. "And what we discovered was that when we started looking back in time, in every case where we have reasonable data, that very intense fishing was the primary factor in causing change."
The scientists tracked signs of change from thousands of years ago using marine sediment cores, fossil records and archeological data. They studied sailing charts and journals from the 15th century. A portrait emerged of a sea teaming with large creatures and such an abundance of shellfish they were navigational hazards in shallow waters. "We discovered, for example, that there were enormous fisheries of species that are virtually eliminated from places now that took place, 200 . . . 300 years ago," Mr. Jackson explained. "And no one would ever think of sea turtles as being a dominant component of the ecology of the Caribbean, but they were."
Jeremy Jackson says historic over fishing of key predators and entire layers of the food chain set off a series of events that is now culminating in toxic algae blooms, dead zones, outbreaks of disease and other symptoms of ecological instability. But, he says those trends could be reversed.
"What we conceived of is very large protected areas in which one either allows the keystone species to come back naturally or even to intervene to do everything we could do to bring back populations," he said.
Jeremy Jackson says his working group hopes to complete studies on the magnitude of the impact of historic overfishing within the next year and then use the research as a framework for restoration.