Posted: May 26th, 2009 - 10:39am
Source: Link

The world's oceans once teemed with life. In Europe, for example, blue whales, orcas and sharks filled the waters, porpoises explored rivers looking for fish and dolphins swam near the coast.
But new research finds that it wasn't the advent of mechanized fishing in the late 19th and 20th centuries that emptied the oceans of many of their native creatures.
Instead, human-caused changes came much earlier than previously thought, finds an extensive effort by marine historians to reconstruct the seas' past life. "Fishing on a large scale happened much earlier than we'd thought previously and with significantly more impact than one would have thought 10 years ago," says Poul Holm, professor at Trinity College, Dublin, and chairman of the History of Marine Animal Population project.
Researchers presented their findings at the Oceans Past II Conference in Vancouver, Canada, over the weekend:
•The first evidence of human effects on fish, shellfish and marine mammals began in the Middle Stone Age, 300,000 to 30,000 years ago. That's 10 times earlier than previously believed.
•By the 11th century some of Europe's major river systems were already fished out.
•Ocean fish populations began to crash in the 1500s when new fishing boats and equipment made deep-sea fishing possible.
The scientists and historians used ship logs, literary texts, tax accounts and newly translated legal documents to envision the oceans' history.