Michael Reilly, Discovery News
June 1, 2009 -- Early humans living off the coast of California may
have been the first "farmers" of the sea.
By managing sea otter populations they maximized their harvest of
abalone and mussels, making them pioneers in the art of sustainable
fishery management, according to a new study.
Jon Erlandson of the University of Oregon and team of researchers
collected thousands of shells from ancient settlements of the Chumash
people in the Channels Islands near Santa Barbara, Calif., dating back
to around 12,000 years ago.
They found that while people were harvesting millions of shellfish
annually from the local kelp forest ecosystem, shell sizes remained
relatively stable even as the local population grew and became more
technologically advanced.
The trend suggests Channel Island settlers may have been the first to
work out a sustainable form of fishing. When certain areas became
depleted, they simply moved to another, effectively imposing a "no-
take zone" in the old fishing grounds. And when harvests dwindled
throughout the region, they switched to hunting and eating otters
until shellfish numbers recovered.
In previous studies, researchers have documented human impacts on
shellfish populations in the Mediterranean Sea as long as 25,000 years
ago. And evidence from South Africa suggests humans were hunting the
seas up to 120,000 years ago.
"For most of the 20th century, we thought any intensive use of marine
resources was limited to the last 10,000 years, the same time as the
agricultural revolution," Jon Erlandson of the University of Oregon
said. "But you have to understand that humans have been messing with
Mother Nature for a long time."
Erlandson presented his findings last week at the Oceans Past 1/
conference in Vancouver, British Columbia.
Daniel Pauly of the University of British Columbia argues the shells
are signs of opportunism, not management.
"Management implies you do something intentionally, you have a plan, a
goal," he said. "I think these people had a strategy to exploit
resources, and when it had a bad result, they switched from shellfish
to otters."
Still, Pauly said the work could teach us a valuable lesson about
managing modern day fisheries. About one-third of the global fish
catch goes to feeding farmed animals like pigs, chickens, salmon and
tuna. And it takes about four kilograms (8.8 pounds) of smaller fish
like sardines or anchovies, to produce one kilogram (2.2 pounds) of
tuna or pork.
Just by eating those smaller fish, Pauly said we might greatly reduce
pressure on global fisheries.
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