Fwd: AP & SF Chronicle on 'Science' Historical Overfishing study

Alina M. Szmant szmanta at uncwil.edu
Sat Jul 28 21:34:39 EDT 2001

>Date: Fri, 27 Jul 2001 10:04:27 -0400
>From: Herb Ettel <hettel at conservefish.org>
>Subject: AP & SF Chronicle on 'Science' Historical Overfishing study
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>Destruction of ocean abundance started long before industrial age, continues
>now, study says
>AP Science Writer
>Associated Press Newswires
>Copyright 2001. The Associated Press. All Rights Reserved.
>WASHINGTON (AP) - Humans started destroying the natural abundance of the seas
>thousands of years ago and tipped a delicate balance that left the
>environment more
>vulnerable to the excesses of the modern age, a study shows.
>By widespread slaughter of sea turtles in the Caribbean, or sea cows off
>the coast of
>Australia or sea otters near Alaska, ancient humans started a damaging
>that changed the Earth, researchers say in a study appearing Friday in the
>Science. It still is being felt.
>"There's been a longtime belief that everything was fine until the ...
>showed up," said Karen Bjordal, a zoology professor at the University of
>"Now we've discovered that the start of the environmental problems (in the
>sea) go
>way back before that."
>"The notion of the native peoples of having a benign impact on the
>environment in
>their vicinity has been challenged," said Charles Peterson of the
>University of North
>Carolina at Chapel Hill. "The general feeling is that there were dramatic
>effects locally
>and not a prudent predation" by ancient humans long before the Colonial and
>industrial eras.
>Based on combined research of 19 scientists on four continents, the study
>that careless and excessive harvesting of food from the sea as early as
>years ago caused changes in the ecosystems and made the environment more
>easily damaged by the wholesale exploitation of modern man.
>James Acheson, a marine scientist at the University of Maine, called the
>research "a
>breath of fresh air" in the understanding of marine ecology and how it has
>affected by humans.
>"They are pointing toward a new way to look at the oceans," said Acheson.
>show that human predation preceded all the other damage" done to the oceans.
>In the study, researchers analyze the effect that the loss of species has
>had on the
>intricate food web of coastal areas in the Americas, Australia and Europe.
>was an analysis of kitchen debris left by ancient humans; reports on the
>of sea life by explorers in the 18th and 19th centuries; and modern wildlife
>population studies.
>"It is astonishing the effect we have had on the Earth," said Peterson.
>Bjorndal said algae now choking and killing many coral reefs in the
>Caribbean can
>be traced to the slaughter more than 3,000 years ago of the green sea
>turtle and to
>other animals that grazed on the sea plant.
>She said a study of kitchen refuse piles from the Amerindian peoples who
>first settled
>the Caribbean showed that they depended heavily on the sea turtle for
>food. The
>animals were easy to catch as they regularly lumbered ashore to lay eggs
>on the
>semitropical islands.
>Bjorndal said an analysis of the kitchen refuse piles at ancient island
>village sites
>shows that at first "a large amount of the meat the people lived on was
>sea turtle."
>But evidence of turtle slaughter in the kitchen refuse grew less and less
>with the
>passage of time until, finally, "The turtles disappear entirely. It is
>clear the nesting
>colonies were wiped out," she said.
>With the turtle gone, the people turned to other food, such as the large
>parrot fish, a
>meaty dweller of the reef. Those, too, eventually became scarce, as did other
>plant-eating animals.
>"We reduced the system to one plant-eating species," a type of sea urchin,
>Bjorndal. "The system continued to function, but it was incredibly
>That was shown when, starting 15 years ago, disease wiped out the sea
>urchin, she
>said. Algae quickly exploded in growth, smothering many coral reefs. This
>in turn,
>doomed many species that lived in the reef.
>"This was a process was set in motion when the (native people) killed off
>the sea
>turtle," Bjorndal said.
>Another example cited by the researchers is the loss of vast kelp forests
>that once
>grew thickly offshore along North America's east and west coasts.
>Overharvesting of the sea otter, starting some 2,500 years ago, led to a huge
>population of sea urchins, the otter's principal food. The sea urchins
>grazed away
>the kelp forests, causing a steep decline in fish populations.
>In modern times, the sea otter has been protected from human hunters, but
>because of mankind, it has a new enemy - the killer whale.
>Peterson said the killer whale normally dines on seals. The population of
>seals has
>fallen dramatically over the last 200 years, however, both because of fur
>hunters and
>later overfishing by humans that deprived the seals of food. Since there
>are few
>seals to feed on, the killer whale now preys on the sea otter. This in
>turn allows the
>sea urchin to graze down the kelp forest.
>Bjordal and her co-authors believe some of the environmental loss can be
>with new programs to protect sea life and control fishing.
>Many of the depleted animals are not extinct and could be brought back to
>restore a
>lost balance, she said. "One of our main messages is that there is hope,"
>she said.
>On the Net: Science magazine: http://www.eurekalert.org
>Study takes historical peek at plight of ocean ecosystems
>Jane Kay
>Chronicle Environment Writer
>The San Francisco Chronicle
>(Copyright 2001)
>Overfishing and hunting of marine mammals over past centuries set the
>stage for the
>current collapse of coastal ecosystems, say scientists in a major new
>study based
>on records dating back 125,000 years.
>In one of the first studies to take a historical look at the problem, the
>found that fishing by aboriginal cultures and European colonialists
>contributed to the
>extinction or severe depletion of many marine species.
>Among the species cited by the study are whales, manatees, sea cows, monk
>crocodiles, swordfish, codfish, sharks and rays.
>The study, released today in the journal Science, was conducted by
>researchers at
>the Scripps Institution of Oceanography, the U.S. Geological Survey and the
>University of California, among others.
>"Contrary to romantic notions of the oceans as the 'last frontier' and of the
>supposedly superior ecological wisdom of non-Western and precolonial
>our analysis demonstrates that overfishing fundamentally altered coastal
>ecosystems during each of the cultural periods we examined," said the
>study, whose
>lead author is Jeremy B. C. Jackson, a marine biologist at Scripps in La
>Jolla (San
>Diego County).
>"Human impacts are also accelerating in their magnitude, rates of change
>and in the
>diversity of processes responsible for changes over time. Early changes
>the sensitivity of coastal marine ecosystems to subsequent disturbances
>and thus
>preconditioned the collapse we are witnessing," they said.
>Hunting and fishing of the oceans came in three distinct but overlapping
>periods: the
>aboriginals starting about 10,000 years ago, the European colonialists
>trading in
>whale oil and marine mammal skins, and the recent global expansion using
>sophisticated technologies and "factory" trawlers.
>Coastal species were suffering from overfishing even before other man-made
>problems, such as pollution, eutrophication (lack of oxygen leading to
>toxic algae
>blooms), physical destruction of habitats, diseases, invasive species and
>change, the study said.
>This is one of the first historical looks at overfishing, offering a
>comparison between a
>vastly abundant sea life found in marine sediments dating back 125,000
>years and
>present day impoverished populations that depend on damaged kelp forests,
>reefs and seagrass beds.
>Until now, scientific understanding has been hampered by mainly local,
>studies conducted after the 1950s. These studies also didn't consider the
>conditions relating to changing temperatures and other climatic events.
>The collapse of ecosystems often occur over a long period.
>In one example, when Aleut hunters killed the Alaskan sea otter about
>2,500 years
>ago, the population of their natural prey, the sea urchin, grew larger
>than its normal
>size. In turn, the urchins grazed down the kelp forests, important habitat
>for a whole
>host of ocean life.
>Then, when fur traders in the 1800s hunted the otters and sea cows almost to
>extinction, the kelp forests disappeared and didn't start to regenerate
>until the federal
>government protected the sea otters in the 20th century. In California,
>the diversity of
>spiny lobsters, sheephead fish and abalone kept down the urchin numbers.
>At present in Alaska, the kelp beds are declining again in areas where
>killer whales
>are preying on sea otters. Biologists think the killer whales switched to
>otters for food
>because there are fewer seals and sea lions to eat.
>The reasons seal and sea lion populations have dropped are still unclear,
>to one of the authors, U.S. Geological Survey marine biologist Jim Estes.
>"One possibility is overfishing," Estes said. "The fishers took food the
>seals and sea
>lions would have eaten. A second could be a less productive ocean, with
>less food
>for the seals and sea lions in the North Pacific, related to ocean
>warming, perhaps
>cyclical or part of a larger human-caused trend. A third possibility is
>predation by killer
>whales or other predators."
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