Dramatic ecosystem shift in Arctic threatens fishing
By Margaret Munro
CanWest News Service / The Vancouver Sun
Friday, March 10, 2006
An international research team that hitches a ride north through the Bering Sea every summer with the Canadian Coast Guard says a "major ecosystem shift'' has occurred in the frigid waters that act as gateway to the Arctic.
Gray whales, walruses and diving seabirds are being replaced by fish that are moving north as ice cover shrinks and waters warm, say the scientists who detail their findings in the journal Science today.
The change is so dramatic the researchers say it threatens both commercial fishing and the livelihood of people such as the Yupik hunters of St. Lawrence Island, near the entrance of Bering Strait, who are watching the ice thin and the seals and walrus disperse.
"It's much more dangerous for them to go out and hunt, it is not the same stable platform they are used to,'' says co-author Fiona McLaughlin of the Institute of Ocean Sciences (IOS) in Victoria.
McLaughlin and her colleagues have been monitoring everything from water temperature and salinity to the behaviour of gray whales, walruses and diving ducks such as spectacled eiders for almost two decades. What emerges from the mass of data is clear evidence, they say, of an ecosystem shift in the shallow and productive waters of the northern Bering Sea.
Creatures that live on the bottom and feed on the bottom, such as whales and sea birds, are giving way to fish that feed within the water column, the scientists say. They believe the change has been triggered by the shrinking of a huge pool of cold water in the Bering Sea where such fish as salmon and pollock can not survive.
"This is a big change,'' says Eddy Carmack, IOS oceanographer and co-author, who likens it to switching from tundra to a boreal forest. As the pool of icy 1 C water shrinks, the fish are not only moving into the northern Bering Sea but they are slipping into the Arctic, the researchers report. Pink salmon are now showing up in rivers that drain into the Arctic Ocean.
The scientists say warm-blooded mammals such as walruses and seals appear to be seeking out colder waters elsewhere. There is also evidence mother walruses are abandoning their pups as the ice thins.
The researchers say the change appears to be tied to climate change and global warming. But they stress the need for more monitoring to understand what is happening and to manage resources.
"Relying on records of past fisheries catches and atmospheric pressure patterns is simply not enough," says Carmack. "You have to go into the field and look."
The scientists travel north through the Bering Sea on the Canadian icebreaker, the Sir Wilfrid Laurier, which heads for the Arctic each summer. Twelve to 14 researchers from the U.S., Japan and Canada typically go along as part of what Carmack calls the "entrepreneurial'' project.
Asked if they are worried about the trends they are seeing McLaughlin says, "it certainly makes you stop and think."
Carmack says he is not a worrier. But he says there is a clear need to better understand what is happening. "I think it would be irresponsible to not observe and report on the ecosystems that are being impacted," says Carmack. "Irresponsible."
http://www.canada.com/vancouversun/news/story.html?id=deb7bfa5-25ff-4926-8c32-c859a55a8283&k=54717
Informant: NHNE
CanWest News Service / The Vancouver Sun
Friday, March 10, 2006
An international research team that hitches a ride north through the Bering Sea every summer with the Canadian Coast Guard says a "major ecosystem shift'' has occurred in the frigid waters that act as gateway to the Arctic.
Gray whales, walruses and diving seabirds are being replaced by fish that are moving north as ice cover shrinks and waters warm, say the scientists who detail their findings in the journal Science today.
The change is so dramatic the researchers say it threatens both commercial fishing and the livelihood of people such as the Yupik hunters of St. Lawrence Island, near the entrance of Bering Strait, who are watching the ice thin and the seals and walrus disperse.
"It's much more dangerous for them to go out and hunt, it is not the same stable platform they are used to,'' says co-author Fiona McLaughlin of the Institute of Ocean Sciences (IOS) in Victoria.
McLaughlin and her colleagues have been monitoring everything from water temperature and salinity to the behaviour of gray whales, walruses and diving ducks such as spectacled eiders for almost two decades. What emerges from the mass of data is clear evidence, they say, of an ecosystem shift in the shallow and productive waters of the northern Bering Sea.
Creatures that live on the bottom and feed on the bottom, such as whales and sea birds, are giving way to fish that feed within the water column, the scientists say. They believe the change has been triggered by the shrinking of a huge pool of cold water in the Bering Sea where such fish as salmon and pollock can not survive.
"This is a big change,'' says Eddy Carmack, IOS oceanographer and co-author, who likens it to switching from tundra to a boreal forest. As the pool of icy 1 C water shrinks, the fish are not only moving into the northern Bering Sea but they are slipping into the Arctic, the researchers report. Pink salmon are now showing up in rivers that drain into the Arctic Ocean.
The scientists say warm-blooded mammals such as walruses and seals appear to be seeking out colder waters elsewhere. There is also evidence mother walruses are abandoning their pups as the ice thins.
The researchers say the change appears to be tied to climate change and global warming. But they stress the need for more monitoring to understand what is happening and to manage resources.
"Relying on records of past fisheries catches and atmospheric pressure patterns is simply not enough," says Carmack. "You have to go into the field and look."
The scientists travel north through the Bering Sea on the Canadian icebreaker, the Sir Wilfrid Laurier, which heads for the Arctic each summer. Twelve to 14 researchers from the U.S., Japan and Canada typically go along as part of what Carmack calls the "entrepreneurial'' project.
Asked if they are worried about the trends they are seeing McLaughlin says, "it certainly makes you stop and think."
Carmack says he is not a worrier. But he says there is a clear need to better understand what is happening. "I think it would be irresponsible to not observe and report on the ecosystems that are being impacted," says Carmack. "Irresponsible."
http://www.canada.com/vancouversun/news/story.html?id=deb7bfa5-25ff-4926-8c32-c859a55a8283&k=54717
Informant: NHNE
rudkla - 12. Mär, 10:51
