Curly
Member
The large freshwater fish, trapped in polluted waters behind dams, may be losing their ability to spawn
Sunday, April 09, 2006
MICHAEL MILSTEIN
Pesticides and other pollution have turned Columbia River reservoirs into chemical stews playing havoc with the bodies of hulking white sturgeon, the largest freshwater fish on the continent.
A team of researchers that examined 174 sturgeon caught by commercial and tribal fishermen found male and immature females tricked by chemicals into thinking they are full of estrogen, a female hormone with feminizing effects. Male fish tainted with a cocktail of compounds including mercury and a byproduct of the banned pesticide DDT showed depressed testosterone levels, which could keep them from maturing enough to spawn.
A few sturgeon even had bizarre combinations of male and female sexual organs.
It suggests the reservoirs behind John Day, The Dalles and Bonneville dams have become catch basins of pollution flushed for decades into the once free-flowing Columbia. Sturgeon do not use fish ladders as do salmon, so they are trapped in the noxious soup reservoirs.
The chemical compounds can confuse their bodies, throwing the natural rhythms that govern reproduction and other functions out of whack, scientists say.
Chemical-laden fish suffered low body weights and weakened immune systems that could compromise their survival, said Deke Gundersen, director of environmental studies at Pacific University and part of the research team.
The Columbia collects pollution from sewage treatment plants, pulp mills, smelters, mining, farm and urban runoff and other sources. PCBs were dumped in the course of dam operations. Scientists found the worst contamination in fish behind Bonneville Dam, the oldest impoundment -- where chemicals from cancer-causing PCBs to toxic mercury have had the longest to collect.
"You see this in a lab and it's one thing," said Carl Schreck of the U.S. Geological Survey and Oregon State University's Department of Fisheries and Wildlife. "But to see it in nature is disturbing."
Contamination in the Columbia is no surprise. State authorities warned a decade ago that chemicals in some river fish, including sturgeon, pose a health risk for people who eat them. The U.S. Army Corps of Engineers plans to test fish near Bonneville Dam for human health risk in coming months, officials said.
But the new study set out to look at the effect on the fish themselves.
It focused on chemical levels in organs of the fish, not in parts people normally eat.
Sturgeon are the prehistoric giants of the river -- living as long as a century, weighing as much as a ton and sometimes as big as small boats. They have long been a staple for Native Americans.
And they are increasingly a featured entree at some of Portland's finest restaurants emphasizing local fresh ingredients. Higgins, on Broadway, is among them, and co-owner Greg Higgins said it is impossible to know precisely where sturgeon are caught and thus estimate their chemical exposure.
Instead, he said, he must "go on a trust basis with the fishermen who bring them in" as to the origin of the fish. His belief, he said, was that fewer chemical concentrations occur in the lower Columbia, so he seeks sturgeon from that area.
Yet sturgeon are in trouble. Populations behind the dams appear dominated by young fish that grow more slowly and take longer to reproduce, said Tom Rien of the Oregon Department of Fish and Wildlife. Adult fish do not spawn as often as they could, and biologists find little sign of young some years.
The most obvious reasons are that they spawn most successfully in cool, fast-moving water, which is lacking in the reservoirs. The dams also limit their access to food they could otherwise find by cruising up and down the river.
"Contaminants are definitely a concern," said Blaine Parker, a fisheries biologist with the Columbia River Intertribal Fish Commission, who was not involved in the research. "But it's on top of everything else."
Researchers originally expected the most contamination in sturgeon dwelling in the Columbia River estuary, toward Astoria and below the dams. They figured fish there would be exposed to more pollution from industrial sources in the Portland area, said Grant Feist, a fisheries biologist at Oregon State.
However, those were among the cleaner and healthier fish, probably because the river's flow carries pollution past. Behind the dams, though, it settles into sediments where sturgeon ingest it as they forage for crayfish, snails and other food on the bottom.
"Sturgeon have adapted to an open river, and these fish are trapped in what essentially are big lakes and exposed to whatever is there," Feist said.
The researchers tested nearly 100 fish caught in 2000 and 2001 for 18 different pesticides and found all the pesticides in at least some fish. Fish showed consistently high levels of DDE, a toxic byproduct left over when DDT is broken down by the body.
They also looked for 28 different PCBs, harmful chemicals used as lubricants and coolants but not manufactured in the United States since 1977. They found 26 of the PCBs in at least some fish.
The expensive battery of testing took several years to complete, and looked only for a fraction of the many chemicals that may be affecting the fish, researchers said.
"There's literally thousands of compounds out there," Feist said.
Male fish behind the dams had very depressed testosterone levels compared to less-contaminated fish in the estuary. Testosterone pushes fish toward maturity so they can reproduce. The scientists believe chemical pollution causes the bodies of the fish to break down the testosterone they need.
"The more contaminants they had, the less testosterone they had," Gundersen said.
They also reported that high levels of DDT and its byproducts in the liver and gonads of fish may keep them producing enough testosterone to reach sexual maturity.
In reservoirs behind John Day and The Dalles dams, male fish had unusually high levels of an egg protein normally triggered by the presence of estrogen in female fish preparing to lay eggs. Its presence suggests that some unknown chemical or mixture of chemicals with feminizing effects fools the fish into producing the protein.
However, researchers found little evidence of it in fish behind Bonneville Dam, which puzzles them because Bonneville is the most tainted.
"This has completely baffled us," Feist said.
Gundersen said he wouldn't hesitate to eat an occasional meal of Columbia River sturgeon. "But I wouldn't make it a major source of protein in my diet," he said.
Reporter Peter Sleeth contributed to this story.
Michael Milstein: 503-294-7689; [email protected]
Sunday, April 09, 2006
MICHAEL MILSTEIN
Pesticides and other pollution have turned Columbia River reservoirs into chemical stews playing havoc with the bodies of hulking white sturgeon, the largest freshwater fish on the continent.
A team of researchers that examined 174 sturgeon caught by commercial and tribal fishermen found male and immature females tricked by chemicals into thinking they are full of estrogen, a female hormone with feminizing effects. Male fish tainted with a cocktail of compounds including mercury and a byproduct of the banned pesticide DDT showed depressed testosterone levels, which could keep them from maturing enough to spawn.
A few sturgeon even had bizarre combinations of male and female sexual organs.
It suggests the reservoirs behind John Day, The Dalles and Bonneville dams have become catch basins of pollution flushed for decades into the once free-flowing Columbia. Sturgeon do not use fish ladders as do salmon, so they are trapped in the noxious soup reservoirs.
The chemical compounds can confuse their bodies, throwing the natural rhythms that govern reproduction and other functions out of whack, scientists say.
Chemical-laden fish suffered low body weights and weakened immune systems that could compromise their survival, said Deke Gundersen, director of environmental studies at Pacific University and part of the research team.
The Columbia collects pollution from sewage treatment plants, pulp mills, smelters, mining, farm and urban runoff and other sources. PCBs were dumped in the course of dam operations. Scientists found the worst contamination in fish behind Bonneville Dam, the oldest impoundment -- where chemicals from cancer-causing PCBs to toxic mercury have had the longest to collect.
"You see this in a lab and it's one thing," said Carl Schreck of the U.S. Geological Survey and Oregon State University's Department of Fisheries and Wildlife. "But to see it in nature is disturbing."
Contamination in the Columbia is no surprise. State authorities warned a decade ago that chemicals in some river fish, including sturgeon, pose a health risk for people who eat them. The U.S. Army Corps of Engineers plans to test fish near Bonneville Dam for human health risk in coming months, officials said.
But the new study set out to look at the effect on the fish themselves.
It focused on chemical levels in organs of the fish, not in parts people normally eat.
Sturgeon are the prehistoric giants of the river -- living as long as a century, weighing as much as a ton and sometimes as big as small boats. They have long been a staple for Native Americans.
And they are increasingly a featured entree at some of Portland's finest restaurants emphasizing local fresh ingredients. Higgins, on Broadway, is among them, and co-owner Greg Higgins said it is impossible to know precisely where sturgeon are caught and thus estimate their chemical exposure.
Instead, he said, he must "go on a trust basis with the fishermen who bring them in" as to the origin of the fish. His belief, he said, was that fewer chemical concentrations occur in the lower Columbia, so he seeks sturgeon from that area.
Yet sturgeon are in trouble. Populations behind the dams appear dominated by young fish that grow more slowly and take longer to reproduce, said Tom Rien of the Oregon Department of Fish and Wildlife. Adult fish do not spawn as often as they could, and biologists find little sign of young some years.
The most obvious reasons are that they spawn most successfully in cool, fast-moving water, which is lacking in the reservoirs. The dams also limit their access to food they could otherwise find by cruising up and down the river.
"Contaminants are definitely a concern," said Blaine Parker, a fisheries biologist with the Columbia River Intertribal Fish Commission, who was not involved in the research. "But it's on top of everything else."
Researchers originally expected the most contamination in sturgeon dwelling in the Columbia River estuary, toward Astoria and below the dams. They figured fish there would be exposed to more pollution from industrial sources in the Portland area, said Grant Feist, a fisheries biologist at Oregon State.
However, those were among the cleaner and healthier fish, probably because the river's flow carries pollution past. Behind the dams, though, it settles into sediments where sturgeon ingest it as they forage for crayfish, snails and other food on the bottom.
"Sturgeon have adapted to an open river, and these fish are trapped in what essentially are big lakes and exposed to whatever is there," Feist said.
The researchers tested nearly 100 fish caught in 2000 and 2001 for 18 different pesticides and found all the pesticides in at least some fish. Fish showed consistently high levels of DDE, a toxic byproduct left over when DDT is broken down by the body.
They also looked for 28 different PCBs, harmful chemicals used as lubricants and coolants but not manufactured in the United States since 1977. They found 26 of the PCBs in at least some fish.
The expensive battery of testing took several years to complete, and looked only for a fraction of the many chemicals that may be affecting the fish, researchers said.
"There's literally thousands of compounds out there," Feist said.
Male fish behind the dams had very depressed testosterone levels compared to less-contaminated fish in the estuary. Testosterone pushes fish toward maturity so they can reproduce. The scientists believe chemical pollution causes the bodies of the fish to break down the testosterone they need.
"The more contaminants they had, the less testosterone they had," Gundersen said.
They also reported that high levels of DDT and its byproducts in the liver and gonads of fish may keep them producing enough testosterone to reach sexual maturity.
In reservoirs behind John Day and The Dalles dams, male fish had unusually high levels of an egg protein normally triggered by the presence of estrogen in female fish preparing to lay eggs. Its presence suggests that some unknown chemical or mixture of chemicals with feminizing effects fools the fish into producing the protein.
However, researchers found little evidence of it in fish behind Bonneville Dam, which puzzles them because Bonneville is the most tainted.
"This has completely baffled us," Feist said.
Gundersen said he wouldn't hesitate to eat an occasional meal of Columbia River sturgeon. "But I wouldn't make it a major source of protein in my diet," he said.
Reporter Peter Sleeth contributed to this story.
Michael Milstein: 503-294-7689; [email protected]
