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Pallid sturgeon come from a genetic line that has lived on this planet for tens of millions of years; yet it has been decades since anyone has documented any of the enormous fish successfully producing young that survive to adulthood in the upper Missouri River basin.
Now, fisheries scientists with the U.S. Geological Survey, Montana State University and the U.S. Fish and Wildlife Service have shown why, detailing for the first time the biological mechanism that has caused the long decline of pallid sturgeon in the Missouri River and led to its being placed on the endangered species list 25 years ago.
In a paper published this week in the journal Fisheries, the scientists show that oxygen-depleted dead zones between dams in the upper Missouri River are directly linked with the failure of endangered pallid sturgeon hatched embryos to survive to adulthood.
“This research is a notable breakthrough in identifying the reason why pallid sturgeon in the Missouri River have been declining for so many decades,” said Suzette Kimball, acting director of the USGS. “By pinpointing the biological mechanism responsible for the species’ decline, resource managers have vital information they can use as a focus of pallid sturgeon conservation.”
“We certainly think this is a significant finding in the story of why pallid sturgeon are failing to recruit in the upper Missouri River,” said Christopher Guy, the assistant unit leader with the USGS Montana Cooperative Fishery Research Unit and the MSU professor who was the lead author on the paper. “We’re basically talking about a living dinosaur that takes 20 years to reach sexual maturity and can live as long as the average human in the U.S. After millions of years of success, the pallid sturgeon population stumbled and now we know why. From a conservation perspective, this is a major breakthrough.”
The study is the first to make a direct link among dam-induced changes in riverine sediment transport, the subsequent effects of those changes on reduced oxygen levels and the survival of an endangered species, the pallid sturgeon.
Adult pallid sturgeon image credit Christopher Guy, USGS.
Read more at USGS.
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