Saturday, July 13, 2019

Failures at Corps of Engineers, SDGF&P bring invasive mussels to Lake Sharpe


The death of the Missouri River ecosystem in South Dakota began with the European invasion, was accelerated by the Homestake Mining Company and sealed with the construction of the mainstem dams.

After massive failures of state agencies the Republican-controlled South Dakota Game, Fish and Plunder is throwing up its hands on invasive species like zebra mussels. The pesky bivalves compete with paddlefish and other native species like the pallid sturgeon. But only recently have the Commissioners for South Dakota's Game, Fish and Plunder implemented mandatory boat inspections after failing the control of aquatic invasive species (AIS) in the lower Missouri River mainstem dams.
“The mussels were initially discovered by members of the U.S. Army Corps of Engineers while performing maintenance at Big Bend Dam, at the lower end of Lake Sharpe,” said Fisheries Chief John Lott. “They were positively identified as zebra mussels by GFP staff. Additional sampling efforts by GFP and the U.S. Fish & Wildlife Service have confirmed that adult zebra mussels are present in multiple areas in the lower portion of the lake.” Zebra mussels can produce up to one million eggs per year, rapidly colonizing new waters. [Zebra mussels confirmed in Lake Sharpe]
Diving ducks like the Canvasback, Redhead, Bufflehead, Lesser Scaup and the Common Goldeneye feed on the invasive zebra mussels that have been plaguing the mainstem dams in the Missouri River since at least 2004 but they're part of over a hundred species at risk to the South Dakota Republican Party.

Rivers often disperse the extra sediment from behind a dam within weeks or months of dam removal. Removal of the Fort Edward Dam on New York’s Hudson River released so much contaminated sediment that the river was later named a Superfund site. A similar fate would befall the Missouri River if dams were not dredged before being decertified and removed; but, migratory fish would recolonize newly accessible habitat within a matter of days.

Lake sturgeon prey on zebra mussels.
Upstream on the Sand Hill River in northwestern Minnesota, sturgeon and channel catfish are returning to their ancient spawning grounds for the first time in decades. The fish had been cut off from the gravel beds of the upper river — ideal habitat for laying and guarding eggs — by a series of concrete low-rise dams dating to the 1930s. As soon as the passages were reopened, the fish started returning, said Jamison Wendel, stream habitat supervisor for the Minnesota Department of Natural Resources (DNR). “It’s almost immediate,” Wendel said. [Minnesota sturgeon returning to ancient spawning grounds as dams are removed]
Christopher Guy, assistant unit leader with the US Geological Survey Montana Cooperative Fishery Unit and professor at Montana State University, is an expert on the endangered pallid sturgeon in the upper Missouri River basin.
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. Given what the new research shows about how no oxygen is available to hatched pallid sturgeon embryos, the authors of the paper propose that officials will need to consider innovative approaches to managing Missouri River reservoirs for pallid sturgeon conservation to have a chance. [press release, US Geological Survey]
The Army Corps of Engineers has cancelled Spring Pulses on the Missouri River not because of low flows but because the silt is so poisonous it would kill the very species it says it's trying to preserve. Below the Missouri River dams pallid sturgeon are showing signs of recovery but above?
According to American Rivers, an advocacy group that tracks U.S. dam removals, 72 dams in 19 states were torn down in 2014, a record. That is roughly double the annual number from 10 years ago. Some 1,185 dams have been removed since 1912, according to the group. The fleet of U.S. dams, however, is still enormous. The Army Corps of Engineers counts at least 87,000 dams in its database. Removing dams produces its own benefits. Public safety is enhanced by reducing the risk of a dam failure, and moribund freshwater fisheries are rejuvenated when a segmented river is reconnected. [Circle of Blue]
Accumulated mercury in large fish causes spontaneous abortions yet record non-native salmon in Lake Oahe go untested.

Although the Oahe Dam was completed in 1962 sequestering most of the silt the soils of the Belle Fourche and Cheyenne Rivers are inculcated with arsenic at levels that have killed cattle. Endangered pallid sturgeon, paddlefish, catfish and most other organisms cope with lethal levels of mercury throughout the South Dakota portion of the Missouri River.

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