Home Forums Hunting & Shooting Hunter's Campfire Quagga mussel treatment takes it's toll

TWIN FALLS — There were winners and losers when it came to fish kill during October’s quagga mussel treatment along a stretch of the Snake River near Twin Falls.

The winners were bigmouth bass and bluegill, which survived quite well.

The losers? The iconic white sturgeon.

There were many other fish killed, including tons of largescale suckers, as documented by Idaho Department of Fish & Game as the agency recently released a report on fish mortality.

All 49 sturgeon, some small, some large, that had been documented by Idaho Power as living in the six-mile treatment zone appear to have been killed, with 48 of them found dead.

And now, Fish & Game is hoping for a rebound. Although it will take time to rebuild the sturgeon population, Terry Thompson, regional communication manager for Fish & Game, said that once waters are re-opened, anglers can look forward to some good fishing.

A lot will depend on whether the treatment killed all the quagga mussels.

Quagga mussel treatment

The largest sturgeon found dead was 8 feet long, about 35 years old, and had its origins at the College of Southern Idaho hatchery in Rock Creek Canyon.

“It obviously was showing some good growth,” Thompson said. “I equate that with how some people grow tall and some short, so the genetics of that fish were good in terms of growth.”

All the sturgeon found were hatchery-raised, despite some people’s notion that 100-year-old fish lived in the stretch of water from Twin Falls Dam to Centennial Park.

“There was nothing to indicate that,” Thompson said.

The loss of the prehistoric-looking fish was a disappointment for Twin Falls resident Keaton Hammet of Twin Falls, who regularly goes sturgeon fishing, and posted a picture on Facebook of an eight-footer he caught three years ago near Pillar Falls.

Sturgeon can be caught in Idaho strictly on a catch-and-release basis.

“Sure hope it wasn’t this fish,” Hammet said, referring to the Fish & Game reports of an 8-footer found dead.

Danny Backman and son Danny Jr. were all smiles as they caught a large sturgeon near Centennial Park shortly before the quagga mussel treatment.

Catching one of the monster fish is like nothing he’s ever done, said the elder Backman.

“Literally when you get a good strong one that rips drag on a 120-pound test line and you have it set high, man it’s amazing,” he said.

Thompson reminds fishing enthusiasts that there is sturgeon fishing below Auger Falls, and recently saw a photo of a large sturgeon caught there. There were no dead sturgeon found below Auger Falls, Thompson said.

Backman, meanwhile, said he’s been told the Snake River near Buhl is among the best sturgeon fishing waters in the country.

There will be plans put into place when one thing happens: The Idaho State Department of Agriculture pronounces the stretch of the river free of quagga mussels. Officials hope the 10-day treatment killed them all, but if any survived they would be dormant now in the cold Idaho winter.

The invasive species, which can foul pipes, irrigation systems, and damage boats and power plants, can begin reproducing when water temperature hits about 55 degrees, and ISDA officials will begin monitoring for veligers, quagga mussel larvae, in the spring.

“It’s a fish we can work to repopulate but won’t do anything at all until we are sure that there isn’t going to be a need for further treatment,” Thompson said.

The new Niagara Springs Sturgeon Hatchery, owned by Idaho Power and operated by Idaho Fish & Game, can provide sturgeon, as well as potentially private hatcheries. Fish & Game will likely translocate sturgeon from other reaches of the river.

Plus, sturgeon get trapped in irrigation canals and they could be transplanted to the stretch of river. Last year, a five-footer was found trapped in a canal near Blackfoot.

Pre-survey, post-survey
Idaho Fish & Game has been busy. Due to Idaho’s quick response to the quagga mussel emergency, the agency had two days to perform a pre-survey to determine what fish numbers existed before the treatment, which consisted of introducing tens of thousands of gallons of the copper-based Natrix into the river to a level of one part per million.

“We were under the gun,” Thompson said, as he described the process that involved crews of three people, one to drive the boat and two to net fish. Data including species and length were collected in three areas, including one of them being at Niagara Springs, outside the treatment area.

F&G used electrofishing and workers handled 4,000 fish, which were released alive.

After the treatment in mid-October, F&G saw a lot of dead fish. It was impossible to quantify the actual number of fish killed because ISDA divers said they saw a lot of dead fish at the bottom of the river, but F&G collected some data from fish but the sheer numbers of dead fish “made it a little overwhelming.”

The good news, perhaps, from an anglers standpoint is that the large majority of fish — five tons of the total six to seven tons handled — were largescale suckers.

Suckers play a role in the ecosystem, Thompson said, and are noted for being algae eaters and scavengers, “but they aren’t typically a fish that is eaten so that is why people look at them as an undesirable fish to catch,” he said. “Nobody wants to spend their day catching a bunch of suckers when they are looking to get a fish they can take home for dinner.”

One ton of combined biomass of common carp and northern pikeminnow were handled, and less than 1,000 pounds of all other fish species. The post-treatment survey at Niagara Springs showed more fish there than before, suggesting that some fish moved downstream to avoid the treatment area and that mortality did not occur downstream from the treatment area.

Perhaps due to physiological reasons, bigmouth bass, bluegill and green sunfish didn’t seem significantly affected by chelated copper treatment, and numbers of those found dead were “very few,” Thompson said.

Few trout live in the stretch of river due to warm water temperatures, Thompson said.

Fish consumption
The fish that survived the treatment are safe to eat, concluded Department of Health and Welfare public health toxicologist Drew Pendleton, in an email to the Times-News in mid-November.

Thompson said he had received numerous inquiries into that matter, but fewer now that the weather has turned colder.

Quagga mussel
Totes, each containing 250 gallons of Natrix, a pesticide used to eradicate quagga mussels, is seen in October near the Snake River.

“Copper is naturally present in the environment and in fish tissue as an important nutrient,” Pendleton wrote. “However, copper does not bioaccumulate in fish muscle and does not pose a health risk in this case.”

The Idaho Fish Consumption Advisory Project determined an advisory was not necessary.

Natrix is a chelated copper treatment, and interrupts the normal function of fish gills by delaying their ability to take in oxygen from the water. “This causes the fish to suffocate,” he said.

No fish in the treatment zone were actually sampled because “the likelihood of consumption of affected fish was very low.”

While copper does not accumulate in fish tissue, it does accumulate in liver and other internal organs, Pendleton said.

Thompson said there wasn’t a study done to determine whether scavengers, including birds, mink or muskrats, ate some of the dead fish, but there weren’t any reports of any dead animals.

The Department of Environmental Quality has been and will continue to monitor the stretch of the Snake River until copper levels are at background levels of 0.001 ppm, Pendleton said, which is well below acceptable risk levels associated with the Safe Drinking Water Act and the Clean Water Act.

Fish consumption advisories are not uncommon in Idaho; such advisories exist for both Salmon Falls Creek and Oakley reservoirs, where there are warnings especially pertaining to children and pregnant or nursing women.

Many advisories in southern Idaho are blamed on mercury contamination caused by gold-mining operations in northern Nevada, but Pendleton said he didn’t have data on the cause.

Moving ahead
Nature is resilient, Thompson said — that is the good thing. The Fish & Game official invokes the recovery of Mount St. Helens area in Washington after the volcano erupted in 1980.

“A lot of times we look at things like they are ruined forever,” said Thompson,” he said, when actually it will just take time for them to mend.

Translocations of fish such as smallmouth bass might be needed in some areas of the treatment area to jumpstart the recovery, and natural recolonization of largescale suckers, northern pikeminnow and yellow perch may occur in the reach downstream of Pillar Falls from fish moving upriver from areas downstream of of Auger Falls.

“Also, we expect fish from upstream reaches to get washed down during high spring flow periods,” Thompson said.

White sturgeon populations will take time to rebuild due to their slow growth rates.

At Mount St. Helens, trees are growing, streams are running clear, “so I always have a lot of faith that nature will rebound,” Thompson said. “I am confident that Mother Nature will get the system back — hopefully, without quagga.”

This fall we talked here about quaggas being found in the Snake River in so. Idaho. The IDFG closed a stretch of the river to treat it before they could spread. The worry was about fish kill. Here's an article from today's paper about the aftermath. The biggest loss was a bunch of sturgeon. Even though their numbers are low and it's catch and release only, fisherman come from all over the northwest for them.

Personally, I don't think the treatment is going to work in the long run. I think the mussels are here to stay. There's no way for them to know how far they'd spread before being discovered. This river has some class 5 rapids and kayakers come from all over to run them. The mussels likely came in on some out-of-stater's boat. That, or a local had his boat in water somewhere else and didn't clean it before coming home.

Why not blame it on some shorebirds, waterfowl, someone dumping a livewell in another reservoir.

Why it always gotta be a kayaker?

Why not blame it on some shorebirds, waterfowl, someone dumping a livewell in another reservoir.

Why it always gotta be a kayaker?

For shear number, they're the majority.

shoulda' ate the Sturgeon before they dumped the Poison...

Why not blame it on some shorebirds, waterfowl, someone dumping a livewell in another reservoir.

Why it always gotta be a kayaker?

On the humorous side: I had to stop at a boat inspection station a couple years back and the attendant asked if I was familiar with quagga mussels. My response was, "that's exactly why I married my wife."

I'm sooooo gonna use that next time I get the raft inspected!