BOISE, Idaho (CBS2) — Idaho Fish and Game report several results from a follow up survey along the section of the Snake River that was treated with copper to kill off the invasive quagga mussels.

Quagga mussels were detected in a stretch of the Snake River in September of this year. Quagga mussels are an invasive species that threaten wildlife, waterways, and agriculture. Once identified, Fish and Game worked with the Department of Agriculture to execute a plan to quickly stop the spread of quagga mussels while they were still relatively manageable.

The plan was to treat the river with chelated copper. It quickly and efficiently kills quagga mussels, but it also kills fish and other wildlife. Fish and Game conducted a series of surveys, catching and marking fish prior to, during, and following the copper treatment.

Idaho Fish and Game report that certain species of fish were harder hit by the copper treatment than others. Most of the fish mortalities were largescale suckers, northern pikeminnow, common carp, and yellow perch. White sturgeon were also significantly impacted, estimating a near 100% mortality rate in the treatment area.

Six to seven tons of dead fish were removed from the river during the two week treatment period.

Fish and Game will continue to monitor the area over the next few years to better understand the recolonization of species back into the treated area. Certain species, like white sturgeon, will take time to rebuild their numbers due to their slow growth rates. Populations that are slow to rebound, or were severely impacted will likely be relocated from other areas to help jumpstart recovery.

Sampling will continue to monitor for quagga mussels to ensure that they do not return.

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