Mystery As Thousands of Fish Wash Up Dead in Washington State

Thousands of fish have mysteriously been washing up dead in Washington's Spokane River.

The phenomenon was first captured on February 7 by local man Tom McClellan, who used to work at Long Lake Dam, which forms the river.

McClellan captured a video of the fish's bodies, floating near the shore of the river. The fish in the video are small. The species captured in the video include perch, walleye bass and crappie.

"I worked at this dam for 30 years before retiring in 2022 and never saw anything like this," McClellan wrote on a Facebook post alongside the video. "I think as they are in the process of raising the lake from the winter drawdown all the dead fish on the shore are floating and being washed downstream. There is thousands of them you can see them float by."

It remains a mystery as to how the fish wound up dead, and all at the same time.

McClellan reported the incident to the Spokane Tribe Fisheries and Water Resource Division. The Department of Ecology has also been involved and initiated a clean-up of the fish, McClellan said on a Facebook comment.

The environmental conservation organization Spokane Riverkeeper has also been involved in the incident, describing the situation on Facebook as "horrifying."

"Although the reason for the fish kill in the Spokane River remains unclear, it is a reflection of how we treat our river. Whether it be from pollution issues or flow management of the river, thousands of dead fish in our river are a cause for deep concern," a spokesperson for the organization told Newsweek.

"We've received reports in previous days of dead fish in the Spokane River at Long Lake Dam. This is horrifying to us. We've taken a sample of these fish, and Spokane Tribal Fisheries are processing their own samples," the conservation group said on a Facebook post.

"Why this happened is unclear, but appears to be a significant event and not a natural occurrence. This coincided with murky, scummy water reported downstream that seemed to originate downstream of the mouth of the Little Spokane River. We will keep you updated if we find out anything more."

In his initial Facebook post, McClellan wondered if it had anything to do with a "mineral oil" spill at a nearby paper plant.

However, there could be other explanations.

In other areas of the United States there have been so-called "fish kills" in which warmer than usual temperatures cause a lack of oxygen in the water. These can also occur due to a change in acidity or salinity. Toxic algae blooms can also be a factor.

Although one of these factors alone may not be enough to kill thousands of fish, when they are combined, many can die.

In September 2023, thousands of dead fish were spotted in two different areas of Florida.

In some areas, these fish kills happen quite often, almost annually. There have also been cases of these fish kills in Texas and Louisiana over the past year.

Update 02/23/24, 04:25 a.m. ET: This article was updated to include comment from Spokane Riverkeeper.

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