Throughout the past two decades, coho salmon die-offs as the fish ventured into urban waterways in the Pacific Northwest have perplexed researchers.
It was assumed some type of chemical leaching into waterways was the reason for the kills, which wasn’t confirmed until a 2021 study’s discovery that a chemical called 6PPD-quinone was the culprit. The reason the chemical went undetected for many years is because it wasn’t a common contaminant routinely searched for in waterways.
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