Fish mystery unfolds at Ustevatn lake in Hol municipality, Norway
Ustevatn, a lake in Hol municipality, covers an area of 12.2 square kilometers and reaches depths of up to 90 meters. Recently, it has become the center of a fish mystery that emerged last week.
On Wednesday, local observers noted unusual behavior among the fish, with many found struggling at the surface. By the next day, even more fish were sighted, and by Friday, hundreds of dead whitefish had been discovered floating at three separate locations.
Kjell Mykkeltvedt, a retired environmental manager and fish biologist, reported never having witnessed such an event before. He described fish swimming aimlessly, some vertical with their heads above water, eventually floating lifelessly. Concerned by these observations, he reached out to the Norwegian Food Safety Authority and the Veterinary Institute.
Investigations were initiated on Monday, involving scientists like Sofie Ottesen from the Food Safety Authority, local landowners, and drone teams from Hafslund E-CO. Mykkeltvedt examined some of the dead fish, focusing on their gills, which exhibited no visible issues.
While theories abound regarding the cause—ranging from water quality concerns to the potential presence of toxins, diseases, or parasites—no unusual emissions have been reported in the vicinity. Fortunately, no additional dead fish have appeared in recent days, and Mykkeltvedt remains hopeful that the Veterinary Institute can provide clarity on the situation soon.