"It's not normal that the fish are dead like that. We fish here every summer," she told CTV Montreal. "We won't fish this summer, and we won't eat the fish either."

Christian Blanchette, regional coordinator of Urgence-Environnement, said scientists came to the river on Thursday and Friday to look for possible causes, including spills, sewage and construction waste. They also took samples of the dead fish.

While officials won't know what's behind the deaths until the test results come in, Blanchette put forth one possibility.