Montreal

Thousands of fish found dead in the Yamaska River

The cause of the mass deaths is unknown to scientists. Several species have been affected, from minnows to larger fish 15 to 20 centimetres in length.

Toxic runoff from nearby industry ruled out as cause

Some yards in Brigham, Que. are flooded following the Yamaska River leaving its bed on Tuesday morning. (Kate McKenna/CBC News)

Thousands of dead fish have been found in the Yamaska ​​River near Saint-Hyacinthe in the last few days.

The cause of the mass deaths is unknown to scientists. Several species have been affected, from minnows to larger fish 15 to 20 centimetres in length.

According to Christian Blanchette, regional coordinator of Urgence-Environnement for the Estrie and Montérégie, some fish were found in the bottom of the river, discoloured and in an advanced state of decay, he said on Friday.

Two wildlife officers have collected samples of dead fish on Friday morning in the hopes of learning more about the cause.

Residents who alerted authorities Thursday night mistakenly believed that the fish were killed by discharges from companies in the industrial park of Saint-Hyacinthe, which emptied their tailings ponds on Thursday.

But since the deaths date back several days, Blanchette quickly ruled out this hypothesis.

Blanchette will consider several possible causes in the coming days, including a possible water contamination caused by construction work near the ​​river, a spill that was not reported to the authorities or a drastic reduction in water's oxygen.

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