The long, harsh, cold winter in the Credit River watershed caused extensive thick ice on local waterways. Therefore, there is likely to be higher than normal fish mortality this spring.

With thick ice, water becomes separated from air for a long time. Fish and decaying plants use up all the available oxygen. Without enough oxygen, fish die. This causes seasonal fish mortality, called winterkill.

Winterkill happens naturally and is common in shallow lakes and ponds. Fish mortalities become obvious when the ice melts and fish are exposed.

Fish mortalities are usually concentrated in places where ice initially melts. The lakes and ponds at Island Lake Conservation Area and Ken Whillans Resource Management Area are susceptible to winterkill events. Please notify Credit Valley Conservation staff if you see results of a large winter die-off.

CVC staff will monitor fish species that experience winterkill and the extent of any die-offs.

If you have any questions or concerns please contact CVC Aquatic Biologist, Jon Clayton (905) 670-1615 ext. 502  [email protected].

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