It is September 30th: 

 

https://www.ontario....ne-16#section-1

 

Atlantic salmon

Season: fourth Saturday in April to September 30
Limits: S-0 and C-0

Brook trout

Season: fourth Saturday in April to September 30
Limits: S-5 and C-2

Brown trout

Season: fourth Saturday in April to September 30
Limits: S-5 and C-2

Channel catfish

Season: open all year
Limits: S-12 and C-6

Crappie

Season: open all year
Limits: S-30 and C-10

Lake sturgeon

Season: closed all year

Lake trout

Season: January 1 to September 30
Limits: S-2 and C-1

Lake whitefish

Season: open all year
Limits: S-12 and C-6

Largemouth and smallmouth bass combined

Season: fourth Saturday in June to November 30
Limits: S-6 and C-2