Ontario Restricted Activity Timing Windows for the Protection of Fish and Fish Habitat

Restricted activity timing windows are applied to protect fish from impacts of works or undertakings in and around water during spawning migrations and other critical life history stages. In Ontario, the Ministry of Natural Resources (MNR) has the responsibility for setting timing window guidelines. These guidelines are determined on a case by case basis according to the species of fish in the water body, whether those fish spawn in the spring or fall, and whether the water body is located in the Northwest, Northeast or Southern Region of Ontario.

Figure 1: Ontario's Northwest, Northeast and Southern Region boundaries for determining application of restricted activity timing windows.
Regional Map

How To Determine Timing Windows

  1. Determine the fish species living in the water body where you wish to do work.
  2. Determine if the water body is located in the Northwest, Northeast or Southern Region of Ontario according to Figure 1.
  3. Use Table 1 to determine the in-water restricted activity timing windows according to the location of the waterbody and all of the species of fish found within that waterbody (spring or fall spawners).
  4. For water bodies with more than one species, the most restrictive timing windows should be combined for all species present (e.g. for a water body with both walleye and bass in Southern Region, the combined timing window should be: Mar. 15 to July 15).

Table 1: Restricted Activity timing windows for the protection of spawning fish and developing eggs and fry.
Dates represent when work should be avoided. Regional boundaries are shown in Figure 1. 

Spawning Period - Spring
Fish Species Northwest Region Northeast Region Southern Region
Walleye April 1 to June 20 April 1 to June 20 March 15 to May 31
Northern Pike April 1 to June 15 April 1 to June 15 March 15 to May 31
Lake Sturgeon May 1 to June 30 May 1 to July 15 May 1 to June 30
Muskellunge May 1 to July 15 May 15 to July 15 March 15 to May 31
Large/
Smallmouth 
Bass
May 15 to July 15 May 15 to July 15 May 1 to July 15
Rainbow Trout April 1 to June 15 April 1 to June 15 March 15 to June 15
Other/Unknown
Spring Spawning
Species
April 1 to June 15 April 1 to June 15 March 15 to July 15


Spawning Period - Fall
Fish Species Northwest Region Northeast Region Southern Region
Lake Trout September 1 to May 31 September 1 to May 31 October 1 to May 31
Brook Trout September 1 to June 15 September 1 to June 15 October 1 to May 31
Pacific
Salmon
September 1 to June 15 September 1 to June 15 September 15 to May 31
Lake Whitefish September 15 to May 31 September 15 to May 15 October 15 to May 31
Lake Herring October 1 to May 31 October 1 to May 31 October 15 to May 31
Other/Unknown
Fall Spawning
Species
September 1 to June 15 September 1 to June 15 October 1 to May 31