What are Hoot Owl Restrictions?

“Hoot Owl” Summer Fishing

In Montana, rivers are now under “Hoot Owl” evening restrictions which are designed to protect fish from being caught in the warmest water temperatures of the day which occur in late afternoon and evenings. We have been receiving a lot of calls from folks asking about fishing restrictions so we thought we would offer some guidance as to how temporary regulations such as “hoot owl” evening restrictions are used to manage Montana’s wild trout fisheries.

What are hoot owl restrictions?

Hoot Owls are put in place to encourage fishing in the early half of the day when water temperatures are best. Fishing is allowed from midnight until 2pm but after 2pm fishing is restricted.

How do water temperatures affect trout?

Colder water holds more dissolved oxygen. Trout are a cold water species and require higher oxygen levels than other “warm water” species such as bass and bluegills. Generally water temperatures in the mid 60s and lower have more than enough oxygen for trout. Brown, rainbow and brook trout begin to experience some if stress around 68 degrees F. Once water temps rise above 70 degrees F fish may still be feeding and can be caught but they do not recover as quickly and the chance of mortality after being released begins to climb. Fish kills due to water temperatures are possible when water temps rise into the upper 70s.

Do water temperatures changes during the day?

Yes, water temperatures are coldest just after dawn and warmest in the early evening (usually between 6-8pm). Often temperatures can fluctuate from 6-10 degrees over the course of the day. Trout tend to focus their feeding on the prime temperature windows. In early spring when water is much colder, trout feed most aggressively in the afternoon when water temperatures are warmer and increase their metabolism. In mid summer trout metabolism is already high, so on most rivers the feed during the cooler water times of the day when dissolved oxygen is highest (mornings and early afternoons).

When will hoot owl restrictions be enforced?

Montana state laws require that a river goes under a hoot owl regulation if the late afternoon water temperatures exceed 73 degrees for three days in a row.

Do all rivers and streams have hoot owl restrictions?

No. Hoot owl restrictions tend to be on the larger rivers or more commonly fished rivers. Smaller mountain streams, spring creeks and medium sized mountain rivers do not receive the evening fishing restrictions.

Float on the Madison River
Float on the Madison River

Are some rivers completely closed to fishing?

Yes. If a river drops below the 5th percentile of its average flow it is closed to fishing. This only occurs on a few rivers or streams that have heavy irrigation draws. Irrigators with senior water rights have legal authority to pull a predetermined volume of water out for agricultural purposes. So for example the lower reaches of the Ruby River upstream of its confluence are currently closed because the flows below the large irrigation draws are so low. Further up the Ruby River near the dam the flows remain good and the river is fully open. Generally river reaches that receive the low flow closures from heavy irrigation use are not midsummer fisheries that we target.

Do Hoot Owl rules mean bad fishing?

No. Hoot owls simply protect wild trout from being caught in the warmer temperatures that occur in the evening hours. Early starts allow us to sync with the best water temperatures of the day when trout are most active.

What are the best angling practices to protect trout in the summer?

Regardless of where you are fishing, it is a good idea to carry a thermometer in midsummer. When water temperatures rise above 65 degrees it is important to take precautions to minimize handling of trout.

• Use strong tippet to help land fish quickly
• Use a net with a rubber basket
• Make sure barbs are crimped
• Pass on fish pictures and get them back fast
• Frequently check water temps. A good rule of thumb is that 70 degrees is the “don’t fish” limit

Water Temperatures Swing Several Degrees From Morning To Evening

This temperature graph was from the past week on the Yellowstone River near Livingston. Water temperatures hit their lowest point around 8am and then begin climbing. Hoot Owl regulations encourage anglers to fish early in the day before 2pm when water temperatures have been below 68degrees. Once temperatures exceed 70 degrees fish mortality increases dramatically after being handled. You can see on July 18th when we had a very hot day in the mid 90s the evening temperature peaked at 72 degrees (while morning temps the same day where around 64.5 degrees).

Current Waterbody Restrictions

On the Bitterroot River

More Restrictions

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