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Episode 7 - Hoot Owl Restrictions

August 2021

This summer has been one marked by intense heat waves and prolonged drought across Montana, with wildfire smoke masking the skies and concealing the mountains. These conditions have caused dangerous health conditions in people and dampened the enjoyment of outdoor recreation, they have also had an impact on our watershed and its wildlife.

Across the state, Montana Fish, Wildlife and Parks has implemented what are known as “hoot owl” restrictions for anglers. With the restrictions recently being enacted on the mainstem of the Bitterroot River, the Water Forum is hoping to share information that will lead to a better understanding in the community. We spoke with Jason Lindstrom, a Fisheries Biologist with Montana Fish, Wildlife & Parks. According to Lindstrom, “’hoot owl’ is basically what we have termed a fishing closure for the afternoons”.

The term “hoot owl”, Lindstrom said is “an old logging term” that came about because of the hours they worked in times of high fire danger. In conditions similar to what we are seeing in our forests, loggers would “quit working about 1 or 2 in the afternoon to avoid the extremely dry, hot portion of the day”. According to Lindstrom, the loggers would “often hear owls hooting in the trees” when they started their work day at first light; they termed it “hoot owl” and “for some reason it stuck”. The fishing closure mirrors the loggers’ working hours, being effective from 2 PM to midnight, and limits fishing to the cooler hours of the day, when fish are less stressed.

Expanding on the temperature element, Lindstrom added that “when temperatures...get above 70 degrees it starts to get stressful for the trout”. The FWP monitors the temperature rise in the water, using the USGS gauges, as well as its flow and angling pressure. Lindstrom explained that “hoot owl” is often put in place due to a temperature criterion, when the FWP records “three consecutive days above 73 degrees Fahrenheit” on a stream that has angling pressure. However, it can also be implemented due to a flow trigger, which occurs when flow decreases to below the bottom 5% of its previously recorded flow rate.

Stretches of the Bitterroot River are home to native cutthroat and bull trout; being cold-water species, they are more sensitive to water temperature fluctuations than other fish. Because of this, the upper Bitterroot and the Missoula area are closely monitored for higher temperatures, which will impact the trout downstream.

Stress is an important factor for fish during the angling season, and there are a variety of sources that can accumulate, increasing the chances for mortality. Lindstrom explained that fish, particularly trout, “can tolerate warmer temperatures if stress levels are low but...all trout have an upper maximum temperature that they can handle”. The 73-degree temperature criteria is close to the limit that these fish can normally tolerate in low stress conditions, especially because warmer water holds less dissolved oxygen. The Fisheries Biologist described how “when it gets warm, the respiration rates of fish go up...the metabolism revs...and then all of a sudden they kind of turn off and they become very stressed”. When this happens, fish tend to not eat well, and they can be triggered by additional stressors their body can’t handle, which can lead to their death.

During this period when fish in the Bitterroot River are quite stressed, there are important things that anglers can do to help prevent fish mortality, with and without “hoot owl” in place. For anglers, FWP recommendations are to “use heavier lines, play the fish quicker...try to keep the fish in the water when you’re releasing it [and] try to be as gentle as possible when you’re unhooking it”. The FWP also suggests self-regulating in areas where “hoot owl” is not currently in place, such as avoiding fishing in the afternoon and late evening, and reducing fishing frequency.

The Bitterroot River is a vital resource to the Bitterroot Valley, and we can all contribute to its health and the protection of its wildlife. If you are interested in learning more about fishing restrictions on the river visit 

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