Missoula, Mont. — Hot summer temperatures can bring hoot-owl fishing restrictions as warmer water harms fish.

Montana Fish, Wildlife & Parks explained that the term traces back to loggers in the early 1900s who worked while owls were still out to avoid the midday heat.

Fishing guide Jake Hensley, the Missoula Fly Guy, said he notices a clear difference in fish when the water warms.

“I definitely think when you're fighting fish, they can be a little more lethargic. We really try to practice upping line strength and trying to get those fish in really fast," he said. "We're not trying to let clients or friends fight fish for a long time. You don't want to wear them out and make them weaker."

Pat Saffel, Pat Saffel, the regional fisheries manager with FWP, said several factors go into deciding when to place hoot-owl restrictions and that rivers in the same area can face different rules.

“We're looking at what species are there and what the temperatures are in different reaches of the river. We have criteria to match those temperature preferences," he said. "When we start to get into temperatures that are stressful for trout, we start implementing restrictions."

In Montana, hoot-owl restrictions typically run from 2 p.m. to midnight.

Hensley said he treats fish like business partners and takes extra steps when overnight temperatures climb. 

“I carry a thermometer. If we're not getting the nighttime temps below 60 degrees, I'm noticing the fish are probably getting too warm," he said. "I don't need the government to necessarily come in and tell me to get off the river. You can use your thermometer. You can use common sense to start implementing your own hoot-owl."

Saffel also said FWP does not always get the timing right when starting or ending restrictions because forecasts and changing river conditions can make those decisions difficult.

He said the best way to fish responsibly is to know the details about what you are fishing for and where you are fishing.