Recent high water temperatures have led to fishing restrictions on the Dear Born River, Smith River, and Sun River in Montana. The three rivers, all located in the Great Falls area, will be closed daily between noon and midnight. Such fishing restrictions are ordered when water temperatures remain at or above 73 degrees Fahrenheit for three days.
According to Fish, Wildlife, and Parks public information officer Bob Gibson, such warm water conditions place a significant strain on fish. Trout, common in the three rivers, thrive around 55-57 degrees Fahrenheit. The higher temperatures make them less likely to survive being caught and released. It also makes it more difficult for the fish to remain healthy even without the threat of fishermen. Ideally, the fishing restrictions will preserve the native fish populations through this period of intense heat and significantly increased water temperature.
Fish get oxygen from the water with their gills and, like humans, require a substantial amount of oxygen to survive. In warm weather, however, water cannot hold as much dissolved oxygen and it becomes a challenge for fish to obtain a sufficient supply of oxygen. Without this oxygen, it becomes much more difficult for fish to feed, mate, and avoid.
The strain of being caught and released would most likely kill the fish as it would likely be unable to “catch its breath” when returned to the water. It would be much like asking a human to run a marathon high in the mountains—the decreased air pressure would make recovery incredibly difficult and the shock could potentially cause lasting harm.
No fishing restrictions have thus far been announced for the Yellowstone River. Mr. Gibson, however, says that such restrictions are likely if the temperatures do not decline soon.
Montana residents and visitors have more than just fishing restrictions to worry about. The Skibstad Fire is posing a threat to numerous structures and has forced evacuations in Stillwater County. Water from the Cooney Dam in Carbon County is being used to refill the helicopters being used to combat the fire. As such, the Cooney Dam is closed for boating, swimming, fishing, and all other recreational uses.