I find it difficult to contemplate the future of US trout fisheries. Several years ago, Chris Wood, president of Trout Unlimited (https://www.tu.org) raised a red flag r.e. the effects global warming would have upon coldwater fisheries. But I think even Chris is likely surprised at the speed and devastation that global warming is causing. The following discussion is likely to ruffle some feathers, but that is probably a good thing. We need to change the status quo if fishing for trout is not to become a thing of the past!

The Status Quo

Montana FWP (fish/wildlife/parks) monitors fish populations in many of its trout streams. It has documented a steady decline over the past decade in some of its most famous streams. Current trout populations are about a third of their historic averages in the Madison, Ruby and Beaverhead rivers. The Big Hole River, a freestone stream, is in even worse shape, and has been closed to fishing most of the past two summers. The other three rivers are tailwaters. As they flow downstream, they gradually warm under the hot, summer sun. Over the past several years, the portions of stream cool enough for trout has continued to diminish. All told, a dozen Montana trout streams were closed or had restrictions imposed this summer due to high water temperatures. Below is a picture of the Ruby River in early September. Hoot Owl restrictions were imposed in early August, that is, no fishing from 2 pm to midnight.

The consensus is that the decline in these fisheries is due primarily to global warming. In the West, global warming has led to reduced snowpack, recurring droughts, low water levels, and increased stream temperatures. Numerous studies have failed to reveal other explanations, such as run-off pollutants, disease, etc. for this decline. In an effort to preserve the trout fisheries, Montana and several other western states impose “hoot owl restrictions” on streams. The specifics vary, but in general, if water temperatures reach 73 degrees for several days, fishing is restricted, that is no fishing, from 2 PM to midnight. For streams inhabited primarily by cutthroat trout, the bar is reduced to 70 degrees.

So how effective or reasonable is this? I think most serious trout anglers know that trout become stressed when water temperatures reach the upper 60’s. As the water warms, oxygen concentration is reduced, and the fish must work harder to gather oxygen. They stop feeding vigorously, and we note a sharp reduction in hook-ups. Thus, if the streams were managed to optimize trout survival, restrictions would be imposed at 68 degrees, not 73. I cannot help but wonder if stream managers are responding to pressure from outfitters and the fly fishing industry rather than fishery science.

Native Trout Restoration

I think another misguided effort is “restore the natives”. In streams shared by native trout (brookies in the East & cutthroat in the West) and exotic trout (rainbows & browns), observations have documented a decline in native trout. It was assumed, without scientific support, that native trout were being out-competed by exotic trout. That is, exotics out-competed for food, spawning gravel, and perhaps even cannabilized native fry.

To restore streams to native fisheries, otherwise healthy fisheries are destroyed by poisoning everything that breathes with gills. Native fish are then re-introduced in the cleansed streams. I have only had the opportunity to observe the results in a few streams, so I will admit there may be some success stories. But in the streams I have watched, the restoration efforts have utterly failed.

So how could this be? Most likely the premise that exotics out-compete natives is flawed.  Natives require colder water temperatures than the exotics. Thus it should be no surprise that exotics have a better survival rate in the changing environment. Hopefully, proponents of “restore the natives” will admit to the dismal results of their efforts, and return fish better suited to the changed environment to these streams.

Dam, Dam, Damn!

Another factor in stream warming is stream flow. As the flow-rate slows, water warms more quickly from the sun. There are more than 90,000 inventoried dams in the US, per the army corp of engineers. It is estimated that there are an additional 300,000 dams for farm and backyard ponds. If streams are indeed a public resource, should these backyard dams be allowed? A permitting process that takes the health of streams into consideration would be a step in the right direction!

When we think of dams interrupting the movement of fish in a stream, we generally think of migrating salmon and steelhead trout. But as streams warm, trout seek streambed spring seeps and cool tributaries. Dams interfere with this natural movement, leading to unnecessary fish kills. Removing a dam and allowing water to flow naturally is the single most impactful way to improve a river’s health, and fish survival.  American Rivers .org plans to remove 30,000 dams by 2050! This is costly, and they need anglers’ support.

Part 2 of 2 to come, with more thoughts r.e.threats to trout, and mitigating actions that we can take.

written by Al Simpson, 09/2024