No one in the world of fly-fishing, especially those employed by the fly shops and guiding services based in Fort Smith, Montana, has yet admitted it, but there has been a major decline in trout numbers in the Bighorn River in the past year. Fish numbers are not the only thing to fall, average fish size is down too. Right now, a fisher is far more likely to catch small and middling-sized fish than the large, heavy browns and rainbows so prevalent in the river in years past. At this time, it isn’t clear what caused the collapse in the Bighorn trout fishery.
In September 2013, when the fishing on the river was unbelievably good, I remember speaking with a fly-fisher who told me the river was primed for a population crash. He said the river had too many trout for the available food and water acreage. There were just too many fish in the river. I never got this fella’s name, but he sounded as if he knew the river and understood trout population dynamics. Unfortunately, his prediction has turned out to be spot on. This year, the river is fishing hard; some would argue it’s fishing terrible.
The speculation on the river, and at the various lodges situated in the Bighorn Valley, is that the Bureau of Reclamation (BOR), the operator of Yellowtail Dam, has been irresponsibly yo-yo’ing the dam’s discharge rates up and down. The Bighorn’s wildly fluctuating flows have wreaked havoc on the stream’s aquatic vegetation and insect hatches. On any given day, riverine vegetation would be producing fantastic insect hatches. Then, the next day, the BOR would drop the river’s level, which exposed the aquatic vegetation to the deadly, drying rays of the sun. The loss of aquatic vegetation has brought on the end of the river’s once-prolific hatches. BOR management decisions disrupted the Bighorn’s famed black caddis, trico, and PMD hatches. Of course, without food, fish go hungry and then die. It is conceivable that Bighorn trout have perished in astronomical numbers in the past 12 months, their bodies descending unseen by human eyes to the river bed or floating downstream on the current, eventually consumed by the many birds of prey flying above the Bighorn’s main channel.
This year, if you’re wade fishing, you’ll be lucky to land five fish in a day. If you net ten fish in a day, well, consider yourself very fortunate. Bighorn trout numbers and fish size collapsed in 2014. The crucial question is this: how long will it take for the fish population to recover to a healthy, self-sustaining level? A recovery in numbers and fish size is unlikely by next year. But will the fishery rebound by 2016 or 2017? No one really knows.