Bugs of the Big Hole

It’s because mayflies, stoneflies, and caddisflies are sensitive to pollution and habitat degradation that the evaluation of diversity & relative abundance is often used to evaluate water and habitat quality. That’s why, 4 years ago, BHRF started a macroinvertebrate monitoring project to begin to address voiced concerns about public observation of declining insect hatches…… the kind both trout & anglers like.

This month, we were joined by the Missoula-based Salmonfly Project for a week in the field to expand that program on the Big Hole. We wanted to get a better understanding of the abundance of some target species that represent important fishery hatches that anglers care about. Naturally, those species include the “big bugs”; Giant Salmonfly and two types of Golden Stonefly (pacifica & sabulosa : golden stone & nocturnal stone). But we also specifically looked for March Browns, Mother’s Day Caddis, Skwalas, Green Drakes, and Mahogonies.

You might be asking, “what about PMD’s and Little Yellow Sallies?”. Short answer - Those are no doubt important hatches! But for this specific purpose, with sampling taking place in late August, those species are too small to identify in the field accurately and reliably.

While the Salmonfly Project studies bug populations in rivers all over the West, BHRF maintains the only consistent bug monitoring program on the Big Hole. This summer’s collaboration will help better inform our upcoming Baseline Bug Health report (shooting for the end of the year) and add another watershed to the Salmonfly Project’s slate of ongoing bug studies throughout the Rockies, as we all seek to better document the state of bug life in some of our most famous trout rivers. In time, a robust dataset will allow us to identify trends and share bioindicators of water quality with FWP Fisheries Biologists and other scientists.

The Big Hole River Foundation works with the Salmonfly Project to expand bug sampling in the Big Hole River.