Bighorn River Fly Fishing

The Bighorn River is a unique river in many aspects and catches many seasoned fly fishermen off-guard when they arrive and assume to be able to drum up a couple with attractor patterns or state-wide favorites.  We have a plentiful trout population, but the gin-clear waters of the Bighorn allow all the trout to become very familiar with their diet of very high numbers of very few types of bugs.  The main diet of the trout in the Bighorn River is Sowbugs, Scuds, Annelids (worms), Midges, Baetis. There are plenty more food sources, but these are the major five that are really focused on.

Sowbugs, Scuds, and Annelids are the meat and potatoes of the Bighorn buffet. This high-protien food is why the girth on the Bighorn trout is often referred to as football shaped. This is most prominent on some of our year and half old trout that have standard sized heads and tails, but very thick midsection where they derive their way above par fighting skills when they get hooked.  These bugs are non-hatching so there is no emerger  form or dry form, just their nymphal state. Below are some pictures of real scuds, sow bugs, and annelids.

Midges, Baetis, PMD, Black Caddis and Trico’s are the main hatching insects that the Bighorn River Trout eat on a consistent basis.  Midges and baetis come in the most numbers in the spring. Starting late February and ending late May you can see fish rising on the Bighorn every day. We see midges and baetis return in the late fall usually mid-October, but not in the numbers we see in the spring. The PMDs, Black Caddis and Tricos are a late summer event.

The Black Caddis is by far the densest hatch on the Bighorn. Fly fishing the Bighorn during the black caddis hatch can be tough because the trout has so many naturals to choose from, but the emerger form and nymphal form of the black caddis is what fly fishermen on the Bighorn River need to focus on during this hatch. Even when you believe they are taking dries above the surface they may still be taking the emergers trapped in the surface film and still breaking the surface with their dorsal fin. Be careful and watch for their snout, if all you can make out is the dorsal fin, think emergers.

PMDs are not a major hatch on the Bighorn these days, we do get a few good days of strong PMD activity and fish really keying in on them, but mainly in the nymphal form. They are on the rebound though and every year we see more and more PMDs on the Bighorn. Trico’s have really suffered on the Bighorn, but are on the mend in a big way. About five years ago there were very few tricos and all were below the 10th mile of the river or so. Now we are seeing them all the way up above three mile and in some decent numbers.  Not quite decent enough to warrant carrying a trico box around with you, but the trout are beginning to look up at them again.

Hoppers are an annual event on the Bighorn and 2008 and 2009 were unprecedented years for the numbers of grasshoppers, as well as the numbers of trout eating grasshoppers on the Bighorn River. It usually begins late July and can continue on into October.

Bighorn River, Fort Smith Montana