When Bull Trout Won’t Bite - Change Your Approach to Make it Happen

The ability to legally target bull trout on the South Fork of the Flathead doesn’t guarantee they will jump all over your flies. It’s hit and miss with these fish. Sometimes they are all out hunters looking to attack and consume everything in site. Other times they will lay low and completely ignore your flies. 

Floating and fishing the South Fork of the Flathead means you will cross paths and most likely have chances at some very large bull trout. The where and how of this whole game is unpredictable however. While they have the Trout in their name, Bull trout do not occupy a short stretch of river and sit in feeding lanes like most trout. The fish are migratory and do not hold their ground in a single run for long periods of time. 


Bull trout spend a good chunk of the year in Hungry Horse Reservoir and migrate throughout the entire South Fork system spring through fall. You may not see a bull for the first several days of your float only to run into several on day three. In fact, when you find one, slow down as there are likely more in the immediate area. In many cases, you will actually see them holding in deep pools or locate aggressive bull trout as they attack a cutthroat on the end of your line.


Ridiculous Flies that Work

Most days, a big double bunny or oversized trout streamer is adequate. When your normal flies do not work and you know bull trout are present, go BIG. And by big, I mean bigger than you ever imagined necessary. I’ve seen a 30+ inch bull trout attack a 20 inch bull trout I was playing. 

Ideally, you will tie up some ridiculously large bunny type streamers in advance. If you are however caught off-guard and unprepared, simply string a few flies together to create on mega fly. Cut off the hook points so they are shank only with no more than two actual hooks in use at a given time. Do not hesitate to fish flies in excess of 10-inches in total length. A large bull trout will have no issue inhaling your largest patterns.

Swing Deep and Slow  

Visually spotting bulls in deep water and watching them ignore your flies is frustrating but it does happen. In some instances, the fish are digesting a meal and in others they are simply sitting in the coldest available water. The only way to move one is to get close. Lengthening your leader and adding split shot will get your flies down quickly. I will simply add 10+ feet of 10 pound fluorocarbon and a few large split shot to get down in a hurry.

Alternatively, you can opt for a fast sinking line and a swinging technique. Position yourself upriver and swing the fly into the fish. Make a long pause at the end of your swing so the line can drop. Retrieve and repeat until a bull trout decides to attack. Working with a spotter is a huge advantage in this situation as they can gauge your fly position and verbalize adjustments until you find the perfect presentation.

Lazy J Bar O Outfitters offers remote fly fishing expeditions into the Bob Marshall wilderness for bull trout and westslope cutthroat. For more information, visit our fly fishing page. You can also call us at 406-932-5687 or contact us online for details.