The FISHING REPORT

South Fork Boise River

The first thing we should mention is the stellar mahogany hatch on the river. Look closely at the rocks and you will see the dark mayfly crawling about. Most are a size 18, but scattered amongst the herd are a few larger, size 16 mahoganies. We could see the fish rising to the full adult mayfly; however, they were more eager to eat the emerging stage. Though the peak of the hatch started in the afternoon, the mahogany was spotted on the rocks early in the morning. As a result, the fish we spotted rising earlier in the day were willing to take the emerging mahogany dun before the hatch really took place.

The BWO (size 18-20) could be spotted on the water as early as 10am, and the fish would often switch from feeding on the mahogany to the BWO. One fish would eagerly feed on the BWO while another would refuse the same fly, resulting in switching fly patterns for a particular fish. The adult mayfly was seen on the water, yet again the fish were eager to take the emerging stage of the mayfly. If a fish was particularly difficult, it would often fall for a cripple pattern, or the looped-wing emerger.

Midges (size 18-24) were on the water as early as we arrived, and were seen as we left the river. We are sure there are locations where the mahogany and the BWO are not as strong, so the fish will key in on the midge. The best midge pattered we used was the looped wing midge and the RS2 midge. However, it’s almost impossible to see either on the water.  Often we would cast in a location and lose sight of our midge; yet setting the hook to a rising fish often proved successful if our fly was in the vicinity.

Caddis are sparsely on the water, and we can’t say there was a “hatch” but we saw a few fluttering around. After the end of the Mahogany hatch, fish were seen rising and were willing to take an October caddis (size 10-12). If you want to stick with a dry fly for the rest of the day and are not seeing any steadily rising fish, it’s worth searching with a caddis. You can drop down to a tan size 12 caddis if you prefer. Fish were willing to take both.

It’s not uncommon to hook into a white fish and have a larger trout take a swipe at it. Lighter colored streamers can often mimic a struggling white fish, which seems to be on the menu lately. We do recommend having a variety of light and dark streamers, as each day could call for one or the other. As the temperature continues to drop in the season, play with your retrieve. As you bring in your streamer, we often find that a slow retrieve, or simply letting your fly swing with the current, can be effective when searching for bigger fish.

Larger stonefly nymphs can grab the attention of trout this time of year. Small dropper flies can easily get picked off by the whitefish while in search of a rainbow trout. As most anglers would say: whitefish are still fish and they are still very fun to catch. We recommend all kinds of nymphs when fishing this river, and each of us have our favorite nymph. From perdigons of all flavors to traditional Copper Johns, getting your fly in the face of the fish seems to be the key element in any approach.