This is an archived article that was published on sltrib.com in 2015, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.
Bozeman, Mont. • Ah, fall. Just the mention of the word brings excitement to anglers. After the manic hustle and bustle of the summer season, autumn brings a sense of relief. The crisp air, the clear skies, the promise of great things . October could last forever.
For anglers across Montana, fall is the season for big brown trout. It's a just paradox that the throngs of tourists that travel to the Treasure State each year in search of magazine-cover trout fish through the heat of summer and clear out just as things are getting good.
Through the summer months pullouts along some of the region's popular rivers are mobbed. But come fall, once the kids are back in school and the Winnebagos have made their exodus, the rivers are left to the locals. And the fish are on the move.
"The brown trout are starting to spawn," said Jake McGlothlin, a Bozeman fly fisherman and contributor to the fishing website chiwulff.com. "The browns are moving out of the lakes and reservoirs. With them getting aggressive, it is a good time of year to throw big streamers."
McGlothlin said anglers need to change the way they fish with the onset of fall. By this time of year the abundance and variety of insect hatches seen through the summer has slowed. A few terrestrials — beetles, grasshoppers and ants — may still be around, but those bugs will die off with the first frosts.
That means subsurface flies — nymphs and streamers — become more important.
Streamers are large flies that are often designed to mimic small fish. Ahead of and during the spawning season brown trout defend their territory and may be more likely to take a streamer than during the summer months. The cooler temperatures of fall give the fish a bit more vigor, and combined with the spawn, can make for great fishing.
Large brown trout that spend the majority of the year in stillwaters move into rivers and tributary streams in the fall to find spawning habitat. Rivers like the Madison and Missouri, that have a series of reservoirs, are good places to seek these fish. Anglers, at least the ones that can pull themselves away from hunting for a day or two, can capitalize on this seasonal migration.
"If you are willing to do a little research there are really good fishing opportunities everywhere," McGlothlin said.
Brown trout prefer to build their nest — called redds — in shallow areas of the river with pea-sized gravel. The fish will clear the river bottom of algae and weeds in preparation for the spawn.
"(Redds) look like brighter areas of the river bed that have been polished by the fish," McGlothlin said. "This time of year the river bottoms are pretty mossy. When you see a patch that is cleaned off, it really stands out."
As the spawn proceeds through October and into November, browns will begin laying eggs on redds. Rainbow trout may follow the browns and position themselves below redds to feed on nutrient-rich eggs swept down by the current of the river. The eggs incubate in the shallow gravel before hatching out as fry, which develop into the next generation of trout.
McGlothlin said anglers who want to pursue fish during spawning season should avoid fishing for actively spawning trout and be careful not to wade over redds.
"People are becoming more aware of it, but there are still those people that want to get their big fish picture," McGlothlin said. "You can get some big trout, but it is not a way to fish ethically or sustainability. The bottom line is don't fish over redds."
For anglers less interested in targeting big trout and more excited about catching trout on dry flies, the fall can be a good time as well. Baetis mayflies hatch in good numbers during the fall and can bring trout to the surface.
The Baetis hatch is temperature and weather dependent. The tiny mayflies prefer overcast days with highs around 45-50 degrees. During last week's cold snap, a good number of Baetis hatched on the Yellowstone River.
"Baetis are the biggest hatch we have each fall," said Jake Adelman, manager of Montana Troutfitters. "Next week's weather is calling for highs in the 50s and 60s with clouds and rain, but I'd plan on the end of November to start seeing more consistent hatches."