Boise Valley Fly Fishers
Since 1971


Brown Trout Spawning Season

01 Oct 2022 11:42 AM | Troy Pearse (Administrator)

October is here, and it is one of my favorite months to fish. Hatches are picking up with Fall Caddis and Blue Winged Olives, and the trout have the feedbag on preparing for winter. But with October comes the brown trout spawning season. The exact timing of spawning depends on water and weather conditions but generally brown trout on the Owyhee start to spawn in October with activity peaking in November and tapering off into December. And on the Boise River in town, browns typically don’t start spawning until the first week of November.

Brown trout like to spawn in gravel that is ½” to 1.5” in diameter, in water that is 1’ to 3’ deep and has some mild current. The tail-out of a run is one of their favorite places, especially if it has gravel. Gravel tail-outs are also an easy place for anglers to cross the river, so it is important to keep your eye out for redds to avoid wading through them.

Redds can be identified by the gravel being rubbed clean as fish build their nest. Redds tend to be circular to oblong shaped and are about the size of a hula-hoop. If there is a large gravel deposit, then you will often find multiple redds built next to each other. Here is a photo of a group of redds at the end of a small side channel on the Boise River. Note the size of the gravel and how it has been rubbed clean. There is also a single redd built along the far bank.

Side channels and bank edges are another common area to find brown trout redds so look before you step into the river. Here are some photos of brown trout redds on the Boise River from last year, and a short REDD-U-Cational Video that shows some brown trout redds in a tail-out.

When you see brown trout working their redds, it is best to leave them to their task as we all want them to succeed and make more brown trout! That doesn’t mean you shouldn’t go fishing. It is perfectly ethical to fish other sections of the river where brown trout are not spawning. There are plenty of rainbow trout that are snacking on the stray egg patterns and fishing in the deeper run below can be quite good. Last year the a pink salmon colored “Eggstacy” fly was my top egg pattern on the Boise River. I was amazed at how well the eggstacy material worked. Tim Camtasia has a nice video on how to tie it.

So get out and enjoy some fall fishing, but remember to watch where you wade. Brown trout redds are vulnerable for several months while the eggs are incubating--in our area that is typically into the month of March. Over time it gets harder to identify the redds as they silt-in from river algae and deposits, so it is best to avoid walking through gravel areas during the winter, especially on the Owyhee where there is so little spawning habitat. In 2019 BVFF worked with ODFW to put signs at vulnerable spawning locations to alert anglers. Watch for those signs, and tredd carefully.

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