Spawning browns and onion fields

The huge "bucknasty" browns are all on the gravel beds doing their thing.  The 14" and under juveniles are eating blue-wings in the hatch riffles.  Every shallow riffle had big spawners doing their thing.  Little guys were rising all afternoon right up through sunset.  Water super-low at 30cfs.

Spawners loaded up above this hatch riffle

Full of rising fish

All about this size

Early on

Of course

Couldn't keep 'em off of this one

Another riffle into a pool loaded with risers

30 CFS.  There was one October that was magic at this flow

This flat was full of rising fish on the drive out

Fading light.  The last image. Seems appropriate.  Fading.  The season.  

One disturbing observation.  A lot of the big browns had white fungus on their bodies.  I also saw a couple dead ones, and some dead carp, both covered with the fungus.    Apparently it happens.  I didn't see it in autumns past.  This is from the Idaho Statesman this past January:

Local anglers are concerned about an unusually high number of dead fish in the Owyhee River this winter. The fish are white, making them easy to spot as you look across the river.

I spoke with Dave Banks, a district fish biologist who manages the Owyhee River for the Oregon Department of Fish and Wildlife. Banks and his colleagues have identified the culprit — a water mold called Saprolegnia.

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“This mold is something that’s always in the water,” Banks said. “But when fish become stressed and get cuts and scrapes during the spawning season, they become more susceptible to it. We do see a few fish die from it every year, but this year is the most I’ve seen.”

Unfortunately, the dead fish are large, adult brown trout — fish that make the Owyhee a trophy trout stream and attract anglers from across our region. Browns are nearing the end of their spawning cycle, which means fish are more tired and stressed than usual. Spawning also causes openings in the skin — females scrape their bodies against the river bottom while building nests, and males aggressively nip at their mates and each other with sharp teeth — where the mold can cause its deadly infection.

There is a silver lining, though. The mold isn’t affecting juvenile fish, which is good news for future populations. Rainbow trout haven’t been impacted, either — they are sterile in the Owyhee, so spawning injuries aren’t a concern.

“We don’t anticipate this will have a major impact on the fishery,” Banks said. “There are still lots of healthy fish, and it’s not affecting younger fish that will fill in the adult population going forward.”

There’s not much anglers can do for now. Banks said Saprolegnia doesn’t have any known impacts on humans, but since browns are catch-and-release only, harvesting infected fish isn’t an option anyway.

All in all, it’s a bummer, but it looks like this fish kill shouldn’t be too harmful in the long run.