Big Hole River Saprolegnia Update 11-3-14

Big Hole River Saprolegnia Update 11-3-14

A Big Hole River brown trout infected with the Saprolegnia fungus.

A Big Hole River brown trout infected with the Saprolegnia fungus.

The Big Hole River is experiencing an outbreak of Saprolegnia, a common fungal disease of fish and their eggs. Saprolegnia is saprophytic, meaning it feeds on dead and dying tissue. Saprolegnia is opportunistic and takes advantage of stressed or weak fish. The affected sections of the Big Hole had too many brown trout per mile and as those trout crowded into spawning area’s the fungus was spread as fish dug their redd’s and spawned. All species of freshwater fish and their eggs are susceptible to saprolegniasis and is endemic in all of our waterways. Read the official Montana Fish Wildlife and Parks Big Hole River Saprolegnia here. Big Hole River  Saprolegnia update

  • From Montana FWP Region 3 Big Hole River Biologist Jim Olsen “The estimated mortality of post spawn brown trout is expected to be 5%. So while it looks really bad because we don’t usually see this many fish being affected, population wise it is not likely going to be that significant.”
  • Montana FWP hasn’t closed the affected section’s of river as this is a naturally occurring disease and typically short lived. It appears that we have seen the worst of the outbreak and fish mortality is declining.
  • In an email from MT FWP Big Hole River biologist Jim Olsen also stated that “Angling and fish handling can also contribute.”
  • Fishtales Outfitting along with group of concerned local outfitter’s and anglers have voluntarily agreed not to fish the river for the remainder of the 2014 season so as not to exacerbate the problem.

TIPS: If you or anyone you know has plans to fish the Big Hole River this fall please consider angling elsewhere as angling and fishing can contribute tovfish mortality. There are plenty of options here in southwest Montana. Give us a call at 406-842-5051 or email if you need help with angling options.


For more information on guided fly fishing on The Big Hole (next year), Beaverhead, Madison or Jefferson Rivers please contact Fishtales Outfitting.




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FishTales Outfitting LLC is a licensed Outfitter with the State of Montana's Board of Outfitters
and Permittee for the Madison, Big Hole and Beaverhead Rivers.

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