Last fall the Big Hole River, in southwestern Montana, experienced an outbreak of Saprolignia fungus that put a big dent in its brown trout population. The naturally occurring fungus that usually attacks weaker, older and otherwise unhealthy fish, this time struck primarily larger, spawning fish.
This spring biologists noted a decline in brown trout numbers in the Jerry Creek to Browns Bridge section. The estimates cut the population by more than half, from 1,871 per mile (an all-time high) to 824. Biologists think the high population density contributed to the spread of the fungus and die off.
It’s not all bad news says biologist Jim Olsen, “While the decline from 2014 to 2015 was notable, the population is still only slightly below the long-term average for brown trout density,” he said. “At the same time, rainbow trout density actually increased in that area from 291 fish per mile in 2014 to 436 fish per mile in 2015.” Lower population densities can also make for healthier and larger fish on average.
Despite the outbreak, angler Dan Soltau says it’s game on. “It’s sad to see some big ones go, but it didn’t affect the whole river and fishing is hot right now. We’re seeing strong, healthy bows and browns come to the net.”
Tom Bie is the founder, editor, and publisher of The Drake. He started the magazine in 1998 as an annual newsprint publication based in Jackson Hole, Wyoming. He then moved it to Steamboat, Colorado (1999), Boulder, Colorado (2001), and San Clemente, California (2004), as he took jobs as managing editor at Paddler, Senior Editor at Skiing, and Editor-in-Chief at Powder, respectively. Tom and The Drake are now both based in Denver, Colorado, where The Drake is finally all grows up(Swingers, 1996) to a quarterly magazine.