Every spring biologists from the Idaho Department of Fish & Game (IDFG) using electrofishing equipment conduct population surveys on the Box Canyon section of the Henrys Fork. This year’s surveys show a dramatic increase in rainbow trout abundance when compared to past years. On average, Box Canyon supports about 3,000 trout per mile, with a peak in abundance of 5,500 trout per mile in 2000. This year’s survey documented over 6,200 trout per mile, which far exceeds any prior estimate.
According to Regional Fishery Manager Dan Garren, “Some of this increase can be attributed to high winter flows during 2011/2012, which our research has shown is critical to trout survival.” Fish that are spawned in the spring need sufficient winter flows from Island Park Dam during their first winter to survive. The higher the flows, the more trout make it through to the next year. During the winter of 2011/2012, winter flows were about 580 cubic feet per second (cfs), which is well above the 280 cfs average over the past decade.
Also, according to Garren, “Additionally, improvements to fish passage on the Buffalo River and habitat restoration efforts on important tributaries may be paying off and contributing to the large increase in the trout population. As a result of the efforts of IDFG and conservation partners like the Henrys Fork Foundation and the Fremont-Madison Irrigation District, anglers should find plenty of trout to chase this year on the Henrys Fork. “
Image courtesy Idaho Department of Fish and Game