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Feared Trout Drop-off Signals Climate Shift in Montana

Warmer temperatures and a longer summer drought season in Montana are expected to have significant impacts on the state's trout fishing industry and ecosystem. In a special report, Heidi Cullen of Climate Central examines how climate-related changes are affecting Montana.

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  • JIM LEHRER:

    And now, the first in an occasional series climate change. We begin with a report on drought and trout in Montana. Our story is produced by Climate Central, a nonpartisan scientific research group. The reporter is Heidi Cullen, a climatologist and correspondent for The Weather Channel.

  • HEIDI CULLEN, Climate Expert, The Weather Channel:

    Montana, known for its big sky and its big trout. The skies are as stunning as ever, but all is not well with Montana's trout population.

    Warmer temperatures are setting off a series of interconnected changes that are affecting Montana, but we begin with the trout. Scientists project that increasing temperatures in the coming decades could cause significant reductions in trout habitat in Montana, placing the more than $300 million fishing industry in jeopardy.

  • CRAIG MATHEWS, West Yellowstone, Montana:

    I started guiding out of West Yellowstone in 1980.

  • HEIDI CULLEN:

    Craig Mathews is a well-known fishing guide and owner of Blue Ribbon Flies in West Yellowstone.

  • CRAIG MATHEWS:

    The changes I've seen in the 30 years that I've been here, I've seen a lot of sedimentation in the streams. I've seen lower water, particularly the last 10 or 12 years.

  • HEIDI CULLEN:

    The summer drought season in Montana has grown longer.

  • JENNY WEST, Hamilton, Montana:

    This is West Fork, and we have a tailwater, which kicks out some cool water in the summer that helps with the fishery.

  • HEIDI CULLEN:

    Jenny West is a fishing guide on the Bitterroot River near Missoula. She's been fishing the Bitterroot since she was 12 years old.

  • JENNY WEST:

    The key is July. If July is dry, then we have a pretty big drought.

  • HEIDI CULLEN:

    In addition to the long summer drought, the winter snow pack is melting earlier.

    STEVE RUNNING, University of Montana, Missoula: And the big trend that we've identified in the last 50 years is that we're getting a bit less snow and it's starting to melt on the order of two or three weeks earlier.

  • HEIDI CULLEN:

    Steve Running is a professor of ecology at the University of Montana in Missoula and a member of the Intergovernmental Panel on Climate Change, which was co-recipient of the 2007 Nobel Peace Prize.

  • STEVE RUNNING:

    Trout are what we call simply a cold-water species. And so a trout literally dies at water temperatures above about 78 degrees.

    It's pretty easy to warm up water above 78 degrees if it's just standing still. And so what keeps our water temperatures cool is that snow melt out of the mountains continuing to flow down through our rivers.

    As our rivers run out of flow and you're left with just sitting pools of water, that 78-degree threshold for trout mortality gets pretty easy to attain.