Invasive Species

The Montana Fish and Wildlife Commission approved an emergency order Thursday requiring anglers in Upper, Middle and Lower Thompson lakes to kill any walleye caught in those bodies of water and turn the fish over to Montana Fish, Wildlife and Parks (FWP).

This comes just a week after FWP discovered two non-native female walleyes in Upper Thompson Lake during a routine fishery survey. The fish are thought to be illegally introduced and can severely alter ecosystems.

Two nonnative walleyes were detected during a routine fishery survey west of Kalispell last week. The species could prove detrimental for a number of lakes in the area, and fishery managers are still deciding how to respond.

Rachel Cramer / Yellowstone Public Radio

Montana Fish, Wildlife and Parks is proposing to remove non-native smallmouth bass from Gallatin Valley ponds. The agency says the Midwestern fish could spread to other water bodies — including the blue-ribbon lower Madison River — and drastically reduce trout populations.

According to the Western Governors Association, species like the Canada thistle and common carp aren’t just nuisances -- they’re a matter of western biosecurity.

In an open field in Longmont, Colorado, about a dozen people crouched in the tall grass, moving slowly and deliberately through mud that squelched underfoot. Some carried huge, serrated knives called hori-hori, a Japanese tool made specifically for gutting weeds. Others wielded gardening shears, saws or chemical sprays as their weapons of choice.

The tamarisk plant, also called saltcedar, is infesting waterways across the West. The scaly-leafed shrub can grow taller than a person. It sucks up a lot of water and spits out salt, making the soil around it too salty for other plants to grow.

“It’s very bad, yes,” says Alex Gaffke, a graduate student in land resources and environmental science at Montana State University.