In the middle of a Montana Fish, Wildlife and Parks public information exchange earlier this month, a man held up a mounted 11-pound westslope cutthroat trout to remind everybody what was at stake. FWP officials put on the exchange to discuss details of their Westslope Cutthroat Trout Conservation Program, which will treat 21 mountain lakes in Flathead’s South Fork watershed with a toxin called rotenone to eradicate hybridized fish.
Poison concerns people. Of the 35 or so people who attended the exchange, some expressed deep skepticism of the project. A few were angry.
FWP officials explained that non-native fish breed with native westslope cutthroats to create hybrids. Hybrids, FWP officials say, water down the gene pool, can reproduce faster than westslopes and could completely wipe out westslope populations. Rotenone treatment will kill all fish in the targeted areas and then FWP biologists will restock genetically pure hatchery westslopes.
Treatment begins in the fall. From then on, every year one or two lakes will be treated until all 21 are done, costing a few hundred thousand dollars in total. There are about 350 lakes in this watershed, though only 50 support fish.
Rotenone is an organic toxin derived from various tropical and subtropical plants. It inhibits a fish’s cellular respiration, or its breathing ability. Long before it became popular in fish management programs throughout the U.S., South American Indians used it to stun fish so they could shoot them with bows and arrows. It is also widely used for insecticides in the U.S.
Studies on rotenone have produced an array of different results, including concern over rotenone’s effects on biodiversity and its possible link to Parkinson’s disease. Another concern apart from the toxin itself is the use of motorized boats and planes in designated wilderness area to apply the toxins.
The man wielding his mounted fish reminds us of what’s at stake: a gorgeous and important watershed, including 11 lakes in the Bob Marshall Wilderness. Flathead’s residents should pay attention no matter what their view is now, as studies on rotenone are continually raising new concerns or disproving old myths. It is a large project and there’s much at stake.
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