Out of Bounds

Not That Kind of Poison

If activists took time to examine rotenone use in the United States, what they’d find is a history of success

By Rob Breeding

News reports suggest there’s a pox befalling the land, a pox emanating from the offices of fisheries biologists. 

Apparently, these evil doers gaze out across the waters of the West, see nothing but inadequate fishes, and concoct potions to broadcast across lakes and streams like manna from Hades, killing non-native fish so these waters can be restocked with species preferred by anglers, thus fulfilling their every piscatorial fantasy.

It’s a media narrative so nonsensical, so filled with flaws, they can’t all be addressed here. 

This much I can say: in response to fear ginned up by gloom-and-doom headlines, environmental groups are in court trying to halt — get this — restoration work intended to shore up biodiversity and return native species to their native habitat.

You’d be forgiven for thinking their intransigence is a response to a litany of horrors: decimated, uninhabitable streams; polluted aquifers; humans struggling from exposure to dangerous, fish-poisoning concoctions.

That’s not what we’re talking about, however. The poison in this case is rotenone, probably the safest, least hazardous piscicide for restoring ecosystems, ever. 

Rotenone is needed, in most cases, because restoration requires the removal of non-native fish. In all but the smallest of waters there is no alternative for eliminating introduced fish.

If activists took time to examine rotenone use in the United States, what they’d find is a history of success. That includes restored westslope cutthroat trout in the upper South Fork Flathead River, and golden trout, California’s state fish and arguably the most beautiful of all trout, thriving in the High Sierra. 

Goldens were headed to extinction before restoration — a process that included using rotenone to wipe out introduced rainbow trout.

Rainbows, remarkable fish in their own right, are often the anti-biodiversity trout. Rainbows arrived to western waters later than cutthroats and other native trout, and these interlopers are remarkably adaptable. They thrive in novel habitats ranging from isolated Great Basin cutthroat streams to concrete hatchery raceways. They hybridize with many trout and rainbow genetics swamp those of more fragile natives.

For some, a fish is a fish. Trout geeks, however, see the biodiversity of trout, which evolved in the harsh conditions of the American West, as a resource too valuable to lose. 

Take the case of the Pyramid Lake (Nevada) Lahontan cutthroat. These fish are legendary, known for growing to enormous size of 20 pounds or more. But Pyramid cutthroats went extinct in the 1940s when their spawning grounds in the Truckee River were drained for irrigation. 

Gone, or so we thought. Biologists discovered a population of Pyramid cutthroats that had been stocked in a small headwater stream in Utah. Genetic analysis revealed their DNA matched museum specimens taken from Pyramid before the fishery collapsed.

Now managers are using those Utah relics to restore the giant Lahontans of Pyramid Lake. That means great fishing for anglers and a return of an important part of the natural heritage of the Pyramid Lake Paiute Indian Tribe.

Rotenone is an organic compound extracted from plants. It has been used for centuries by Indigenous people in the tropics to capture fish for food. It is safe and effective, doesn’t bioaccumulate and quickly dissipates from waters where it is deployed. For decades it has been an instrumental tool in the restoration of native fish.

Rotenone opponents profess a commitment to biodiversity. It seems what they’re really committed to are donations raised when the media amplifies their outrageous, anti-restoration rhetoric.

Rob Breeding writes and blogs at www.mthookandbullet.com.

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