Thursday May 23, 2024

Idaho Department of Fish and Game

Fisheries managers often face tough choices to fix those situations. That might include adjusting fishing regulations or closing fishing seasons, netting unwanted fish, draining a waterbody, and sometimes chemical treatments that completely reset the system when necessary. The most common “reset button” is a fish pesticide called rotenone, which is a naturally occurring chemical found in the roots of certain tropical plants. 

For centuries, rotenone has been used by native tribes of Central and South America to catch fish for food. Since the 1930s, it has also been used by fishery managers to control and remove unwanted fish. Rotenone blocks the exchange of oxygen across the gills of fish and essentially suffocates them, and it works in very low concentrations (as low as 50 parts per billion). When properly applied to ponds, reservoirs, and streams, rotenone is an extremely effective tool for fish control. 

While it is very effective at removing unwanted fish, it also kills desirable fish as well. But that doesn’t mean all good fish are lost. Managers often use nets or electrofishing to remove desirable fish before using rotenone so those fish can be restocked after the rotenone treatment. 

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