Assessment of the sensitivity of Percina caprodes (logperch) to the pesticide 4-nitro-3-(trifluoromethyl)phenol

A continuous-flow streamside toxicity test was completed to evaluate the risk posed by the use of 4-nitro-3-(trifluoromethyl)phenol (TFM), used to control Petromyzon marinus (sea lamprey), to Percina caprodes (logperch). Logperch are a host fish to the parasitic glochidia life stage of the federally endangered Epioblasma triquetra (snuffbox mussel). Streams with an extant population of snuffbox must be treated before May 1, 2023, to prevent inadvertent take through TFM-related mortality of glochidia-infested fish. Although the concentration of TFM required to induce 99.9 percent mortality of sea lamprey was 6.52 milligrams per liter, the TFM required to induce 25 percent mortality of logperch was 10.14 milligrams per liter. Our data indicate that logperch are not as sensitive to TFM as previously suggested.