The lampricide 3-trifluoromethyl-4-nitrophenol (TFM) stimulates oxygen consumption by larval sea lamprey in a dose-dependent manner

Sea lamprey (Petromyzon marinus) are an invasive species in the Laurentian Great Lakes, where parasitism by blood-feeding juvenile lampreys greatly reduced populations of economically and culturally important native fishes in the early-mid 1900s. To control sea lamprey populations, the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) is added to streams infested with larval sea lamprey. Sea lamprey have a lower capacity to detoxify TFM than most non-target fishes, making it a highly effective pesticide. TFM decreases ATP production by disrupting oxidative phosphorylation in the mitochondria, leading to an increase in mitochondrial oxygen consumption. However, little is known about how TFM affects whole animal oxygen consumption in sea lamprey and other fishes. To test the hypothesis that TFM has dose-dependent effects on larval sea lamprey metabolic rate, we measured the mass-specific oxygen consumption rates (${Ṁ}_{O_2}$) of larval sea lamprey using intermittent-flow respirometry during TFM exposure. Exposure to increasing concentrations of TFM led to stepwise increases in ${Ṁ}_{O_2}$ in larval sea lamprey, resulting in death after ${Ṁ}_{O_2}$ reached levels equivalent to their known maximum metabolic rates. Similar measurements of ${Ṁ}_{O_2}$ could be used to determine the relative TFM sensitivity of non-target species to better assess the potential impacts of TFM on resident fisheries.