Concerns regarding the exposure of wildlife to TFM and niclosamide that would result from the consumption of sea lamprey (Petromyzon marinus) larvae exposed to these chemicals has prompted a need to investigate uptake of these chemicals in larval lampreys. A study to address concerns regarding the exposure of the endangered common term during the treatment of the St. Marys River was completed in 1999. Ammocoetes exposed to a lethal concentration of niclosamide contained an average of approximately 3.53 g of niclosamide per gram of tissue. Complimentary data on TFM has not been generated. We propose to complete the data base by conducting a study to determine residues of TFM and niclosamide in ammocoetes following exposure to TFM and a TFM/1% niclosamide mixture.