Lampricide concentrations in larval sea lamprey (Petromyzon marinus) carcasses collected following two TFM and two TFM/Bayluscide treatments were determined to support risk assessments for non-target organisms that may consume lampricide-laden carcasses. Carcasses were removed from the treated streams either immediately after completion of the treatment or 2-days post mortem. The estimated average TFM concentration in the fresh carcasses (n = 80) collected from the rivers was 4.58 µg·g-1 (SEM =1.06 µg·g-1). The average concentration of niclosamide (the active ingredient in Bayluscide) in the fresh carcasses from the two rivers treated with TFM and Bayluscide was 0.492 µg·g-1 (SEM = 0.210 µg·g-1). The mean 2-day post mortem carcasses from the Chippewa River TFM/Bayluscide treatment contained 3% of the TFM and 64% of the niclosamide found in the freshly-killed larvae group. The mean 2-day post mortem carcasses from the Chippewa River TFM treatment contained 12% of the TFM present in the fresh group. The datasets included are as follows: Code to summarize mass, Length, Condition, Niclosamide concentration, and TFM concentration based on treatment group. (RawDataComb)