Me. Rev. Stat. tit. 12, § 6023

The commissioner shall designate a deputy commissioner, who serves at the pleasure of the commissioner. The deputy commissioner is responsible, under the direction of the commissioner, for the administration and enforcement of the marine resources' laws and has all the powers of a marine patrol officer. The deputy commissioner serves as the commissioner in the commissioner's absence or disability or if the office of the commissioner becomes vacant. The commissioner may appoint an appropriate administrative officer in the department to perform the functions of the commissioner if both the commissioner and deputy commissioner are disabled or absent.