A Knox County man will serve time in jail and be required to pay a fine after pleading guilty to shooting a seal off the coast of Acadia National Park. The seal apparently died.

Joseph A. Martin, 54, of Warren pleaded guilty Monday in U.S. District Court in Bangor to the misdemeanor charge of taking a federally protected marine mammal.

Magistrate Judge John C. Nivison sentenced Martin to serve three days in jail and to pay a $1,000 fine.

Acting United States Attorney Richard W. Murphy issued a statement Monday describing the circumstances behind the killing of the seal.

Murphy said Martin was acting as a captain of a fishing vessel on Oct. 10, 2016, when “multiple protected seals began to approach” the vessel, which was off the coast of Acadia National Park at the time. Court records do not specify the exact location.

“The defendant retrieved his rifle and began to shoot at the seals in the ocean,” Murphy said in the statement. “After the shooting took place, one seal could be seen floating in the water with a dark liquid surrounding its body.”

Court records indicate that the seal that Martin fired his rifle at was either a harbor seal or a gray seal.

Assistant U.S. Attorney Andrew McCormack, who would have prosecuted the case if it had gone to trial, said in court documents that the government was prepared to prove through witness testimony and video evidence – specifically, footage from a video camera that was mounted on Martin’s fishing vessel, the FV Sunlight – that Martin used his rifle to shoot at a group of seals that approached his boat.

“The FV Sunlight had been fishing for Atlantic herring and was returning to Maine from Massachusetts,” McCormack said.

The investigation was conducted by the National Oceanic and Atmospheric Administration’s Office of Law Enforcement.

James Landon, director of that office, said federal law protects seals and other marine mammals from being harmed.

He said NOAA’s Office of Law Enforcement “is dedicated to enforcing those laws and seeing that those who violate them are held accountable for their illegal actions.”