BANGOR — The captain of a commercial fishing vessel was sentenced Monday in U.S. District Court for shooting a seal in waters off Acadia National Park.

Joseph Martin, 54, of Warren was captain of the fishing vessel Sunlight when, on Oct. 10, 2016, he grabbed a rifle and began shooting into a group of harbor or grey seals that were approaching the boat. At least one of the federally protected animals was killed.

“There were multiple shots fired into the water,” said the prosecutor, Assistant U.S. Attorney Andrew McCormack. “I don’t know if additional ones were shot.”

Martin was charged with one count of taking a federally protected marine mammal. On Monday, he waived his rights to a trial and pleaded guilty to the charge. He was sentenced to serve three days in prison and pay a $1,000 fine.

Martin faced a maximum sentence of one year in prison, a $20,000 fine and one year of probation.

If the case had gone to trial, McCormack said he would have presented the testimony of crew members and video evidence of the shooting. The video was captured by a camera installed by a fishing regulatory agency to monitor the vessel’s catch, he said.

Sunlight was returning to Maine after fishing offshore for herring, according to court documents. McCormack said he could not pinpoint the exact location of where the shooting took place. He said Acadia National Park property could be seen in the video footage.

McCormack said he did not know who owns Sunlight, but according to the website of O’Hara Bait of Rockland, the vessel is one of two herring fishing vessels it owns to supply lobster bait to fishermen.

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