PORTLAND, Maine (AP) — Prosecutors charged a group of fishermen with federal conspiracy and other charges stemming from an investigation into the sale of unreported herring.

Five fishermen from Maine and New Hampshire and one corporation were named in the indictment, prosecutors said Friday. The defendants have been charged with conspiracy, mail fraud and obstruction of justice stemming from a scheme to sell the Atlantic herring and falsify fishing records, prosecutors said.

Atlantic herring is the subject of a major fishing industry on the East Coast that has faced tighter regulations in recent years due to concerns about the health of the fish’s population. Atlantic herring are used as bait and food.

Prosecutors said the owners, captains and crew involved in the conspiracy sold more than 2.6 million pounds of herring that was not reported to federal authorities in accordance with regulations. The indictment states that crew members were paid directly by fish dealers and lobster boat operators for the unreported catch.

James Landon, director of the law enforcement office for the National Oceanic and Atmospheric Administration, said the scheme was centered on “unscrupulous and unlawful fishing.”

Phone calls to fishermen who were charged were not returned. It was unclear Friday if they had hired attorneys.