PORTLAND, Maine — Federal officials have extended their endangered species listing to salmon on three of Maine’s largest rivers.

The U.S. Fish and Wildlife Service and the National Oceanic and Atmospheric Administration’s Fisheries Service announced Monday that they have added fish in the Penobscot, Kennebec and Androscoggin rivers and their tributaries to the endangered list.

Salmon on eight smaller rivers in Maine were placed on the list in 2000. The expanded protection, which was opposed by the state, applies to large rivers that are home to industries and hydroelectric dams.

Federal officials say the expanded protection is necessary if the species is ever to recover. They pledged to work with the state and industries to ensure that the effect on economic activities is minimized.