The federal government is asking boaters to slow down in an area 70 nautical miles east of Portland, Maine, to protect a group of endangered right whales.

The National Oceanic and Atmospheric Administration says three right whales were seen in the area on July 30. The administration is announcing a voluntary vessel speed restriction zone in the area until Aug. 14. The area is just south of Penobscot Bay.

The administration asks mariners to route around the area or travel through it at 10 knots or fewer.

The western Northern Atlantic right whale population is believed to be about 400. The administration reminds boaters that approaching a right whale closer than 500 yards is a violation of federal laws.