NANTUCKET, Mass. (AP) — The federal government has announced a new voluntary speed restriction zone to try to protect rare whales off Massachusetts.

The National Oceanic and Atmospheric Administration said the new “slow zone” is located southeast of Nantucket and began on Aug. 1. It’s in effect through Aug. 16.

The zone is designed to protect North Atlantic right whales, which number only about 360.

The agency is asking mariners to route around the area entirely or transit through it at 10 knots or less.