In this April 10, 2008, file photo, three right whale tails surface in Cape Cod Bay near Provincetown, Massachusetts. Credit: Stephan Savoia | AP

BOSTON — Federal ocean managers are asking mariners to continue slowing down east of Boston because of sightings of rare whales in the area.

The National Oceanic and Atmospheric Administration said it is asking mariners to go around the area or travel through it at 10 knots or less until May 9.

The group of whales was spotted on April 24. Right whales number only about 400 and are one of the rarest large ocean animals.

The whales are migrating at the moment. Baby right whales were spotted in Cape Cod Bay earlier this month. The whales come to the bay every year as they travel north from Florida and Georgia.