ATLANTIC CITY, N.J. — Federal officials have instituted a speed restriction off the coast of New Jersey to protect a group of endangered whales.

NewsWorks reports ( ) that the National Oceanic and Atmospheric Administration placed the voluntary vessel speed restriction on boaters in the region after eight right whales were seen along the coast.

NOAA asks that boaters either avoid the area or travel at 10 knots or less. The notice is in effect through June 1.

Boaters have also been asked to stay 500 yards away from any visible right whales. The whales feed on plankton just below the surface which puts them at risk.

NOAA says there are around 500 right whales inhabiting the Atlantic Ocean between Florida and Canada. Groups of the whales have been spotted near Cape Cod this spring.