NEW YORK — Scientists have detected a rare species of whale southeast of New York City, and the federal government is using a voluntary protected zone to try to keep them safe.

There are fewer than 350 North Atlantic right whales left, according to scientists.

The National Oceanic and Atmospheric Administration said the protected zone, which is south of Long Island and east of New Jersey, will be in effect until Sunday.

NOAA said mariners are asked to avoid the area altogether or move through it slowly. The whales are vulnerable to ship collisions and entanglement in fishing gear.

An acoustic array detected the presence of the whales in the area on Nov. 20, NOAA said.

Other zones to protect the whales are off Maryland and Massachusetts.