The federal government is recommending a speed limit for commercial ships along the Atlantic coast, where collisions with the endangered right whale threaten its existence.

About 300 of the whales are left in the wild, and they migrate annually between their southeastern Atlantic breeding grounds to feeding areas off the Massachusetts coast, intersecting busy shipping lanes.

The rule would set a 10 knot speed limit within 23 miles of major mid-Atlantic ports and the whale's breeding and feeding areas for five years. The rule then would expire or have to be renewed.

Those requirements differ from an earlier draft challenged by the White House, which disputed the science linking ship speed to whale deaths.