Warning: slow down for whales.

To protect right whales in the northwest Atlantic--one of the most depleted cetacean populations worldwide--the National Oceanic and Atmospheric Administration (NOAA) has proposed seasonal speed limits for large, ocean-going vessels. Currently, ship strikes pose the greatest threat to the population, NOAA says, with at least one or two deaths reported from such collisions each year.

Under the new proposal, ships 65 feet and longer could travel no faster than 10 knots in eastern U.S. waters near areas where the whales have been spotted. Normally, such vessels travel at 15 knots or faster.

Although protected from hunting since 1935, the species' population off the eastern United States and Canada is around only 300. This population's calving rate has risen in recent years to about 20 annually. Still, it doesn't fully compensate for adult-whale deaths sustained over the past 2 decades, NOAA reported in a June 26 Federal Register announcement of the proposed new rule.

The locations and sizes of go-slow zones will vary by season, and their duration will always be at least 15 days.

Roughly 70 percent of large commercial ships traveling along the East Coast passes through the right whale's critical habitat, researchers reported last year in the July-September Coastal Management. They found that most of those vessels moved at "speed[s] at which large whales may be critically injured."--J.R.