Sources: Cornell University Lab of Ornithology; Hal Mueller/Sailwx.info; National Oceanic and Atmospheric Administration; OBIS-SEAMAP; Woods Hole Oceanographic Institution

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When a container ship strikes a 60-ton right whale, no one on board usually notices. The whale, however, may die from massive trauma, hemorrhage, and broken bones. Ship propellers slice whales up “like a loaf of bread,” says Michael Moore of the Woods Hole Oceanographic Institution.

North Atlantic right whales—one of the world’s most endangered species, with only about 400 living in the wild—are particularly vulnerable. They feed, breed, and migrate along the Eastern Seaboard, where, as the map at right shows, they encounter increasingly heavy ship traffic. In 2008, eastern U.S. ports saw 23,362 calls from large oceangoing vessels, and that number is expected to roughly double by 2023.

In response, scientists from the National Oceanic and Atmospheric Administration are testing a range of creative ideas to reduce ship strikes, including aerial surveys, whale-sighting hotlines, acoustic buoys that detect whale calls, and new shipping lanes that direct heavy traffic away from whale habitats.

But perhaps NOAA’s most important step, taken in December 2008, was mandating speed restrictions in vulnerable areas. The probability that a strike will cause serious injury or death increases with ship speed—from roughly 45 percent at 10 knots to more than 90 percent at 17 knots—and targeted speed restrictions have reduced deaths of other species, like manatees. Preliminary data suggest that the rule may be working. But because of pressure from the shipping industry—which argued that the restrictions would cause costly delays—the Bush administration ensured that the rule would expire in 2013.

That may be too soon for the whales. According to the New England Aquarium, ship strikes and fishing-gear entanglement until recently were killing the whales faster than they could reproduce. “Laws aside, there are fundamental reasons not to knowingly and willingly destroy a species,” says Moore. “Once it’s gone, it is forever.”