They found that whales are at risk "across the world's oceans," with 91.5 percent of all blue, fin, humpback, and sperm whale ranges containing shipping activity. High-risk hot spots were identified in all ocean regions except Antarctic waters in the Southern Ocean, with continental coastlines at particular risk. But coasts weren't the only unsafe areas for whales, the researchers wrote, noting that "ship-strike risk is high anywhere that shipping routes intersect with key habitat or migratory corridors."

Despite the threat, researchers said, fewer than 7 percent of ship-strike hot spots have measures in place to prevent large ships from colliding with whales.

Large ships travel "thousands of times the distance to the moon and back within these species' ranges each and every year, and this problem is only projected to increase as global trade grows in the coming decades," senior author Briana Abrahms, an assistant professor of biology at the University of Washington and researcher with the Center for Ecosystem Sentinels, said in a news release.

Climate change could expand the risk, the researchers noted, as sea ice melts in the Arctic and new trade routes open.

But there is hope for whales, said Abrahms. "As much as we found cause for concern, we also found some big silver linings. Implementing management measures across only an additional 2.6 percent of the ocean's surface would protect all of the highest-risk collision hot spots we identified."