LOS ANGELES — A satellite study of blue-whale movements shows the endangered creatures cluster for long periods in busy shipping lanes off the California coast, putting them at risk for collisions with large vessels.
The study, originally published in the science journal Plos One, discovered the whales seem to congregate in two particularly rich feeding areas that are crossed by shipping lanes off the California coast.
Researchers said they used satellites to track 171 tagged blue whales over 15 years.
"It's an unhappy coincidence," said Ladd Irvine, a marine mammal ecologist at Oregon State University who led the study. "The blue whales need to find the densest food supply. There's a limited number of those dense places, and it seems as though two of the main regular spots are crossed by the shipping lanes."
Previous surveys, based simply on whale sightings, hadn't revealed such a potential problem, the Los Angeles Times (lat.ms/1nDfh7K) reported Sunday.
Monica DeAngelis, a marine mammal biologist with the National Oceanic and Atmospheric Administration who was not involved with the study, said satellite data produce a more accurate study of whale movement.
Blue whales, the largest animals on Earth, can reach a length of more than 100 feet and a weight of more than 150 tons. About 2,500 of the estimated worldwide population of 10,000 are found in West Coast waters. International regulations prohibit hunting them.
Two years ago, the International Maritime Organization rearranged shipping lanes off the central California coast to protect the whales.
Shippers and shipping regulators plan to meet with researchers in the fall to discuss these latest findings.
In the meantime, T.L. Garrett, vice president of the Pacific Merchant Shipping Association, said his organization supports such studies, but he cautioned that any changes should be examined carefully to avoid putting other marine life at risk.
"You wouldn't want to put something in place that would be beneficial to the blue whales but then might be detrimental to humpback whales or fin whales," she said.