This Technology Could Save Endangered Blue Whales From Colliding With Cargo Ships
Scientists are developing a near real-time computer model that predicts where endangered blue whales will congregate as they ply the Pacifc Ocean off California. Ships can then be notified to minimize chances that the largest animal on the planet will die in a collision with an even larger boat.
Think of it as a blue whale traffic-congestion map.
Called WhaleWatch, the program merges the past movements of satellite-tagged blue whales with current environmental conditions off the California coast that influence where the whales travel.
“We’ll be able to say, given the current conditions, this is a whale hot spot,” said Helen Bailey, a marine mammal specialist at the University of Maryland’s Center for Environmental Science.
“The hot spot might only coincide with the shipping lane a few months of the year,” added Bailey, who leads WhaleWatch. “If the shipping lanes could be modified, it would reduce the risk of a whale strike.”
Collisions with cargo ships are the primary threat to endangered blue whales. In 2007, four blue whales were killed, likely by ship strikes, in and near the Santa Barbara Channel. In 2010, five whales, including two blues, were killed in the San Francisco area and elsewhere along the north-central California coast.
“Only three can be killed per year to keep the population sustainable, and anytime we hear a number close to that is reason for concern because it’s probably a large underestimate,” said Bailey.
About 2,500 blue whales live in the North Pacific and another 500 in the North Atlantic. Estimates suggest the global population of blue whales sits between 10,000 and 25,000. They are the largest animals on Earth, stretching to more than 100 feet—longer than a basketball court. Since 1900, the blue whale population has declined or remained flat, even though it is a protected species.
Scientists and the shipping industry have been looking for ways to reduce the number of collisions between ships and the endangered whales, but they have had little solid data on the whales’ whereabouts.
Now scientists have assembled an up-close look at the animals’ movements throughout the year. They found that shipping lanes near Los Angeles and San Francisco crisscross the blue whales’ key feeding grounds.
In 1993, Ladd Irvine, a marine mammal ecologist at Oregon State University’s Marine Mammal Institute, and his colleagues began fixing satellite tags to blue whales off the California coast. By 2008, they had tagged 171 blue whales.
They watched the whales swim to the Gulf of Alaska and the southern tip of Baja, Mexico. In the summer and early fall, the whales returned to the California coast, where they gorged on krill in nutrient-rich waters before migrating south for the winter.
“It gave us a nice detailed look of where the whales spend their time in U.S. waters from year to year and the timing of when they are present and when they leave,” said Irvine, whose research was published Wednesday in the journal PLOS ONE.
“It happened that the two most heavily used areas were crossed by these shipping lanes.”
Most of the tags stayed with the whales for about two or three months, but one whale held on to its transmitter for more than 500 days, giving the researchers a unique look at its annual route. Whale No. 3300840 followed its prey over the summer season and returned to several spots within a week of having been there the previous year.
“It was amazingly consistent,” said Irvine, “especially considering the different ocean conditions in 2004 and 2005.”
Upwelling—the movement of nutrient-rich waters to the ocean surface—and the growth of microscopic plantlike organisms called phytoplankton happened late in the year in 2005 and produced less food for whales.
According to the study, restricting use of San Francisco’s northernmost shipping lane during the summer and fall, when more whales are foraging in the area, or extending and bifurcating one of the lanes farther offshore could minimize the overlap. Moving vessel traffic in the Los Angeles and Santa Barbara areas south of the Channel Islands during the feeding frenzy may lower the risk of a collision.
The same data has been folded into WhaleWatch, which along with satellite-monitored environmental data—including sea surface temperature, chlorophyll concentration (a proxy for phytoplankton), and upwelling—could spell out more precisely where and when blue whales will congregate along shipping routes.
If the model forecasts a whale hot spot, ships could be rerouted or their speeds reduced to avoid collisions.
Until now, most whale data had been collected through observations from airplanes, research vessels, and smaller craft traveling closer to shore. The results were often inconsistent, and getting that data was expensive, said Bailey.
The National Oceanic and Atmospheric Administration is planning a review of shipping lanes in the Southern California area.
“Having more information from the whale perspective helps NOAA look at the broader story to see if there is a way to reduce the risk of strikes,” said Monica DeAngelis, a marine mammal biologist at NOAA.
The International Maritime Organization rerouted several shipping lanes in June 2013 to protect endangered whales along the California coast. The three lanes approaching San Francisco Bay were extended farther from shore to reduce the overlap of ships and endangered marine species. Two of the lanes were also narrowed. The lanes in Southern California into the ports of Los Angeles and Long Beach were narrowed and modified to avoid whales.
“Knowing the timing of when these whales are in the shipping lanes is a huge piece of the information we need,” said Irvine.