Researchers are seeking ways to protect whales from container ships that continue to mow down them down as they make their way to and from the ports of Los Angeles and Long Beach.
New shipping lanes set to be introduced later this year promise to pose less risk for feeding blue whales, but a report published in the current edition of Conservation Biology indicates that humpback and fin whales may face higher risks unless shipping routes are altered again.
The report, "Assessing the Risk of Ships Striking Large Whales in Marine Spatial Planning,' documents a 2009 change in shipping traffic that resulted from a state law requiring ships to burn cleaner fuel when passing coastal areas. Ships have altered their routes to southern lanes farther away from shore as a result, landing them in humpback and fin whale feeding grounds.
"The number of fin whales hit by ships in 2009 was the second-highest number in 20 years,' said La Jolla-based Southwest Fisheries Science Center biologist Jessica Redfern. "That's because shipping traffic moved to a fin whale hot spot.'
Redfern, the article's lead author, said the once-popular Santa Barbara Channel route to and from the ports of Los Angeles and Long Beach has been used less since a 2009 state law required ships traveling close to the coast to burn cleaner fuels. Now, ships are using central and southern routes through whale feeding areas.
"What we found is that humpback whales have a hot spot in the north, and fin whales are found in the south,' Redfern said. "So it would be complex to minimize risk for both species. But you can ameliorate risk for both if you put a route in the center.'
The International Maritime Organization approved a narrowing of Santa Barbara Channel shipping routes later this year to give blue whales a larger buffer zone between shipping lanes and feeding areas.
Blue whales are harder to predict and protect because they are less likely to group together with other whales and instead tend to spread out over vast areas, she said. The report, published in the current issue of Conservation Biology, found that blue whales face the greatest risk from ship strikes because their small population numbers (roughly 2,000 in the North Pacific Ocean) make them vulnerable.
"Further research is needed to determine whether ship strikes could be limiting population growth for blue whales and how to reduce ship-strike risk,' the report states.
About 100 whale deaths have been attributed to ship strikes since 1988, including three last year. But researchers believe that is only a fraction of the number of actual strikes, said National Oceanographic and Atmospheric Administration biologist Monica Deangelis. Though that may not pose an urgent problem for growing fin and humpback whale populations, it is an issue for blue whales, she said.
"One of the greatest things about this report is that is really highlights that blue whales are complex and should be a priority," said Deangelis, who co-authored the report. "Blue whale populations are stable at best. That means that if a blue whale is struck, it doesn't necessarily equate to a fin whale being struck. "
Deangelis said, according to the Marine Mammal Protection Act, any human-caused deaths of blue whales higher than 3.1 a year will keep the population from growing. Researchers believe more than three or four blue whales are killed by ships each year, even though that has not been confirmed by dead whale sightings.
In 2010, two blue, one humpback and two fin whales were killed off the California coast. In 2007, four blue whales were hit and killed in the Santa Barbara Channel - one of the areas that will be affected by this year's implementation of International Maritime Organization's revised shipping routes.
Cascadia Research biologist John Calambokidis, who co-authored the study and also is evaluating how blue whales respond to ships, said he supports rerouting shipping lanes and calling for slower speeds in shipping channels.
"We've noticed very little movement (of blue whales) away from ships, even when' ships nearly hit them, Calambokidis said. "The threat of being struck by a massive high-speed ship is so new to their species, they haven't seemed to have evolved a response.'