Blue whales return to the same feeding spots every year; data on where these locations are could help mitigate human threats imposed on the aquatic mammals.
The new study, published in the July 23, 2014 in the open-access journal PLOS ONE, looks at satellite tracking of blue whales off the U.S. West Coast over the course of 15 years. The study was published by Oregon State University researchers.
The endangered blue whales' population has been slowly recovering since protection was established in the mid-1960s; ship strikes are believed to be a factor in the animals' sub-par recovery. In order to better understand where shipping lanes overlap with whale feeding grounds researchers attached satellite tags to 171 whales off the coast of California and tracked their movement between 1993 and 2008.
The travel distance and ranges of the whales was found to vary greatly , but despite ocean conditions
(such as El Niño and La Niña) these animals seemed to stick to the same feeding grounds as they usually did. The two areas most commonly used as feeding grounds were found to be the Gulf of the Farallones, off central California, and the western part of the Channel Islands in southern California.
The team suggested movement variability between individual whales was linked to different feeding strategies. Tagged whales tended to depart U.S. waters between mid-October and mid-November.
The researchers reported a heavy overlap between whale feeding ground and those used as regular shipping lanes. Moving shipping lanes could help reduce potentially-fatal collisions.
"We found that the two areas of highest use by tagged blue whales off the U.S. West Coast during the summer and fall are crossed by busy shipping lanes leading to major ports. This information may be used to help mitigate human threats to the blue whale population," Ladd Irvine from Oregon State University, said.
