Thursday, July 24, 2014

24/07/2014: Most detailed study yet of where whales go

Blue whales cluster for long periods in the busy shipping lanes off the California coast, according to a new study that raises concern about collisions between vessels and the endangered animals.
Shipping lanes cross whales densest food supply areas

“It’s an unhappy coincidence,” said Ladd Irvine, a marine mammal ecologist at Oregon State University who led the study published Wednesday in the journal Plos One. 

“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.”

Irvine and his colleagues used satellites to track 171 tagged blue whales over 15 years. 

They produced the most-detailed maps to date of the feeding zones of the giant whales, which are protected from hunting under international regulations.

The biggest overlap between blue whales and ships occurs from July to October near the western Channel Islands off Santa Barbara, the researchers reported. They also found somewhat smaller overlaps near the Gulf of the Farallones off San Francisco, and at the northern edge of Cape Mendocino.

The study's conclusions are at odds with previous research that suggested that shifts in shipping lanes would not help the whales because they are too widely dispersed. That research was based on whale sightings, which are more rudimentary than the tracking method used in the new study.

With the tags and satellites, Irvine’s group recorded individual whales over longer periods of time — an average of two to three months. One whale remained tagged for nearly a year and a half.

“This is far and away the most-detailed look that we’ve gotten on where these whales go,” Irvine said.

Read more HERE.

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