Speedy Blue Whales Seen from Space
22nd February 2002
(United Press International via COMTEX) -- New satellite data shows blue whales, the world's largest living animals, zip around the oceans at speeds much faster than previously believed.
"They are like a streak," said marine biologist Bruce Mate of Oregon State University in Corvallis. "One animal migrated more than 10,000 miles in 10 months."
These new findings, presented at an American Geophysical Union ocean sciences meeting in Honolulu, suggest scientists may have underestimated how many of the endangered whales there are. Only a small population of 7,000 to 8,000 of the giants is thought to exist.
"We could be underestimating by up to perhaps 1,000 whales," said biologist Jay Barlow with the National Marine Fisheries Service in La Jolla, Calif. "It's amazing that we can still be learning so much about these whales."
The scientists hope to use satellites to help protect the whales by locating their critical feeding and breeding habitats and figuring out how they get there.
"We're seeking out where they go, why and when. We're trying to proactively find out what the endangered habitats are so we can disentangle human activities issues before they become out of control," Mate said.
Blue whales grow up to 100 feet long and 80 to 100 tons in weight by grazing only on tiny crustaceans called krill. Despite the whales' staggering size, however, little was known about their migration habits until scientists developed new technologies to study them.
"In the old days, we would tag a whale and have to follow it by boat to stay within 5 miles because that's how far the signal traveled," Mate said. "If it got out of range, that was it. And we could only track one animal at a time."
Since 1993, Mate and colleagues have developed satellite-monitored radio tags to track blue whales off the California coast via satellite. They can now receive data on 15 to 20 blue whales simultaneously, tracking them for months.
"We tracked one blue whale for 307 days before the batteries were exhausted. That provides a lot of data," Mate said.
The scientists found that blue whales apparently travel much farther and faster than scientists thought, rapidly zooming from one fertile zone to another and feeding throughout the year, unlike other whales such as humpbacks. For example, 45 whales Mate tracked traveled 143,000 miles over the span of months.
"Think about a 20-minute mile -- that's what most people walk. Now imagine walking day and night for months at a time... and these are animals that weigh 80 tons," Mate said. "And our estimates of their speed are very conservative... when they migrate, they're moving much faster than this rule of thumb."
During the strong El Nino of 1998, about half the blue whales Mate saw were visibly emaciated. Their rapid migration patterns and their normally huge fat reserves are adaptations that help them survive such events.
"They can't afford to waste a lot of time in low-density food zones, so they really move from one high productivity area to another," Mate pointed out. "When the wind dies down and the krill goes away, these blue whales just take off and go."
The data reveals there still are a lot of mysteries remaining about the blues. A mother blue whale tagged in the Sea of Cortez during the winter never returned to California during the summer as expected, staying with her calf instead.
"It was thought that all of the whales in the Sea of Cortez were 'California whales.' The fact that a mother and her calf stayed down there is interesting. If those movements are typical, it may suggest that we've been underestimating calf production and perhaps the entire population," Mate said.
The researchers are planning to tag more blue whales in the Sea of Cortez in March.