blue whales
September 6, 2014

North Pacific Blue Whale Population Rebounds To Near-Historic Levels

Chuck Bednar for redOrbit.com - Your Universe Online

California blue whales have become the first group of the endangered species to experience a population rebound, demonstrating their ability to rebound when carefully managed, according to new research appearing in the journal Marine Mammal Science.

Blue whales are the largest animals on Earth, reaching nearly 100 feet in length and weighing nearly 200 tons when they reach adulthood. They are also the heaviest creature to ever live, weighing twice as much as the largest known dinosaur, but the study authors report they have been hunted to the brink of extinction.

According to Rachel Feltman of the Washington Post, the species has been hit hard as commercial whalers seek them out for their meat and oil. While the practice of hunting blue whales for commercial purposes has been prohibited by the International Whaling Commission since 1966, they still face threats from illegal whaling, as well as incidental fatalities related to other types of fishing, shipping, and pollution, she added.

Now, the authors of the new study report that the North Pacific blue whale population is the largest in the world, and has reached about 2,200. Scientists previously believed that the pre-whaling population was much higher than that, but the new study suggests otherwise. The authors reviewed data from 1905-1971 to estimate the number of whales caught from each population, and now believe the current population is 97 percent of the historical high.

“If California has always had a relatively small blue whale population, it explains why the area's population growth has slowed in recent years: It may be almost back to normal,” Feltman said. “The researchers believe that our nasty habit of running into whales with our ships (at least 11 were struck along the west coast last year) isn't actually a major concern. They believe that the population can maintain its stability regardless.”

“My impression is that they are fairly robust,” lead author Cole Monnahan a doctoral student in quantitative ecology and resource management at the University of Washington, told BBC News environmental correspondent Matt McGrath on Thursday. “If you can whale them pretty extensively for 50-70 years and they are able to recover I think that says a lot about moving forward.”

Monnahan was joined on the study by Trevor Branch and Andre Punt, both of the UW School of Aquatic and Fishery Sciences, and based on their findings, they conclude that the North Pacific blue whale population most likely never dropped below 460 individuals. The research was funded by the Joint Institute for the Study of the Atmosphere and Ocean, a collaboration between UW and the US National Oceanic and Atmospheric Administration (NOAA).

“Our findings aren’t meant to deprive California blue whales of protections that they need going forward,” said Monnahan. “California blue whales are recovering because we took actions to stop catches and start monitoring. If we hadn’t, the population might have been pushed to near extinction – an unfortunate fate suffered by other blue whale populations. It’s a conservation success story.”

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