A Whale of a Comeback

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blue whaleWith all the doom and gloom about climate change and vanishing species, it’s sometimes nice to hear about an environmental success story. Here’s one. According to recent research from the University of Washington, the California blue whale population is back to near historic levels. Once hunted nearly to extinction, this is the only population of blue whales to have recovered. Today the population is estimated at about 2,200 or likely 97% of the historic level.

Using previously unavailable Russian data on whale catches, researchers estimated that only about 3,400 California blue whales were caught between 1905 and 1971. This compares to 346,000 caught near Antarctica during the same period, thus they know that the California population was historically quite small.

The recovery of the California blue whale population is a conservation success story. Cole Monnahan, a University of Washington doctoral student in quantitative ecology and resource management said, “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.”

The California population is now growing more slowly, but it’s thought that is because the habitat limit is being reached, not because of some human-caused reason, such as noise or pollution. Although the whales are no longer hunted, they are sometimes killed by ship strikes. But, an analysis suggests that a large decline in population will not be caused by ship strikes. In fact there would have to be an 11-fold increase in the number of ships before there is a 50 percent chance that the population would drop below a “depleted” level. Approximately 11 whales are struck each year along the West coast. But, of course, it would best if this were reduced to zero. “Even accepting our results that the current level of ship strikes is not going to cause overall population declines, there is still going to be ongoing concern that we don’t want these whales killed by ships,” said Trevor Branch, University of Washington assistant professor of aquatic and fishery sciences.

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