Despite being hunted from 1905–1971, the California blue whale has rebounded so that today it is approximately 97% of pre-whaling levels. The journal Marine Mammal Science recently published a study, “Do ship strikes threaten the recovery of endangered eastern North Pacific blue whales?” The analysis by the researchers from the University of Washington investigated why the observed increase in the whale population has slowed in recent years. They asked whether the cause might be ship strikes — whales being killed when hit by ships. They concluded that while ship strikes were too frequent, the reason that the rate of growth of the blue population has leveled off is because they have reached the capacity of the habitat to support them.
“The real key finding here is that they are close to recovery, which is a bit of a surprise. … Our perspective is that we’d rather there were no ship strikes at all, and they are over the legal limit,” said Dr. Trevor Branch in an interview with the BBC. “They have to do something to stop it, but 11 per year is so much lower than historic catches.”