From Wildlife Extra:
Has the California blue whale population made a complete recovery?
Analysis of numbers of California blue whale suggest that the population has achieved a complete rebound, with as many of the whales living off the Californian coast as there were before they were hunted to near extinction 110 years go.
In the 1930s, when whaling was at its peak, the population of blue whale dropped to between 500 to 1,000 individuals, according to researchers. After whaling became illegal in the 1970s, the population had a chance to recover and by the 1990s had grown to around 2,200 individuals. However, this figure levelled out, and remains the same today.
In order to assess whether this number represented a complete comeback for the whales, the research analysed published data looking at today’s number of California blue whales, the number that were killed by whalers during the 20th century, and the number killed each year by ship strikes. Using this data, scientists concluded that California blue whale numbers are currently 97 per cent as large as they were prior to 1905.
That the number is almost the same could explain why the population stopped growing in the 1990s. Cole Monnahan, a doctoral student in ecology and resource management at the University of Washginton, explains: “Before this study some people thought that number should be going up, but if there were about 2,200 whales to begin with, then that is what the environment can support.”
However, the findings were greeted with a certain amount of cynicism by some. Jay Barlow, National Ocean and Atmospheric Administration research scientists, says, “It all depends on whether you believe the whaling statistics or not, and my guess is there are more underestimates of whales killed, rather than overestimates.”
If the number of whale deaths during the 20th century were underestimated, it could suggest that California blue whale numbers are not in fact fully recovered. But if the data is indeed correct, it would make them the only species of blue whale to have made a full recovery.