A new study from Scripps Institution of Oceanography at UC San Diego reveals that blue whale populations have remained steady in Southern California, while fin whales have experienced an upward population trend.
Blue and fin whales, both classified as endangered species, are commonly found in the Southern California Bight, but researchers don’t know exactly what they do in this area. To close some of these gaps, Scripps researcher Ana Širović collected acoustic data from 2006 to 2012, using 16 High-frequency Acoustic Recording Packages (HARPs).
Širović and her colleagues studied the “call abundance” of blue and fin whales, providing the first detailed view of how the whales use these waters.
The acoustic data revealed that blue whale calls were typically heard between June and January, which fits the seasonal migration pattern of blue whales. Fin whale calls, however, could be heard year-round, supporting previous suggestions that Southern California has a resident fin whale population.
The researchers also found that the blue whale population remained steady, while fin whale populations increased.
“I think it’s an interesting difference in trends because both of the species were subject to whaling earlier in the twentieth century, and now they’re clearly responding differently,” said Širović, said in a news release.
“It seems that for fin whales, things are probably improving,” said Širović. “For blue whales, it’s a little bit harder to tell. There is a question right now as to whether their population has grown to its maximum capacity, because there are many lines of evidence showing that their population is not growing currently.”
“So the question remains, is it because that’s just what their population size can be maximally, or are there factors that are keeping them from growing further,” Širović asked.
To learn more:
- Read the full news release: A Tale of Two Whales: Seven-Year Study Indicates Steady and Upward Trends for Blue and Fin Whales in Southern California.
- Read the full study: Seven years of blue and fin whale call abundance in the Southern California Bight.
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