Oct 19

Scientists have increased their estimate of the number of humpback whales in the North Pacific Ocean, according to a report published in the journal Marine Mammal Science.

Photo of humpback whales, two adults breaching

The revised estimate follows analysis of data compiled in 2008 as part of the largest survey ever undertaken to assess humpback whale populations in the North Pacific.

Photographic survey

The original study, known as the ‘Structure of Populations, Levels of Abundance and Status of Humpbacks’ (SPLASH), was a three-year project involving scientists from a number of different countries. The project used photographs to determine whale numbers, relying on the unique fluke patterns of the whales to identify individuals.

By matching photos from the species’ northern feeding grounds around the Pacific Rim with photographs of the same individuals in the warm tropical waters of their southern feeding grounds, the scientists were able to produce an estimate of the overall humpback whale population.

Photo of humpback whale fluke

The pattern of pigmentation on a humpback whale’s tail fluke is unique and can be used like a ‘fingerprint’ to identify individuals

The 2008 study originally estimated humpback whale numbers in the North Pacific at just under 20,000 individuals, based on a preliminary examination of the data. However, the new report indicates the population to be over 21,000, or possibly even higher.

According to Dr Jay Barlow, a researcher at the NOAA Southwest Fisheries Science Center in La Jolla, California, “These improved numbers are encouraging… We feel the numbers may even be larger since there have been across-the-board increases in known population areas and unknown areas have probably seen the same increases.”

Photo of humpback whale swimming

Humpback whale recovery

One of the major targets of the whaling industry, the humpback whale population was decimated by commercial whaling during the 20th century. However, the new population estimate shows a significant improvement on the 1,400 individuals recorded at the end of commercial whaling in 1966.

Although the humpback whale is still vulnerable to a range of threats, including marine pollution and climate change, these figures give encouraging evidence that the species is recovering from overexploitation.

Photo of a pair of humpback whales with extended throat pleats

This latest revision to the study provides an accurate estimate for humpback whales in an entire ocean that could not have been possible without researchers working together to pool data,” said John Calambokidis, one of the founders of Cascadia Research.

While populations of some other whale species remain very low, this shows that humpback whales are among those that have recovered strongly from whaling.”

View the original Marine Mammal Science article.

Read more on this story at Eurekalert – New, higher estimates of endangered humpback whales in the North Pacific.

View photos and videos of the humpback whale on ARKive.

Liz Shaw, ARKive Species Text Author

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