The flukes of humpback whales have unique shapes and patterns, and these characteristics can be used to identify individuals. To estimate humpback whale populations, researchers analyzed over 190,000 images of flukes collected between 2002 to 2021 in Okinawa and other areas including Japan, Philippines, Hawaii, Mexico, America, and Russia.
The results showed that in the North Pacific Ocean from 2002 to 2012, humpback whales increased in number from approximately 16,875 individuals to 33,488 individuals. Then from 2012 to 2021, the number of humpback whales declined to 26,662 individuals. The population of humpback whales breeding around Hawaii peaked in 2013, then began gradually decreasing. By 2021 the population had decreased by nearly 34%.
The results suggest the population of humpback whales in the North Pacific Ocean reached its limit environmental carrying capacity. The strongest recorded marine heat wave that occurred between 2014 to 2016 may have had a long-term effect on humpback whale populations and their recovery. We will continue to cooperate in this research across the North Pacific Ocean to better understand the changes in humpback whale populations and the effects of climate change.

Unique humpback whale flukes

Author

Ted Cheeseman, Jay Barlow, …, Nozomi Kobayashi, …, Haruna Okabe …, Phil Clapham (and other 69 co-authors)

Title

Bellwethers of change: population modelling of North Pacific humpback whales from 2002 through 2021 reveals shift from recovery to climate response

Journal

Royal Society Open Science

Link

https://doi.org/10.1098/rsos.231462