In a comprehensive study spanning international waters, researchers have observed a notable decrease in the population of humpback whales in the northern Pacific since 2012. Despite the species' remarkable recovery from the brink of extinction, findings published in the Royal Society Open Science journal indicate a roughly 20% decline in their numbers over the past decade.
Thomas Doniol-Valcroze, leading the cetacean research program for Fisheries and Oceans Canada's Pacific Biological Station and one of the study's many contributors, emphasized that while the results are unexpected, they do not warrant immediate alarm. "It's not catastrophic news just yet," he stated in an interview with CBC's On the Island.
The study, titled Bellwethers of Change, involved collaboration among 46 organizations and utilized data collected by nearly 4,300 community science contributors, including thousands of photographs of Northern Pacific humpbacks. Doniol-Valcroze highlighted the challenges of precisely counting these elusive marine mammals but expressed confidence in the observed trends.
Humpback whales, once hunted to near extinction, experienced a significant resurgence following governmental protections implemented in 1976. By 2012, their population had exceeded 33,000, surpassing initial expectations. However, according to University of British Columbia zoology professor Andrew Trites, this rapid recovery may lead to overshooting population levels before stabilizing.
Despite this setback, the Committee on the Status of Endangered Wildlife in Canada now categorizes humpback whales as of "special concern," acknowledging ongoing threats such as ship strikes, toxins, and ocean noise pollution. The primary concern, however, stems from marine heat waves impacting their food supply.
Doniol-Valcroze attributed the recent decline in humpback populations to environmental changes, particularly prolonged marine heat waves associated with climate change. While the long-term effects remain uncertain, researchers are closely monitoring the situation.
Trites commended the utilization of data from numerous contributors as a testament to the power of citizen science. He emphasized the need for continued research and collaboration to understand the complex interactions affecting humpback whale populations in the face of environmental challenges.
Source: David P.Ball (Mar 04, 2024). Humpback whale numbers fall 20% but scientists aren't worried yet. CBC News. https://www.cbc.ca/news/canada/british-columbia/whales-pacific-science-1.7131768
