A newly released study has raised alarm bells about the North Pacific humpback whale population, indicating a sharp 20% decline in less than ten years, potentially due to marine heatwaves. Despite successful conservation efforts and the cessation of commercial whaling in 1976, the humpback whale population saw a steady increase until 2012. However, researchers have now observed a significant downturn, as detailed in the Royal Society Open Science journal.
A team of 75 scientists utilized an extensive photo-identification dataset spanning from 2002 to 2021 to track North Pacific humpback populations, identifying over 33,000 individuals through their unique tail patterns. Contrary to expectations of population stabilization, a notable and steep decline was recorded from 2012 to 2021, with numbers plummeting from approximately 33,000 to just over 26,600 individuals. In Hawaii, a subgroup of humpbacks experienced an even more severe decline of 34%.
Ted Cheeseman, a whale biologist and study author from Southern Cross University, expressed astonishment at the magnitude of the decline, estimating that around 7,000 whales may have perished due to starvation during this period. The researchers attribute this decline to extreme marine heatwaves, which likely reduced the carrying capacity threshold for humpbacks, leading to a collapse in population dynamics.
The study underscores the broader implications of ocean warming on marine ecosystems, affecting not only humpback whales but also other species such as tufted puffins, sea lions, seals, and commercial fisheries. It highlights the critical need for continued conservation efforts and climate action to safeguard the well-being of these remarkable creatures in the face of rapidly changing ocean conditions.
The occurrence of the strongest and longest marine heatwave on record from 2014 to 2016 significantly impacted the Pacific northeast, with temperature anomalies exceeding three to six degrees Celsius. This unprecedented heatwave disrupted the marine food chain and availability of humpback prey, exacerbating the decline in whale populations beyond initial projections.
