Mongabay · Climate & nature

Marine Heatwave Linked to Hawaiian Humpback Whale Decline

A marine heatwave in the northeastern Pacific Ocean from 2013-2016 significantly impacted the Hawaiian humpback whale population, causing a sharp decline that has not yet recovered. This event also led to reduced adult survival rates.

Researchers analyzed over 27,000 whale fluke photos from 2002-2023. They found the Hawaiian humpback whale population decreased by 37% between the 2014-2015 and 2021-2022 breeding seasons.

Adult survival rates dropped from approximately 99% pre-heatwave to an estimated 68% during the event. This period also saw an unusual mortality event in Alaska and British Columbia, with whales found starving.

The study estimates around 5,000 fewer humpbacks existed post-heatwave, with many likely having died. This research offers insights into potential future impacts of climate change on whale populations.

The North Pacific is currently experiencing another marine heatwave, alongside a strong El Niño, leading to above-average ocean temperatures.

The unrecovered population is more vulnerable to threats like entanglements, ship strikes, and pollution. Climate system disruptions could affect humpback whale populations globally.

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