Monday April 28, 2025
Oceanographic —
An outbreak of domoic acid linked to one of the largest harmful algae blooms ever recorded along the Southern California coast has led to the illness and deaths of thousands of marine mammals and birds in recent months, including California sea lions, common dolphins, and confirmed cases in at least two species of whales.
Results of postmortem analysis carried out on a juvenile female humpback whale and a subadult male minke whale confirmed the presence of high levels of domoic acid – a potent neurotoxin produced by harmful algal blooms – in multiple samples from both, including within their faeces, stomach contents, and urine.
The findings have supported suspicions that domoic acid toxicosis was the cause of death.
Like sea lions and dolphins, humpback and minke whales feed on small schooling fish such as sardines and anchovies, which are known to accumulate domoic acid. These new results reveal how the domoic acid event is right now reverberating through the marine food web, affecting more species as it continues.