The California sea lion (Zalophus californianus) is a sea mammal that has been around for 220,000 years on this earth. They are found along the western coast of North America, British Columbia and Mexico. Known for their playful behavior and agility, they are strong swimmers and can dive to impressive depths. On land, they gather in large, noisy groups on beaches, docks, and buoys, where their distinctive barking calls are often heard. 

In 1987 in Canada, a marine neurotoxin had its first outbreak called Domoic acid. Domoic acid is an algae that was first isolated in Japan 1959 from a red alga which then spread through shellfish ingesting the phytoplankton carrying the toxic algae. Canada had 150 cases of neurological symptoms which were memory loss, seizures, comas, and reported cases of marine animals attacking people. Scientists have known about domoic acid and what toxic algae can do to species, but this year hit a record high for California sea lion mortality rates. In just a few months of 2025, 1500 marine animals sick, specifically to sea lions over 200 deaths. Marine animal centers were overwhelmed with the number of sick animals this year, yet this isn’t the first time it’s happened. In 2023 over 1,000 sea lions had poisoning which lead to the deaths from these toxic algae.

Some people would say “Why do we care about sea lions getting affected by these algae if it isn’t harming us”? In a way, this is harming us in ways we can’t see. Even though the origin of Domoic acid wasn’t caused by humans directly, we have managed to exacerbate the situation tenfold, from climate change. Runoff and warming waters are huge parts to factor in how this biotoxin was able to spread rapidly. Domoic acid favors warmer waters so it can grow quicker, and runoff (from sewage, agricultural fertilizer, etc..) can also fuel the levels of domoic acid. We are responsible for climate change, and the consequences that go along with it. Icecaps melting, animals losing their homes, rising temperatures for which we can’t explain, extreme weather events and essential animals getting sick. Sea lions are one of the very few apex predators that’re key to keeping our ocean alive. Sea lions keep the fish population balanced, maintain a healthy food web and serve prey for even bigger apex predators. They are a crucial part in keeping a diverse food web consistent.

The rise of biotoxins in California sea lions is a reminder that what happens in the ocean eventually comes back to us. If these animals are being harmed at such a fast pace, it’s only a matter of time before we feel the impact too. Change really does start with us, and the choices we make today can help create a healthier future—not just for ourselves, but for the animals that share the ocean with us.