Sea Lions Suffer

Since I frequent the same California beaches weekly, I can't help but keep tabs on the big things that wash up. The picture above is of a decaying sea lion. My friend pointed it out about a week before the photo was taken. At that point the animal was alive and exhibiting a behavior she called “the Stevie Wonder”. Swaying his head back and forth, it was clear the animal wasn't well.

These days, this isn't an unusual sight. There are many sick or decaying seals and sea lions on the beach. Many of them sway, wallow and make their way, eventually, back to “health”. The cause: domoic acid, a neurotoxic product of what's called an algal bloom. These harmful blooms are increasing and the marine mammals are suffering.

A report published in the Proceedings of The Royal Society B (February 2008) shows that domoic acid exposed sea lions are developing a chronic condition. Researchers from several agencies including California's Public Health and the National Oceans Services examined hundreds of sea lions suffering from domoic acid poisoning over the last ten years.

What they've noticed is that, aside from initial acute symptoms, the animals may develop a “chronic epileptic syndrome characterized by behavioral changes, seizures and atrophy of the hippocampal formation.” They become lazy, vomit and twitch.

The results section of the paper references specific cases of strange activities. “Abnormal behaviors included standing in atypical locations (sleeping in a public restroom, climbing onto police cars, found up to 100 miles inland in an artichoke field, car dealership or walking down the road).”

On the upside, the authors conclude that these sick animals may provide a good model for human epilepsy and also serve as a tell tale for dangerous seafood.

On the downside, as the algal booms increase, marine mammals are likely to suffer more. And if the upside is knowing when our food is bad, the obvious negative is the potential of domoic acid poisoning for you and me.

Goldstein, T., Mazet, J., Zabka, T., Langlois, G., Colegrove, K., Silver, M., Bargu, S., Van Dolah, F., Leighfield, T., Conrad, P., Barakos, J., Williams, D., Dennison, S., Haulena, M., Gulland, F. (2007). Novel symptomatology and changing epidemiology of domoic acid toxicosis in California sea lions (Zalophus californianus): an increasing risk to marine mammal health. Proceedings of the Royal Society B: Biological Sciences, 275(1632), 267-276. DOI: 10.1098/rspb.2007.1221