Toxoplasmosis in California Sea Otters

I’ve always been fascinated by otters – all kinds of otters. One of my favourite books is “Ring of Bright Water” by Gavin Maxwell. Another otter book, “Tarka the Otter” written by Henry Williamson after World War I, which describes the adventures of an otter in North Devon, England, is on my bookshelf, too. My older son was captivated by Nathaniel Benchley’s “Oscar Otter,” and when he was three years old I had to read it to him over and over again.

The Arizona Sonora Desert Museum west of Tucson has a wonderful exhibit of river otters. You can watch them from above and also see them swimming through an underwater viewing window. It's one of my favourite places; I could watch them for hours.

When we camped on the California coast, I was introduced to sea otters. I loved their playfulness and the fascinating ways they adapt to the environment. Quite recently, I watched a documentary and saw a sea otter carefully wrapping itself in long strands of kelp to keep from floating away while it slept on the surface of the ocean. The Monterey Bay Aquarium’s web site includes a web cam of their sea otters.

So it was with great dismay that I read in BBC Web News last Sunday that Toxoplasma parasites are killing off sea otters, according to Patricia Conrad of the Wildlife Health Center at the University of California, Davis. Dr Conrad was speaking at the American Association for the Advancement of Science annual meeting in St Louis, Missouri.

According to Dr. Conrad, cat feces carrying the parasites wash into U.S. waterways. From there, the parasites travel to the sea where they infect the sea otters by causing deadly brain infections.

"What appears to be happening is that cats deposit their faeces - with the parasite - on land. When rainfall comes, it washes that into waterways and the fresh water takes it into the ocean." Once the parasite reaches the sea, it may be concentrated in mussels, oysters and clams, a major source of food for some otters. "For the sea otters, we don't exactly know how it gets in," said Dr Conrad, "but it must be through ingestion. "Because so many are dying, we are looking for things that concentrate the infection."

I'm also a cat lover, and I know how much cats love to hunt and prowl. However I believe it's definitely not a good idea to let them roam. Here in the desert, they can be taken by raptors, mountain lions, bobcats, or coyotes. And, as the article points out, they can fall victim to diseases when they hunt birds and small animals. Dr. Conrad is calling for owners to keep their cats indoors. She says:

“I know that's tough; I hate cleaning cat litter boxes as much as anybody. … But by keeping the cats indoors, we reduce the chance they're going to get infected by eating infected birds or rodents, and the chance they are going to shed their faeces outdoors."