Otterly Kelpless

CK: Well, with sewage, they do make an effort to dump it a mile or more offshore. But how much of it comes back is not known.

But an outdoor cat who has this parasite just sheds millions and millions of these Toxo eggs. One cat pooping along a creek bed near the shore could really infect the area. That's why, for example, we want to see what feral and outdoor cats are doing. Feral cats just love to live along the coastline. People feed them.

CK: There's some work being done at UC Davis on that now -- to figure out that marine cycle. Are the eggs getting collected somewhere, like in filter feeding shellfish, and is that allowing otters to ingest them?

CD: Are there other parasites that otters are contracting?

CK: Well, to complicate things further, there's one called Sarcocystis neurona. It's a protozoa like Toxoplasma. But this one is found in Virginia opossums, which like cats, are an introduced species here. They've been increasing in population, and they shed Sarcocystis, which gets into otters and also causes a massive brain infection. We found that seven percent of otter deaths were caused by this. That's a new finding.

So those are two protozoal pathogens that are supposed to be on land, but they've ended up in the ocean somehow. They're definitely killing otters. Work is being done now to see if they may be killing other marine species.

After this female otter lost her pup, she treated this Rolling Rock bottle like
a youngster, and carried it around with her for several days.
Photo: Stan Foster, Pacific Images (831) 724-8666

And then on top of that, we've been finding otters that have been attacked by sharks. Usually, sharks hang at rookeries and just pick off elephant seal pups. But they're getting otters too. We've been finding otters that have big slashes taken out of them. And the thing is, the otters we've found attacked by sharks are three times as likely to have toxo. What we think is that the parasite alters their behavior enough that maybe they're not able to evade sharks. Or maybe they're drawing attention to themselves because they're having seizures. Or maybe they swim offshore because they don't know what they're doing.