What specific modern threat, originating from terrestrial domestic pets, is fatal to the California sea otter population?

Answer

The protozoal parasite *Toxoplasma gondii*

The protozoal parasite *Toxoplasma gondii*, shed in the feces of domestic and wild cats, is carried by runoff into the ocean and has been identified as a cause of increased mortality in sea otters.

What specific modern threat, originating from terrestrial domestic pets, is fatal to the California sea otter population?
locationanimalwildlifesea otter