For decades scientists have been studying why some California sea otters are dying. Recently researchers led by the UC Davis School of Veterinary Medicine’s Karen C. Drayer Wildlife Health Center and the California Department of Fish and Wildlife (CDFW) have linked feral and domestic cats as the source of Toxoplasma that is killing sea otters.
The parasite forms egglike stages referred to as oocysts. Feral cats eat rodents and birds that have the oocysts in their bodies. From there the oocysts live in the cats until they are passed through the cat feces. The feces are washed into the sea and live in the kelp. Then snails eat the oocysts and the sea otters eat the snails.
People who own cats can help by keeping their cats indoors. Cat feces should not be flushed into septic or public wastewater systems since they will cycle back into the ground.
The oocysts are also washed into the waterways by rainwater, therefore preserving wetlands, forests and grasslands will help keep the parasite and other pollutants out of the oceans. Managing storm water runoff and replacing pavement with permeable surfaces will help.
If all cat owners in California, especially those who live near the ocean, do what they can to help, we can reduce the death rate of sea otters.