The fecal viral flora of California sea lions

California sea lions (Zalophus californianus) are one of the major marine mammal species along the Pacific coast of North America. They are susceptible to wide variety of viruses, some of which can be transmitted to or from terrestrial mammals. Using an unbiased viral metagenomic approach we surveyed the fecal virome in California sea lions of different ages and health status. An average of 1.5 and 2.5 distinct mammalian viral species was shed by pups and juvenile sea lions respectively. We characterized numerous, previously undescribed, mammalian viruses from four RNA (Astroviridae, Picornaviridae, Caliciviridae, and Reoviridae) and one DNA virus families (Parvoviridae). The first complete or partial genomes of sapeloviruses, sapoviruses, noroviruses, bocavirus and dependovirus in marine mammals are reported. Astroviruses and bocaviruses showed the highest prevalence and abundance in California sea lion feces. This study increases our understanding of the viral diversity in marine mammals and highlights the high rate of enteric viral infections in these highly social marine mammals.