pinniped population monitoring

Año Nuevo Island and the adjacent mainland host a large pinniped colony, including four different species: the northern elephant seal, northern sea lion, California sea lion, and harbor seal. Since 1967, researchers from the University of California, Santa Cruz, and the Smithsonian Institution have been doing regular counts of all individuals of all four throughout the colony; particular attention is focused on counts of breeding females and pups of the elephant seal and northern sea lion. The number of elephant seal pups born annually at Año Nuevo was below 200 in 1968, but grew steadily until 1995; since then it has stabilized at 2600-2800. The number of northern sea lion pups was as high as 350 yearly in the late 1970s, but has declined since. California sea lions have few pups at Año Nuevo, but they are the most numerous of the four species, with more than 10,000 observed on some occasions. Harbor seals breed routinely on the island, but in small numbers (and breeding females are shy and hard to count). A fifth species, the northern fur seal, was recorded on several occasions in the mid-1970s