Pinniped behavior, foraging theory, and the depression of metapopulations and nondepression of a local population on the southern Northwest Coast of North America

Models derived from foraging theory suggest that high-value prey will be depressed (encounter rates will decrease) relative to low-value prey as human predation intensifies. Numerous case studies in ethnographic and zooarchaeological settings indicate depression of prey is very common. Exceptions to depression are few and have been cited as evidence of conservation and resource management. Reanalysis of pinniped and ungulate data from sites on the Oregon coast indicates that the metapopulation (entire population in the region) of otariids was depressed but a single local population of Steller sea lions exploited over a span of 600 years reached an equilibrium with human predation and was not subsequently depressed. This local population was not historically documented, and thus must have been extirpated by commercial sealing in the late nineteenth century. This singular case of prehistoric epiphenomenal conservation was an unintentional result of human predation that took advantage of the lack of escape behaviors among breeding male Steller sea lions.