| Pacific harbor seals (Phoca vitulina richardii) are the most abundant and only year-round resident pinniped in the National Parks of the San Francisco Bay Area, California. Seals haul out, breed, and pup at 5 major (>400 seals) and 3 minor (<200 seals) colonies along the coastlines of Point Reyes National Seashore and Golden Gate National Recreation Area. During the 1970s-1990s, after passage of the 1972 Marine Mammal Protection act, populations grew rapidly and logistically (Sydeman and Allen 1999). However, from the late 1990s to present, colony attendance and pup production has fluctuated overall and within colonies. We investigated (1) oceanographic, geomorphological, predatory, and anthropogenic factors associated with the observed population dynamics, (2) predicted future population growth, and (3) assessed whether individual colonies operate in isolation or comprise a larger regional population. |