Conservation, management, and protection of harbor seats come under the purview of the Marine Mammal Protection Act (MMPA) of 1972 (Public Law 92-522). A primary directive of the MMPA is to protect marine mammal stocks from declining below their optimum sustainable population. To fulfill this directive in California, the California Department of Fish and Game (CDFG), in cooperation with the National Marine Fisheries Service (NMFS), has been conducting annual, state-wide, aerial surveys of harbor seals to assess the status of the population.

Tomales Bay harbor seals: a colony at risk

The Golden Gate National Recreation Area and the Point Reyes National Seashore include the surface waters of Tomales Bay, a twelve-mile long estuary that floods the northwest end of the fault-generated Olema Valley. The bay differs from other, generally shallower, Pacific coast estuaries and lagoons in having a much greater area of open water at low tide and therefore more waterbird habitat through the tidal cycle. Tide flats providing suitable habitat for most shorebird species are concentrated at opposite ends of the bay, in the vicinities of the deltas of Lagunitas and Walker creeks.

Inventory of winter waterbirds and shorebirds on Tomales Bay: 1998-1999

The modification of natural landscapes by humans has led to changes in habitat quality and quantity that adversely affect many avian species, while other species benefit from such changes. For example, corvid populations are increasing throughout much of the United States, apparently because of their ability to exploit a variety of human-produced food sources. In addition, many corvids are opportunistic predators on other avian species and have the potential to adversely affect their populations.

Audubon Canyon Ranch Raven Project