2004 Harbor Seal Pupping Season at Point Reyes National Seashore
Contact: John Dell'Osso, 415-464-5135
Contact: Dr. Sarah Allen, 415-464-5187
Point Reyes National Seashore has the largest mainland breeding colony of harbor seals in California. Resting and pupping harbor seals come onshore in various parts of the park particularly in Tomales Bay, Tomales Point, Double Point, and Drakes Estero. Several hundred seals congregate within the Estero and numerous seals assemble near the mouth of Tomales Bay on tidal sand bars off Dillon Beach.
From March 15 through June 30, an annual closure of Drakes Estero is implemented to protect the harbor seals during this most sensitive time of year. The closure applies to kayak and canoe usage but is applicable to surfers, windsurfers, and other water sport users around harbor seal colonies in the area. The National Park Service asks park visitors to avoid disturbing seals to ensure a successful pupping season. Research has demonstrated that harbor seal populations rapidly decline when disturbed during the breeding season.
Last year, about 5,400 harbor seals were counted, 1,118 of which were pups, which marked good productivity for the colony rebounding from previous years. The Seashore staff is conducting long-term monitoring throughout the Seashore to gain further scientific knowledge on this species.
The east side of Hog Island in Tomales Bay is also terrestrial resting site for harbor seals and seabirds’ year round. Harbor seals haul out on the sand bar at Hog Island throughout the year but are most abundant during the winter when their preferred prey, Pacific herring, spawn in Tomales Bay. During the spring months, females with pups may also haul out there.
To ensure that harbor seals are not disturbed, visitors are asked to stay at least 100 yards (300 feet) away from resting seals. Visitors should never pick up a seal pup that may look abandoned. Although, harbor seal pups may appear abandoned. Often they are waiting for their mother to return.
A few species of seabirds roost on Hog Island including brown pelicans and double-crested cormorants, which occur in Tomales Bay during the summer and fall months of the year. They forage on various species of small schooling fish that congregate in Tomales Bay.
Both harbor seals and brown pelicans are protected and therefore, it is unlawful to disturb them while they are resting onshore. Harbor seals are protected under the Marine Mammal Protection Act of 1972, and brown pelicans are listed as a federally-endangered species under the Endangered Species Act.