2007 Harbor Seal Pupping Season at Point Reyes National Seashore

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Date: March 6, 2007
Contact: Sarah Allen, 415-464-5187
Contact: John Dell'Osso, 415-464-5135

Harbor seal pup © Sue Van Der Wal

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, Drakes Estero and Bolinas Lagoon. 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 1 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, abalone divers, 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 at Point Reyes has demonstrated that harbor seal populations rapidly decline when disturbed during the breeding season.

Last year, about 4,000 harbor seals were counted, over 1,000 of which were pups, which marked good productivity for the colony although the average number of adult seals was around 13% lower than 2004, likely related to poor food availability. The number of seals breeding at Point Reyes represents around 20% of the California mainland population estimate. The Seashore staff is conducting long-term monitoring throughout the Seashore to gain further scientific knowledge on this species and to guide management in their protection.

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, they are waiting for their mother to return. Pups are about two feet long and weigh about 24 pounds and are weaned at 30 days after birth.

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, and cormorants nest on the island in the spring and summer.

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.

Map of Estero closures (299 KB PDF)
Map of Hog Island closure (42 KB PDF)


Last updated: April 5, 2019

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Point Reyes Station, CA 94956


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