Last updated: August 15, 2019
Article
2019 Harbor Seal Monitoring Updates
Breeding Season Summary
The 2019 harbor seal pupping season (March–May) was an average one. The maximum number of pups recorded during Pinniped Monitoring Program surveys at the main Marin County locations was approximately 1,060. That count is very similar to the baseline average of 1,100 pups. Drakes Estero was the most popular pupping site, with 368 pups recorded. This is an average count for Drakes Estero, but biologists saw an increase in the number of pups at Bolinas Lagoon, and decreases in pups at Double Point and Tomales Point, compared to their respective site averages. Very low pup mortality was recorded, indicating a successful season.
NPS / Kris Liang
Molting Season Summary
Following the pupping season, the seals are monitored during the molt season (June–July). During this time, all age groups come ashore at the main haul-outs to shed their fur. This gives biologists a good estimate of the total number of seals at the main Marin County locations. In 2019, the maximum number of seals recorded during the molt season was approximately 2,800, which is less than the baseline average of 3,670 seals and follows the past two years of low counts. All sites had a decrease in seals compared to their respective averages except Bolinas Lagoon, Duxbury Reef, and Point Bonita. Bolinas Lagoon has had higher than average counts since 2014, while Double Point has had extremely low counts since 2016. The peak counts recorded at Tomales Bay and Tomales Point were among the lowest counts ever recorded at each of those sites. The reasons for the decreases at these sites are unknown. During the molt season, the sites with the highest number of seals recorded was Drakes Estero (940) and Bolinas Lagoon (615).
Preliminary Data
2019 Maximum Harbor Seal Count By Site
Maximum Harbor Seal Pup Counts, 2000-2019
Maximum Harbor Seal Molt Counts, 2000-2019
The Details: 2019 Weekly Maximum Harbor Seal Counts By Site
For More Information
Contact
Webpages
San Francisco Bay Area Network - Pinniped Monitoring
Pacific Coast Science and Learning Center - Harbor Seals
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