Article

2026 Harbor Seal Monitoring Updates

By National Park Service Marine Ecologist Sarah Codde

Simplified map of Marin County, CA, with six, labeled dots indicating harbor seal breeding/monitoring locations. From North to South, they are Tomales Point, Tomales Bay, Drakes Estero, Double Point, Duxbury Reef, Bolinas Lagoon, and Point Bonita.

Each spring, harbor seals gather in large groups on sheltered beaches and sandbars in Golden Gate and Point Reyes for their breeding season. During this time, female harbor seals give birth to single pups. Then in the summer, harbor seals of all ages return to these areas to molt, or shed their fur. The Harbor Seal Monitoring Team—a group of dedicated volunteers, partners, and staff—surveys these breeding and molting seals to learn about when/how/why their population size and breeding success changes over time. After all, these sensitive, curious seals are our parks’ only year-round marine mammal residents. And their population health is a great proxy for the health of our parks’ nearshore ecosystems.

Breeding Season Summary

Mother and pup harbor seals, the mom large and mottled brown and the pup small and mottled gray, float side by side in a large, calm, and clear tidepool.
Harbor seal mother and pup in a tidepool off of Tomales Point.

NPS / Dan Russell

In 2026, we wrapped up our breeding season surveys at the end of May. We counted around 690 pups at seven sites throughout the parks. This count is one of the two lowest counts on record during the 27-year monitoring period, along with the count from 2024. We’ve been seeing low pup counts since 2021.

Table with rows for each monitoring site showing simple graphs of pup counts over time in the middle and 2026 counts to the right. The graphs are bumpy but lately dipping to new lows at Double Point, Drakes, & Tomales Point but more stable elsewhere..
The simple line graphs represent harbor seal pup counts at each site from 2000 to 2026. Their y-axes all range from 0 to 500 pups. In 2026, Bolinas Lagoon had the highest count, with 237 pups. Drakes Estero fell to the number two spot with 172 pups. Sites were not surveyed in 2020.

NPS

Double Point, Drakes Estero, and Tomales Point all had pup counts that were far below their respective long-term averages. In fact, they had the lowest counts on record for each of their sites. We continued to see the ongoing presence of coyotes at Drakes Estero and Double Point this year, which possibly led to the large declines at those sites.

Not all sites experienced record low counts though! Point Bonita, Tomales Bay, and Duxbury Reef had counts that were similar to their respective long-term averages, and Bolinas Lagoon had an above-average count. For only the second time in our monitoring program's history, Bolinas Lagoon had the highest count of all Marin County locations with 237 pups. Drakes Estero fell to the number two spot with 172 pups.

Molt Season Summary

Stay tuned! The molt season is still underway.

Preliminary Data

2026 Maximum Harbor Seal Count By Site

Bar graph of maximum harbor seal counts at Tomales Point, Tomales Bay, Drakes Estero, Double Point, Bolinas Lagoon, Duxbury, and Point Bonita. Bolinas Lagoon has the highest breeding season adult and pup numbers, followed by Drakes Estero.
Maximum harbor seal adult and pup counts by site during the breeding season (adults and pups).

NPS

Maximum Harbor Seal Pup Counts, 2000-2026

Line graph showing maximum harbor seal pup counts have mostly remained fairly steady around the mean (average). The lowest count was in 2024 and was far below the mean. It bounced back a little in 2025, but is back to far below the mean in 2026.
Maximum harbor seal pup counts for 2000-2025 at Marin County sites. The black solid line on the graph represents the mean, or average, of the maximum pup counts from 2000-2024 (mean = 1,037), and the dashed lines represent one standard deviation from the mean. Not all sites were surveyed in 2020.

NPS

The Details: 2026 Weekly Maximum Breeding Season Harbor Seal Counts By Site

Graph of maximum harbor seal counts by site (Tomales Point, Tomales Bay, Drakes Estero, Double Point) and survey week from late February through May.
Graph of maximum harbor seal counts by site (Double Point, Bolinas Lagoon, Duxbury Reef, Point Bonita) and survey week from late February through May.
Maximum weekly harbor seal counts by site and survey week.

NPS

For More Information

Logo text reads "SF Bay Area Inventory & Monitoring". Circular illustration of a scene combining distinctive rock formations, a redwood tree, and the Golden Gate Bridge over the SF Bay, each outlined in white. Illustrated binoculars overlap the scene.

Webpages

San Francisco Bay Area Network - Pinniped Monitoring

Pacific Coast Science and Learning Center - Harbor Seals

Data

Pinniped Monitoring for the San Francisco Bay Area Network: 1983-2025 - Data Package

Contact

Sarah Codde

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Tags: golden gate national recreation area, point reyes national seashore, marine mammals, pinnipeds, harbor seals, breeding season, seasonal update, san francisco bay area, marin county, drakes estero, bolinas lagoon, tomales point, tomales bay, point bonita, double point, duxbury reef, sfan, sarah codde

Golden Gate National Recreation Area, Point Reyes National Seashore

Last updated: July 14, 2026