Aug 26, 2022

San Francisco Bay has been experiencing a major harmful algae bloom (HAB) event. Early signs of the developing bloom were reported in late July 2022 within the Oakland Estuary (between Alameda and Oakland). By early August, the bloom had spread to South Bay west of Alameda, and by mid-August expanded over large swaths of South Bay. Recent observations suggest the bloom may also be reaching into regions of Central and San Pablo Bays. 

The HAB organism, Heterosigma akashiwo, can form blooms that have toxic impacts on fish and lead to fish kills. While fish mortality events were not observed during the HAB event's early stages, fish-kill reports began emerging around August 22, shared by researchers studying the bloom and Bay Area residents. To assess the HAB event’s impacts on Bay wildlife, documentation of fish mortality is urgently needed over the coming days and weeks. However, the Bay's size (area: 1600 mi2; shoreline: >300 mi) makes data-gathering a daunting challenge -- one that would benefit from for an ‘all-hands’ approach.

We are therefore seeking the assistance of Bay Area residents to report dead fish sightings. Please contribute to this regional effort: If you observe dead fish while navigating the Bay’s waters or traversing its shoreline, follow the link below, upload photo(s), and provide other relevant information about what you observe.  Thank you!

Add Your Observation


Scientists from USGS CA-WSCSFEI, and UC Santa Cruz are also closely tracking the bloom, to monitor bloom-related water quality impacts, and to understand the factors that promoted its growth and ultimately lead to its termination. Updates on water quality findings will be available shortly.

This citizen science project documenting SFB fish mortality is a collaboration between SFEI, Baykeeper, and UC Davis researchers, and supported by the San Francisco Bay Nutrient Management Strategy (NMS).

For additional information, please contact [email protected]

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