California HAB Bulletin: Summer 2025

Summer 2025: July, August, September

Summary written by Dr. Kasia Kenitz & Dr. Clarissa Anderson on October 28, 2025

    •  SUMMARY:  Following the decline of the spring domoic acid (DA) event, harmful algal bloom (HAB) activity varied along the California coast from July through September. While Southern California remained dominated by mostly harmless dinoflagellates such as Akashiwo and Prorocentrum, Central California experienced elevated Pseudo-nitzschia activity both nearshore and offshore. A particularly intense bloom was observed at Santa Cruz Municipal Wharf in mid-July, where P. nitzschia (primarily of the “delicatissima” size class) reached an exceptional 19 million cells/L, coinciding with elevated particulate DA concentrations. Elevated abudnances of Pseudo-nitzschia “delicatissima” group were also observed at Monterey Wharf and at Cal Poly Pier in July and August. The more toxigenic P. “seriata” group was elevated at Monterey Bay and Cal Poly Pier in early August, and Cal Poly Pier also recorded elevated particulate domoic acid at that time. Notably, Pseudo-nitzschia abundances declined substantially across coastal sites by September. Offshore persistence of Pseudo-nitzschia was documented by early August and late September research cruises, which detected concerning abundances offshore in Santa Barbara Channel and in Central California, where Pseudo-nitzschia populations extended as far north as Point Arena. Marine mammal strandings suspected to be associated with DA exposure remained very low, however – only seven suspect DA strandings reported statewide since July – consistent with generally low coastal pDA and Pseudo-nitzschia activity at coastal monitoring sites but inconsistent with offshore bloom levels in mid-to-late summer. A concerning persistence of very high abundances of Alexandrium offshore should be watched closely given the chance of developing cyst beds on the shelf that might lead to a recurring issue with Alexandrium and PSP risk.
    • C-HARM model predictions continue to indicate high risk for toxic Pseudo-nitzschia spp. bloom development along the entire California coast, encompassing both nearshore and offshore regions. By the end of July, the probability of alert-level particulate domoic acid (pDA) in Southern California declines, only to increase again by late August and throughout much of September, with high probabilities reported across both coastal and offshore zones. Elevated pDA probabilities persist through July around the Channel Islands and Central California. During August and September, certain coastal areas in Central California periodically exhibit reduced probabilities of alert-level pDA, while elevated risk remains offshore. High probabilities of bloom-level abundances of Pseudo-nitzschia are predicted along much of the California coastline from July through September. In the Southern California Bight, localized patches of elevated bloom probability appear along the coast, whereas offshore areas show near-zero probabilities of high Pseudo-nitzschia abundances. Similarly, near-zero risk predictions for cellular domoic acid (cDA) across most nearshore and offshore regions of Southern California suggest that any coastal blooms in this region are unlikely to be toxigenic. In contrast, the Channel Islands and both nearshore and offshore areas of Central and Northern California remain high-risk regions for the development of toxic Pseudo-nitzschia blooms throughout July to September. These areas consistently show elevated probabilities for both high Pseudo-nitzschia abundances and cDA, with notable hotspots near Monterey, Santa Cruz, and across much of the Northern California coast in July. Although the risk of high cellular DA remains elevated in August and September, it is generally lower than the risk levels observed in July. Overall, C-HARM predictions are broadly consistent with observations, which indicate high Pseudo-nitzschia and DA risk in Central California in July, low to non-detectable Pseudo-nitzschia abundances at coastal monitoring stations along the California coast in August September, but sustained high abundances offshore, as reported by offshore cruises in Central California.
    • Weekly HABMAP sampling of phytoplankton exceptionally high abundances of the less toxigenic Pseudo-nitzschia “delicatissima” group in Central California during July, particularly at Santa Cruz Municipal Wharf. On July 16, Pseudo-nitzschia reached a striking 19 million cells/L — one of the highest concentrations recorded this season, if not ever — dominated by the “delicatissima” size class. This bloom coincided with a notable increase in particulate domoic acid (pDA) concentrations at the site (1.79 ng/mL). As reported by the Kudela lab, “At the levels observed in the lab, this bloom would have exceeded the toxin thresholds used in NOAA’s C-HARM model by nearly twofold, while cell counts surpassed the model’s waring threshold over 400 times. This finding raises important questions about overlooked Pseudo-nitzschia species and their potential to cause ecological and public health impacts.” Pseudo-nitzschia remained abundant through late July before declining to “common” levels in August and disappearing completely by the end of September. Elsewhere in Central California, elevated Pseudo-nitzschia abundances were also observed at Monterey Wharf on July 23 (2,164,000 cells/L) and at Cal Poly Pier in early and mid-August (858,000 cells/L on August 4 and 930,000 cells/mL on August 18). The more toxigenic Pseudo-nitzschia “seriata” group reached peak concentrations in the first half of August, exceeding 57,000 cells/L at both Cal Poly Pier and Monterey Bay, and coinciding with elevated pDA concentrations at Cal Poly Pier (0.71 ng/mL on August 4). Pseudo-nitzschia abundances declined substantially across coastal sites by September. No pDA was detected in seawater samples collected between July and September at Southern California sites: SIO Pier, Santa Monica Pier, or Stearns Wharf. Although concerning Pseudo-nitzschia abundances were not observed at Stearns Wharf in Santa Barbara since early May, during a UCSB research cruise (August 5, 2025) aboard the R/V Shearwater, offshore samples showed abundances of 80,000 cells/L for Pseudo-nitzschia “delicatissima” and 75,000 cells/L for Pseudo-nitzschia “seriata” – levels considered concerning and indicating that the bloom persisted offshore. A subsequent research cruise in late September, spanning Central to Northern California, confirmed that offshore <em”>Pseudo-nitzschia populations extended as far north as Point Arena, with elevated abundances also detected in Monterey Bay. It is important to note that alongside the Pseudo-nitzschia bloom at Cal Poly Pier, very high and concerning abundances of Alexandrium were also recorded throughout much of August, peaking at 39,981 cells/L on August 4. Alexandrium abundances increased again toward the end of September, reaching 40,514 cells/L, which is reaching new records for many places in coastal California and should continue to be looked at carefully with both shore station and offshore sampling!
    • The Imaging Flow Cytobots (IFCBs) — robotic microscopes recording hourly observations at the same piers and on two moorings out on the shelf — typically corroborate HABMAP observations and offer detailed insight into HAB community dynamics. However, this summer the IFCBs continued to underdetect Pseudo-nitzschia, failing to capture the the intense July bloom of P. nitzschia observed by HABMAP at Santa Cruz and Monterey Bay. In contrast, IFCB data remained consistent with HABMAP in showing the dominance of Akashiwo and Prorocentrum along much of the coast. There is no IFCB deployed at Cal Poly Pier, so direct comparison with HABMAP data there is not possible. In Monterey Bay, the IFCB deployed on the offshore M1 Power Buoy detected elevated Pseudo-nitzschia abundances, recording up to 8,000 chains/L in mid-August. However, these levels were overshadowed by concurrent nearshore blooms of Akashiwo sanguinea and Prorocentrum spp. Contrary to the late September cruise observations, which reported the subsurface chlorophyll maximum to be dominated by Pseudo-nitzschia and Akashiwo populations in Monterey Bay, the offshore IFCB on the M1 Power Buoy did not detect Pseudo-nitzschia. This mismatch is likely due to differences in sampling depth: IFCB samples are collected at the surface, whereas cruise samples were taken from the chlorophyll maximum ~30-35 feet below the surface. Overall, IFCB data confirm that coastal HAB communities were overwhelmingly dominated by Akashiwo and/or Prorocentrum from July through September, corroborating HABMAP reports from coastal stations.
    • Marine Mammal Strandings continued to drop, with only 7 suspect DA sea lion strandings reported for the entire California coast since July 2025. These more recent DA strandings are suspected to be chronically impacted sea lions with permanent brain damage as a result of past bloom events. The lack of acute DA cases is in general agreement with a low Pseudo-nitzschia activity observed at the HABMAP and IFCB coastal sampling stations, and a low DA levels recorded at the coast.
    • California Department of Public Health (CDPH) conducts its own phytoplankton monitoring and shellfish and seafood testing for PSP toxins and DA. CDPH monitoring detected Pseudo-nitzschia at common levels (>10% of the phytoplankton community) at San Luis Obispo and Morro Bay, as well as at several Northern California sites, including Point Arena, Mendocino, and Humboldt Bay. In contrast, most Southern California sites showed only rare to present levels (<1%), consistent with HABMAP and IFCB data. The highest proportion of Alexandrium along the California coast was observed at San Luis Obispo, where it contributed approximately 5% to the plankton community, consistent with HABMAP and offshore observations. Elevated PSP toxin levels (256 µg/100 g) were detected in mussels collected from the Cal Poly Pier on August 26, followed by moderate levels (70 µg/100 g) on September 8. A recreational shellfish advisory was in effect and lifted on September 30. No alert-level concentrations of PSP or DA toxins were detected along the coast during September and October.
    • Currently, CDPH is advising the public not to consume sport-harvested mussels, clams, scallops, or oysters from the Northern Channel Islands and razor clams from Humboldt County, due to elevated DA levels detected in shellfish in those areas. In addition, a statewide mussel quarantine is in effect annually from May 1 through October 31.

 

Particulate Domoic Acid

Particulate domoic acid (pDA) is the measurement of total domoic acid toxin that is potentially extant in a given area. This forecast provides a probability for where that concentration of toxin is predicted to exceed the threshold that classifies a Harmful Algal Bloom (> 500 nanograms per liter).

The C-HARM v4 model generates nowcast and forecasts of the probability of Pseudo-nitzschia concentrations of in excess of 10,000 cells/L, the probability of particulate domoic acid > 500 nanograms/L, and the probability of cellular domoic acid > 10 picograms/cell in California and Southern Oregon coastal waters. Inputs for the model include near real-time satellite observations, gap-filled chlorophyll a, 486nm reflectance, and 551nm reflectance fields from the S-NPP NOAA VIIRS sensor plus nowcast and forecast data of surface salinity, sea surface temperature, and surface currents from WCOFS ROMS.

Cellular Domoic Acid

Cellular domoic acid (cDA) is the measure of total domoic acid toxin calculated per cell of Pseudo-nitzschia. This forecast provides a probability for where those cells are expected to be producing toxin at high levels (> 10 picograms per cell).

The C-HARM v4 model generates nowcast and forecasts of the probability of Pseudo-nitzschia concentrations of in excess of 10,000 cells/L, the probability of particulate domoic acid > 500 nanograms/L, and the probability of cellular domoic acid > 10 picograms/cell in California and Southern Oregon coastal waters. Inputs for the model include near real-time satellite observations, gap-filled chlorophyll a, 486nm reflectance, and 551nm reflectance fields from the S-NPP NOAA VIIRS sensor plus nowcast and forecast data of surface salinity, sea surface temperature, and surface currents from WCOFS ROMS.

Pseudo-nitzschia

Pseudo-nitzschia is a neurotoxin producing diatom that is observed along the California Coast. Blooms of this phytoplankton can be detrimental to surrounding marine ecosystems. This forecast provides a probability for where the concentration of cells in the water exceed the threshold of a Harmful Algal Bloom ( > 10,000 cells/L).

The C-HARM v4 model generates nowcast and forecasts of the probability of Pseudo-nitzschia concentrations of in excess of 10,000 cells/L, the probability of particulate domoic acid > 500 nanograms/L, and the probability of cellular domoic acid > 10 picograms/cell in California and Southern Oregon coastal waters. Inputs for the model include near real-time satellite observations, gap-filled chlorophyll a, 486nm reflectance, and 551nm reflectance fields from the S-NPP NOAA VIIRS sensor plus nowcast and forecast data of surface salinity, sea surface temperature, and surface currents from WCOFS ROMS.

California Harmful Algal Bloom Monitoring & Alert Program

Differentiating Pseudo-nitzschia species by light microscopy is difficult. For this reason, Pseudo-nitzschia “seriata” does not refer to an actual species but rather the larger size class of Pseudo-nitzschia, which is generally a more toxigenic group of species. Alternatively, Pseudo-nitzschia “delicatissima” refers to the smaller size class that is generally non-toxigenic. The dashed line on the plots demarcates the 10,000 cells/L “bloom” threshold designated here for Pseudo-nitzschia populations only.

Data for some stations are not shown as they are not yet recorded in the public HABMAP archive.

These time series focus on data collected through the scope of this bulletin and the 12 month period that precedes it. Explore the variables and regions that make up the CalHABMAP collective dataset using the plot controls.

More information and data visualizations on the statewide HAB network and forecasting system is found on the California HABMAP website and on the SCCOOS Harmful Algal Bloom page.

A network of Imaging FlowCytobots (IFCBs) continuously photographs particles, such as plankton, in the water. Using machine learning, plankton species can be automatically identified. This will help improve the ability to detect and respond to Harmful Algal Blooms, including the ability to assess conditions that may lead to toxin production or blooms of toxin-producing algae.

These data, coupled with the image classification algorithms developed in collaboration with SCCOOS and CeNCOOS, allow for estimates of species composition over time. The time series below depict sampling outcomes across several California sites. Support provided by NOAA IOOS and CA OPC.

Bodega Bay Marine Lab IFCB
Santa Cruz Municipal Wharf IFCB
MBARI Power Buoy
Stearns Wharf IFCB
Newport Beach Pier IFCB
Del Mar Mooring IFCB
Scripps Pier IFCB

Additional images and data are available on the IFCB dashboard.

 Each month, water samples are collected by volunteers and sent to the California Department of Public Health (CDPH) for analysis. The relative abundance of DA-producing Pseudo-nitzschia ‘seriata’ size class (upper) and PSP toxin-producing Alexandrium spp. (lower) are catalogued from sample locations within each county.

Pseudo-nitzschia ‘seriata’
Alexandrium spp.
July 3
Del Norte
____

CDPH warns consumers not to eat recreationally harvested mussels, clams, scallops or oysters from Del Norte County due to dangerous levels of paralytic shellfish poisoning (PSP).

July 10
Santa Cruz through LA
____

CDPH has removed warnings that advised against eating recreationally harvested bivalve shellfish from the waters of Santa Cruz, Santa Barbara, Ventura and Los Angeles Counties (except the Northern Channel Islands).

July 29
Marin, Del Norte
____

CDPH has removed warnings that advised against eating recreationally harvested bivalve shellfish from the waters of Marin County, as well as removed warnings for sport-harvested razor clams in Del Norte County.

August 11
Orange County
____

CDPH has removed warnings that advised against eating recreationally harvested bivalve shellfish from the waters of Orange County.

August 29
San Luis Obispo
____

CDPH warns consumers not to eat recreationally harvested mussels, clams, scallops or oysters from San Luis Obispo County due to dangerous levels of paralytic shellfish poisoning (PSP) toxins.

September 9
Humboldt
____

CDPH warns consumers not to eat recreationally harvested mussels, clams, scallops or oysters from Humboldt County due to dangerous levels of domoic acid detected.

September 30
Del Norte, SLO
____

CDPH has removed warnings that advised against eating recreationally harvested bivalve shellfish from the waters of Del Norte and San Luis Obispo County.

Percent composition categories help us look at phytoplankton trends across an entire region to evaluate risk of biotoxin presence. Many other factors contribute to our evaluation of risk in an area. These samples are posted for informational purposes only. They are not intended to inform the public of the presence or lack of risk. For the latest health advisory information, see the CDPH Health Advisory Map below.

Water Sample Detailed Data
Date_SampledCountySample_SitePN_Percent_CompPN_DensityAL_Percent_CompAL_Density
2025-07-01VenturaVentura, Port Hueneme Pier3PRESENT0ABSENT
2025-07-07HumboldtHumboldt Bay, Indian Is. Ch.0ABSENT0.5RARE
2025-07-07San Luis ObispoMorro Bay, Boat Launch0.5RARE0.5RARE
2025-07-07MarinTomales Bay, Lease #M430-151PRESENT0ABSENT
2025-07-02Santa BarbaraGoleta Pier0ABSENT0ABSENT
2025-07-09HumboldtTrinidad Pier0ABSENT0.5RARE
2025-07-04San FranciscoSan Francisco, Presidio Pier0.5RARE4PRESENT
2025-07-16Santa CruzSanta Cruz Wharf0ABSENT5PRESENT
2025-07-21MarinTomales Bay, Lease #M430-150.5RARE0ABSENT
2025-07-16Santa BarbaraGoleta Pier0.5RARE0.5RARE
2025-07-21San Luis ObispoMorro Bay, Boat Launch0ABSENT0ABSENT
2025-07-22MarinDrakes Bay, Chimney Rock LBS0ABSENT0ABSENT
2025-07-09Santa CruzSanta Cruz Wharf1PRESENT0ABSENT
2025-07-14MarinTomales Bay, Lease #M430-153PRESENT0ABSENT
2025-07-14San Luis ObispoMorro Bay, Boat Launch0.5RARE0ABSENT
2025-07-14HumboldtHumboldt Bay, Indian Is. Ch.0ABSENT0ABSENT
2025-07-02San DiegoOceanside Harbor15COMMON0ABSENT
2025-07-02MendocinoMendocino, Noyo Harbor0ABSENT0ABSENT
2025-07-14SonomaBodega Harbor, USCG Dock4PRESENT0ABSENT
2025-07-11San MateoPacifica, Mori Point0ABSENT4PRESENT
2025-07-02OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-07-03San DiegoImperial Beach Pier8PRESENT0ABSENT
2025-07-02Santa CruzSanta Cruz Wharf20COMMON0ABSENT
2025-07-03San DiegoSan Diego Bay, U.S. Navy Pier0ABSENT0ABSENT
2025-07-03OrangeBolsa Chica2PRESENT0ABSENT
2025-07-04San MateoGFNMS, San Mateo Line 23W20COMMON0.5RARE
2025-07-28HumboldtHumboldt Bay, Indian Is. Ch.0ABSENT0.5RARE
2025-07-08OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-07-11Santa BarbaraSanta Barbara Ch., Naples Pt1PRESENT0ABSENT
2025-07-14Del NorteHunter Rock, north0ABSENT0ABSENT
2025-07-08San DiegoPacific Beach Pier0ABSENT0ABSENT
2025-07-11OrangeBolsa Chica5PRESENT0ABSENT
2025-07-08OrangeDana Pt. Harbor0ABSENT0ABSENT
2025-07-24San Luis ObispoSan Luis Obispo, Cal Poly Pier0ABSENT0ABSENT
2025-07-24San Luis ObispoCayucos Pier0ABSENT0ABSENT
2025-07-22Del NorteHunter Rock, north0.5RARE0ABSENT
2025-07-13Los AngelesPalos Verdes Rocky Pt Offshore0.5RARE0ABSENT
2025-07-14SonomaKashia Coastal Reserve2PRESENT0ABSENT
2025-07-15SonomaShell Beach, Sea Ranch3PRESENT0ABSENT
2025-07-15Del NorteHidden Beach0.5RARE0.5RARE
2025-07-07San DiegoLa Jolla, Scripps Pier5PRESENT0ABSENT
2025-07-07Los AngelesPalos Verdes, OFFSHORE0.5RARE0ABSENT
2025-07-22SonomaSea Ranch0.5RARE0ABSENT
2025-07-21MendocinoPoint Arena Pier1PRESENT0ABSENT
2025-07-16San MateoPillar Point Harbor0ABSENT0ABSENT
2025-07-23Santa CruzSanta Cruz Wharf0.5RARE0.5RARE
2025-07-04Los AngelesPalos Verdes, OFFSHORE0ABSENT0ABSENT
2025-07-01San Luis ObispoPort San Luis, Diablo Cove0ABSENT0.5RARE
2025-07-05Los AngelesPalos Verdes, OFFSHORE2PRESENT0ABSENT
2025-07-07Los AngelesRedondo Beach Pier0.5RARE0ABSENT
2025-07-11Santa BarbaraSanta Barbara, Mohawk Reef0.5RARE0ABSENT
2025-07-15MendocinoMendocino, Noyo Harbor5PRESENT0ABSENT
2025-07-17San Luis ObispoCayucos Pier0.5RARE0ABSENT
2025-07-17OrangeSan Clemente Pier0ABSENT0ABSENT
2025-07-18San DiegoSan Diego Bay, U.S. Navy Pier0ABSENT0ABSENT
2025-07-19San Luis ObispoSan Simeon Pier0ABSENT0ABSENT
2025-07-28San Luis ObispoMorro Bay, Boat Launch0.5RARE0ABSENT
2025-07-06San Luis ObispoSan Simeon Pier0ABSENT0.5RARE
2025-07-20Del NorteWilson Creek0.5RARE0ABSENT
2025-07-09San DiegoImperial Beach Pier6PRESENT0ABSENT
2025-07-10San DiegoSan Diego Bay, U.S. Navy Pier1PRESENT0ABSENT
2025-07-16San Luis ObispoPort San Luis, Diablo Cove0.5RARE0.5RARE
2025-07-11San FranciscoSan Francisco, Presidio Pier0.5RARE0.5RARE
2025-07-03Santa CruzGFNMS, Santa Cruz Line 27E10COMMON1PRESENT
2025-07-05San MateoGFNMS, San Mateo Line N10-WN4PRESENT1PRESENT
2025-07-07SonomaGFNMS, Sonoma Line 13E3PRESENT0ABSENT
2025-07-01MarinGFNMS, San Francisco Line 6E5PRESENT0ABSENT
2025-07-18San FranciscoSan Francisco, Presidio Pier0.5RARE0ABSENT
2025-07-15OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-07-17Los AngelesPalos Verdes Rocky Pt Offshore5PRESENT0ABSENT
2025-07-21Del NorteWilson Creek0ABSENT0ABSENT
2025-07-28MarinTomales Bay, Lease #M430-150ABSENT0ABSENT
2025-07-08SonomaGFNMS, Sonoma Line N15-EN0.5RARE0ABSENT
2025-07-24San DiegoPacific Beach Pier0ABSENT0ABSENT
2025-07-14San DiegoLa Jolla, Scripps Pier3PRESENT0.5RARE
2025-07-21San DiegoLa Jolla, Scripps Pier0.5RARE0.5RARE
2025-07-18OrangeBolsa Chica0ABSENT0ABSENT
2025-07-07SonomaGFNMS, Sonoma Line 13M1PRESENT0ABSENT
2025-07-08SonomaGFNMS, Sonoma Line 15M1PRESENT0ABSENT
2025-07-09MarinGFNMS, Marin Line N2WN0.5RARE0ABSENT
2025-07-07SonomaGFNMS, Sonoma Line N13-WN6PRESENT0ABSENT
2025-07-10Del NorteWilson Creek0.5RARE0.5RARE
2025-07-08SonomaGFNMS, Sonoma Line 15-E1PRESENT0ABSENT
2025-07-05San MateoGFNMS, San Mateo Line 10E2PRESENT0.5RARE
2025-07-27HumboldtTrinidad Pier4PRESENT5PRESENT
2025-07-29Los AngelesSanta Monica Pier0ABSENT0ABSENT
2025-07-30MendocinoMendocino, Noyo Harbor0.5RARE0ABSENT
2025-07-30San DiegoSan Diego Bay, U.S. Navy Pier0ABSENT0ABSENT
2025-07-25San DiegoSan Diego Bay, U.S. Navy Pier0ABSENT0ABSENT
2025-07-26San Luis ObispoCayucos Pier0ABSENT0.5RARE
2025-07-30San DiegoImperial Beach Pier3PRESENT0ABSENT
2025-07-22OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-07-25San FranciscoSan Francisco, Presidio Pier0ABSENT0ABSENT
2025-07-28San DiegoLa Jolla, Scripps Pier0ABSENT0.5RARE
2025-07-02San MateoGFNMS, Santa Cruz Line 24E20COMMON0.5RARE
2025-07-18MendocinoMendocino, Noyo OFFSHORE3PRESENT0ABSENT
2025-07-22Los AngelesSanta Monica Pier0ABSENT0.5RARE
2025-07-25Los AngelesPalos Verdes Rocky Pt Offshore0ABSENT0ABSENT
2025-07-25OrangeBolsa Chica0ABSENT0.5RARE
2025-07-28San DiegoImperial Beach Pier0ABSENT0.5RARE
2025-07-22Los AngelesPalos Verdes, OFFSHORE0.5RARE0ABSENT
2025-07-25MendocinoMendocino, Noyo Harbor7PRESENT0ABSENT
2025-07-30Santa BarbaraGoleta Pier0.5RARE0ABSENT
2025-07-24San DiegoImperial Beach Pier0ABSENT0ABSENT
2025-07-29San MateoBean Hollow State Beach0ABSENT0ABSENT
2025-07-29San MateoPillar Point Harbor0ABSENT0ABSENT
2025-07-30Santa CruzSanta Cruz Wharf0ABSENT0ABSENT
2025-07-01MarinGFNMS, San Francisco Line 6W0.5RARE0ABSENT
2025-07-06San MateoGFNMS, San Mateo Line N8-WN10COMMON2PRESENT
2025-07-24MarinGFNMS, Marin Line 4E0ABSENT1PRESENT
2025-07-28MarinGFNMS, Marin Line 2E0ABSENT0.5RARE
2025-07-02Santa CruzGFNMS, Santa Cruz Line 25E6PRESENT0.5RARE
2025-07-25MarinGFNMS, Marin Line N4-WN0ABSENT0.5RARE
2025-07-28MarinGFNMS, Marin Line N2WN0ABSENT0ABSENT
2025-07-23San FranciscoGFNMS, San Francisco Line N6W0.5RARE0ABSENT
2025-07-04San MateoGFNMS, San Mateo Line 23E25COMMON1PRESENT
2025-07-03Santa CruzGFNMS, Santa Cruz Line 27W20COMMON3PRESENT
2025-07-06San MateoGFNMS, San Mateo Line 8W5PRESENT0.5RARE
2025-07-05San MateoGFNMS, San Mateo Line 10W4PRESENT0.5RARE
2025-07-09MarinGFNMS, Marin Line N4-WN15COMMON0.5RARE
2025-07-23MarinGFNMS, San Francisco Line 6W0ABSENT0ABSENT
2025-07-29MarinGFNMS, Marin Line 11E0.5RARE0ABSENT
2025-07-23MarinGFNMS, San Francisco Line 6E0.5RARE0.5RARE
2025-07-24MarinGFNMS, Marin Line 4W0.5RARE0ABSENT
2025-07-28MarinGFNMS, Marin Line 2W0ABSENT0ABSENT
2025-07-29SonomaGFNMS, Marin Line 11-M1PRESENT0ABSENT
2025-08-11OrangeSan Clemente Pier0.5RARE0ABSENT
2025-08-01Los AngelesPalos Verdes Rocky Pt Offshore0ABSENT0ABSENT
2025-08-01San FranciscoSan Francisco, Presidio Pier0ABSENT0.5RARE
2025-08-01OrangeDana Pt. Harbor0ABSENT0ABSENT
2025-08-04Los AngelesPalos Verdes Rocky Pt Offshore0.5RARE0ABSENT
2025-08-01Santa BarbaraSanta Barbara Ch., Naples Pt59ABUNDANT0.5RARE
2025-08-01OrangeBolsa Chica0.5RARE0ABSENT
2025-08-01San Luis ObispoPort San Luis, Diablo Cove20COMMON0.5RARE
2025-08-04HumboldtHumboldt Bay, Indian Is. Ch.0.5RARE0ABSENT
2025-08-04MarinTomales Bay, Lease #M430-150.5RARE0ABSENT
2025-08-04San Luis ObispoMorro Bay, Boat Launch5PRESENT0.5RARE
2025-08-01SonomaBodega Harbor, USCG Dock0ABSENT0ABSENT
2025-08-01MarinDrakes Bay, Chimney Rock LBS0ABSENT0ABSENT
2025-08-04San DiegoLa Jolla, Scripps Pier2PRESENT0.5RARE
2025-08-04MendocinoPoint Arena Pier0ABSENT0ABSENT
2025-08-04San Luis ObispoCayucos Pier4PRESENT0ABSENT
2025-08-07VenturaVentura, Port Hueneme Pier0ABSENT0ABSENT
2025-08-15MarinDrakes Bay, Chimney Rock LBS0ABSENT0ABSENT
2025-08-15SonomaBodega Harbor, USCG Dock0ABSENT0ABSENT
2025-08-14MarinPoint Richmond, Ferry Point0ABSENT0ABSENT
2025-08-11HumboldtHumboldt Bay, Indian Is. Ch.9PRESENT0ABSENT
2025-08-11MarinTomales Bay, Lease #M430-150.5RARE0ABSENT
2025-08-18HumboldtHumboldt Bay, Indian Is. Ch.7PRESENT0ABSENT
2025-08-18MarinTomales Bay, Lease #M430-150ABSENT3PRESENT
2025-08-29SonomaBodega Harbor, USCG Dock0.5RARE0ABSENT
2025-08-23San MateoPillar Point Harbor2PRESENT0ABSENT
2025-08-29MarinPoint Richmond, Ferry Point5PRESENT1PRESENT
2025-08-15OrangeBolsa Chica0ABSENT0ABSENT
2025-08-06Santa CruzSanta Cruz Wharf0ABSENT0ABSENT
2025-08-04Del NorteWilson Creek0ABSENT0ABSENT
2025-08-13Santa CruzSanta Cruz Wharf10COMMON0.5RARE
2025-08-05SonomaRussian River, Jenner0ABSENT0ABSENT
2025-08-08San FranciscoSan Francisco, Presidio Pier0.5RARE0ABSENT
2025-08-08San DiegoSan Diego Bay, U.S. Navy Pier0ABSENT0ABSENT
2025-08-08OrangeBolsa Chica0.5RARE0ABSENT
2025-08-11San Luis ObispoMorro Bay, Boat Launch5PRESENT3PRESENT
2025-08-18San Luis ObispoMorro Bay, Boat Launch10COMMON2PRESENT
2025-08-12MendocinoMendocino, Noyo Harbor15COMMON0.5RARE
2025-08-13San DiegoOceanside Harbor0ABSENT0ABSENT
2025-08-08Los AngelesPalos Verdes Rocky Pt Offshore0ABSENT0ABSENT
2025-08-16MendocinoPoint Arena Pier10COMMON0ABSENT
2025-08-15Los AngelesPalos Verdes Rocky Pt Offshore0ABSENT0ABSENT
2025-08-13Los AngelesSanta Monica Pier0ABSENT0ABSENT
2025-08-11San DiegoLa Jolla, Scripps Pier0ABSENT0.5RARE
2025-08-18San DiegoLa Jolla, Scripps Pier1PRESENT0.5RARE
2025-08-25MarinDrakes Bay, Chimney Rock LBS0.5RARE0ABSENT
2025-08-25HumboldtHumboldt Bay, Indian Is. Ch.5PRESENT0ABSENT
2025-08-25San Luis ObispoMorro Bay, Boat Launch0ABSENT0.5RARE
2025-08-25MarinTomales Bay, Lease #M430-151PRESENT0ABSENT
2025-08-15Los AngelesRedondo Beach Pier0ABSENT0ABSENT
2025-08-22OrangeSan Clemente Pier0ABSENT0ABSENT
2025-08-23OrangeBolsa Chica0.5RARE0ABSENT
2025-08-20San DiegoImperial Beach Pier0.5RARE0ABSENT
2025-08-21Los AngelesPalos Verdes Rocky Pt Offshore0.5RARE0ABSENT
2025-08-15San Luis ObispoPort San Luis, Diablo Cove15COMMON5PRESENT
2025-08-26San MateoBean Hollow State Beach1PRESENT0ABSENT
2025-08-07San Luis ObispoSan Simeon Pier7PRESENT0ABSENT
2025-08-17San Luis ObispoCayucos Pier6PRESENT3PRESENT
2025-08-22HumboldtTrinidad Pier36COMMON0ABSENT
2025-08-24San DiegoPacific Beach Pier0ABSENT0ABSENT
2025-08-25SonomaShell Beach, Sea Ranch25COMMON0ABSENT
2025-08-25Los AngelesCatalina Island, Toyon Bay0ABSENT0ABSENT
2025-08-18Del NorteWilson Creek10COMMON1PRESENT
2025-08-19MendocinoMendocino, Noyo Harbor20COMMON0.5RARE
2025-08-20MarinRichardson Bay0ABSENT0ABSENT
2025-08-20MarinRichardson Bay0ABSENT0.5RARE
2025-08-27Santa CruzSanta Cruz Wharf4PRESENT0.5RARE
2025-08-25SonomaKashia Coastal Reserve0.5RARE0ABSENT
2025-08-26San MateoPillar Point Harbor0.5RARE0ABSENT
2025-08-27Santa BarbaraGoleta Pier0ABSENT0ABSENT
2025-08-13Los AngelesSanta Monica Bay, 35010ABSENT0ABSENT
2025-08-12OrangeNewport Bay, Back Bay0.5RARE0ABSENT
2025-08-12Del NorteWilson Creek64ABUNDANT0.5RARE
2025-08-20Santa CruzSanta Cruz Wharf0ABSENT0ABSENT
2025-08-17San Luis ObispoMontana de Oro State Park0ABSENT0.5RARE
2025-08-15San Luis ObispoSan Luis Obispo, OFFSHORE0ABSENT0ABSENT
2025-08-25San DiegoLa Jolla, Scripps Pier3PRESENT0ABSENT
2025-08-13Santa BarbaraGoleta Pier10COMMON0ABSENT
2025-08-01OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-08-12Los AngelesSanta Monica Bay, 39010ABSENT0ABSENT
2025-08-20OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-08-15San DiegoSan Diego Bay, U.S. Navy Pier0ABSENT0ABSENT
2025-08-29Los AngelesCatalina Island, Avalon Bay0ABSENT0ABSENT
2025-08-16San Luis ObispoSan Luis Obispo, OFFSHORE52ABUNDANT0ABSENT
2025-08-14San Luis ObispoSan Luis Obispo, OFFSHORE65ABUNDANT2PRESENT
2025-08-29OrangeBolsa Chica0ABSENT0ABSENT
2025-08-28San Luis ObispoPort San Luis, Diablo Cove5PRESENT5PRESENT
2025-08-29Los AngelesPalos Verdes Rocky Pt Offshore0ABSENT0ABSENT
2025-08-29Los AngelesCatalina Island, Avalon Bay0ABSENT0ABSENT
2025-08-27San DiegoSan Diego Bay, U.S. Navy Pier0ABSENT0ABSENT
2025-08-29San DiegoOceanside Harbor0ABSENT0ABSENT
2025-08-25Del NorteWilson Creek0.5RARE0ABSENT
2025-08-27Santa BarbaraSanta Barbara, Mohawk Reef0.5RARE0ABSENT
2025-08-26Los AngelesSanta Monica Pier0ABSENT0ABSENT
2025-08-23San Luis ObispoCayucos Pier0.5RARE0ABSENT
2025-08-27Santa BarbaraSanta Barbara Ch., Naples Pt0.5RARE0ABSENT
2025-08-14Los AngelesSanta Monica Bay, 32010ABSENT0ABSENT
2025-08-27MendocinoMendocino, Noyo OFFSHORE25COMMON0ABSENT
2025-08-27San DiegoImperial Beach Pier5PRESENT0ABSENT
2025-08-27MendocinoMendocino, Noyo Harbor3PRESENT0.5RARE
2025-08-15MendocinoPoint Arena Pier3PRESENT0ABSENT
2025-08-27OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-08-07OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-09-05San Luis ObispoSan Simeon Pier9PRESENT2PRESENT
2025-09-01MarinTomales Bay, Lease #M430-150.5RARE0ABSENT
2025-09-02HumboldtHumboldt Bay, Indian Is. Ch.35COMMON0ABSENT
2025-09-02San Luis ObispoMorro Bay, Boat Launch15COMMON0ABSENT
2025-09-08San Luis ObispoMorro Bay, Boat Launch0.5RARE0ABSENT
2025-09-08MarinTomales Bay, Lease #M430-150.5RARE0ABSENT
2025-09-08HumboldtHumboldt Bay, Indian Is. Ch.3.5PRESENT0ABSENT
2025-09-02MarinRichmond, Marina Bay Harbor8PRESENT0ABSENT
2025-09-15MarinDrakes Bay, Chimney Rock LBS0ABSENT0ABSENT
2025-09-15HumboldtHumboldt Bay, Indian Is. Ch.0.5RARE0ABSENT
2025-09-15San Luis ObispoMorro Bay, Boat Launch0ABSENT2PRESENT
2025-09-09Del NorteHunter Rock, north5PRESENT0ABSENT
2025-09-10Del NorteWilson Creek6PRESENT0ABSENT
2025-09-03San DiegoSan Diego Bay, U.S. Navy Pier0ABSENT0ABSENT
2025-09-01MendocinoPoint Arena Pier15COMMON0ABSENT
2025-09-10Santa CruzSanta Cruz Wharf0.5RARE0ABSENT
2025-09-02San DiegoLa Jolla, Scripps Pier2PRESENT0ABSENT
2025-09-15MarinTomales Bay, Lease #M430-150ABSENT0ABSENT
2025-09-06Los AngelesPalos Verdes Rocky Pt Offshore0ABSENT0ABSENT
2025-09-05San MateoPacifica Pier0ABSENT0ABSENT
2025-09-08VenturaVentura, Port Hueneme Pier3PRESENT0ABSENT
2025-09-05Los AngelesPoint Dume, offshore0ABSENT0ABSENT
2025-09-03Santa CruzSanta Cruz Wharf0ABSENT0ABSENT
2025-09-11San FranciscoSan Francisco, Presidio Pier1PRESENT1PRESENT
2025-09-09Los AngelesSanta Monica Pier8PRESENT0ABSENT
2025-09-04Del NorteWilson Creek1PRESENT0ABSENT
2025-09-03OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-09-04San DiegoImperial Beach Pier0ABSENT0ABSENT
2025-09-05OrangeBolsa Chica0.5RARE0ABSENT
2025-09-11OrangeDana Pt. Harbor0ABSENT0ABSENT
2025-09-12OrangeBolsa Chica0ABSENT0ABSENT
2025-09-14San MateoPillar Point Harbor0.5RARE0ABSENT
2025-09-06Santa BarbaraSanta Barbara Island0ABSENT0ABSENT
2025-09-09OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-09-10San MateoBean Hollow State Beach0ABSENT0ABSENT
2025-09-10San MateoPillar Point0ABSENT0ABSENT
2025-09-22HumboldtHumboldt Bay, Indian Is. Ch.1PRESENT0ABSENT
2025-09-26San Luis ObispoCayucos Pier0ABSENT0.5RARE
2025-09-07Los AngelesCatalina Island, Pedestal Rock0ABSENT0ABSENT
2025-09-22MarinTomales Bay, Lease #M430-150.5RARE0.5RARE
2025-09-22San Luis ObispoMorro Bay, Boat Launch1PRESENT0.5RARE
2025-09-10Santa BarbaraGoleta Pier5PRESENT0ABSENT
2025-09-17Santa CruzSanta Cruz Wharf0ABSENT0ABSENT
2025-09-23San Luis ObispoPismo Pier0ABSENT0ABSENT
2025-09-23San Luis ObispoSan Luis Obispo, Cal Poly Pier10COMMON0ABSENT
2025-09-08San DiegoLa Jolla, Scripps Pier4PRESENT0.5RARE
2025-09-03Santa CruzCDFG Trawl Block 501, Waddell11COMMON0ABSENT
2025-09-22San DiegoLa Jolla, Scripps Pier3PRESENT0ABSENT
2025-09-26OrangeBolsa Chica0ABSENT0ABSENT
2025-09-16OrangeBolsa Chica0ABSENT0ABSENT
2025-09-23MendocinoMendocino, Noyo Harbor0.5RARE0ABSENT
2025-09-19San DiegoSan Diego Bay, U.S. Navy Pier0ABSENT0ABSENT
2025-09-22Del NorteWilson Creek0ABSENT0ABSENT
2025-09-23Los AngelesPalos Verdes, OFFSHORE3PRESENT0ABSENT
2025-09-24San DiegoImperial Beach Pier0ABSENT0ABSENT
2025-09-24OrangeNewport Bay, Back Bay0ABSENT0ABSENT
2025-09-15San DiegoLa Jolla, Scripps Pier1PRESENT0ABSENT
2025-09-24Santa BarbaraGoleta Pier0ABSENT0ABSENT
2025-09-29San Luis ObispoMorro Bay, Boat Launch0.5RARE0.5RARE
2025-09-24Santa CruzSanta Cruz Wharf0ABSENT0ABSENT
2025-09-28MarinFort Baker0ABSENT0.5RARE
2025-09-29SonomaBodega Harbor, USCG Dock0ABSENT1PRESENT
2025-09-11Del NorteWilson Creek0ABSENT0ABSENT
2025-09-09Los AngelesManhattan Beach Pier0ABSENT0ABSENT
2025-09-11OrangeSan Clemente Pier0ABSENT0ABSENT
2025-09-10Los AngelesCatalina Island, Toyon Bay0ABSENT0ABSENT
2025-09-14VenturaVentura Pier0ABSENT0ABSENT
2025-09-18Del NorteWilson Creek0ABSENT0ABSENT
2025-09-23San MateoPillar Point Harbor0ABSENT0ABSENT
2025-09-13Los AngelesPalos Verdes Rocky Pt Offshore0.5RARE0ABSENT
2025-09-23MarinGFNMS, Marin Line 4E0ABSENT1PRESENT
2025-09-29HumboldtHumboldt Bay, Indian Is. Ch.0ABSENT0.5RARE
2025-09-29MarinTomales Bay, Lease #M430-150ABSENT1PRESENT
2025-09-07San Luis ObispoSan Simeon Pier2PRESENT0ABSENT
2025-09-27Los AngelesPalos Verdes Rocky Pt Offshore0.5RARE0ABSENT
2025-09-19OrangeBolsa Chica0.5RARE0ABSENT
2025-09-29OrangeSan Clemente Pier0ABSENT0ABSENT
2025-09-21San MateoPacifica Pier0.5RARE0ABSENT
2025-09-08San Luis ObispoPort San Luis, Diablo Cove8PRESENT0.5RARE
2025-09-10San DiegoSan Diego Bay, U.S. Navy Pier0ABSENT0ABSENT
2025-09-24MarinGFNMS, San Francisco Line 6E0.5RARE1PRESENT
2025-09-23MarinGFNMS, Marin Line 4W4PRESENT0ABSENT
2025-09-22San FranciscoGFNMS, San Francisco Line N6WN0.5RARE0ABSENT
2025-09-03MendocinoMendocino, Noyo Harbor25COMMON0ABSENT
2025-09-08Los AngelesPalos Verdes, OFFSHORE0ABSENT0ABSENT
2025-09-28San Luis ObispoSan Simeon Pier4PRESENT0ABSENT
2025-09-28HumboldtTrinidad Pier0ABSENT0ABSENT
2025-09-28San Luis ObispoCayucos Pier0ABSENT0ABSENT
2025-09-06SonomaKashia Coastal Reserve0ABSENT0ABSENT
2025-09-17MarinGFNMS, Marin Line 2E0ABSENT3PRESENT
2025-09-19MarinGFNMS, Marin Line N11-WN0ABSENT0ABSENT
2025-09-21MarinGFNMS, Marin Line N4-WN0ABSENT1PRESENT
2025-09-29San DiegoLa Jolla, Scripps Pier0ABSENT0.5RARE
2025-09-24MarinGFNMS, San Francisco Line 6W0ABSENT0.5RARE
Domoic acid-related strandings, July - September 2025
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Domoic acid (DA) is a potent neurotoxin produced by some diatom species of the genus Pseudo-nitzschia. Species exposed to DA can result in seizures, epilepsy, cardiomyopathy, and death depending upon the ingested dose. DA toxicosis commonly occurs in California sea lions (Zalophus californianus), presumably due to a combination of foraging behavior and seasonal movements.

The Marine Mammal Center (TMMC), Channel Islands Marine Wildlife Institute (CIMWI), California Wildlife Center (CWC), Marine Mammal Care Center Los Angeles (MMCC-LA), Pacific Marine Mammal Center (PMMC), SeaWorld, and Southwest Fisheries Science Center (SWFSC) act like an emergency room by working to rescue and rehabilitate sick and injured marine mammals, seabirds, and sea turtles.

California's Marine Mammal Stranding Network Map

Featured Image: SCCOOS scientist & IFCB operator, Dr. Kasia Kenitz, performs maintenance on an Imaging FlowCytobot, Del Mar, CA.
Photo credit: Rich Walsh, SIO.

California HAB Bulletin

All data and reports have been synthesized by SCCOOS for the California Harmful Algal Bloom Monthly Bulletin.

Data Access & Resources:

C-HARM, NOAA CoastWatch ERDDAP
Toxic Phytoplankton Observations, CDPH
Imaging FlowCytoBot Dashboard
CalHABMAP Datasets, SCCOOS ERDDAP