The National Centers for Coastal Ocean Science (NCCOS) Harmful Algal Bloom Event Response program has funded efforts to help understand the extent and severity of recent harmful algal blooms (HAB) in Kachemak Bay, AK. NCCOS supported a network of tribal, state, and federal agencies that coordinated sampling and testing efforts to notify communities about potential impacts to human health and wildlife in the region.
In early September, elevated abundances of the HAB-forming phytoplankton Alexandrium were detected by Kachemak Bay National Estuarine Research Reserve staff. Concurrently, elevated levels of paralytic shellfish toxins were detected by State of Alaska staff in Kachemak Bay. In response to the Alexandrium bloom, a public service announcement was released to warn surrounding communities about the elevated risk of paralytic shellfish poisoning (PSP) in the area.
Blooms of Alexandrium may produce potent neurotoxins that can accumulate in shellfish, and consuming contaminated shellfish can cause a potentially fatal illness called PSP. Initial sampling and toxin analysis of blue mussels by members of the Alaska HAB Network (AHAB) in early September found paralytic shellfish toxin levels over twice the regulatory limit. On September 22, further testing efforts found some samples of butter clams from Kachemak Bay that contained over double the regulatory limit for PSP toxins.
Local outreach efforts led by the AHAB Network and the Kachemak Bay National Estuarine Research Reserve helped keep the public, including subsistence harvesters, commercial shellfish farmers, and human health professionals, informed about the risk associated with the consumption of recreational and subsistence seafood.
Shellfish in the area may still contain toxin concentrations above the regulatory limit as certain species may hold toxins for up to two years. While testing efforts have been completed for this event, harvesters can inquire with the Chugach Regional Resource Commission’s Alutiiq Pride Marine Institute’s laboratory about testing shellfish before consumption. For more information on this HAB event please contact Rosie Masui (rmmasui@alaska.edu).
This NCCOS supported event response is separate from a July 2025 NCCOS-funded response effort that also occurred in Kachemak Bay due to a bloom of Psuedo-nitszchia.
The event response was led by the AHAB Network in partnership with the Alaska Department of Environmental Conservation, Alaska Veterinary Pathology Services, the Alaska Ocean Observing System, Chugach Regional Resources Commission, Kachemak Bay National Estuarine Research Reserve, Seldovia Village Tribe, the U.S. Fish & Wildlife Service’s Alaska Maritime National Wildlife Refuge, the U.S. Geological Survey’s Alaska Science Center, and NOAA’s Wildlife Algal-toxin Research and Response Network for the U.S. West Coast.
The NCCOS HAB Event Response Program is a national program that provides immediate support to help state, tribal, and local officials manage events and advance the understanding of HABs as they occur. For more information, contact nccos.hab.event.response@noaa.gov.
NOAA is authorized to respond to harmful algal bloom events by the Harmful Algal Bloom and Hypoxia Research and Control Act (33 U.S.C. §§ 4001 et seq.).
If you are experiencing symptoms of shellfish poisoning, call 911 or your local health care provider immediately. Alaska healthcare providers who suspect or diagnose a disease that represents a public health emergency should immediately call 1-907-269-8000 during business hours or 1-800-478-0084 after hours.
Partner Links:
- Alaska Department of Environmental Conservation (ADEC)
- Alaska Harmful Algal Bloom (AHAB) Network, Alaska Ocean Observing System (AOOS)
- Alaska Maritime National Wildlife Refuge, U.S. Fish & Wildlife Service (USFWS)
- Alaska Science Center, U.S. Geological Survey (USGS)
- Alaska Veterinary Pathology Services
- Chugach Regional Resources Commission (CRRC)
- Kachemak Bay National Estuarine Research Reserve (KBNERR)
- Seldovia Village Tribe (SVT)
- Wildlife Algal-toxin Research and Response Network for the U.S. West Coast (WARRN-West), NOAA
Related Links: