Sargassum at the Divi Carina Bay Hotel in July 2022. Photo: VI Consortium

In a public advisory issued Friday, the Division of Fish and Wildlife, through the Department of Planning and Natural Resources, warned that Virgin Islands beaches are likely to experience significantly higher-than-normal amounts of sargassum this year. The forecast is based on recent findings from the University of South Florida College of Marine Science’s Optical Oceanography Lab, developed in collaboration with DPNR’s Division of Fish and Wildlife, the University of South Florida, regional partners, and supported by the National Oceanic and Atmospheric Administration’s Monitoring and Event Response for Harmful Algal Blooms Research Program.

According to a bulletin released January 5, satellite observations from December 2025 showed sharp increases in sargassum throughout the Eastern Caribbean Sea and the western Atlantic compared with the previous month. Two large sargassum masses were identified, one in each region. Analysts reported that accelerated local growth has pushed sargassum abundance across the Atlantic to more than 75 per cent above historical averages.

“Because of the rapid growth from November to December and because of the high Sargassum amount in most regions, 2026 is likely another major Sargassum year,” the oceanography lab stated. The analysis further warned that continued growth in the Caribbean is likely, increasing the chances of beaching events across the Mexican Caribbean coast and several islands in the Lesser Antilles. Some early beaching has already been observed, an unusual development that researchers expect to continue in the coming months.

What is Sargassum?

Sargassum is a brown, free-floating macroalgae that historically proliferated in the Sargasso Sea, where it provides habitat for a variety of marine species. Since 2011, however, a new bloom originating near the mouth of the Amazon River has led to recurring large-scale accumulations along Caribbean coastlines, including the U.S. Virgin Islands.

Once washed ashore, decomposing sargassum releases hydrogen sulfide, producing a strong “rotten egg” odour. The gas can cause eye, nose, throat, and respiratory irritation, particularly for individuals with asthma. Officials say the most effective way to reduce exposure is to avoid beaches with large amounts of decaying sargassum.

While sargassum in open water is not considered harmful to swimmers, the algae can harbour marine organisms such as jellyfish that may cause skin irritation upon contact. Large clumps can also pose hazards to motorised vessels by becoming entangled in propellers. In such cases, boat operators are advised to place the motor in reverse to clear the obstruction.

The Division of Fish and Wildlife noted that small-scale sargassum that cannot be avoided may be removed manually by hand or with rakes. For more severe accumulations, beachfront businesses may apply for permits through DFW and the Division of Coastal Zone Management to use mechanical equipment for removal. The deployment of containment booms requires a separate permit from the U.S. Army Corps of Engineers. DFW also provides required training to ensure that removal activities follow ecological best practices and comply with Virgin Islands Code.