The French West Indies, a archipelago consisting of Martinique, Guadeloupe, Saint-Martin, and Saint-Barthélemy, is renowned for their pristine beaches, vibrant cultures, and beautiful landscapes. However, for over a decade, these islands have been grappling with the recurrent issue of sargassum influxes, resulting in a range of health, economic, and environmental challenges.

Country / Region

Ongoing efforts

Similar to many Caribbean nations grappling with the challenges of massive sargassum influxes, the French public authorities have implemented measures within the constraints of available resources. In 2014, the sargassum situation had escalated to a point where it demanded immediate attention. Consequently, an emergency plan at the local level was implemented in 2014, followed by an emergency plan at the national level in the summer of 2015.  In late 2015, The Agence de l’Environnement et de la Maîtrise de l’Energie (ADEME) published a call for expressions of interest (EOI) to collect sargassum with the following aims: to improve local monitoring and forecasting tools for sargassum influxes; to define suitable ways to collect washed up sargassum on land or at sea and to identify and introduce systems to recover seaweed. Ten projects were selected and tested in Martinique and Guadeloupe, primarily focusing on collecting seaweed.

Shortly after in 2016, Ministries of the French Republic published a report titled ‘Le phénomène d’échouage des sargasses dans les Antilles et en Guyane’. This report generally provided recommendations for clean-up and disposal (manual, mechanical, onshore, nearshore, treatment – within three days), forecasting, governance (integrate sargassum into existing risk management plans at multiple authority levels), monitoring, research and reuse (agriculture). In 2018, the former French minister for the environment presented a €10 million plan to combat the problem. However, due to the scale of the problem, a total amount of €13 million was reallocated by the funding partners from the French National Research Agency to tackle the sargasum crisis.

Following an international conference on sargassum held in Guadeloupe in October 2019, the Regional Council of Guadeloupe designed a regional project called Sarg’Coop. Ultimately, the goal is to have a centralized system for alerting citizens and monitoring regional health conditions based in Guadeloupe that will anticipate the occurrence of hazards linked to the accumulation of sargassum on shores. This will allow for the implementation of appropriate preventive measures.

Recently in 2022, another sargassum seaweed plan was announced by the French government. The problem has also been raised in the European parliament in November, 2022.

In St. Bart’s, the local government created a dedicated committee to combat sargassum. This committee works on several fronts, including monitoring sargassum influxes, investing in cleanup efforts, and participating in research and prevention initiatives. As part of these efforts, the government invested nearly 1.6 million euros to remove approximately 12,000 tons of sargassum from its shores in 2022. In addition to the cleanup efforts, St Barts participated in research and prevention initiatives to address the sargassum problem. For example, in 2019, St Barts hosted a conference on sargassum, which resulted in the creation of the Sargasse Project, which seeks to transform sargassum into a valuable resource.

Containment, collection and disposal

Collection and removal has been the absolute priority of the French government to mitigate the harmful effects of sargassum strandings.  The ADEME management of Martinique and Guadeloupe, published a call for expressions of interest to undertake studies, set up prototypes and test technology for forecasting, collection, transfer and recycle of sargassum. As a result, several collection methodologies were selected and tested in Martinique and Guadeloupe including offshore barriers, mechanised offshore collection, manual onshore collection, mechanised onshore collection and collection assistance equipment. There has been much experimentation with various collection techniques and some were quite successful. For instance the mechanised beach rake to clear low to medium volumes of sargassum and cane loaders to pick up large quantities of sargassum. The “Sargator”, designed by a company in Guadeloupe has been used to harvest sargassum at sea. It is a specialized barge outfitted with a treadmill capable of harvesting 6 tons of algae per hour, and designed for use in calm waters. A full evaluation of these methodologies was published by Chereau (2019). Fisherfolk have been actively involved in developing solutions, using booms and adapting their boats to collect large quantities of sargassum.

The French Government funded the recruitment and training of unemployed persons to form Green Brigades for the
manual removal of sargassum. The workers are equipped with gloves, masks and boots and use spades and rakes
to collect seaweed, and take it away in wheelbarrows. Safety has definitely been a priority and The French Agency for Food, Environmental and Occupational Health and Safety has recommended that workers equip themselves with portable H2S detectors and wear personal protective equipment when concentrations exceed 10ppm. The use of heavy machinery is required when the sargassum layer is too thick.

Le Robert in Martinique was especially hard hit by influxes and in some instances 16 truckloads were required to transport sargassum for disposal. To protect the coastline, the city council installed 6 kilometers of floating containment booms to divert the seaweed to a collection area. In 2018, on the island of St Barthélemy, 8,600 tons of seaweed was collected, amounting to nearly 1,050,000€ and in 2019 an even larger amount of seaweed, 9,200 tons, was collected, totaling 1,350,000€.

Efforts were also made to improve sargassum storage conditions and ensure environmental and public health safety. The Department of Environment, Planning and Housing of Martinique (DEAL) and the Bureau of Geological and Mining Research (BRGM) conducted a study to characterise the environmental issues associated with the eight sargassum storage sites in Martinique. Soil samples were tested for leachates and recommendations on improvements to storage conditions and/or monitoring, were made as well as on remediation in the event of proven environmental contamination.

Regulations and legal instruments

The French Government adopted a second interministerial plan for the period 2022-2025. It is endowed with nearly 36 million euros for 4 years. This plan follows the first national plan for the prevention and control of sargassum, launched by the State in October 2018.

Monitoring, modeling and early warnings systems

The French islands of Guadeloupe and Martinique have been notably proactive in establishing and enhancing monitoring, modeling, and early warning systems to address the challenges posed by Sargassum influxes. Within the framework of an  agreement signed on 23 November 2020 with the French Ministry of Ecological Transition (MTE), Mercator Ocean International provides Météo France with reliable and accurate subsurface current data for the Caribbean arc region, in order to improve sargassum drift forecasts and, in particular, to better anticipate mass sargassum strandings on the coasts of Guadeloupe and Martinique. Using these models and information, Météo France delivers a forecast bulletin to the local authorities of Guadeloupe and Martinique, allowing for authorities to anticipate the risks associated with the massive arrival of algae and take appropriate actions.

The “FOREcasting seasonal Sargassum Events in the Atlantic – FORESEA” project also focuses on developing seasonal forecasts of the quantity of sargassum in key regions of the Tropical Atlantic Ocean. The Project is led by the Institut de Recherche et de Dévelopment (IRD), and funded by the French National Research Agency (ANR), the Regional Council of Guadeloupe and the Territorial Collectivity of Martinique.

In-situ monitoring has also been conducted through the use of remote cameras to monitor sargassum seaweed washing up on beaches and coastline dynamics in the French Caribbean. Using image processing algorithms, an alert system to inform the authorities in real time of changes in seaweed accumulation at the studied sites was designed. The system was installed in 2018 at seven sites in Guadeloupe and 15 in Martinique.

Under the Sarg’COOP project, a network for measuring air quality was also implemented to monitor health conditions.

Socioeconomic and environmental impacts

The arrival sargassum influxes have caused notable impacts on the French islands in the Caribbean, including Martinique, Guadeloupe, Saint-Martin, and Saint-Barthélemy. These impacts span various aspects of the environment, economy, public health, and local communities.

For affected communities, these strandings have been raising serious health concerns. Between January and August, 2018, doctors in Guadeloupe reported more than 3341 cases, and doctors in Martinique reported more than 8061 cases of acute exposure, some of which were admitted to intensive care. The most common symptoms reported were headache, dizziness, abdominal pain, cough, rashes, eye disorders, and effects on mood. The situation in Guadeloupe escalated to the point where a health alert was officially issued. In a 2022 study of more than 3,000 pregnant Martinican women, emissions from decomposing sargassum were linked to earlier onset of preeclampsia among those diagnosed with the condition. In order to protect their health and well-being, some coastal residents were forced to sell their dream houses which were becoming unlivable, some have abandoned their schools and workplaces for lack of a solution to this scourge.

The brown carpets have also been adversely affecting tourism activities. In St. Martin, ferry services, kayaking and snorkeling tours were disrupted. An owner of a watersports business, said he had to close his business for four months an estimated a lost of at least $10,000 EUR. In Guadeloupe some tourism businesses were forced to close several times a year due to the odour of the rotting seaweed. In 2022, The Collectivité de Saint-Barthélemy issued a notice for temporary prohibition of swimming and nautical activities in several bays.

Masses of sargassum also have strangled the fishing industries. An overabundance of sargassum was blamed for the recent deaths of thousands of fish in Martinique. In St. Barts many fishermen reportedly lost their lobster catches during a massive influx in a lagoon. Activists in Martinique were also concerned about the plight of endangered turtles, with some dying at sea entangled in seaweed or unable to lay their eggs given the accumulations of the seaweed covering the sand.

Potential uses

Sargassum, despite being a challenging issue in the French Antilles, has also presented opportunities for various potential uses. Research institutions, businesses and organisations in Martinique and Guadeloupe have been actively researching the potential utilization of sargassum for various uses. The popular uses include: paper and cardboard items, compost, soil amendments, activated carbon, biochar, bioplastics, and bioenergy.

Increasing interest in transforming this hazard into opportunity has spurred the rapid development of numerous projects in the French Antilles, many through collaboration with Martinique and Guadeloupe. Projects range from agricultural uses to biofuel and bioplastics; from bioremediation and antifouling to construction material, paper and cardboard products. In St. Barts there has been experimentation with bioenergy and paper products. In St. Martin, a burst of creativity emerged with the release of “Suddenly Sargassum” by Mark Yokoyama, a user-friendly resource on sargassum featuring captivating photographs and informative content.

The French Antilles has placed emphasis on evaluating the potential presence of harmful substances, heavy metals, and contaminants in sargassum that could impact its use, primarily in agriculture and bioproducts. The Agence de l’environnement et de la maîtrise de l’énergie (ADEME) and Direction de l’Environnement, de l’aménagement et du Logement (DEAL), have been closely monitoring and testing samples for heavy metal levels to ensure they are compliant with health and safety standards.


Written by R. Speede

Desrochers, A., Cox S-A., Oxenford H.A., and van Tussenbroek B. 2020. Sargassum uses guide: a resource for Caribbean researchers, entrepreneurs and policy makers. Report funded by and prepared for the Climate Change Adaptation in the Eastern Caribbean Fisheries Sector (CC4FISH) Project of the Food and Agriculture Organization (FAO). Centre for Resource Management and Environmental Studies (CERMES), University of the West Indies, Cave Hill Campus. Bridgetown: Barbados. CERMES Technical Report No. 97, 172 pp.

Ministère des Outre-Mer, Ministère de l’Environnement, de l’Énergie et de la Mer, and Ministère de l’Agriculture, de L’Agroalimentaire et de le Forêt. 2016. ‘Le Phénomène d’échouage Des Sargasses Dans Les Antilles et En Guyane’.

Oxenford, H.A.; Cox, S.-A.; van Tussenbroek, B.I.; Desrochers, A. 2021. Challenges of Turning the Sargassum Crisis into Gold: Current Constraints and Implications for the Caribbean. Phycology: 1, 27–48.

Resiere D., Kallel H., Florentin J., Banydeen R., Compton K., Gueye P., Mehdaoui H., and Neviere R. Sargassum seaweed in the Caribbean: A major public health problem still unsolved. J Glob Health. http://2023 Mar 17;13:03017. doi: 10.7189/jogh.13.03017. PMID: 36929738; PMCID: PMC10024476. 2022. The Sargasse Project: Transforming Seaweed into Sustainable Materials.

Schmidt C. 2023. Escape from Sargasso Sea: Tremendous Sargassum Blooms Challenge Caribbean and Atlantic Communities. Environ Health Perspect.: 131(9):92001.

Chereau, E. 2019. Monitoring and evaluation of Sargassum collection operations – Summary report. 15MAG007. ADEME, SAFEGE and SUEZ. 227 pp.

The Agence Française de Développement (AFD) Group. Sarg’Coop: Supporting the Creation of a Caribbean Network to Fight Against Sargassum Algae.

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