Sargassum: the first barriers were installed in August
Planned since May 2025, the installation of sargassum-diverting barriers is finally set to begin in Saint-Martin. The roll-out will take place in two stages: first in Cul-de-Sac Bay in August, then in September at the mouth of the Étang aux Poissons in Quartier d’Orléans.
Since 2011, Sargassum has been washing up in large quantities and on a regular basis along the coast of Saint Martin. This phenomenon raises concerns regarding public health, the environment and the local economy. In Cul-de-Sac Bay for several years now, Sargassum has become a real problem, particularly around the jetty and for vessels travelling to the islets of Pinel or Tintamarre. Manufactured in Spain to specifications tailored to the local area, the barriers consist of a submerged skirt. “Wildlife can pass underneath, whilst the fresh seaweed is contained by the net,” explains Igor Rembotte, a project officer within the Collectivité’s Environment Department. Driven by the currents, the sargassum will then be diverted towards a collection point to speed up its removal. At Cul-de-Sac, two sections measuring 180 and 520 metres – totalling 700 linear metres – will be arranged in a zigzag pattern. A marked channel will be maintained between them to ensure unimpeded maritime traffic.
At Étang aux Poissons, two further sections measuring 123 and 104 metres will be installed at the start of the school year.
More closely monitored navigation
In August, the company Antilles Travaux Sous-Marins (ATSM) will take charge of deploying the nets and will carry out maintenance and repairs on these structures for one year. This installation is now possible thanks to changes to the navigational conditions in the bay. Whilst passing through the barriers will be completely prohibited, this will also be accompanied by a “ban on anchoring within a 25-metre strip on either side of the nets”, explains Igor Rembotte. Furthermore, the Collectivité’s services state that the net anchorage points will have only “little impact on the reefs, as they are located in sandy areas with few seagrass beds”. In the event of heavy swells, strong winds or a cyclone risk, the equipment may be lowered or removed. With 16,000 tonnes of Sargassum to be collected by 2025, the Collectivité hopes to better manage the influx and optimise daily collection operations. The total cost of the scheme at the two sites amounts to €896,550 excluding VAT, of which €320,000 is funded by the State.
