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A few patches of Sargassum continue to wash up on the island’s beaches. However, this is nothing compared to the massive influxes of June 2025. Near Marigot, the first trial of a barrier designed to block and divert Sargassum seaweed is ongoing. Initial adjustments were made shortly after the barrier was temporarily taken down in early August.
“We faced several challenges,” confirms Rudi Laplace, territorial councilor and chair of the environmental committee within the Territorial Collectivity. “The mooring (securing the net to the shore, ed.) wasn’t working very well because the Sargassum was passing underneath. We realized there was a stronger current on one side, which was pushing the sargassum underneath. The net was extended by twenty meters and made five meters deeper. The sargassum got stuck at the edge, but the swell still pushed it through. ” So we had to find other solutions. We consulted with the company designated by the territorial authority to install the barrier. “There was also the risk of the net breaking,” explains Rudi Laplace.
Therefore, with a view to long-term deployment, the net was moved slightly further up the bay to test its effectiveness.
“We’re moving forward one step at a time”
A few weeks earlier, due to a forecast of bad weather, it had been decided to retract the net. “But I wanted to leave part of it in place to see how it would react to the waves,” explains Rudi Laplace. However, the effects of the swell—which was less choppy than expected—didn’t provide much additional insight. “The next step will be to move the net a little higher,” says the territorial councilor. “Since this is a pilot project, we planned to be able to relocate it three times, because we’re not sure where the ideal spot is. We’re moving forward step by step. We’re also realizing that the landing system isn’t something that’s very well-developed in the industry yet. There are solutions. We’re going to use this pilot project to explore the techniques and find one that works.”
One of the primary objectives of this full-scale trial—beyond testing the system’s effectiveness—is to verify its durability, particularly in so-called open-sea conditions. “During our technical discussions with various net manufacturers, we realized that elsewhere, they mainly specialized in bay barriers, but few had experience in open-sea conditions,” says Rudi Laplace. “The equipment we currently have might be a little flimsy. But what’s interesting is that we’ll be able to refine all of this for those bidding on future contracts—so they can offer sturdier equipment, because it does exist. We’re moving forward one step at a time.”
A New Sargassum Storage Site
One of the well-identified challenges facing Saint Barthélemy is that the island lacks large bays, unlike Guadeloupe or Martinique. “We’re immediately out in the open ocean,” notes Rudi Laplace. “And then there are the coral reefs that prevent us from working. So it’s quite complex. But the idea remains the same: to divert as much sargassum as possible to avoid having to collect it from the beaches. Because that causes various problems, such as erosion.” Not to mention the traffic from collection trucks or the storage of sargassum in Saint-Jean. This site will soon have to be relocated to make way for Paprec’s new waste sorting center for residential customers, which will free up space at its public site so that EDF can install engines there during the power plant’s reconstruction. This temporary sorting center (to remain in operation for between seven and nine years) will cost approximately 3.8 million euros to build, as was specified during the territorial council meeting on Thursday, August 27.
Returning to the installation of barriers to combat Sargassum strandings, the contract for project management and installation of the barriers, signed earlier this year with the company Egis Water and Maritime, totals 419,700 euros. Once the pilot project in Marigot has proven successful, additional barriers are expected to be deployed in Anse des Cayes and Cul-de-Sac. Initially, the Territorial Collectivity had estimated a two-year timeline for the installation of all these barriers.
