The Benin Environment and Education Society (BEES) have proposed to local authorities in Benin, a country in West Africa, to visualize zones threatened by erosion or by abusive human installations, with the use of UAVs. They want to use images and data collected by the drone cameras to create maps and videos, to allow their government to act more quickly.
On Lake Nokoué, which stretches over 339 hectares between Cotonou and Porto Novo, the 75,000 inhabitants of lakeside villages live mainly from fishing. But the increase in the number of fishermen and the misuse of traditional fishing techniques are now threatening the renewal of fisheries resources.
The lake is saturated with “acadja”, fish parks made of branches that make navigation difficult and modify the ecosystem. This practice, normally prohibited by law, but actually not controlled by the authorities, has been denounced for several years by the BEES.
In short, the technique, which takes unfair advantage of the lake’s resources, involves planting branches in shallow waters in which fish take refuge, feed and reproduce. The fishermen then surround this fish park with a net and can recover a good amount of a sudden.
This poses problems because the fishermen constantly put new branches without removing the old ones. As a result, the plants rot and then participate in the filling of the lake bottom, so that piles of residues accumulate, reducing the depth of the lake. This practice can destroy the local ecosystem and makes it difficult to navigate the lake as there is little water in places.
In November 2017, the activists decided to change their strategy by inviting the Department of Fisheries Production (DPH), an agency attached to the Ministry of Agriculture, Livestock and Fisheries, to participate in three days of workshops to map the area using drones and thus better visualize the abuse of these parks. A conclusive experience that allowed the authorities to act quickly, says the project leader of the NGO, Arnaud Adikpeto.
“With a simple report, maybe our alert would not have been taken into consideration,” he said.
After this three-day visit to Lake Nokoué, the Fish Production Department decided to regulate the practice and intervene in the field to relieve the lake. French magazine Les Observateur saw them in action on the lake last February to remove some of these parks.
Giving them the opportunity to understand the work and assess risks with BEES through aerial visualizations and mapping was success: the DPH informed the group they would invest in three drones to monitor the occupation of the lake.
Building on this first success, BEES now intend to continue raising the awareness of other areas threatened by human activities to decision-making authorities. Activists are particularly concerned about the erosion of the coastline, which, according to the Institute of Fishery and Oceanological Research of Benin, can go back up to 30 meters per year by place.
Stemming this unsustainable fishing practice is a priority, says the Beninese government. In 2014, Benin completed the construction of eight “spikes”, artificial dykes 200 to 300 meters long for a total of 70 million euros of investment.
However this is perhaps not the best approach, as these dikes have aggravated the situation in some places, according to Arnaud Adikpeto.
The dikes put in place by the government have improved the situation in some places, but these infrastructures also cause a transfer of the erosion process downstream of the facility. Housing and businesses located downstream from Cotonou, towards Nigeria, are therefore also affected by the practice.
BEES teams have already trained six other environmental associations in their network to use the drone, thanks to a partnership with the Dutch committee of IUCN, the International Union for the Conservation of Nature. “It is also thanks to them that we have been able to procure drones,” says the BEES project manager, who is also financially supported by the French Fund for the Global Environment or by the Embassy of the Netherlands in Benin.