With our correspondent in Nairobi, Sébastien Németh

Decades of civil war and lack of resources for authorities have made Somali coasts an eldorado for illegal fishing. A phenomenon at the origin of maritime piracy in the region, but which had never really been assessed.

Over the period studied, the NGOs Global Fishing Watch and Trygg Mat Tracking counted nearly 200 vessels operating without any authorization. The vast majority are Iranian. Some also come from India, Pakistan and Sri Lanka.

A discovery resulting from more than a year of satellite image studies capable of distinguishing metal vessels, even through clouds. The criminals were also detected because of their increasingly frequent use of AIS, an anti-collision system transmitting their positions continuously.

For Duncan Copeland, lead analyst at Trygg Mat Tracking, "the number of boats is enormous, beyond the capacities of any national surveillance program. It will deplete fish stocks", he says.

The Somali minister of fisheries warned that "these illegal activities would not be tolerated. They threaten the country's food security, economy and environment". A case file has been filed with the Indian Ocean Tuna Commission. The countries concerned, notably Iran, have 60 days to investigate and take measures.