Walk along the shore of either island at low tide and you will see them — long V-shaped lines of palm fronds stuck into the seabed, running out into the shallow water for hundreds of metres. The charfia is the traditional fishing trap of the Kerkennah Islands, and it has been used here in essentially the same form since Roman times. Each weir belongs to a family or a small co-operative; the fishermen check them at low tide, walking out across the sand and shallow water to collect the catch.
The best way to see the charfia in action is to ask one of the local boatmen at Sidi Frej or Mellita to take you out for a morning. You can watch the fishermen at work, see the geometry of the trap from above, and often buy fresh fish on the spot. The system is fragile — overfishing, plastic pollution, and the rising cost of palm fronds all threaten it — but for now it remains the dominant way of fishing the shallow waters around the islands.