Glass eel fisheries have developed in estuarine areas and are influenced by the tide. Migration takes place in open estuaries such as the Loire, Gironde or Adour, but is also blocked by dams such as the Arzal dam on the Vilaine.

Estuarine waters can be clear, like those of the river Adour, which blocks the ascent of glass eels to the surface and reduces their catchability by fishing gear. They can be turbid, such as those of the Loire or Gironde, which allows glass eels to reach the surface, even during the day. Further upstream, glass eels are distributed near the banks and sometimes, depending on the hydrological conditions, concentrate in quiet areas where they can be caught by hand sieves.

Glass eels can also be caught on the coast. This is the case on the coastline of the Landes where some fishermen practice the so-called “wave fishing” and capture glass-eels in the waves with a hand sieve on the seashore. Glass eel fishing is also practised in the open sea in the Pertuis Charentais areas. Fishing is no longer done with a hand sieve, but by vessels armed with two “pibalours” that filter the coastal waters.