The depletion of the eel stock in European freshwater leads to define a survey program for this resource. The Conseil Supérieur de la Pêche (CSP) requested the Cemagref to define some criterion to choose representative sampling stations for the eel demographic structure. Electric fishing data since 1980 and from the French territory were available on computer file. These results allow to establish two fishing operations typologies, one using eel length structure, the other using fish communities. It was not possible to explain the first one with the second one. The rare mesologic information show the importance of habitat diversity but do not allow to forecast eel length structure. The a priori choice of representative stations is presently impossible. An iterative approach (selection, a posteriori validation, modification of the selection, ...) seems to be better. This data base leads to propose a new mechanism hypothesis of eel colonisation : for a sea distance, an eel searches the zone the most "typologically upstream". At the end, some recommendations are made to improve data gathering in order to facilitate the interpretation.