Les flottilles de pêche dans la mer territoriale du golfe de Gascogne

The regular aerial survey over the Bay of Biscay (France) by the French Custom Air Service enabled us to record precisely in 2001 the geographical positions of French fishing vessels inside the 12 nautical miles of the French Bay of Biscay (from Bay of Audierne to Spanish border). Among the 2396 ships counted in this area, 1810 were identified, corresponding actually to 900 boats since most of them (52 %) were seen several times. These 900 boats referred to 4 different "métiers", i.e. type of fishing activity: most of them (59 %) were bottom trawlers, 28 % gillnetters, 5 % potters and 5 % longliners; those which used another gear were less than 4 %. General characteristics of the 900 ships were identified: tonnage and power were respectively 25 TJB and 185 kW for 20-year old vessels of 13 m length on average. The smallest ships fished more easily in spring and in summer, while the largest ones had an offshore fishing activity during the same period. From north to south of Bay of Biscay, the trawlers exhibited a decreasing gradient of appearance and the gillnetters an increasing gradient. The potters were localised mainly in south Brittany (rocky bottom) and the longliners in the south of the Loire estuary. In 2000-2001, more than 50 % of the gillnetters, potters and longliners, and 25 % of the trawlers were found inside the 3 nautical miles². Description of the boat position according to their registration district showed that most of the boats worked close to their landing ports and the overlap was small between the areas of two neighbour fleet. A Geographical Information System was used to link the presence of "métiers" and the sedimentary features of the bottom and allowed to calculate an index of selection (ratio between the number of vessels per "métier" and sediment characteristics). Values of the selection index confirmed that the trawlers were present preferentially in the light bottoms with sand and mud, while the 3 other "métiers" used gears on harder bottoms, especially potters.