Évolution récente du statut de la loutre dans le Parc National des Cévennes

In the south east of the Massif central, the Parc National des Cévennes covers the area along the dividing line between the Atlantic and Mediterranean catchment areas. The climatic conditions of these medium-sized mountains are very varied, with a high degree of seasonality affecting the hydrologic regime of the rivers. The otter seems to have disappeared from that region around the 1960's. Some years ago, evidence was found again on a regular basis in some of these rivers. From 1990, the evolution of this otter population has been monitored by systematic observation of their signs in the principal watercourses covering an area of about 3000 square kilometres. At the same time, a preliminary study of the diet (spraint analysis) has been undertaken. otter signs have been first evidenced on the upper reaches of the rivers Tarn and Lot. In subsequent years, signs have also been discovered on some tributaries and on a watercourse flowing to the Mediterranean side : the river Luech. ln the river Tarn (upper barbel zone), the most frequent prey is the gudgeon, reaching more than 50 % of the total number of prey. However, when the biomass intake is considered, the barbel appears to play the major role, accounting for 46 % of the total food intake. The occurrence of the brown trout (11 %) and its relative biomass (18 %) are weak when compared with the composition of the river fish fauna (25 to 43 % of the estimated fish biomass).