Résumé
Population parameters and behaviour of the herbivorous fish Sarpa salpa, present differences between protected and non-protected seagrass meadows of the north-western Mediterranean Sea. Larger individuals are more abundant inside protected areas, where their grazing pressure on seagrass is disproportionately greater than that of smaller fish feeding on algae and seagrass in unprotected areas. The feeding rate (bites per minute per individual) of smaller fish in unprotected areas is relatively high; however, the denser populations of larger fish in protected areas consume more forage because individual mouth gape is greater and larger fish remove more forage per bite. All these differences suggest a higher impact on seagrass meadows inside protected areas.