An oceanographic cruise in 1991 along the English Channel and Atlantic coasts of France indicated the value of dragonet Callionymus lyra Linnaeus, 1758 as a target species for monitoring biological effects. Ethoxyresorufin-O-deethylase measurements in this species provided a first assessment of the effects of hydrocarbons (PCB, PAH, dioxins) on the marine environment. The specific behavior of dragonet was defined by biochemical characterization. Biological data were obtained during 3 additional oceanographic cruises to study changes in the abundance and distribution of the species in the English Channel and the Bay of Biscay. This first assessment, carried out in the context of the National Observation Network, indicated that pollutants do not have important chronic effects on marine organisms collected along the Atlantic coasts except at a few heavily contaminated sites.