Contribution of infauna and mussel-raft epifauna to demersal fish diets

The contribution of infauna and mussel-raft epifauna to the diet of 3 dominant species in the demersal fish community of the Ria de Arosa, N. W. Spain -Lesueurigobius friesji (Gobiidae), Callionymus lyra (Callionymidae) and Tn.sopterus luscus (Gadidae)was determined.Intense raft mussel culture in the Ria de Arosa supports a rich epifauna which constitutes the main food resource for the fishes studied.In contrast, infauna density is low and contributes only a small proportion to fish diets.Prey consumed was similar in the 3 fish species.Gut contents consisted mainly of the small crab Pisjdja longicomis.This decapod is a dominant component of the raft epifauna, and electivity indices indicate that it is selected by the fishes.In the Ria de Pontevedra, which contains fewer mussel rafts, these flsh fed on infauna.Thus, one effect of intense mussel aquaculture has been to change the food habits of these 3 fishes from predominantly infauna to raft epifauna diet.