Forensic DNA analysis reveals use of high trophic level marine fish in commercial aquaculture fish meals

Employing a short fragment of the mitochondrial 16S rDNA as a molecular tool we have analyzed commercial samples of three types of fish meal employed to feed aquarium cichlids, farmed salmonids and aquarium marine fish in Spain. We have identified a minimum of eight different marine fish species in their composition, all of them predators belonging to high trophic levels. Although some of them could be derived from the fish processing industry, the origin of at least two species is probably from extractive fisheries. These results suggest that more efforts are necessary for replacing fish protein in commercial fish meals in order to minimize the risks of feeding farmed fish with wild fish.

► Fisheries cause diversity losses.
► Aquaculture was considered a way of supplying fish protein for human nutrition.
► Three different fish feed commercialized in Europe were analyzed.
► Fish meals require high quality protein for fish development from extractive fisheries.
► Spanish aquaculture industry contributes to increase fisheries demand.