Species identification in fish meal from urban fisheries biomass with DNA metabarcoding analysis

Abstract As demand for ingredients for fish feed has increased, fish meal and fish oil converted from fisheries by‐products have gained importance as ingredients to replace forage fish. It has been demonstrated that high quality fish oil and fish meal made from urban fisheries biomass, which is fisheries by‐products collected downstream in the seafood supply chain, could be produced. However, a problem with this is that traceability is not ensured due to the wide variety of fish used. Here, a DNA metabarcoding method for monitoring biodiversity was applied to fish meal from the fisheries biomass produced in Japan. This method was shown to be able to detect fish species present at more than 0.001% by weight, and quantitatively detect more than 0.01% by weight; we successfully detected 81–122 species in amplicon sequence variants obtained from fish meals collected throughout a 1‐year period. Bray–Curtis similarity classified the samples into two clusters: one in spring to autumn and one in winter, indicating a considerable influence of skipjack tuna ( Katsuwonus pelamis ) on the fish constituting the fisheries biomass. Among the detected fish species present at more than 0.01% in fish meal, southern bluefin tuna ( Thunnus maccoyii ) and Japanese eel ( Anguilla japonica ) might be of concern for their stock and illegal, unreported, and unregulated fishery risks. However, from the food recycling perspective, fish oil and fish meal from the fisheries biomass should be utilized, as long as these fish comprised in the biomass are not caught for feed purposes.