Analyses of microplastics in the digestive tract of bottom-trawled fishes in Southwest Taiwan

Abstract

This study provides the first insight of microplastic in by-catch fish digestive tract in Southwest Taiwan. We dissected and isolated microplastics from six common species/families, Benthosema pterotum (Myctophidae), Equulites oblongus (Leiognathidae), Ostorhinchus pleuron (Apogonidae), Sardinella gibbosa (Clupeidae), Trachinocephalus trichinus (Synodontidae), and Upeneus japonicus (Mullidae), from Kezailiao Fishing Port, Kaohsiung, Taiwan, and found 67.2% specimens had swallowed microplastics, with an average of 2.2 pieces per specimen. Furthermore, the result of the relationships between trophic level, size, habitat, and the number of microplastics suggested that the number of microplastics inside a fish is environmental relative, not the biological characteristics of the fish. In conclusion, neritic fishes such as cardinalfish are not a suitable source for the feed industry while pelagic fishes such as sardines are recommended.