Microplastics in Commercial Fishes and By-Catch from Selected FAO Major Fishing Areas of the Southern Baltic Sea

SIMPLE SUMMARY: A variety of plastics are produced and used in packaging, construction, transport, medicine, electrical, and clothing industries. Despite many advantages, plastics pose a serious threat to ecosystems, mainly due to the high generation of waste. Microplastics of diameter below 5 mm can either result from the degradation and weathering of larger items (secondary microplastics), or from the direct discharge of materials originally manufactured at that size (primary microplastics). Many of them are released directly or indirectly to fresh and salty water reservoirs. The size of microplastic particles and appealing coloration allow for easy ingestion by fish, which in turn leads to physical damage to the gastrointestinal tract or tissue and organ toxicity. This study aimed to assess the presence of microplastics in organs of fish from the southern Baltic Sea acquired as a raw material of commercial value (for food processing plants) and as by-catch. Microplastics abundance in gills, digestive tract and liver ranged from 1 to 12 items per fish, with an average of around 4. Blue fibers were prevalent among other forms such as particles and pellets. Fish guts and gills can be regarded as important organs in monitoring ecological risks for fishes exposed to contamination with microplastics. ABSTRACT: According to recent world wide studies, microplastics (MPs) have been found in many fish species; however, the majority of research has focused only on the gastrointestinal tract, neglecting edible organs. This study aimed to assess the presence of microplastics in the non-edible (gills, digestive tract) and edible organs (liver) of three commercial fish species and twoby-catch species from the southern Baltic Sea. Fish (Clupea harengus, Gadus morhua, Platichthy sflesus, Taurulus baublis, Cyclopterus lumpus) were caught in 108 and 103 FAO Fishing Zones belonging to the Polish fishing zone. The abundanceof MPs ranged from 1 to 12 items per fish, with an average of 4.09 items. MPs were observed in different organs, such as the liver, gills, and digestive tract of all five tested species. MPs recognized as fibers were the most abundant. Other shapes of polymers found in fish organs were pellets and particles of larger plastic pieces. The dominant color of the MPs was blue, but there were also red, black, transparent, yellow, green, and white items found. According to dimensions, dominant MPs were between 0.1 and 0.5 mm in size. The chemical characterization of polymers accomplished by the use of Fourier Transform Infrared (FT-IR) Spectroscopy demonstrated the abundance of cellophane, polyamide, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl propionate, polyacrylonitrile, and polyester.