No evidence of negative effects on the fish

According to the researchers’ findings, there is also “no health risk to consumers.” For nine weeks, the scientists fed sticklebacks a diet containing as much microplastic fiber as seawater. In comparison, other fish were fed food with natural cotton fibres. A third experimental group was given a fiber-free diet.

Even at moderately higher concentrations of microplastics in the sea, the scientists do not expect any significant damage to the fish. The study by the team led by fisheries ecologist Jörn Peter Scharsack was recently published in the journal Science of the Total Environment.

According to the researchers, the North Sea is significantly more polluted with macro waste than the Baltic Sea. In the study areas of the North Sea, the researchers found 70.7 pieces of waste per square kilometer, in the Baltic Sea 9.6. The waste in the North Sea consisted of 91.3 percent plastic, that in the Baltic Sea 62.2 percent. About 80 percent of plastic waste settles on the seabed. There it breaks down into smaller and smaller parts due to environmental influences, most of which are made of polypropylene.

Fish in the North Sea and the Baltic Sea investigated
Microplastics are found in the bodies of all marine animals studied to date, from plankton to fish to large marine mammals, it said. The researchers first determined the levels of microplastics in the digestive tract of wild fish towed twice a year from the North Sea and Baltic Sea. In particular, dab, a flatfish species, and herring were examined. The researchers were able to detect microplastic particles in the digestive tract of dabs, but less than ten particles per animal.