Can the Fulton and hepatosomatic indexes be good indicators of charity of the baltic fish according to microplastics pollution?

Pollution with MPs and health condition of herring and by-catch species like cod, flounder, sprat, long-spined bullhead, and lumpfish from the Baltic Sea were assessed. Fish were characterized by varying biometric features and condition indexes (i.e. the Fulton factor (K) and the hepatosomatic index (HSI)). MPs items were identified in all species, with the highest contribution in lumpfish (78.9%) and the lowest in sprats (21.4%). The number of items per fish ranged from 1 to 12, averaging 3.14, with MPs observed in the gills (46%), liver (16%), and digestive tract (38%). Multidimensional analysis showed a relationship between fish pollution with MPs and health condition indexes. It revealed that the shoals of Baltic herrings could be assessed based on condition indexes according to fishing zones and, in general confirms, that there is a link between pollution of MPs and fish health condition. The analysis showed that Baltic herring less contaminated with MPs were characterized by a higher K value, indicating better health in comparison to individuals more contaminated with MPs. Proposed methodology can be considered as important tool in monitoring of ecological risks for fish exposed to MPs pollution and other environmental stressors.