Parasite load of Atlantic cod <i>Gadus morhua</i> in the Baltic Sea assessed by the liver category method, and associations with infection density and critical condition

During the 2010s, Atlantic cod Gadus morhua L. in eastern Baltic Sea experienced increasing infection loads of parasitic nematode Contracaecum osculatum (Rudolphi) their livers. Starting 2021, a mandatory part routine sampling protocol on monitoring surveys is to assign liver category individual livers, based number nematodes visible surface, follow spatiotemporal changes loads. The validity method has never been evaluated. Based data from 642 was verified and found be good predictor total nematodes. Moreover, probability being critical condition increased with parasite load. In addition direct applicability cod, present findings may inspire others working disease fish stocks include monitoring.