This data contains monitoring data of the RV ALKOR cruise AL568b conducted in January 2022 (January 24th – February 1st) in the Western Baltic Sea by the University of Hamburg. The cruise was part of the 5-year monitoring programme Winter cod 2021-25 (Monitoring winter spawning activity of Western Baltic cod (Gadus morhua) (2021-25)) of the University of Hamburg aiming at investigating the early-winter spawning activity of Western Baltic cod to identify potential climate-induced shifts in spawning phenology. The data set contains cod stomach content data. Stomachs of cod were taken during single fish parameter measurements directly on board. Stomachs were immediately frozen on -20°C and subsequently analysed in the laboratory of the University of Hamburg. Cod stomach samples were defrosted and adherent veins were carefully removed from the outer stomach tissue. Adherent water was removed for approximately 5 seconds with paper tissues and stomachs were weighted (accuracy: 0.001 g). Subsequently, stomachs were opened, and the contents and mucus were removed before the empty stomachs weights were recorded.Stomach content weights were derived from the differences between full and empty stomach weights. Prey organisms were identified to species level (mostly fish, and decapods), order level (e.g. for Peracarida), class level (e.g. for Echinodermata, Mollusca), or only to phylum level (e.g. for Annelida). If the digestion of the prey was already progressed too far to allow identification to the levels described above, items were allocated to the categories unidentified fish, unidentified crustaceans or unidentified invertebrates.