Lipid composition of supercritical CO2 (SC-CO2) extracts, residual oil in muscle and changes in sarcoplasmic proteins after extraction of Atlantic mackerel were characterized. Dehydration of the muscle to 10.2% (w/w) resulted in high oil yield with minimum changes in protein content and composition. Sarcoplasmic protein content of fish muscle following SC-CO2 treatment was lower than that of original muscles at all moisture levels (3.8–64%, w/w). Analysis of sarcoplasmic proteins by capillary electrophoresis indicated aggregation of low molecular weight proteins during SC-CO2 extraction. SC-CO2-extracted muscle also had lighter color than original samples. The SC-CO2 extraction showed potential to provide high quality oil and protein meal.