Sodium, Potassium, and Magnesium Concentration and Weight Changes in Fish Stored in Refrigerated Sea Water in Relation to Biochemical Changes Associated with Rigor Mortis

SUMMARY In trout stored in refrigerated sea water (RSW), sodium ions did not penetrate the white muscle appreciably until the adenosine triphosphate of the muscle had been largely destroyed. It appeared that the skin might also exert control over sodium penetration, particularly during the first day of storage. Loss of potassium ions did not become evident until later, the commencement of appreciable loss corresponding approximately to the exhaustion of the muscle as judged by cessation of lactic acid formation. No relation between magnesium ion uptake by the white muscle and these biochemical changes was detected. Trout and sockeye salmon stored in RSW lost weight during the first day or two of storage and gained weight thereafter. The period of weight loss appeared to correspond to the period during which slime secretion from the skin continued post‐mortem, and was apparently independent of the state of exhaustion of the fish at death. In contrast, weight changes in skinned muscle were dependent on the state of exhaustion of the fish. Muscle from unexercised fish lost weight during the first day of storage and gained weight thereafter, while muscle from exhausted fish gained weight from the time of immersion.