A comparison of cystatin activity in the various tissues of chum salmon Oncorhynchus keta between feeding and spawning migrations

Abstract 1. 1. Cystatin was found to be widely distributed in various tissues of chum salmon. Most of the cystatins in the salmon tissues appeared to have a molecular weight between 10,000 and 20,000. They were considered to belong to the low molecular weight form cystatin, the type 1 and/or type 2 cystatins. 2. 2. The activity in the liver of the salmon in spawning migration was significantly higher than that of the fish in feeding migration, while the activities of the serum, kidney, intestine, stomach, gill, skin and white muscle in spawning migration were apparently lower than that of the fish in feeding migration. 3. 3. Such differences in the cystatin activity were considered to relate closely to the physiological conditions such as sexual maturation and/or starvation during spawning migration of the fish.