THE BLOOD OF THE ATLANTIC SALMON DURING MIGRATION

Abstract

The blood of Atlantic salmon caught in the brackish water of Gaspe Bay was compared with the blood of salmon caught in the fresh water of the rivers draining into the Bay. In brackish and fresh water the avg. properties of the blood are respectively: O2 capacity, 12.3 and 8.8 vols. per %; cell vol., 39.4 and 24.8%; O2 tension for half saturation at T CO2=1 mm., 23 and 19 mm.; freezing point of the serum, [long dash]0.79 and [long dash]0.64. The O2 combination at P O2 = 150 mm. in the presence of large tensions of CO2 is reduced to about 60% of saturation. Hemolysis does not much reduce the CO2 effect. The cells swell greatly as the CO2 tension is increased. There appears to be a dilution of the blood as the fish goes from salt to fresh water. This is seen in the decrease in cell vol., O2 capacity, and freezing point depression of the blood. In fresh water the affinity of the Hb for O2 is greater than in salt water. The changes observed in the blood may be related to the change in salinity of the environment. In the warm water of rivers in summer small changes in temp. and O2 saturation may be critical in determining whether or not the blood can be saturated with O2.