Impaired Osmoregulation in Infected Salmon, Salmo Salar L.

Abstract

Euryhaline fishes, such as the salmon and the eel, adapt the osmoregulatory mechanisms of their gills, kidney and intestine so that they retain water while they are in the sea but retain salt while in fresh water (e.g. Krogh, 1939). Thus on entering fresh water the osmotic pressure of plasma in the Atlantic salmon, Salmo salar L., only falls from some 410 m-osmole/1 to about 340 m-osmole/1 (calculated from the freezing point data of Benditt, Morrison & Irving, 1941), although the osmotic pressure of the environment falls from around 1000 m-osmole/1 to almost zero.