Treatment with thiamine hydrochloride and astaxanthine for the prevention of yolk-sac mortality in Baltic salmon fry (M74 syndrome).

Two practical methods are reported for treating feral Baltic salmon with thiamine hydrochloride against M74 syndrome (abnormally high yolk-sac fry mortality of the Baltic salmon). Both bathing of the yolk-sac fry in thiamine hydrochloride (1000 mg l-1, 1 h) and a single intraperitoneal injection given to the female brood fish (100 mg kg-1 fish) during the summer 3 mo before stripping were shown to elevate the whole body total thiamine concentration in the fry. Both treatments were also shown to be effective in preventing mortality due to M74 syndrome.

Seasonal changes in certain metabolic and haematologic responses of Salmo gairdneri acutely exposed to dehydroabietic acid (DHAA).

Physiological effects of a high sublethal DHAA exposure on respiration, ammonia excretion and haematology of rainbow trout were studied in July at 15 degrees C and in December at 10 degrees C. In the control fish plasma glucose concentration was higher (P less than 0.001) in December than in July, but plasma protein (P less than 0.

Blood oxygen transport of hypoxic Salmo gairdneri.

The in vivo blood oxygen binding properties of rainbow trout were studied in normoxia and hypoxia (PO2 55-60 mmHg). Owing to hypoxia the in vivo oxygen dissociation curve of blood was shifted to the left; the P50 value decreased from 37 mmHg in normoxia to 27 mmHg in hypoxia. Hypoxia also caused an increase in the erythrocytic volume, a decrease in the concentrations of ATP and hemoglobin inside the cell, and an increase in the intraerythrocytic pH.

Oxygen transfer, gill resistance and structural changes in rainbow trout (Salmo gairdneri, Richardson) gills perfused with vasoactive agents.

1. Gill resistance (Rg) and oxygen transfer (To2) were measured in perfused rainbow trout gills. After perfusion the gills were analysed morphometrically.