The effects of aroclor 1254 and no. 2 fuel oil on smoltification and sea-water adaptation of coho salmon (Oncorhynchus kisutch)

Coho salmon, Oncorhynchus kisutch (Walbaum), were swum at constant speed in a ‘Brett-type’ tunnel respirometer. Blood PO2, PCO2 and pH as well as total CO2 content and red blood cell pH were unchanged during swimming. The RE (respiratory exchange ratio) was slightly less than 0.7 when the fish was swimming in normal sea water, indicating that some CO2 retained by the fish. Lowering seawater bicarbonate concentration increased HCO3− transfer, presumably because of passive bicarbonate loss. A reduction in seawater pH from 7.95 to 7.1 sharply reduced both CO2 and hydrogen ion transfer, resulting in very low RE values of about 0.2. Hydrogen ion excretion was elevated during prolonged swimming following high speed swimming activity. It would appear that CO2 and hydrogen ion transfer by fish need not be matched and changing internal and external conditions can have a marked and separate effect on hydrogen ion and CO2 excretion and therefore on the RE value.

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Effects of FinnStim on growth and sea water adaptation of Coho salmon

Aquaculture ◽

10.1016/s0044-8486(98)00368-8 ◽

1998 ◽

Vol 168 (1-4) ◽

pp. 423-429 ◽

Cited By ~ 12

Author(s):

Hilda Castro ◽

Juan Battaglia ◽

Erkki Virtanen

Keyword(s):

Coho Salmon ◽

Sea Water ◽

Sea Water Adaptation

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Changes in Ouabain-Sensitive Adenosine Triphosphatase Activity in Gills of Coho Salmon (Oncorhynchus kisutch) During Parr–Smolt Transformation

Journal of the Fisheries Research Board of Canada ◽

10.1139/f76-007 ◽

1976 ◽

Vol 33 (1) ◽

pp. 54-62 ◽

Cited By ~ 36

Author(s):

M. A. Giles ◽

W. E. Vanstone

Keyword(s):

Enzyme Activity ◽

Coho Salmon ◽

Incubation Temperature ◽

Sea Water ◽

Oncorhynchus Kisutch ◽

Sharp Decrease ◽

Total Activity ◽

Sodium Ions ◽

Relative Contribution ◽

Sodium Activation

The effects of incubation temperature, pH, sodium, potassium, and ATP concentration, and ouabain on the activity of Na+–K+-activated ATPase of the gills of seawater-adapted juvenile coho salmon (Oncorhynchus kisutch) were determined. The temperature and pH optima were 40 C and 7.4, respectively. The apparent Km for ATP at equimolar Mg++ concentration was 0.2 mM at Na+ and K+ concentrations of 100 and 20 mM, respectively. Maximal enzyme activity for Na+ concentration of 10.50 and 100 mM occurred at K+ concentrations of 12.5, 15.0, and 20.0 mM, respectively. The Ki for ouabain was 2 × 10−6 M and 7 × 10−6 for K+ concentrations of 10 and 20 mM, respectively.A large portion (up to 60%) of the ouabain-sensitive ATPase activity in freshwater fish was activated by sodium ions in the absence of potassium ions (Na+-activation). Exposure to sea water resulted in a large increase in total ouabain-sensitive activity and a sharp decrease in the proportion of sodium activation. These changes occurred within 14 days after transfer to full strength sea water.On a seasonal basis, total ouabain-sensitive enzyme activity in juvenile freshwater coho was low (less than 5 μmol Pi/mg N per h) to the end of November, increased to a peak (over 125 μmol Pi/mg N per h) in mid-January, and subsequently declined by late February. A slow, steady rise in activity occurred during the smoking period of March and April and the relative contribution of sodium ions to the total activity declined in this period.

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Differences in Measurements of Smolt Development Between Wild and Hatchery-Reared Juvenile Coho Salmon (Oncorhynchus kisutch) Before and After Saltwater Exposure

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f94-218 ◽

1994 ◽

Vol 51 (10) ◽

pp. 2170-2178 ◽

Cited By ~ 50

Author(s):

J. Mark Shrimpton ◽

Nicholas J. Bernier ◽

George K. Iwama ◽

David J. Randall

Keyword(s):

Citrate Synthase ◽

Coho Salmon ◽

Sea Water ◽

Salt Water ◽

Oncorhynchus Kisutch ◽

Sodium Concentration ◽

Chloride Cells ◽

Plasma Sodium ◽

Hatchery Fish ◽

Saltwater Tolerance

We compared the saltwater tolerance of coho salmon (Oncorhynchus kisutch) juveniles that were reared in different environments. The groups examined consisted of fish reared exclusively in the hatchery, a hatchery group transplanted into the upper watershed of the river (colonized), and wild fish from natural spawning broodstock in the river. Although hatchery fish were much larger than their wild or colonized counterparts, they consistently showed a reduced saltwater tolerance as assessed by a much greater perturbation in plasma sodium concentration following transfer to salt water. Within each group there was no relationship between size of the fish and saltwater tolerance. Following transfer to sea water, hatchery fish showed a significant decline in haematocrit and a significant increase in circulating plasma cortisol concentration. Neither of these changes was seen in wild smolts. Hatchery fish possessed fewer chloride cells, and lower specific activities of the enzymes Na+K+ATPase and citrate synthase. The weaker osmoregulatory ability of hatchery fish led to a greater mortality following abrupt transfer to 35‰ seawater. We believe that the differences in saltwater tolerance seen among the different groups of fish are due to rearing environment.

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