scholarly journals Histological Changes of Various Organs in the Fry of Chum Salmon and of Rainbow Trout During the Seaward Migration or Following the Experimental Transference into Sea Water from Fresh Water

1969 ◽  
Vol 35 (3) ◽  
pp. 273-283 ◽  
Author(s):  
Masao SHIMOMURA
Keyword(s):  
Rainbow Trout ◽  
Fresh Water ◽  
Chum Salmon ◽  
Sea Water ◽  
Histological Changes ◽  
Seaward Migration

Behavioral Ecology of Chum Salmon Fry (Oncorhynchus keta) in a Small Estuary

1974 ◽  
Vol 31 (1) ◽  
pp. 83-92 ◽  
Author(s):  
J. C. Mason
Keyword(s):  
Fresh Water ◽  
Behavioral Ecology ◽  
Chum Salmon ◽  
Oncorhynchus Keta ◽  
Natural Systems ◽  
Active Selection ◽  
Resource Managers ◽  
Salmon Fry ◽  
Seaward Migration ◽  
And Behavior

Chum salmon fry (Oncorhynchus keta) in the estuary of a small coastal stream exploited fresh water, estuarine, and marine food chains and, by so doing, were exposed to marked, daily fluctuations in salinity that demanded active selection of fresh water on ebbing tides day and night. The resulting delay in seaward migration and associated behavioral observations are inadequately reflected in published accounts of the life history and behavior of chum fry in natural systems and laboratory situations, and the downstream displacement theory. The biological basis for delayed seaward migration of chum fry merits the attention of fishery researchers and resource managers alike.

Effects of ergocryptine, prolactin, and growth hormone on survival and ion regulation in rainbow trout, Salmo gairdneri

1978 ◽  
Vol 56 (11) ◽  
pp. 2394-2401 ◽  
Author(s):  
K. J. Brewer ◽  
B. A. McKeown
Keyword(s):  
Growth Hormone ◽  
Rainbow Trout ◽  
Fresh Water ◽  
Sea Water ◽  
Salmo Gairdneri ◽  
Elevated Plasma ◽  
Ion Regulation ◽  
Simultaneous Injection ◽  
Ion Concentrations ◽  
Peripheral Action

Ergocryptine, an ergot alkaloid that suppresses prolactin (PRL) secretion and also affects growth hormone (GH) levels in mammals, was injected into juvenile rainbow trout, Salmo gairdneri, averaging 8 to 31 g. In fresh water the drug caused few fatalities but lowered plasma Na+, plasma Ca2+, muscle K+, muscle Mg2+, and haematocrit values. The simultaneous injection of low doses of PRL or GH did not significantly modify the results obtained with the drug alone except for an increase in muscle Mg2+ levels. This suggests a possible peripheral action of the drug.Ergocryptine caused the death of S. gairdneri in dilute sea water, while in certain circumstances PRL and GH prevented mortalities. In this medium the drug caused elevated levels of plasma Ca2+ and muscle K+. The simultaneous injection of ergocryptine plus PRL in hyperosmotic media produced an elevated plasma Na+ concentration but a decrease in intracellular Na+ content and concentration.The results suggest that PRL is not critical for the survival of S. gairdneri in fresh water but may still be necessary to maintain body ion concentrations. In hyperosmotic media, however, PRL and GH may be essential for survival and may act on general metabolic processes rather than specific osmoregulatory organs.

Decreased Seawater Adaptability of Chum Salmon (Oncorhynchus keta) Fry Following Prolonged Rearing in Freshwater

1982 ◽  
Vol 39 (3) ◽  
pp. 509-514 ◽  
Author(s):  
Munehico Iwata ◽  
Sanae Hasegawa ◽  
Tetsuya Hirano
Keyword(s):  
Body Weight ◽  
Chum Salmon ◽  
Sea Water ◽  
Oncorhynchus Keta ◽  
Direct Transfer ◽  
Chum Salmon Oncorhynchus Keta ◽  
Salmon Fry ◽  
Seaward Migration ◽  
Osmoregulatory Ability

Chum salmon (Oncorhynchus keta) fry weighing about 1 g maintained plasma Na+ concentrations at 134–140 mmol/L during seaward migration in the Otsuchi River. The plasma Na+ level increased slightly in the estuary, and reached 150–160 mmol/L in the fry caught in the bay. On direct transfer from freshwater to seawater, the plasma Na+ concentrations of the fry weighing 0.4–2.3 g increased markedly after 1 h and reached a maximum after 3–12 h. The fry of < 1.4 g attained sea water-acclimated plasma Na+ level of 156 mmol/L within 24 h after transfer, whereas fry of 1.8–2.3 g failed to adapt to seawater within 24 h. When seawater adaptability of fry of different lots was examined simultaneously in late April, 83–109 d after hatch, the smaller fry adjusted their plasma Na+ levels more easily than the larger fry: the smallest fry attained seawater level after 12 h without showing any peak. Changes in seawater adaptability of the same lots of fry were also followed until 5 mo after hatching, and the osmoregulatory ability of the fry in seawater decreased gradually with an increase in body weight or in the time spent in freshwater.Key words: chum salmon fry, seaward migration, plasma Na+ concentration, seawater adaptability, Oncorhynchus keta

Changes in Body Chloride, Density, and Water Content of Chum (Oncorhynchus keta) and Coho (O. kisutch) Salmon Fry when Transferred from Fresh Water to Sea Water

1951 ◽  
Vol 8b (3) ◽  
pp. 164-177 ◽  
Author(s):  
Virginia Safford Black
Keyword(s):  
Water Content ◽  
Fresh Water ◽  
Chum Salmon ◽  
Coho Salmon ◽  
Sea Water ◽  
The Body ◽  
Oncorhynchus Keta ◽  
Normal Range ◽  
Experimental Conditions ◽  
Salmon Fry

Changes in body chloride, density and water content of chum and coho salmon fry were measured when these fish were transferred from fresh water to sea water, and the reverse. Both species tolerated 50% sea water (8–9‰ Cl). Chum fry survived direct transfer from fresh water to sea water (15–17‰ Cl), but showed a marked increase in body chloride during the first 12 hours, followed by a return to the normal range between 12 and 24 hours. Coho, however, died within the first 36 hours, after a 60% increase in chloride. Coho fry lost more water than chum fry after introduction to sea water. The density of both species approximated that of the water within an hour of transfer to the new medium. When returned to fresh water after 12 hours in sea water the body chloride, density, and water content of both species regained normal levels within 10 hours. Chum salmon go to sea as fry, whereas cohos remain in fresh water a year or more. Although coho fry seem capable of some adjustment to sea water after a preliminary period in 50% sea water, permanent acclimatization could not be demonstrated under the experimental conditions.

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