Smolting Status of Downstream Migrating Atlantic Salmon (Salmo salar) Parr

1990 ◽  
Vol 47 (6) ◽  
pp. 1136-1139 ◽  
Author(s):  
Tim P. Birt ◽  
John M. Green ◽  
William S. Davidson
Keyword(s):  
Moisture Content ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Salinity Tolerance ◽  
Sodium Concentration ◽  
Plasma Sodium ◽  
Atlantic Salmon Salmo Salar ◽  
Plasma Sodium Concentration ◽  
Gradual Development ◽  
Freshwater River

Significant numbers of Atlantic salmon (Salmo salar) parr have been observed to accompany seaward migrating smolts in some rivers. Downstream migrating parr in Freshwater River Newfoundland, have lower salinity tolerance and branchial Na+–K+ ATPase activity than smolts. However, moisture content in downstream migrating parr was similar to that of smolts; both groups had higher mean moisture content than nonmigratory parr. Mean plasma sodium concentration was significantly higher than in smolts, but somewhat lower than in nonmigratory parr. Elevated moisture levels and slightly depressed plasma sodium concentrations are consistent with the view that seaward movement is associated with osmoregulatory imbalance in both parr and smolts. Brackish water found in estuaries appears important for gradual development of salinity tolerance in these migrants.

Changes in Gill ATPase Activity and Smolt Status of Atlantic Salmon (Salmo salar)

1978 ◽  
Vol 35 (12) ◽  
pp. 1542-1546 ◽  
Author(s):  
Richard L. Saunders ◽  
Eugene B. Henderson
Keyword(s):  
Moisture Content ◽  
Atlantic Salmon ◽  
Atpase Activity ◽  
Salmo Salar ◽  
Salinity Tolerance ◽  
Atlantic Salmon Salmo Salar ◽  
Photoperiod Regime ◽  
Natural Photoperiod ◽  
Salmon Smolt ◽  
Photoperiod Manipulation

Gill Na+K+-activated ATPase activity increased during winter–spring in Atlantic salmon (Salmo salar) held at 10 °C and subjected to simulated natural or reciprocal (light/dark ratio opposite that of natural) photoperiods. ATPase activity increased earlier and was greater under the reciprocal than under the natural photoperiod regime. Body lipid decreased and moisture content increased sooner and more sharply in reciprocal than in natural photoperiod fish. Salinity tolerance (to 40‰) increased between March and April. Exposure to 40‰ salinity for periods up to 14 d gave marked increases in ATPase activity over levels measured in freshwater. Gill ATPase activity is a sensitive indicator of the ability of Atlantic salmon to osmoregulate in seawater. Together with lipid-moisture content, tolerance to high salinity, and migratory behavior, gill ATPase activity provides a valid indication of smolt readiness to migrate to sea. Key words: smolt criteria, photoperiod manipulation, Atlantic salmon, smolt physiology, salinity tolerance, osmoregulation

Parr–Smolt Transformation of Yearling Atlantic Salmon (Salmo salar) at Several Rearing Temperatures

1981 ◽  
Vol 38 (10) ◽  
pp. 1189-1198 ◽  
Author(s):  
C. E. Johnston ◽  
R. L. Saunders
Keyword(s):  
Atlantic Salmon ◽  
Atpase Activity ◽  
Salmo Salar ◽  
Salinity Tolerance ◽  
Elevated Temperatures ◽  
Salt Water ◽  
Effect Of Temperature ◽  
Atlantic Salmon Salmo Salar ◽  
Thermal Effluent ◽  
Thermal Regimes

Six different rearing conditions were used to study the effect of temperature on seasonal changes in growth, condition factor, body silvering, body moisture and lipid content, salinity tolerance, and gill Na–K-ATPase activities of laboratory and pond-reared yearling Atlantic salmon (Salmo salar). Growth during the winter was greatest at the highest rearing temperature (16 °C) whereas those under simulated natural conditions grew slowest. Increasing temperatures in the spring stimulated growth more than constant temperature. Based on increased salinity tolerance, elevated ATPase activity, and growth in salt water, smolt development proceeded at all temperatures up to 16 °C. More smolts were produced in the high thermal regimes resulting in the best growth and the largest proportion of fish reaching smolt size. Unlike some Pacific salmonids, Atlantic salmon develop smolt status at temperatures as high as 16 °C. Yearling smolts can be produced at elevated temperatures and the use of thermal effluents for this purpose is promising.Key words: smoltification, smolt criteria, salinity tolerance, ATPase activity, rearing temperatures, elevated thermal regimes, thermal effluent, Salmo salar

scholarly journals Effects of dietary moisture content of extruded diets on physical feed quality and nutritional response in Atlantic salmon (Salmo salar)

2014 ◽  
Vol 20 (4) ◽  
pp. 451-465 ◽  
Author(s):  
M. Oehme ◽  
T.S. Aas ◽  
H.J. Olsen ◽  
M. Sørensen ◽  
M. Hillestad ◽  
...  
Keyword(s):  
Moisture Content ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Feed Quality ◽  
Atlantic Salmon Salmo Salar

Some physiologic distinctions between freshwater and diadromous forms of the Atlantic salmon, Salmo salar L.

1983 ◽  
Vol 61 (5) ◽  
pp. 1165-1170 ◽  
Author(s):  
S. E. Barbour ◽  
E. T. Garside
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Salinity Tolerance ◽  
Lipid Content ◽  
Temperature Cycle ◽  
Temperature Cycles ◽  
Atlantic Salmon Salmo Salar ◽  
Freshwater Salmon

Parr of the diadromous and freshwater forms of the Atlantic salmon, Salmo salar L., were cultured through the smolt stage in photoperiod and temperature cycles that were delayed 3 months relative to those in nature. Such environmental manipulations caused a delay of approximately 3 months in smoltification of diadromous parr, as measured by changes in water and lipid content and salinity tolerance. These changes did not occur in parr of freshwater salmon exposed to the same modified photoperiod and temperature cycle. The implications of this are discussed.

Photoperiod Control of Parr–Smolt Transformation in Atlantic Salmon (Salmo salar): Changes in Salinity Tolerance, Gill Na+,K+-ATPase Activity, and Plasma Thyroid Hormones

1987 ◽  
Vol 44 (8) ◽  
pp. 1462-1468 ◽  
Author(s):  
Stephen D. McCormick ◽  
Richard L. Saunders ◽  
Eugene B. Henderson ◽  
Paul R. Harmon
Keyword(s):  
Atlantic Salmon ◽  
Thyroid Hormones ◽  
Atpase Activity ◽  
Salmo Salar ◽  
Salinity Tolerance ◽  
Continuous Light ◽  
Day Length ◽  
Atlantic Salmon Salmo Salar ◽  
First Feeding ◽  
Photoperiod Control

Atlantic salmon (Salmo salar) were subjected to artificial photoperiods to determine the manner and extent of photoperiod control of the parr–smolt transformation. Exposure to continuous light (L24) at first feeding and maintained throughout the rearing period inhibited increases in salinity tolerance and gill Na+,K+-ATPase activity that occurred in spring in fish raised under simulated natural photoperiod (SNP). Fish reared under continuous light and returned to SNP in October (L24OCT) underwent normal increases in salinity tolerance and gill Na+,K+-ATPase activity, whereas those returned in December (L24DEC) underwent delayed and intermediate increases. Plasma thyroxine peaks occurred simultaneously in all groups but were diminished in the L24 and L24DEC groups. Plasma 3,5,3′-triiodo-L-thyronine levels were not affected by any photoperiod treatment. Inhibition of the parr–smolt transformation decreased the potential for growth in seawater. In spite of changes in the timing of the transformation induced by photoperiod treatment, salinity tolerance and gill Na+,K+-ATPase activity were strongly correlated; correlation between changes in salinity tolerance and plasma thyroid hormones were, by comparison, weak. The results demonstrate that continuous light applied early in ontogeny and maintained throughout the rearing period inhibits osmoregulatory changes associated with parr–smolt transformation, whereas increasing day length during winter–spring stimulates transformation.

Development of salinity tolerance in underyearling smolts of Atlantic salmon (Salmo salar) reared under different photoperiods

1995 ◽  
Vol 52 (2) ◽  
pp. 243-251 ◽  
Author(s):  
Åse I. Berge ◽  
Arne Berg ◽  
Trygg Barnung ◽  
Tom Hansen ◽  
Hans Jørgen Fyhn ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Atpase Activity ◽  
Salmo Salar ◽  
Salinity Tolerance ◽  
Continuous Light ◽  
Short Photoperiod ◽  
Subsequent Reduction ◽  
Atlantic Salmon Salmo Salar ◽  
First Feeding ◽  
Natural Photoperiod

Groups of Atlantic salmon (Salmo salar), first fed in mid-February 1989, were reared under continuous light (LL) at 12–15 °C until late June. One group remained on LL, while the FEB, MAR, and MAY groups were subjected to segments of a simulated naturally increasing photoperiod (61°N), with initial daylength corresponding to February 1, March 15, and May 1, respectively. The MAR and FEB groups developed important smolt characters (increase in gill Na+,K+-ATPase activity, hypoosmoregulatory ability, and salinity tolerance) during the experiment whereas LL and MAY groups showed only incomplete changes in smolt status. The combination of continuous light during first feeding and early parr stages with a subsequent reduction to short daylength followed by a segment of simulated natural photoperiod allow important parts of the parr–smolt transformation to be completed. The period of exposure to short photoperiod is critical for the synchronization of smolt characters in underyearling Atlantic salmon.

Contrasts in development and smolting of genetically distinct sympatric anadromous and nonanadromous Atlantic salmon, Salmo salar

1991 ◽  
Vol 69 (8) ◽  
pp. 2075-2084 ◽  
Author(s):  
Tim P. Birt ◽  
John M. Green ◽  
William S. Davidson
Keyword(s):  
Atlantic Salmon ◽  
Atpase Activity ◽  
Growth Performance ◽  
Salmo Salar ◽  
Salinity Tolerance ◽  
Condition Factor ◽  
Chloride Cells ◽  
Group Differences ◽  
Atlantic Salmon Salmo Salar ◽  
Breeding Populations

Parameters associated with the parr–smolt transformation were compared in cultured 1+ anadromous and nonanadromous Atlantic salmon derived from wild broodstock collected in Gambo River, Newfoundland. Progeny of nonanadromous salmon were significantly longer at swim-up than progeny of anadromous salmon, although consistent differences in growth performance were not observed during most of the 1 st year of development. Anadromous salmon grew more rapidly than nonanadromous salmon in the spring months during the smolting period. Distinct differences were noted between groups in seasonal levels of body silvering, gill Na+–K+ ATPase activity, and size and number of gill chloride cells. Most male nonanadromous salmon matured as "post-smolts," whereas maturation was not observed among female nonanadromous nor among either sex in the anadromous group. Differences between anadromous and nonanadromous salmon were not observed in seasonal levels of body moisture, plasma Na+ and Cl−, condition factor, or salinity tolerance. Differences noted between groups are probably genetic in nature and suggest that the two forms of salmon in Gambo River represent separate breeding populations.

Responses of Juvenile Atlantic Salmon (Salmo salar) to Episodic Increases in Acidity of Nova Scotia Rivers

1987 ◽  
Vol 44 (8) ◽  
pp. 1475-1484 ◽  
Author(s):  
Gilles L. Lacroix ◽  
Donald R. Townsend
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Plasma Sodium ◽  
Ph Change ◽  
Atlantic Salmon Salmo Salar ◽  
Cough Response ◽  
Dissolved Aluminum ◽  
Electrolyte Loss ◽  
Decreasing Ph ◽  
Chloride Concentrations

Toxicity of different pH levels to Atlantic salmon (Salmo salar) parr held in floating pens for 54 d was assessed in four acidic streams of Atlantic Canada during the autumnal episode of increasing acidity. All parr died in the two streams where pH levels decreased below pH 4.7. Mortality was related to the rate of pH change and to parr size. Plasma sodium and chloride concentrations decreased by about 50–70 mmol∙L−1in parr of these two streams, and the rate of electrolyte loss was related to the rate and severity of pH change. In the other two streams, pH levels were never lower than pH 4.8 and no fish died. Plasma sodium and chloride concentrations in these parr decreased by 20–30 mmol∙L−1, but only after 30 d of exposure. Increased hematocrit, increased respiratory–cough response, and decreased feeding response, especially for parr in the most acidic streams, were also the result of stress apparently related to decreasing pH levels. Concentrations of labile aluminum were usually less than 10% of total dissolved aluminum and always less than 50 μg∙L−1in the four streams. Accumulation of aluminum in the gills of parr was not a significant factor in the lethal effects observed, which were more likely due to low pH.

Effect of Fluoride Complexation on Aluminum Toxicity Towards Juvenile Atlantic Salmon (Salmo salar)

1990 ◽  
Vol 47 (7) ◽  
pp. 1446-1452 ◽  
Author(s):  
Kevin J. Wilkinson ◽  
Peter G. C. Campbell ◽  
Pierre Couture
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Aluminum Toxicity ◽  
Mixed Ligand Complex ◽  
Gill Tissue ◽  
Plasma Sodium ◽  
Ligand Complex ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Fluoride Complexation

In 7-d semistatic bioassays, fluoride complexation attenuated Al toxicity to juvenile Atlantic salmon (Salmo salar; age 1 +) and the accumulation of Al in gill tissue, but not to the extent predicted by the free-ion model of metal toxicity. Bioaccumulation and toxicity persisted even in the presence of an excess of the complexing ligand. An equilibrium model, involving the formation of a mixed ligand complex (F–Al–L-gill) at the gill surface, is proposed to explain this residual toxicity (L-gill = ligand at the gill surface). Exposure to Al, or to a combination of Al and F, led to a decrease in the plasma sodium levels even for sublethal conditions. Aluminum concentrations as low as 2 μM adversely affected the salmon. The similarity of the osmo-regulatory response to the H+-ion, to Al3+, and to Al(F)x suggested that the mechanism of toxicity in the presence of fluoride did not differ markedly from that observed by previous workers for salmonid species exposed to moderately acidic media containing Al but without added fluoride.

Effects of Increases in Freshwater Temperature on Loss of Smolt Characteristics in Atlantic Salmon (Salmo salar)

1991 ◽  
Vol 48 (2) ◽  
pp. 164-169 ◽  
Author(s):  
J. Duston ◽  
R. L. Saunders ◽  
D. E. Knox
Keyword(s):  
Atlantic Salmon ◽  
Atpase Activity ◽  
Salmo Salar ◽  
Salinity Tolerance ◽  
Plasma Osmolality ◽  
Inorganic Phosphorus ◽  
Control Group ◽  
Atlantic Salmon Salmo Salar ◽  
Natural Photoperiod ◽  
And Control

Two-year-old (2+) Atlantic salmon (Salmo salar) raised under ambient temperature and simulated natural photoperiod (45°N) completed smolting between February and May, exhibiting significant increases in gill Na+, K+-ATPase activity and salinity tolerance (96 h, 37.5 ppt) but no significant changes in plasma osmolality. On May 2 the smolts were divided into four groups (each n = 80) and subjected to a rapid (2–3 h) increase in temperature from ambient (5 °C) to 10, 13, or 16 °C or remained ambient (control) which rose to 12 °C by the end of the experiment on June 5. In the 10, 13, and 16 °C groups, mean gill Na+, K+-ATPase activity (micromoles inorganic phosphorus per milligram protein per hour) declined significantly from 6.6 units on May 2 to 4.3, 3.6, and 2.3 units, respectively, on May 23. In the control group, Na+, K+-ATPase activity showed no significant changes during the study. Plasma osmolality was maintained in all groups between 290 and 304 mosmol∙kg−1. Salinity tolerance tests revealed a significant decline in survival in the 16 °C group from May 2 and in the 10 °C, 13 °C, and control groups from May 13, but no significant differences were observed among the three groups. The results support the hypothesis that increases in freshwater temperature accelerate the loss of hypoosmoregulatory capacity.

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