Endocrine-mediated photostimulation of growth in Atlantic salmon

1989 ◽  
Vol 67 (6) ◽  
pp. 1505-1509 ◽  
Author(s):  
M. P. Komourdjian ◽  
J. C. Fenwick ◽  
R. L. Saunders
Keyword(s):  
Phase Shift ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Growth Rates ◽  
Cell Types ◽  
Growth Cycle ◽  
Day Length ◽  
Atlantic Salmon Salmo Salar ◽  
Natural Photoperiod ◽  
Photoperiod Manipulation

The response of the Atlantic salmon (Salmo salar) pituitary to photoperiod manipulation was investigated histologically, and the observations were related to gross morphometric changes. Salmon were placed under either a simulated natural photoperiod (NP), a photoperiod complementary to the natural photoperiod (RP) or constant daylight (CL) in December. The latter two regimens stimulated the pituitary, particularly the somatotrops, and enhanced growth. After 6 weeks, the CL fish were longer than all others (P < 0.01) and their pituitaries showed marked hypertrophy, with many somatotrops and other cell types in mitosis. The RP fish were also longer (P < 0.01) than the NP animals at that time but their pituitaries appeared less stimulated than those of CL fish. However, the stimulation in CL and RP fish was not maintained beyond 3 months. At that time NP pituitaries more closely resembled the stimulated condition shown earlier by the RP glands. Our results confirm that changes in day length elicit corresponding changes in pituitary cytology and growth rates, albeit without eliminating an apparently innate growth cycle. While increased day length in winter may stimulate the pituitary, such regimens appear to render the gland refractory and cause a phase-shift in the rhythm. It is proposed that suitable interruptions in photostimulation may prolong stimulation.

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

Different Adaptation Strategies of Atlantic Salmon (Salmo salar) Populations to Extreme Climates with Special Reference to some Cold Norwegian Rivers

1986 ◽  
Vol 43 (5) ◽  
pp. 980-984 ◽  
Author(s):  
Arne Johan Jensen ◽  
Bjørn Ove Johnsen
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Temperature Regime ◽  
Growth Rates ◽  
Temperature Limit ◽  
Fixed Temperature ◽  
Sea Temperature ◽  
Atlantic Salmon Salmo Salar ◽  
Lower Temperature Limit ◽  
Lower Temperature

Some of the salmon rivers on the western and northern coasts of Norway are very cold, and the sea temperature outside these rivers is almost always higher than that in the river. Growth rates of Atlantic salmon (Salmo salar) parr and smolt ages and sizes have been examined in three such cold rivers. We found indications that the lower temperature limit for growth of Atlantic salmon is not a fixed temperature, but varies from population to population according to the temperature regime of their environment. Smolts are small, with average sizes of 12–13 cm total length. Females dominated in number among the smolts, but the dominance was less pronounced than in most other rivers. Strategies used by Norwegian salmon in cold rivers are therefore different from those employed by salmon in the northern extremes of the salmon's range in Canada.

scholarly journals Effects of growth hormone on gill chloride cells in juvenile Atlantic salmon (Salmo salar)

1994 ◽  
Vol 266 (3) ◽  
pp. R850-R857 ◽  
Author(s):  
P. Prunet ◽  
M. Pisam ◽  
J. P. Claireaux ◽  
G. Boeuf ◽  
A. Rambourg
Keyword(s):  
Growth Hormone ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Cell Types ◽  
Chloride Cells ◽  
Alpha Cells ◽  
Gh Treatment ◽  
Sodium Efflux ◽  
Atlantic Salmon Salmo Salar ◽  
Accessory Cells

Experiments were performed to investigate the effects of ovine growth hormone (oGH) on both the ultrastructural features of chloride cells and the ability of gills to extrude Na+ after transfer into seawater. February presmolts and June parrs of the Atlantic salmon (Salmo salar) were implanted with oGH. In such animals, spontaneously showing a poor ability to adapt themselves to seawater life, GH significantly increased gill Na(+)-K(+)-adenosinetriphosphatase activity as well as gill sodium efflux into seawater. When examined by electron microscope, two types of chloride cells (alpha- and beta-types) were identified in control parrs and presmolts. GH treatment induced an increase in size and number of alpha-cells that displayed an extensive tubular system, while the beta-cells, thought to be specific to freshwater life, decreased in number. There was, concomitantly, an increase in number of accessory cells associated with the apical portion of the alpha-cells and, as a result, the formation of extensive shallow junctions between these cell types. Such functional and ultrastructural modifications that mimicked those naturally occurring during the last steps of the smoltification strongly suggest that GH stimulates the differentiation of freshwater chloride cells toward a seawater type.

Performance of farmed, hybrid, and wild Atlantic salmon (Salmo salar) families in a natural river environment

2012 ◽  
Vol 69 (12) ◽  
pp. 1994-2006 ◽  
Author(s):  
Øystein Skaala ◽  
Kevin A. Glover ◽  
Bjørn T. Barlaup ◽  
Terje Svåsand ◽  
Francois Besnier ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Growth Rates ◽  
Egg Size ◽  
Relative Survival ◽  
Hybrid Progeny ◽  
Wild Salmon ◽  
Farmed Salmon ◽  
Atlantic Salmon Salmo Salar ◽  
Sib Families

Survival, growth, and diet were compared for farmed, hybrid, and wild Atlantic salmon (Salmo salar) families from the eyed egg to the smolt stage in River Guddalselva, Hardangerfjord, Norway. All individuals that survived until the smolt stage were captured in a Wolf trap and identified to one of the 69 experimental families using microsatellite markers. Survival of farmed salmon progeny was significantly lower than that of hybrids and wild progeny. However, survival varied considerably, from 0.17% to 6.4%, among farmed families. Egg size had an important influence on survival. Half-sib hybrid families with a farmed mother had higher survival when fathered by wild salmon than by farmed salmon. The overall relative survival of farmed families compared with that of their hybrid half-sib families fell from 0.86 in the second cohort to 0.62 in the last cohort with increasing fish density. Smolts of farmed parents showed significantly higher growth rates than wild and hybrid smolts. The overlap in diet among types of crosses demonstrates competition, and farm and hybrid progeny therefore will reduce the river’s capacity for production of wild salmon.

Growth, Parr–Smolt Transformation, and Changes in Growth Hormone of Atlantic Salmon (Salmo salar) Reared under Different Photoperiods

1991 ◽  
Vol 48 (11) ◽  
pp. 2100-2108 ◽  
Author(s):  
Sigurd O. Stefansson ◽  
Björn Th. Bjömsson ◽  
Tom Hansen ◽  
Carl Haux ◽  
G. Lasse Taranger ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Rate ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Continuous Light ◽  
Plasma Growth Hormone ◽  
Hormone Levels ◽  
Light Regimes ◽  
Atlantic Salmon Salmo Salar ◽  
Natural Photoperiod

Potential 1+ smolts of Atlantic salmon (Salmo salar) were reared under three light regimes: simulated natural photoperiod (LDN), continuous light (LD24:0), or a combination of continuous, low-intensity background light and a superimposed simulated natural photoperiod (dual photoperiod, LDD). Growth rate in freshwater was enhanced by LD24:0 and LDD, and changes associated with smoking (increased salinity tolerance, reduced condition coefficient) were advanced under LD24:0. Plasma growth hormone levels were initially high on LD24:0 and LDD whereas on LDN, plasma growth hormone levels increased gradually from February through April. Overall GH levels were negatively correlated with condition coefficient during the final stages of smoking. After 16 mo in seawater, there were no significant size differences among the groups. The incidence of sexual maturation as postsmolts was higher in the LD24:0 and LDD groups whereas the incidence of grilsing was higher in LDN. Results demonstrate the significant influence of photoperiod on growth and smoking in Atlantic salmon. An abrupt increase to continuous light in winter may be sufficient to advance important aspects of the parr–smolt transformation. Dual photoperiod may be a way to combine the increased growth rate observed under continuous light and the normal parr–smolt transformation associated with natural photoperiod.

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.

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