FACTORS INFLUENCING SEASONAL CHANGES IN THYROID ACTIVITY IN JUVENILE STEELHEAD TROUT, SALMO GAIRDNERI

1965 ◽  
Vol 43 (5) ◽  
pp. 719-729 ◽  
Author(s):  
J. G. Eales
Keyword(s):  
Body Weight ◽  
Seasonal Changes ◽  
Late Summer ◽  
Salmo Gairdneri ◽  
Thyroid Cell ◽  
Steelhead Trout ◽  
Thyroid Activity ◽  
Cell Height ◽  
Factors Influencing ◽  
Tall Cell

Seasonal changes in thyroid cell height and radioiodide indices of thyroid activity (CR and T/S) were measured in yearling and 2-year-old steelhead trout held in freshwater. Cell height was high in yearlings in mid-June and in 2-year-olds in late April and May at parr–smolt transformation; in both it was low in late summer and moderately high in winter. CR and T/S were high both at parr–smolt transformation and in late summer, but were low in winter. Only at parr–smolt transformation did cell height and radioiodide indices agree.Two-year-old potential smolts were held from January to May under four controlled temperature and photoperiod regimes. These experiments revealed that at parr–smolt transformation, both rising temperature and lengthening photoperiod induced the characteristically high CR and T/S values, but that the tall cell height depended on the lengthening photoperiod. Cell height and T/S were measured in yearlings (non-migrants) subjected to similar regimes at the same season. T/S was uninfluenced by photoperiod but responded to rising temperature. Cell height responses were more complex and indicated involvement of other variables.In September, small yearlings possessed significantly higher T/S and CR values than did large yearlings. A relationship between thyroid function and body weight could explain seasonal changes not attributable to temperature or photoperiod.

Seawater adaptation independent of photoperiod in steelhead trout (Salmo gairdneri)

1974 ◽  
Vol 52 (7) ◽  
pp. 805-812 ◽  
Author(s):  
Harry H. Wagner
Keyword(s):  
Atpase Activity ◽  
Seasonal Changes ◽  
Adenosine Triphosphatase ◽  
Salmo Gairdneri ◽  
Steelhead Trout ◽  
Seawater Adaptation ◽  
Immediate Transition

As evidenced by immediate-transition experiments, seawater adaptation in juvenile steelhead trout was independent of photoperiod and the onset of parr–smolt transformation. Increased survival occurred as the fish grew larger, and euryhalinity was reached at 12 to 13 cm. There was no marked regression in the hypoosmoregulatory mechanism in the summer. The regression reported in earlier studies was discussed in terms of seasonal changes in lipid reserves and Na+- and K+-activated adenosine triphosphatase (ATPase) activity in gill microsomes.

Steelhead Trout (Salmo gairdneri) on the North Shore of the Gulf of St. Lawrence, near Sept-Îles, Québec

1981 ◽  
Vol 38 (2) ◽  
pp. 245-246 ◽  
Author(s):  
Frederick G. Whoriskey jr. ◽  
Robert J. Naiman ◽  
Peter H. Heinermann
Keyword(s):  
Late Summer ◽  
Geographic Range ◽  
Salmo Gairdneri ◽  
Steelhead Trout ◽  
Exotic Fish ◽  
Potential Threat ◽  
North Shore ◽  
The North ◽  
Large Numbers ◽  
Early Fall

Fourteen steelhead trout (Salmo gairdneri) were captured in the Matamek and Moisie rivers on the North Shore of the Gulf of St. Lawrence, near Sept-Îles, Québec, in the late summer and early fall of 1979. Steelhead trout are not indigenous to this area. The relatively large numbers of fish taken and their presence in these two rivers on the North Shore may indicate an expanding distribution and a potential threat of colonization in this area of pristine Atlantic salmon (Salmo salar) habitat.Key words: steelhead trout, Salmo gairdneri; geographic range, exotic fish

THE INFLUENCE OF TEMPERATURE ON THYROID HISTOLOGY AND RADIOIODINE METABOLISM OF YEARLING STEELHEAD TROUT, SALMO GAIRDNERI

1964 ◽  
Vol 42 (5) ◽  
pp. 829-841 ◽  
Author(s):  
J. G. Eales
Keyword(s):  
High Temperatures ◽  
The Other ◽  
Salmo Gairdneri ◽  
Staining Reaction ◽  
Steelhead Trout ◽  
Thyroid Activity ◽  
Influence Of Temperature ◽  
Thyroid Uptake ◽  
Influence Of Temperature On ◽  
Thyroid Histology

The thyroid activity of yearling steelhead, as measured by radioiodine methods (CR and T/S), increased with temperature from 6 to 18 °C. The thyroid uptake of I131 peaked at 12 °C. However, this method was found unreliable, since plasma I131 clearance, upon which it depends, also increased with temperature.The staining reaction of the colloid (Azan stain) indicated greater thyroid activity at high temperatures. On the other hand, measurements of thyroid mean epithelial height implied greater activity at low temperatures.A hypothesis resolving; anomalies between various criteria of thyroid activity, based on a TSH-independent influence of temperature on the poikilotherm thyroid, is presented.

Digestive Response of Rainbow Trout, Salmo gairdneri, to Pellet Diets

1969 ◽  
Vol 26 (7) ◽  
pp. 1801-1812 ◽  
Author(s):  
John T. Windell ◽  
David O. Norris ◽  
James F. Kitchell ◽  
James S. Norris
Keyword(s):  
Body Weight ◽  
Rainbow Trout ◽  
Dry Matter ◽  
Laboratory Experiments ◽  
Corn Oil ◽  
Saturated Fat ◽  
Methyl Cellulose ◽  
Salmo Gairdneri ◽  
Gastric Evacuation ◽  
Gastric Contents

Quantitative data are presented for three laboratory experiments concerning rate of gastric evacuation of pellets (fed in gelatin capsules) and pellet components. Rainbow trout, Salmo gairdneri, acclimated to a constant water temperature of 15 C were killed 12 hr after consuming an experimental meal. Subtraction of amount of dry matter remaining at autopsy from dry matter consumed yielded amount of food digested or evacuated or both, from the stomach per unit time.Meals of encapsulated pellet were evacuated from the stomach more rapidly (65.8% decrease in 12 hr) than encapsulated corn oil (42.6%), gelatin (50.8%), a combination of corn oil and gelatin (47.3%), saturated fat (28.8%), or methyl cellulose (50.3%).Groups of fish consuming five capsules equal to approximately 0.65 % of their body weight evacuated 35.9, 45.1, 64.2, 95.5, and 100% at intervals after killing from 6 to 36 hr, respectively. Similar groups consuming seven capsules equal to approximately 1.0% of their body weight evacuated 23.7, 57.9, 70.5, and 86.6% at intervals after killing from 4 to 20 hr, respectively.Ten groups of trout consuming amounts of dry matter equal to 0.24, 0.40, 0.74, 1.11, 1.31, 1.19, 1.59, 1.56, 1.91, and 2.26% of their body weight evacuated 90.7, 81.3, 64.2, 57.9, 56.6, 52.5, 53.4, 51.3, 58.7, and 50.0% in 12 hr, respectively. Gastric motility remains relatively constant once food has entered the stomach. However, when larger meals are fed a greater quantity is evacuated per unit time. This could only be accomplished by changes in volume of gastric contents pumped per peristaltic stroke or number of strokes per unit time.

The regulation of day–night changes in hydroxyindole-O-methyltransferase activity in the pineal gland of steelhead trout (Salmo gairdneri)

1976 ◽  
Vol 54 (9) ◽  
pp. 1530-1534 ◽  
Author(s):  
John R. Smith ◽  
Lavern J. Weber
Keyword(s):  
Pineal Gland ◽  
Sharp Increase ◽  
Pineal Region ◽  
Salmo Gairdneri ◽  
Steelhead Trout ◽  
Methyltransferase Activity ◽  
Surgical Exposure

Elevation in pineal hydroxyindole-O-methyltransferase (HIOMT; EC 2.1.1.4) activity in juvenile steelhead trout was associated with the dark portions of three different photoperiods with a sharp increase in pineal HIOMT activity occurring in the first 4 h of darkness. This pattern of activity could be abolished by bilateral enucleation but not by surgical capping of the pineal region. Surgical exposure of the pineal region in blinded fish did not restore HIOMT responses to changes in lighting.

Movements of Rainbow Steelhead Trout (Salmo Gairdneri) in Lake Ontario and a Hypothesis for the Influence of Spring Thermal Structure

1986 ◽  
Vol 12 (4) ◽  
pp. 304-313 ◽  
Author(s):  
James M. Haynes ◽  
David C. Nettles ◽  
Kevin M. Parnell ◽  
Michael P. Voiland ◽  
Robert A. Olson ◽  
...  
Keyword(s):  
Thermal Structure ◽  
Lake Ontario ◽  
Salmo Gairdneri ◽  
Steelhead Trout
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