Food consumption, feeding behaviour, and growth of triploid and diploid Atlantic salmon, Salmo salar L., parr

1994 ◽  
Vol 72 (4) ◽  
pp. 609-617 ◽  
Author(s):  
C. G. Carter ◽  
I. D. McCarthy ◽  
D. F. Houlihan ◽  
R. Johnstone ◽  
M. V. Walsingham ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Growth Rates ◽  
Feeding Behaviour ◽  
Specific Growth ◽  
Dorsal Fin ◽  
Atlantic Salmon Salmo Salar ◽  
Consumption Rates ◽  
Specific Growth Rates ◽  
Mixed Groups

To test whether triploid Atlantic salmon (Salmo salar L.) parr were at a disadvantage compared with diploid parr the growth and feeding behaviour of individual parr in separate and mixed groups of diploid and triploid fish were studied in two experiments. At the end of the first experiment (separate groups) the diploid parr had significantly higher mean specific growth rates than the triploid parr. This was due to significantly higher growth during the first 40 days of the experiment; growth was not significantly different over the last 52 days. The consumption rates of individual parr were measured using radiography. There were no consistent differences in consumption rates between triploid and diploid parr in mixed or separate groups. However, at the start of the experiment the mean consumption rates of the triploid parr were significantly lower than those of the diploid parr and could explain their lower growth rates. There were no differences in the amount of damage to the caudal fin between triploid and diploid parr in either experiment. However, in a mixed group, damage to the dorsal fin of triploid parr was more severe than to the dorsal fin of diploid parr, which suggested that triploid parr in mixed groups were more likely to be the recipients of agonistic actions than the diploid parr. However, the specific growth rates of the diploid and triploid parr in mixed groups were not significantly different. It was concluded that under certain circumstances. triploid and diploid Atlantic salmon parr may exhibit differences in growth and feeding behaviour.

Food consumption and growth in maturing Atlantic salmon (Salmo salar)

1999 ◽  
Vol 56 (11) ◽  
pp. 2019-2028 ◽  
Author(s):  
Selina M Stead ◽  
Dominic F Houlihan ◽  
H Anne McLay ◽  
Ray Johnstone
Keyword(s):  
Atlantic Salmon ◽  
Food Consumption ◽  
Salmo Salar ◽  
Growth Rates ◽  
Specific Growth ◽  
Steroid Hormone ◽  
Hormone Levels ◽  
Early Maturation ◽  
Atlantic Salmon Salmo Salar ◽  
Specific Growth Rates

Circulating levels of the steroid hormones 11-ketotestosterone (11-KT) and 17β-estradiol (E2), voluntary food intake, and growth performance were measured in individual Atlantic salmon (Salmo salar) over the year preceding their maturation as grilse. 11-KT and E2 were measured by radioimmunoassay, and X-radiography was used to measure food consumption rates. Two phases of sexual maturation were identified: the early phase (October 1992 - April 1993) was characterized by slowly rising steroid hormone levels concomitant with relatively high rates of food consumption and growth, and in the late phase (May-October 1993), steroid hormone levels increased more rapidly and growth rates decreased in association with inappetence. Significant linear relationships were observed between food consumption and specific growth rates of fish throughout the study (ANCOVA, p < 0.05). Slopes and intercepts of regressions were similar for fish during early maturation, while a lower intercept and steeper slope (ANCOVA, p < 0.05) was observed during the later stages of maturation. In November, January, February, and April, fish in which steroid hormone levels were elevated were significantly heavier than those in which hormone levels were basal. There were no significant differences in specific growth rates (except in February), food consumption, or weight-specific food conversion ratio (except in August and October) associated with maturation status.

Effects of turbidity on prey consumption and growth in brook trout and implications for bioenergetics modeling

2001 ◽  
Vol 58 (2) ◽  
pp. 386-393 ◽  
Author(s):  
John A Sweka ◽  
Kyle J Hartman
Keyword(s):  
Growth Rates ◽  
Brook Trout ◽  
Specific Growth ◽  
Abiotic Factors ◽  
Foraging Strategies ◽  
Turbid Water ◽  
Daily Consumption ◽  
Consumption Rates ◽  
The Difference ◽  
Specific Growth Rates

Brook trout (Salvelinus fontinalis) were held in an artificial stream to observe the influence of turbidity on mean daily consumption and specific growth rates. Treatment turbidity levels ranged from clear (<3.0 nephelometric turbidity units (NTU)) to very turbid water (> 40 NTU). Observed mean daily specific consumption rates were standardized to the mean weight of all brook trout tested. Turbidity had no significant effect on mean daily consumption, but specific growth rates decreased significantly as turbidity increased. Brook trout in turbid water became more active and switched foraging strategies from drift feeding to active searching. This switch was energetically costly and resulted in lower specific growth rates in turbid water as compared with clear water. Bioenergetics simulations were run to compare observed growth with that predicted by the model. Observed growth values fell below those predicted by the model and the difference increased as turbidity increased. Abiotic factors, such as turbidity, which bring about changes in the activity rates of fish, can have implications for the accuracy of predicted growth by bioenergetics models.

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.

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