Fine-spotted Brown Trout (Salmo trutta): Its Phenotypic Description and Biochemical Genetic Variation

1987 ◽  
Vol 44 (10) ◽  
pp. 1775-1780 ◽  
Author(s):  
Øystein Skaala ◽  
Knut E. Jørstad
Keyword(s):  
Genetic Variation ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Morphological Characteristics ◽  
Genetic Data ◽  
Small Population ◽  
The Body ◽  
Black Spots ◽  
Brown Trout Salmo Trutta ◽  
Biochemical Genetic

Initial studies on a small population of brown trout (Salmo trutta) in the Hardangervidda area in Norway revealed specimens with remarkable morphological characteristics. About one third of the population was classified as "fine-spotted trout" due to the occurrence of small black spots on the body and fins. These individuals also have from four to seven black spots located around the pupil of the eye. Genetic data, obtained by electrophoresis of tissue enzymes, demonstrated large differences compared with other brown trout populations. According to the information available, the abundance of fine-spotted trout has decreased during the last eight decades, which focuses on the need for preservation of the population and its habitat.

The Relation Between Growth and Food Consumption in the Brown Trout (Salmo Trutta)

1939 ◽  
Vol 16 (4) ◽  
pp. 446-473
Author(s):  
F. T. K. PENTELOW
Keyword(s):  
Body Weight ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Simple Relation ◽  
The Body ◽  
Average Weight ◽  
Loss Of Weight ◽  
Brown Trout Salmo Trutta ◽  
Summer Growth ◽  
Food Produce

1. The growth of brown trout (Salmo trutta), fed on Gammarus pulex, in their first and second years has been studied. 2. The growth in weight varies considerably from week to week but, generally speaking, it increases with increasing size of the fish. It is assumed that in these experiments the second point of inflection of the normal S-shaped growth curve was not reached because the fish were too young. 3. In all the fishes studied there was a period of slow growth during the winter and during the summer. Growth is at its maximum at temperatures between 50 and 60° F. 4. By careful adjustment of the rations it was possible to keep the body weight of the fish approximately constant from week to week. The amount of food required for this purpose varied from 51 to 270 mg./g. of body weight per week, but was mainly between 70 and 102 mg. and was apparently affected by the water temperature, being higher when the water was warmer. 5. Starved fish lost more weight at higher temperatures than at lower, but the loss of weight could not be related to the amount of food required to maintain the body weight constant at a given temperature. 6. The appetite of fully fed fish increases as the temperature rises to 60° F. but generally declines at temperatures higher than this. Between 40 and 50° F. the amount of growth made is roughly directly proportional to the amount of food eaten, but above 50° no such simple relation exists. 7. G. pulex is a very efficient food for trout; generally speaking about 5 g. of this food produce 1 g. increase in weight. If from this amount the quantity required to maintain the body weight constant is subtracted, it is found that 1 g. increase in weight is produced by about 3 g. of food available for growth. 8. The average weight of the Gammarus used as food in this experiment was 0.026 g., and it is estimated that for every gram increase of weight each fish consumed between 200 and 300 Gammarus.

scholarly journals Genetic variation in brown trout Salmo trutta across the Danube, Rhine, and Elbe headwaters: a failure of the phylogeographic paradigm?

2013 ◽  
Vol 13 (1) ◽  
pp. 176 ◽  
Author(s):  
Estelle Lerceteau-Köhler ◽  
Ulrich Schliewen ◽  
Theodora Kopun ◽  
Steven Weiss
Keyword(s):  
Genetic Variation ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Brown Trout Salmo Trutta

Introduction and extinction of brown trout (Salmo trutta L.) in an impoverished subantarctic stream

1992 ◽  
Vol 4 (1) ◽  
pp. 9-14 ◽  
Author(s):  
J. Cooper ◽  
J.E. Crafford ◽  
T. Hecht
Keyword(s):  
Brown Trout ◽  
Life Style ◽  
Salmo Trutta ◽  
Small Population ◽  
Marion Island ◽  
Resident Population ◽  
Brown Trout Salmo Trutta ◽  
Alien Fish

Brown trout were introduced to the Van den Boogaard River on subantarctic Marion Island in 1964, and a small population became established. The last individual was seen in 1984, and the species is now considered to be extinct on the island. Their diet was exclusively allochthonous, with snails and spiders predominating. Ages estimated at six to eleven years showed that spawning must have occurred since the original introduction. Since the Van den Boogaard River enters the sea via a waterfall, it is postulated that trout were not able to practice an anadromous life-style, and that this, as well as other factors connected with the impoverished nature of the stream, led to dwarfing of the resident population. No further introductions of alien fish to Marion Island should be contemplated.

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