scholarly journals Feeding habit of Brown trout (Salmo trutta fario) in upper parts of river Swat, Pakistan

2022 ◽  
Vol 82 ◽  
Author(s):  
W. Khan ◽  
S. M. H. M. Naqvi ◽  
H. Ullah Khan ◽  
M. Rafiq ◽  
B. Ahmad ◽  
...  
Keyword(s):  
Body Weight ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Gut Contents ◽  
Relative Importance ◽  
Feeding Intensity ◽  
Total Length ◽  
Index Of Relative Importance ◽  
The Relationship ◽  
Salmo Trutta Fario

Abstract Salmo trutta fario is the most important fish species of family Salmonidae inhibited in cool waters all over the world including the nortern parts of Pakistan. This study was aimed to find out the prey selection and feeding habits of the species. One hundred and eighty five Salmo trutta fario were captured from March 2016 to April 2017. Feeding intensity as represented by a fullness index (FI), changing with various length groups and season. Out of 185 Brown trout 24 fish stomaches were found empty. The most important and common food items of brown trout were Brachycentridae, Blepharocera, Hydropsychidae, ephemerella spp. Kruskal Wallis H-test were applied on feeding intensity groups consisting of three month group. The test statistic for K.W-H-test were (H=8.13 with df =3) had a p-value of 0.043 < (alpha=0.05 indicates favor of the alternative hypothesis of at least one difference among the feeding intensity groups. The linear relationship of N with index of relative importance and %IRI denoted by least square regression line (N = 35.2 + 22.1%IRI), shows that for 22 prey there is 1% change in IRI. The relationship between total length (mm) and fish body weight (gm) is expressed by Pearson correlation coefficient (r = 0.976), showed that total length (mm) and fish body weight (gm.) is highly correlated. Descriptive statistics are used for the stomach fullness, which shows that feeding intensity was recorded higher from March to May. A total of 2289 preys was recorded including the most common were; Trichoptera, Hydropsychidae, Brachycentridae, diptera, blepharocera, ephemerala, chironomida, honey bees, grass hopper, locust, trout egg, trochanter, plant tissue, stones were retrieved from the gut contents of brown trout. According to index of relative importance IRI% four preys represents major components of the diet. The highest IRI% was recorded in Brachycentridae (39.38%), followed by blepharocera (13.23%), Hydropsychidae (10.76%) and ephemerella spp (8.28%). The relationship between IRI and FO is (r =0.556) is moderately correlated with coefficient of determination (r2=0.31). This study will help in the development of an artificial diet for the species for better growth performance in captivity.

Evaluation of brown trout (Salmo trutta fario) fillets’ shelf life: Fed with a humic supplemented diet

2021 ◽  
Vol 29 ◽  
pp. 100675
Author(s):  
Muhammed Atamanalp ◽  
Arzu Ucar ◽  
Esat Mahmut Kocaman ◽  
Gonca Alak
Keyword(s):  
Shelf Life ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Brown Trout Salmo Trutta ◽  
Salmo Trutta Fario

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.

Interpopulation variation in male parr maturation of anadromous brown trout (Salmo trutta) in Norway

1990 ◽  
Vol 68 (9) ◽  
pp. 1983-1987 ◽  
Author(s):  
Jan Henning L'Abée-Lund ◽  
Arne Johan Jensen ◽  
Bjørn Ove Johnsen
Keyword(s):  
Fresh Water ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Mature Male ◽  
Good Growth ◽  
Effective Population ◽  
Poor Growth ◽  
Total Length ◽  
Mature Male Parr ◽  
Smolt Age

We studied male parr maturation in anadromous brown trout in nine Norwegian rivers. Mean age at maturity increased from 1.5 years in southern populations to 5.2 years in northern populations, but the latitudinal correlation was not significant. Mean age of male parr at maturity was negatively correlated with mean total length of 0- and 1-year-old parr. The proportion of mature male parr varied between 0.06 and 0.6 among populations, and was positively correlated with mean total length of 0- and 1-year-old parr. The proportion of mature male parr decreased significantly with increasing mean smolt age of males. This indicates that in populations with relatively poor growth in fresh water (i.e., high smolt age) males mainly spawn as sea-run migrants, whereas in populations with relatively good growth in fresh water the mature male parr potentially contribute twice to the genetic makeup of the population, further increasing the effective population size.

scholarly journals Spatial and seasonal changes in the diet of Oligosarcus hepsetus (Characiformes, Characidae) in a Brazilian Reservoir

2005 ◽  
Vol 65 (1) ◽  
pp. 1-8 ◽  
Author(s):  
F. G Araújo ◽  
C. C Andrade ◽  
R. N Santos ◽  
A. F. G. N Santos ◽  
L. N Santos
Keyword(s):  
Seasonal Changes ◽  
Prey Capture ◽  
Gut Contents ◽  
Relative Importance ◽  
Food Items ◽  
Dietary Shifts ◽  
Index Of Relative Importance ◽  
Almost All ◽  
Previous Autumn ◽  
Very High

We assessed spatial and seasonal changes in the diet of Oligosarcus hepsetus in order to describe the strategy developed by this species that allows their very high abundance in Lajes reservoir, Rio de Janeiro, Brazil. Fish samplings were carried out using gill nets, deployed during ca. 12 and 24 hours, between April 2001 and May 2002. A total of 289 individuals were examined, of which 97 showed gut contents. We used the index of relative importance (IRI) to compare probable dietary shifts, and the frequency of occurrence (% OC) to analyze possible ontogenetic influences on feeding. O. hepsetus showed carnivorous habits, feeding preferably on fish and insects, the latter of which occurred in 71.0% of the guts presenting contents. O. hepsetus consumed different items along the three reservoir zones: insects (61.0% IRI) and Cichla monoculus (38.9% IRI) in the lower zone; Lepidoptera (57.0% IRI) in the middle zone; and C. monoculus (77.0% IRI) in the upper zone. Food items changed seasonally with C. monoculus predominating in autumn 2001, and Hymenoptera and Lepidoptera in the winter. In spring almost all food was Lepidoptera (99.8% IRI), while in the summer Hemiptera dominated in the diet. In autumn 2002 Hemiptera (97.0% IRI) was dominant, in significant contrast with the previous autumn. Individuals smaller than 190 mm SL fed heavily on insects, while fishes predominated in the diet of individuals larger than 190 mm SL. Shifts in prey-capture ability among length classes suggest decreasing intraspecific competition. A higher food plasticity seems to be the strategy employed by this opportunist species, which used food resources available in the reservoir.

Environmental concentration of methamphetamine induces pathological changes in brown trout (Salmo trutta fario)

Chemosphere ◽  
2020 ◽  
Vol 254 ◽  
pp. 126882 ◽  
Author(s):  
Maria Eugenia Sancho Santos ◽  
Kateřina Grabicová ◽  
Christoph Steinbach ◽  
Heike Schmidt-Posthaus ◽  
Eva Šálková ◽  
...  
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Pathological Changes ◽  
Environmental Concentration ◽  
Brown Trout Salmo Trutta ◽  
Salmo Trutta Fario
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