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

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.

Monitoring pond water quality to improve the production of Labeo rohita (Hamilton, 1822) in Bannu Fish Hatchery of Bannu district, Khyber Pakhtunkhwa province; An Implications for artificial fish culture

“…There are about 233 fish species had been reported in the freshwater reservoirs all around Pakistan and most of these species were belonging to the Cyprinidae family (Ullah et al, 2014). Studies on the economically important fish species of the region have been taken in recent years (Ahmad et al, 2020;Khalid et al, 2020;Khan et al, 2021a;Khan et al, 2021b;Khan et al, 2021c;Khan et al, 2021d;Shah et al, 2021;Ullah et al, 2021). Nowadays, carp species including, Cirrhinus mrigala, Hypophthalamichthys nobilis, Hypophthalamichthys molitrix, Cyprinus carpio, and Labeo rohita are particularly raised in the fish hatcheries of Pakistan (Karim et al, 2016).…”

Assessments of some trace metals in water samples of nursery pond of Grass Carp (Ctenopharyngodon idella, Valenciennes, 1844) in Bannu Fish Hatchery of Khyber Pakhtunkhwa, Pakistan

“…Though, due to the introduction of these carp fish cultures in the last few years, fisheries and aquaculture practices had now become a part of economics that contribute efficiently to fish food production in both government and private sectors (Yousafzai et al, 2010;Cudmore et al, 2017). Some of the economically important fish species of the region have been studied recently (Ahmad et al, 2020;Khalid et al, 2020;Khan et al, 2021a;Khan et al, 2021b;Khan et al, 2021c;Khan et al, 2021d;Shah et al, 2021;Ullah et al, 2021).…”