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Feeding preferences of Silver Carp (Hypophthalmichthys molitrix) with a focus on the potential for biological control of algal communities in Qeshlaq reservoir, Sanandaj, Kurdistan
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Ronak Zareii   , Habibollah Mohammadi * , Barzan Bahrami kamangar , Edris Ghaderi , Erfan Karimian |
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Abstract: (5 Views) |
The introduction of various pollutants into lakes leads to eutrification, algal blooms, and the development of unpleasant taste and odor in the water. This study aimed to investigate the effect of silver carp (Hypophthalmichthys molitrix) on controlling algal communities in the Qeshlagh reservoir and reducing the taste and odor of drinking water in Sanandaj. To this end, the planktonic composition of both the environment and the digestive system of silver carp was examined. Water and fish samples were collected from two dam stations, followed by laboratory analyses of plankton composition, biometric parameters, nutritional indices, reproductive status, and digestive system contents. The environmental planktonic population analysis revealed that the Bacillariophyta phylum (70%) and the Arthropoda phylum (54%) had the highest densities of algae and zooplankton, respectively. Fish from four age groups (3+ to 6+ years) had an average weight of 1130.4 g and an average total length of 482.7 mm. The average relative intestine length index and condition factor were 4.3 and 0.98, respectively, with an intestinal emptying index of zero. Examination of the digestive contents identified 54 genera and species of phytoplankton and 11 genera and species of zooplankton, compared to 37 genera and species of phytoplankton and 16 genera and species of zooplankton in the environment. Within the digestive system, Bacillariophyta (54%) and Chrysophyta (43.8%) predominated among phytoplankton, while Rotifera (59%) and Ciliophora (40%) were the most abundant zooplankton. The genera Dinobryon and Melosira were predominant in the diets of fish from both stations, with Melosira also having the highest density in environmental phytoplankton samples. The Ivlev selectivity index indicated that Bacillariophyta (45%) was the most frequently consumed phytoplankton group by silver carp. Melosira demonstrated the highest prey abundance at both stations (100%), while Fragillaria, Cyclotella, and Dinobryon showed high frequencies of 100% in station 1 and 94%, 88.9%, and 88.9%, respectively, in station 2. The sexual maturation index suggested that environmental conditions in Gheshlagh reservoir are not conducive to the growth and development of silver carp gonadal tissues, indicating likely absence of natural spawning and ovulation for this species. Overall, silver carp appears to be an effective species for controlling algal biomass in lake ecosystems. This study provides valuable insights into the biocontrol potential of silver carp for managing algal blooms and improving water quality in reservoir ecosystems.
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| Keywords: Drinking water, Bloom algae, Silver carp, Feeding indices, Gheshlagh reservoir |
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Type of Study: Research |
Subject:
Special
Received: 2025/09/3 | Accepted: 2025/11/20 | Published: 2025/12/8
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