University of Tehran Journal of Natural Environment 2008-7764 78 2 2025 09 21 The relationship of age and sex of Dori bleak (Alburnus doriae) and Brond Snout (Chondrostoma regium) with their diet in the Zayandeh-Rud River The relationship of age and sex of Dori bleak (Alburnus doriae) and Brond Snout (Chondrostoma regium) with their diet in the Zayandeh-Rud River 329 344 104390 10.22059/jne.2025.392367.2789 FA Omidvar Farhadian Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran. Javad Bagheri Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran. 0009-0007-8848-1230 Nasrollah Mahboobi Soofiani Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran. Safiollah Heidari Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran. Eisa Ebrahimi Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran. Journal Article 2025 03 30 This study, with the aim of investigating the effect of age and sex on diet and food resource allocation patterns, focused on Alburnus doriae and Chondrostoma regium. In order to achieve this goal, a total of 400 specimens (200 samples from each species, including male, female, and juvenile) were collected seasonally over a full year from the Zayandeh-rud River, located in Chaharmahal and Bakhtiari Province. To quantify the relative importance of food groups and compare them, the Numerical Importance Index was used, which indicates the frequency or number of prey in the digestive tract. Analysis results showed that in both species, Insects had the highest numerical importance and were recognized as the main food for all age and sex groups. An important finding was the noticeable decrease in diet diversity with increasing age in both species, which indicates specialization of the diet in larger fish. Furthermore, A. doriae showed greater food diversity and a more specialized tendency compared to C. regium (which is more flexible in its food resources). The diet of both species is strongly dependent on benthic insect resources of the Zayandeh-rud River. This specialization of diet with increasing age, as a size-related diet change strategy, helps in the better management of energy needs in larger fish. The difference in feeding strategies between A. doriae (a more specialized insectivore) and C. regium (a more flexible omnivore), provides an opportunity for resource partitioning and stable coexistence in this aquatic ecosystem. This study, with the aim of investigating the effect of age and sex on diet and food resource allocation patterns, focused on Alburnus doriae and Chondrostoma regium. In order to achieve this goal, a total of 400 specimens (200 samples from each species, including male, female, and juvenile) were collected seasonally over a full year from the Zayandeh-rud River, located in Chaharmahal and Bakhtiari Province. To quantify the relative importance of food groups and compare them, the Numerical Importance Index was used, which indicates the frequency or number of prey in the digestive tract. Analysis results showed that in both species, Insects had the highest numerical importance and were recognized as the main food for all age and sex groups. An important finding was the noticeable decrease in diet diversity with increasing age in both species, which indicates specialization of the diet in larger fish. Furthermore, A. doriae showed greater food diversity and a more specialized tendency compared to C. regium (which is more flexible in its food resources). The diet of both species is strongly dependent on benthic insect resources of the Zayandeh-rud River. This specialization of diet with increasing age, as a size-related diet change strategy, helps in the better management of energy needs in larger fish. The difference in feeding strategies between A. doriae (a more specialized insectivore) and C. regium (a more flexible omnivore), provides an opportunity for resource partitioning and stable coexistence in this aquatic ecosystem.

https://jne.ut.ac.ir/article_104390_08446c230242bedf268a23965c09e324.pdf