Investigating the factors affecting on declining of Luciobarbus capito stocks in the Caspian Sea basin (Case study: Sefidrood River) and proposing solutions for its protection

The aim of this study was to investigate the environmental factors affecting the population of the bulatmai barbel (Luciobarbus capito) in Sefidrood River, as one of the important habitats of fish in the Caspian Sea basin. For this purpose, two stations after Sefidrood Dam and one station near Rudbar (Guilan province) were selected for the study. Fish sampling was performed using electroshocking device and backup net. Immediately after sampling, water physicochemical parameters including water temperature, alkalinity (pH), Total Dissolved Solids (TDS), Dissolved Oxygen (DO), nitrate (NO3) and phosphate (PO4) were recorded. In the present study, the correlation between physicochemical variables of water was investigated using Pearson correlation test. Also, Canonical Correspondence Analysis (CCA) was used to investigate the relationship between environmental parameters and species presence information. The results showed that there is a significant relationship between pH and DO. Based on the results of CCA analysis, the first station was more affected by DO and pH and the second station was more affected by TDS. Also, the results showed that in the third station, water temperature and phosphate had an effective role on the population of L. capito. In general, this study showed that the water quality situation in Sefidrood River is not very favorable, the main causes of which can be influenced by human activities such as construction of dams, the entry of pollutants and sand extraction. The present study recommends that the prevention of destructive human activities, protection of habitats and spawning and reproduction sites of L. capito in the Caspian Sea basin should be considered as conservation priorities.