Using biotic communities for determining suitable areas for releasing Persian sturgeon (Acipenser persicus) fingerlings in Sepidrud river

One of the priorities in costly fisheries stocks rehabilitation measures is releasing of sturgeon fingerlings in original habitats which has been conducted by Iranian fisheries organization for some decades and it is very necessary to increase sturgeon releasing performance in administrative section that is overemphasized by related governmental officials. During research carried out from January 2024 for 12 months, 12 sampling conducted in 3 selected stations in Sepidrud entry to upstream and biotic and abiotic parameters were measured. Benthic were sampled with 3 replications by grab with 225 cm2 area. Through investigation of river in sampling stations, 123 Persian sturgeon fingerlings with mean weight of 7.5±3.4g and mean length of 9.02±2.9 cm were caught by persein with mesh size of 6 to 20 mm. The most and the least biomass and density of benthic near the estuary belongs to Chironomidae larvae in 23.5-56.99 range with 56.99 n/m² and barnacles with 0-06 n/m² frequency, respectively. The most and the least density of benthic that observed in fish stomachs were 83.87% Chironomidae and 0.8% Acartia sp., respectively. The results of this study showed that 1.4km distance from estuary is suggested for releasing due to suitable feeding situation, long survival (one month) and appropriate depth and granulation which can be noticed in reviewing sturgeon stock rehabilitation measures by administrative section of fisheries organization.