Rivers in the southern Caspian Sea basin—including the Sefidrud, the largest among them—play a crucial role in stock restoration. This significance stems from their attraction of various migratory fish species, the importance of their estuaries, and their vital role in the release of fingerlings produced through artificial propagation, particularly sturgeon and Caspian kutum. This study was conducted 4 kilometers downstream of the Sefidrud River to examine changes in the abundance of migratory, estuarine, and riverine fish; fish sampling was carried out using a beach seine net (6 mm mesh size) at four riverine stations and one coastal station during June 2024 and June-July 2025. The results revealed the presence of 25 fish species in the first year and 33 species in the second year—totaling 34 species belong to 17 families—in the study areas; over the two-year period, 14, 7, and 13 species were classified as riverine, rianadromous, and estuarine-marine, respectively. Across the four downstream stations of the Sefidrud River, the dominant species in terms of individual count during July 2024 were Caspian bitterling, sand goby, round goby, and juveniles of Vimba and shemaya, accounting for 33.8%, 17.1%, 11.1%, 10.7%, and 9.8% of the total, respectively. In contrast, the dominant species during the combined period of June and July 2025 were bighead goby, shemaya juveniles, bitterling, Vimba juveniles, Kutum juveniles, and sand goby, representing 18.6%, 14.6%, 12.8%, 12.8%, 11.4%, and 11.2% of the total, respectively; a difference is thus observed between the two years. The Iranian sturgeon (Acipenser persicus) was caught at all five stations during the months of June and July 2025; this indicates that some individuals remained in the Sefidrud River for at least one month after releasing and that some moved upstream—up to 1.5 kilometers—from the release site. It is recommended that continuous downstream monitoring of rivers be conducted—at least from April to September each year—to assess the quantity and quality of migratory and estuarine juvenile fish, particularly the remain times of released juveniles, and that the updated data be made available to executive managers in the country's northern coastal provinces.
Mousavi Golsefid S A, Hosseini S A, Gorbani R, Abbasi Ranjbar K, Abdolmaleki S, Behrooz Khoshghalb M et al . Assessment of fish abundance in the downstream reaches of the Sefidrud River during the years 2024 and 2025. JAIR 2026; 14 (3) :1-10 URL: http://jair.gonbad.ac.ir/article-1-954-en.html