Investigating the status of stocks of the common kilka Clupeonella cultriventris caspia in the Iranian waters of the Caspian Sea (2020-2021)

In this study, the biological indicators (length, weight, age) and the stock of the common kilka (Clupeonella caspia) in the Iranian waters of the Caspian Sea were investigated in 2020 and 2021. The results showed that the amount of kilka caught was 20050 tons in 2020, reached 20138 tons in 2021, and presented fairly stable. The catch per unit effort (CPUE) was 2.298 and 2.321 tons per vessel per night, respectively. The average fork length (± standard deviation) of common kilka (male and female) was 100.9 ± 11.1 mm, and the minimum and maximum were 62.5 and 137.5 mm, respectively. In the catch composition, age groups of 3 and 4 years dominated the catch, representing 78.9% and 77.9%, respectively. In the years 2020 and 2021, the total biomass was estimated to be 92653 and 78135.3 tons, age 3 had the highest biomass (31615.1 and 22672.6 tons, respectively). The biomass of mature individuals were 44277.6 and 41606.5, respectively. The ratio of matures to the total biomass was 47.8% and 53.2%, respectively. The acceptable biological catch (ABC) of this species was estimated at 18,000 tons with a precautionary approach. During the last decade, the average catch of this species was 22769 ± 1904 tons, which is more than the estimated ABC.