Stock assessment and management implications of anchovy kilka (Clupeonella engrauliformis) in Iranian waters of the Caspian Sea

Recent changes in sea level of the Caspian Sea and ecological impacts caused by the invasive ctenophore (Mnemiopsis leidyi) have altered the ecosystem. A consequence is the changes in the absolute and relative abundance of the commercially important anchovy kilka (Clupeonella engrauliformis) in Iranian waters. To adjust to this change more rigorous management of this fishery is required. This paper examines the maximum sustainable yield (MSY) and fishing intensity at MSY. The paper presents estimates of f_MSY, yield-per-recruit and spawning biomass-per-recruit under various harvest strategies of F_max, F_0.1 and F_40%. We propose a method for estimating acceptable biological catch (ABC) that accounts for large differences in the quality and quantity of information and available data. The MSY and f_MSY were estimated 44,652 mt (metric tons) and 18,609 vessel × nights (a unit of effort). The ABC was estimated at 2190 mt in 2004. In 2005, however, the catch of anchovy kilka was about 4300, over twice the estimated ABC. In 2008 (from January to October) the catch declined to 220 mt. The analyses indicate that overfishing, especially between 2005 and 2008, is the main reason of the collapse of anchovy kilka in the Caspian Sea.