Stock assessment and maximum sustainable yield of common kilka (Clupeonella cultriventris Borodin, 1904) in Iranian waters of the Caspian Sea

Abstract

The main objectives of the present study were to estimate of biomass during 1997-2014 and maximum sustainable yield of common kilka Clupeonella cultriventris Borodin, 1904 in 2013 in Iranian waters of the Caspian Sea. This paper examines the maximum sustainable yield (MSY) and fishing intensity at MSY (fMSY) and then using fMSY, yield-per-recruit and spawning biomass-per-recruit under various harvest strategies of Fmax, F0.1 and F40%; the acceptable biological catch (ABC) was estimated. During 1997-2014, the biomass of common kilka was increased from 22000 in 1997 to 112000 t in 2009 then declined to 83300 in 2013. In the period, the instantaneous coefficient of fishing mortality varied between 0.246/yr to 1.640/yr and the exploration rates were 0.327 and 0.764. The reference points of common kilka at F0.1 and F40% were estimated 0.92 and 0.80 year−1 , respectively. According to Schafer model the MSY and fMSY were estimated 22670 t and 8690 vessel×nights (a unit of effort). During 2013, the ABC of common kilka was estimated 17500, 20060, 23500 and 18900 t in tiers 2, 3, 4 and 5, respectively. However, for the implementation of a precautionary management approach the lower and more accurate ABC-value, based on more information, should be selected and thus the catch should be restricted to 17500 t.