en Stock assessment Stock assessment پژوهشي Orginal research papers Population structure of three kilka fishes (<em>Clupeonella</em> spp.), particularly anchovy kilka (<em>C. engrauliformis</em>), in Iranian waters of the Caspian Sea was surveyed in 2003. A total of 3230 biweekly samples were collected from commercially landed kilka at 3 stations in Mazandaran and Guilan provinces. Catch and effort statistics were obtained from the relevant organization. Results showed a great decline in the commercial kilka catch from 95000 tons in 1999 to 15497 tons in 2003. The contribution of anchovy kilka to the total kilka fishery also showed a decline from 71% in 1999 to 52.5% in 2003, while common kilka (<em>C. cultriventris</em>) increased from 13.7% in 1999 to 48.9% in 2003. Fork length range of anchovy kilka showed an increase from 89.2&plusmn;12mm in 1999 to 100.4&plusmn;4.9mm in 2003. The age composition of anchovy ranged between 1+ to 7+ years and the dominant group was 5+ years old (age group of 4+ and 5+ comprised 84.6% of population). The K value and L&infin; calculated 0.598/year and 110.13 mm respectively. Natural, fishing and total mortality coefficient was estimated 0.69, 0.31 and 1 per year respectively. The results showed a sex ratio of F: M= 68.2: 31.8.<br> &nbsp; Clupeonella engrauliformis, Catch, Growth coefficient, Age, Length, Caspian Sea, Iran 73 86 http://jifro.ir/browse.php?a_code=A-10-120-4&slc_lang=en&sid=1 M. Sayyad Bourani mohammadborani@yahoo.com 100319475328460024184 100319475328460024184 Yes S. Abdolmalaki 100319475328460024185 100319475328460024185 No A.A. Khanipour 100319475328460024186 100319475328460024186 No H. Fazli 100319475328460024187 100319475328460024187 No K. Khedmati 100319475328460024188 100319475328460024188 No