The objective of the present study was to determine chemical composition and fatty acid profile of common Kilka, CLUPEONELLA CULTRIVENTRIS CASPIA, in the CASPIAn Sea. The chemical analysis revealed that the protein and lipid content of common Kilka were 15.05 and 6.5% of the fresh weight, and total MUFA, PUFA and SFA were found to be 37.00, 32.89 and 29.03% respectively. Palmitic acid (16: 0) among total SFAs, oleic acid (18: 1n-9) among MUFAs, Docosahexanoid acid (DHA) (22: 6n-3) among n-3 PUFAs and linoleic acid (LA) (18: 2n-6) among n-6 PUFAs were the most abundant fatty acids. The obtained results revealed that common Kilka is a better source ofw-3 PUFAs than w-6. DHA and eicosapentaenoic acid (EPA) were the major components of w-3 PUFAs. Levels of DHA and EPA were 20.79% and 6.97% respectively. The PUFA/SFA ratio was 1.13 in common Kilka. This ratio was more than the recommended minimum value (0.45).The EPA/DHA ratio was 0.34 in common Kilka. The present study suggests that common Kilka is rich in essential unsaturated fatty acids of the w-3 family, especially DHA which may be considered nutritionally attractive for human.

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.

The Feeding habits of CLUPEONELLA CULTRIVENTRIS CASPIA Bordin, 1904 in Iranian waters were investigated by examining the stomach contents of 240 specimens collected in 2008. The mean of fork length, weight common kilka were 101. 8± 7. 2 mm, 10. 6± 2. 4 gr. Condition factor calculated 1. 9± 0. 12. The results of this study show that their diet consisted of different prey, Copepoda representing the most important prey group (FP=59. 6%) as a magor food items and Acartia tonsa the dominant prey species (100%). The others prey were Cirripedia (Cypris balanus) (FP=37. 7%) as a secondry food items and Cladocera (Podon polyphemoides) (FP=2. 7%) that as a accidentally fed. In summer, the fish fed on a wider density )504± 101 specimen per fish) of food items than in the others seaons. The lowest feeding activity was recorded in spring (112± 10 specimen per fish). The mean of RLG was 0. 39± 0. 8. The amount RLG<1, so common kilka is carnivore. Now, due to the dominance of species A. tonsa in the CASPIAn sea, especially in coastal areas, as a habitat suitable food is inevitable for Common Kilka.

This study evaluates the genetical structure of CASPIAn Sea Common Kilka (CLUPEONELLA CULTRIVENTRIS CASPIA) during winter and Spring of 2013 by sequencing method.30 samples were gathered from Mazandaran and Gilan fisheries ports and the fins samples lived in ethanol 96%. Then the genetical studies were done in biotechnology laboratory of CASPIAn Seas ecological research center. The DNA genomic samples of soft ports of the fish fin extracted by ammonium acetate method. The chain reaction of polymerase (PCR) was used by a pair of designed primer, on fish's DNA genomic. The abundant of Alles, the true number of Allelles, the observed and expected Heterozygosity, the genetic likeness and difference and the amount of Fs+caluculated by Tajmia and Nei test of genetic software (Bio Edit and Arlequin). Dendrogram of genetic difference drawn by Mega 4 genetic software. Based on drawn phylogenetic tree, the samples of Guilan were divided from Mazandarn samples. The dendrogram of these fish showed that the D-Loop gene indentified the genetic structure of CASPIAn Seas Common Kilka and separates Mazandaran and Guilan populations directly.

The changes in biological structure and growth of common kilka were investigation during 2008-2017 in the Iranian waters of the CASPIAn Sea. Kilka fishing ships discharged theirs catch in three parts: Babolsar, Amirabad and Anzali. The sample based on the length of 5 mm were classified. Fork length ranged from 52. 5 to 142. 5 mm and mean (± SD) 101. 9± 10. 5 and fish fork length 92. 5-112. 5 mm of the population have been dominant 81(%) (n= 49759). The slight fluctuations in the average length with values were between 100 and 105 mm. During this period, fish of +3 and +4 years old have been dominant with frequency of 80-70%. The stability length and weighted mean of generation growth rate was indicative of relative stability and the average age of common kilka stability, the stability of the population are descendants entered and confirmed. The results showed that in the year 2008 the frequency of young fish 1-2 years was 15. 2% of the catch, but gradually in the following years, the abundance of these fish in the hake decreased, so that in 2017, only 10% of the catches were allocated. Pressure on young fish stocks is an opportunity to rehabilitate stocks of this species.

The natural antioxidants effects of f)-carotene in concentration of 100ppm (BC 100) combined with ascorbic acid as a synergist agent (0.lg) and green tea polyphenols in concentration of 200ppm (pp200) on quality of common kilka (CLUPEONELLA CULTRIVENTRIS CASPIA) during storage with ice powder were studied. Values of PV and TBA at 14, 38 and 62 hour after fishing was compared with control (sample without any antioxidant). Statistical analysis showed although PV and TBA values increased significantly in all treatments (BCl00, pp200 and C) during storage times, but the antioxidant treated samples showed significantly lower PV and TBA values (P<0.005) than the control for the same time period. Sensory evaluation (color, odor, texture, taste and flavor, off flavor) showed no significant differences between both antioxidants; therefore, it is proposed using both antioxidants in preservation of common kilka.

This paper examines the changes in the population biology and biomass of common kilka (CLUPEONELLA CULTRIVENTRIS CASPIA) in the Iranian waters of the CASPIAn Sea from 1995-2004. For most years during this 10-year period, we estimated the age structure of the catch, length-weight relationship, von Bertalanffy growth parameters, condition factor, sex ratios, maturity stages determined from ovarian analysis, natural and fishing mortality, age at first capture and biomass. Growth parameters were estimated as L¥=132mm, K=0.259/yr, t0=-1.285/yr. The instantaneous coefficient of natural mortality was estimated as 0.506/yr and the instantaneous coefficient of fishing mortality varied during the 10-year period between 0.125/yr to 1.487/yr. Biomass of the common kilka increased from about 16,000mt in 1995 to more than 41,000mt in year of 2002. This increase in common kilka was simultaneous with a sharp decline in anchovy kilka, changes in zooplankton abundance and composition, and especially increase in zooplankton species used by common kilka. We concluded that at the present time, the stock of common kilka is being over-fished.

In this study, the some kinetic and biochemical properties of trypsin enzyme from common kilka and porcine were assessed. The results showed that the optimum temperature and pH for common kilka trypsin and porcine trypsin were 60oC and 8, respectively. Thermal and pH stability were also 45°C and 7-10 for common kilka trypsin and 50oC and 4-11 for porcine trypsin. CaCI2 and MgCI2 significantly increased the trypsin activity in common kilka and porcine (P<0.05). NaCI and KCI had no significant effect on trysin activity in common kilka (P>0.05) while it was significantly decreased in porcine in presence of them (P<0.05). The trypsin activity in common kilka was significantly increased in presence of MnCI2 (P<0.05) but in porcine, showed a significant decrease (P<0.05). The comparison of inhibitors of SBTI, TLCK, PMSF and p-aminobenzamidine revealed the except for p-aminobenzamidine, the other inhibitors showed no significant difference on enzyme activity in common kilka and porcine (P>0.05) but enzyme activity was significantly decreased by p-aminobenzamidine in porcine than common kilka (P<0.05). Vmax value of common kilka trypsin was significantly higher max than that from porcine trypsin (P<0.05). Km value of common kilka trypsin was significantly lower than that from porcine trypsin (P<0.05). The results of this study showed that common kilka trypsin was more efficient that porcine.trypsin and it could be considered as an additive in industries and biotechnological researches in future.

Kilka belongs to pelagic fish in the CASPIAn Sea and they feeds on zooplankton. They are the most abundant fishes of the CASPIAn Sea. There are three species of kilka fish included of anchovy (CLUPEONELLA engrauliformis, Svetovidov 1941) bigeyes (C grimmi, Kessler, 1877) and Common kilka (C. CULTRIVENTRIS Bordin, 1904). All three species have been existed in Iranian coastal waters and common kilkahad minimum relative frequency. 1.34, 2.5 and 5.5% of total catch belong to it in 1990-91, 1997-98 and 1998-99 respectively. After Mnemiopsis leidyi invasion in the CASPIAn Sea, relative frequency of this fish increased more than 10%. During 1997 to 2001, some important indexes such as length frequency, weight, sex, sexual maturity stages and age of this fish were studied in catch regions. Spawning of common kilka occurred in Spring in 1997-99 while in 2000-2001 spawning started later, in mass on April and continued to Augusts. We did not see any female at maturity stage VI_II, and stage V was rare. The fork length average was reduced from 92.7mm in 1997 to 81.5 mm in 2000 and increased to 88.3 mmin 2001, but fork length limits were less. The female was dominated. Age structure had 6 age classes (0+- 5+). Age classes 0+- 3+ included 95% during 1997-1999. In 2000 age classes 0+ and 1+ was reduced and 2+ - 4+ were 93.8%. Biological characteristics such as length and age indicated that common kilka population tolerate a pressure but probably because of dispersion of habitat its share in commercial catch has increased during recent years.