Structure of macrobenthic invertebrate population in the southern coast of Caspian Sea for fish cage culture establishment

This research in line with fish cage culture plan in the southern coast of the Caspian Sea was carried out. Sampling was seasonally in 8 transects at the depth of 5-100 m from Astara to Torkaman areas in 2008-2009. The aim of this study was to investigate the distribution, abundance and biomass of macrobenthic invertebrate. The highest abundance and biomass were found in transects of Amirabad with average 10931.7±7301.4N/m2 and Astara with mean 86.2±160.3g/m2, respectively. This could be due to the presence of alien species into the Caspian Sea, Streblospio gynobranchiata in 2003 and is the dominant population of macrobenthic invertebrate concern up to 58.4% and increased of S. gynobranchiata (high power compatibility) and mussels of Cerastoderma glaucum (large size) is relevant, respectively. The abundance and biomass have fluctuations in different seasons and the highest abundance with average 6280.1±5693.1N/m2 and biomass with mean 66.1±126.9g/m2 was in winter and spring, respectively. A significant difference between abundance and transects (p0.05), significant difference between biomass and depth (p0.05) were found. Also, according to multivariate analysis of benthic invertebrate on the abundance at various depths revealed that depths of 5, 10 and 20 meters from the importance of certain fisheries in terms of frequency, abundance and biomass of the macrobenthic invertebrate, slope substrate, substrate, close to the beach, the accumulation of nutrients, Nursery ground, feeding ground and Spawning ground is important for different important species in the Caspian Sea. Therefore, the establishment of fish cage culture was recommended more than 20-meter depths according to the plans of fish cage culture in the southern coast of the Caspian Sea of the Iranian Fisheries Organization

Reproduction, sexual maturity and fecundity of anchovy kilka (Clupeonella engrauliformis Svetovidov 1941) in Iranian waters of the Caspian Sea

Reproduction period, spawning peak and sexual maturity in anchovy kilka were investigated during the year 2006 for sustainable yield assessment in Iranian waters of the Caspian Sea. The mean fork length, total weight and age were 118±5.9mm, 11±1.7g and 4.6±1.2 year, respectively. Mean (±SD) absolute fecundity was 12625±5533 ovules. More than 50 percent of the fish specimens matured when their length exceeded 92.5mm. The results showed that reproduction of anchovy kilka occurred in autumn, and spawning occurred throughout the year and especially in winter. The length and age ranges were found to be shortened compared to the past years with many older fish and less younger ones (< 2 years) in the catch which sharply decreased recruitment. This phenomenon is thought to be due to overfishing synchronized with invasion of M. leidyi pushing kilka to spawn in winter, which all cause collapse of anchovy kilka stocks in the Caspian Sea. We postulate that anchovy kilka has adopted the strategy of spawning year round to mitigate the negative effects of overfishing and invasion of M. leidyi

Age and growth of bigeye kilka (Clupeonella grimmi Kessler, 1877) in Iranian waters of the Caspian Sea

Age and growth of Bigeye Kilka, Clupeonella grimmi, were studied in Iranian waters of the Caspian Sea from early May 2006 to April 2007. The sagitta otoliths were removed for each 5 mm length interval up to a total number of 262 fish. Fork length and weight ranged from 92.5 to 142.5 mm and 4.2 g to 23.4 g, respectively. The largest length-groups was observed from December to February and the lowest in April, which was coincided with spawning period and feeding during wintering, respectively. The overall sex ratio (male:female) was 0.33:1 which differed significantly from the expected ratio of 1:1. The length-weight regression was W= 0.0000744 FL^3.14 for females and W=0.0000341FL^3.16 for males, indicating the Caspian Bigeye grew isometrically for both sexes. Age determination based on otoliths readings showed that the population was composed of six- groups from 2 to 7 years old which observed a rapidly growth during the second year. In the age compositions, the four years old specimens with a mean fork length and weight 115.5±7.8 mm and 11.9 ± 2.8 g were the most abundant age group and accounted for 40.1%. The condition factor was 0.7-0.8 which varied in difference months and coincided to the gonad development. Age-at-length data were used to determine von Bertalanffy growth parameters for this population in both sexes, indicating that K value and L∞ of females was more than that of males. The results showed that C. grimmi is a rapidly-growing species in the southern parts of the Caspian Sea

Marine food web dynamics of small-sized pelagic fish in the Caspian Sea (Iranian’s water)

A mass-balance Ecopath model of coastal areas in the Caspian Sea has been constructed for a quantitative description of the trophic structure of the ecosystem. The model is used to estimate the important biological parameters and relationships among the different ecologically important groups. Twenty five species were used in the present analysis. The model is based on the data collected of Kilka fisheries, beach seining (Bony fish fisheries), and set Gillnet (Sturgeon Fisheries) and also dietary information. Total landings along the Iranian portion of southern Caspian coast reached 39647 t, including sturgeon (41 t), kilka (22873 t) and bony fishes (16733 t) in 2014. Two species of kilka (Common kilka and Anchovy) are important commercially in the Caspian Sea, together accounting in the past decade for > 60 % of the total catch, as well as being a crucial part of the food chain. The mean average trophic level was estimated at 3.17 by Ecopath software. In this research, the mean level were studied between eight species varied from 2.56 to 4.04, Sander lucioperca occupy the highest and the as vimba vimba was the lowest level. The ranges of total mortality varied from 0.5 to 2.56 per years. The food consumption rate was estimated about 101.56 per year Mixd trophic level index (MTI) showed small pelagic fishes as prey, have crucial role in feeding of pelagic predators population such as invasion of the ctenophore Mnemiopsis leidyi, bream fish and benthic fish such as sturgeon. In general, niche overlap was greater in more species such as Alburnus chalcoides, Rutilus rutilus, Clupeonella cultriventris, Rutilus kutum and M. leidyi who consumed large amounts of plankton. In conclusion small pelagic fish exert a major control on the trophic dynamics of the Caspian Sea ecosystems and constitute midtrophic-level populations

Study on macrobenthic communities in the range of fish cage-culture area (before breeding) in the southern Caspian Sea (Mazandaran coast-Kelarabad)

The abundance and biomass of benthic macroinvertebrates were studied in the place of fish cage culture in southern coasts of Caspian sea (Mazandaran waters- kelarabad). The goal of this study was to consider of fish cage culture effects on the abundance and biomass of benthic macroinvertebrates. The sampling was carried out in 3 stations in depth of 20 meter of Kelarabad waters monthly. In this study 7 species were identified belonged to 5 genus of 4 family. Totally 23442 sample of benthic invertebrates were counted that the lowest and highest abundance were in station 1(23.4%) and station 2(46.8%) respectively. The results of stations study showed that the highest abundance and biomass were in stations 2 and 3 with the average of 646 ± 1230.4 n/m^2 and 0.526 ± 1.001 gr/m^2 respectively. This coulld be respectively dependant to not settling of cage (witness station) and appearance of Cerastoderma glaucum because of its large body in station 1. The difference of abundance and biomass between different stations was not significant (p ›0.05). The study on abundance and biomass in different seasons showed that the highest abundance in autumn with the avarage of 888.13 ± 1371.58 n/m^2 belonged to Strblospio gynobranchiata and the highest biomass belonged to C. glaucum which was because of appearance of not native species of polychaeta and also the species with shell covering from bivalvia. The results showed that the specie of S. gynobranchiata from polychaeta including 93.3% of abundance was the dominant specie that could be related to appropriate ecological conditions for living and high adaptability. It was concluded that the abundance and biomass of benthic macroinvertebrates in station 1 was lower than other stations which was related to fish cage culture activity and its effects on benthic macroinvertebrates. So it is suggested that each mariculture activity in southern coasts of Caspian Sea should be carried out with regarding to environmental considerations and performance of comparative evaluation project of environmental effects