Caspian Sea is the largest enclosed body of water on the earth. Since the collapse of Soviet Union in 1991 and discovering large oil and gas fields, some issues such as political, economic and environmental events, made the Caspian Sea important. The ecology of the Sea are being endangered due to several issues such as petroleum extraction, river and Sea pollutions, water level rise, biological damages, decline of Caspian Seals and lack of legal regime among the neighbors. Tremendous infrastructures have had serious impacts on the ecosystems around the Caspian Sea and have often imposed long term damages to the Sea. Activities around the Caspian Sea endangered the balance of this very sensitive and fragile ecosystem. Large oil stains on the Sea level and thousands of acres of soil contaminated by oil leaking from abandoned wells are some parts of the pollutions. Some people must endure to the Caspian borders. In addition, there are various pollution-related industries, especially chemical and mineral industries, large non-irrigated agricultural and also domestic wastes. on human welfare and wildlife of the area. Ecological balance of the Caspian Sea is nearly going to be ruined (Efendieva & M. Dzhafarov 1993). The increase of pollutions in the area has made many problems. The negative effects of shipping activities, oil and gas extraction and oil transport through the Sea, have always been problematic. Destruction of flora and fauna are of the consequences of pollution. Finally, exploitation of Caspian Sea oil and gas provide the new challenges about the ecosystem of the environment. The natural resources of environment are the source of potential wealth. So they can easily increase the conflict for example legal aspects between neighbors as well as the risk of security in the region.

In this study 16 groups of zooplankton belong protozoa, arthropoda, rotifer and cyliophora were investigated. The number of these zooplanktons were accounted in m3 and also their biomass (mg/m3) was measured. The average biomass of zooplankton was measured 531. 74, 30. 77, 225. 07 and 96. 26 mg/m3 respectively and the total was attained 883. 83 mg/m3. The maximum and minimum biomass of all zooplanktons was estimated in November and July, 3446. 23 and 6 mg/m3 respectively. Furthermore, the maximum and minimum numbers of zooplanktons were found in September and July which were 48. 4 and 0. 002 millions respectively and the average number was 8. 4 ind/m3.

Caspian Kutum (Rutilusfrisii kutum) is one of the most important commercial bony fishes in Iranian coastal waters of the Caspian Sea that constitute more than 50% of the total annual catch of the bony fishes. In the fishing Season of 2003-2004, 5 mobile working groups gathered biometry data in the regions Anzali, Kiashar, Noshahr, Babolsar and Torkmen.Catch statistics of bony fishes was gained from fishing and landing harbors. Total catch of the commercial bony fishes was estimated at 15.5 thousand tons from which the Kutum amounted to 8477 tons, 45.5% of the total. Also, catch of the bony fishes of beach seine cooperatives was estimated at 10667 tons where the Caspian Kutum comprised 5180 tons (48.65%). The catch per unit effort (CPUE) of the Caspian Kutum amounted to 93.3 kg/set with the highest value recorded in Noshahr and the lowest amount observed in Anzali and Kiashahr regions. The mean fork length of the species was 36.7±6.1 cm showing a range of 21 to 69 cm. The meanage was measured as 3.82±1.37 years with the range of 1 to 8 years. The age groups 3, 4 and5 years old comprised 87% of the total catch age composition. Von Bertalanffy growth parameters such as L¥ k and t0 were determined as 70.1cm, 0.138/year and -1.557 years, respectively. Total mortality, natural mortality and fishing mortality rates of the species were estimated at 1.1/year, 0.28/year and 0.83/year, respectively (considering a surface water Temperature of 14°C). The biomass of the fish was estimated at 25 thousand tons.

Caspian Sea is the world’s largest lake; located between Asia and Europe and has no natural connection to oceans and free Seas. Before the collapse of the Soviet Union in 1991, Caspian Sea was divided between Iran and the Soviet Union and was known as a joint Sea according to bilateral treaties signed by Tehran and Moscow in 1921 and 1940. Following the collapse of the Soviet Union and emergence of three new states; Kazakhstan, Turkmenistan, and Azerbaijan, Caspian Sea was practically surrounded by five states. This was the beginning of differences over legal regime of the Caspian Sea and how to the exploit the Seabed and underground resources of the Sea. According to negotiations which were carried out after collapse of the Soviet Union, various methods were proposed to divide the Caspian Sea none of which has been accepted by all littoral countries yet. Geographical characteristics of the Caspian Sea, existence of huge oil and gas resources, in addition to presence of regional and transregional powers have given rise to various viewpoints on the territorial waters in Caspian Sea and determination of Sea borders. This paper discusses the legal regime of the Caspian Sea after collapse of the Soviet Union through a descriptive – analytical approach and in view of the aforesaid facts, explains factors which have been effective in preventing determination of Sea borders among littoral countries of the Caspian Sea.

Waves play an important role in the geometry and composition of beaches. Iran has 700 km of coastline with the Caspian Sea, which is important understanding its waves. By reviewing sources, this study provides a comprehensive and analytical knowledge of the waves of Caspian Sea, so that the Caspian waves are wind-driven waves, and the prevailing waves of the southern Caspian are the western waves at first and then the northern waves (with a maximum height of 5. 57 m). The maximum wave height is random due to the number of waves reaching the area and break of waves are more of spilling brakers. The exact pattern of the wind field (at the wave heights of 0. 5-1. 5 m), and the dimensions of the basin under the wind affect the formation of waves. Among the different simulation methods (JONSWAP, CEM, SPM, SMB, MIKE21 model (SW package), regression decision trees method and artificial neural networks) that can be seen in different studies, the last two methods with close answers have double accuracy in compare with others. However, the latter two methods lowerestimate the height of the wind waves slightly and overestimates the wave period slightly in compare with the measurement in South Caspian Sea.

The significant effect of waves on coastal and marine activities urges the precise identification of wave characteristics using field, theoretical studies, physical modeling or numerical simulations In order to study thoroughly the wave climate in the Caspian Sea, a wave modeling and hind cast project was performed by Iranian National Center for Oceanography In this study, one of the latest versions of numerical wave models (3rd generation) was employed for long-term simulation of waves in the Caspian Sea using wind data. The wind field was obtained from ECMWF global operational model after a few local modifications were made. For calibrating the model, in-situ measurements and available satellite data were used Extreme value analysis was the next stage in which for different return periods the wave characteristics were calculated. Finally, user-friendly software was developed with the aim of presenting the results of the project.

Bream (Abramis brama orientalis) is one of the most commercial valuable fish species of the Caspian Sea. Total catch of this species was 17 tons in 2000 -2001 fishing Season, which constitute 0.10 % of the all commercial catch of fish species in Iranian coastal water. The mean fork length, weight and age of this species was 21.7±3.3 cm, 191±99.9 gr and 2.72±0.91 year (X±S.D) respectively. Length - Weight relationship was expressed as W = 0.2312 L 2.90 (R 2= 83.34 %, r = 0.91, N=160). Length growth parameters of bream based on Von Bertalanffys can be written as: Lt = 45 [ 1 -exp -0125(t+2.768)] The instantaneous rate of total (Z) , Natural (M) and fishing (F) mortality coefficients were 0.92 year -1, 0.28 year -1 and 0.64 year -1 respectively .The exploitation ratio (E) was calculated as 0.7 . Based on cohort analysis, the biomass of this species was calculated as 46.362 tones and according of this amount of biomass, the MSY was estimated as 14.99 tones which is less than the catch of this species.