Investigation and comparison of heavy metals in sediment, water and popular fishes of Golestan Province of south Caspian Sea

Golestan coast at south of Caspian Sea is the most important aquasystems, because of its relation to lagoon, bay and fresh water rivers and of its role in life cycle of bony fishes. The study of heavy metals, as a kind of chemical and environmental pollution is an essential program; because, they accumulated in the aquatic environment and human food chain that cause ecological damages. In this study, we determine the concentration of four heavy metals (Cd, Cr, Zn, Pb) in some most consumed fishes, such as Liza auratus, Cyprinus carpio and Rutilus frisii kutum in winter, spring and summer seasons locating at 11 sites (west and east coast, Gomishan Lagoon and Gorgan Bay). The fishes which were caught from the mentioned areas after biometry, immediately freezed and transferred to laboratory for further analyses. Then, water and sediment samples were acid digested and assessed for determination of Cadmium, Lead, Zinc and Chromium levels using atomic absorption spectrometer (AAS). The results showed that the highest concentration of Lead (214.83 ppb) was related to Gomishan Lagoon and the lowest Chromium level (28.83 ppb) was observed in the water specimens sampled from east coast in winter. Otherwise, the highest concentration of Zinc (300.7 ppb) was found in sediment specimens sampled from Gomishan in summer and the lowest concentration of Cadmium (12.7 ppb) in Gorgan Bay in summer. According to the results, the concentrations of heavy metals in liver tissues excised from fishes were higher than that in muscle tissues. Also, there was significant differences were observed between Chromium concentrations in muscle tissue of Cyprinus carpio with sex but there was not for other fish. In this investigation, we found a positive liner relationship between accumulation lead with age for Rutilus frisii kutum. On the other hand, no significant relationship was found between accumulations of heavy metals with age for other fish. Comparison of the resulted mean concentrations of heavy metals with international standards (WHO, UK (MAFF), NHMRC), showed lower concentrations in liver and muscle tissues of sampled fishes

Stock assessment of the bony fishes in Iranian coastal waters of the Caspian Sea (2005-2007)

Exploitation of bony fishes resources started on 12 October 2005 and finished on 9 April 2006 in 2005-2006. 142 beach seines caught about 14333.4 tons of bony fishes by 47101 hauling. The total catch was estimated 21844.7 tones (Includes illegal fishery). Kutum, mullets and common carp comprised more than 97 percent of total catch. Length classes 39-40, 31-32 and 40-41 cm predominated for kutum, golden grey mullet and common carp, respectively. Age groups 3 to 5 year comprised 84.2, 74.8 and 83.7 percent for Kutum, golden grey mullet and common carp, respectively and age group 4 year was dominant with 42.0, 35.9 and 43.0 percent, respectively. K value and L_∞ calculated 0.26 (/year) and 58.3 cm for Kutum and 0.15 (/year) and 61.5 cm for golden grey mullet, respectively. The total biomass and MSY estimated about 24733.7 and 8550.4 tones for kutum and about 16948.0 and 4999.0 tones for golden grey mullet, respectively. Exploitation rate (E) calculated 0.71 and 0.70 for Kutum and golden grey mullet, respectively. In 2006-2007, the exploitation of bony fishes resources started on 12 October 2006 and finished on 7 April 2007 in 2006-2007. 134 beach seines caught about 14120.0 tons of bony fishes by 48470 hauling. The total catch was estimated 23801.8 tones (Includes illegal fishery). Kutum, mullets and common carp comprised more than 98.5 percent of total catch. Length classes 39-40 and 38-39 cm predominated for kutum and common carp, respectively and length classes 27-28 and 29-30 cm predominated for golden grey mullet. Age groups 3 to 5 year comprised 80.2 and 71.8 percent for kutum and golden grey mullet, respectively and age groups 4 to 6 year comprised 71.8 percent for common carp. Age group 3, 4 and 5 year was dominant with 35.5, 32.1 and 27.1 percent for kutum, golden grey mullet and common carp respectively. K value and L∞ calculated 0.27 (/year) and 60.7 cm for Kutum, 0.2 (/year) and 58.4 cm for golden grey mullet and 0.19 (/year) and 66.7 cm for common carp, respectively. The total biomass and MSY estimated about 46654.9 and 14801.4 tones for Kutum, about 19549.0 and 5748.4 tones for golden grey mullet and about 10584.3 and 2186.0 tones for common carp, respectively. Exploitation rate (E) calculated 0.69, 0.53 and 0.52 for kutum, golden grey mullet and common carp, respectively