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This study was conducted to determine growth parameters, catch and fishing effort trends, stock assessment of Caspian Sea mullets in the Iranian coastal waters of Caspian Sea in the fishing season of 2013-2014. For gathering of data on biometry and catch statistics, 5 mobile working group in the regions of Anzali, Kiashahr, Noshahr, Babolsar and Torkmen were involved from the start to the end of fishing season.Gathered data Were entered to the computer. For data analysis, common methods were undertaken for estimation of growth parameters, mortality rates, biomass and Maximum Sustainable yield (MSY) as well. According to the result, the number of beach seines cooperatives was 124 and fishing efforts were 44688 beach seining haul. The catch per unit of effort CPUE) was calculated 53 kg/haul during this fishing season. The total catches of Caspian Sea mullets (including illegal fishing estimated as 2373 mt. Growth parameters of golden gray mullet (Liza aurata) were estimated as K=0.16/yr, L_∞=57.4 cm, t_0=-0.45/yr. Based on catch-at-age data, in the fishing season of 2013-2014, the total biomass, from the biomass-based cohort analysis were estimated 12473.3. mt. Based on these results, the fishing mortality rate in fishing season of 2013-2014 were 0.575/yr. In this survey, the Maximum sustainable yield were estimated as 2558.6 mt respectively. Generally from three Northern Province’s cooperatives 3406 samples collected. Results of biometry of golden gray mullet (Liza auratus) showed that the mean length and weight and age of this species were 32.3±6.1 cm and 383.5±74.823.4 g and 1.2±5.6 y respectively and leaping gray mullet (Liza saliens) showed that the mean length and weight and age of this species were 24.8±3.3 cm and 119±25.5 g and 2.5±0.6 y respectively. The biometric results showed that, 97.5% of the samples belonged to golden gray mullet and population of leaping gray mullet was sever declined. Also, the fishing of the mullet was increased over the last year by 10.3 % from 2151 tons to 2373 tons per year during 1391-92 and 1392-93, respectively .

This study was conducted to determine catch and fishing effort trends, length and age composition, growth and mortality parameters and estimate biomass and acceptable biological catch of Kutum in the Iranian coastal waters of Caspian Sea from 2013 to 2015. The catch of Kutum was 6112.8 and 5599.2 tons and CPUE were 181.1 and 183.5 kg/haul in 2013-2014 and 2014-2015, respectively. The mean (± SD) of fork length were observed 39.4±6.1 and 40.7±5.6 cm and for total weight were 805.1±378.0 and 891.5±384.6 gram in 2013-2014 and 2014-2015, respectively. The most predominated of length class was obtained 40-42 cm and frequency of immature individuals were observed 37.8 and 44.4 percent during two sampling period, respectively. The range of age was from 2 to 11 year and fish with 4 to 6 years comprised up to 84 percent. In length – weight relationship a, b and r2 were calculated 0.011, 3.02 and 0.96 respectively. K value, L_∞ and t0 were calculated 0.19 (/year), 61.3 cm and -0.99 respectively. Mortality parameters such as Z, M and F were calculated 0.82, 0.36 and 0.46 respectively and Exploitation rate were calculated 0.56. The biomass of kutum estimated 41000 tons and the acceptable biological catch calculated 8250 to 9750 tons. The biomass of Kutum decreased in recently years in spite of produce and release of huge fingerlings. This recruitment (produce and release fingerlings) must be continued for stability of stocks and fishing stress must be decrease by anyway.

Studies show that thyroxine can play an important role in regulating growth and other physiology activities. Since the direct role of thyroxine in growth metamorphose larval of bony fishes hasn't been proved yet, during the experiment accomplished in Shahid Ansari and Jajrood station, the hormones function in the survival of development of silver carp, grass carp and rainbow trout were studied. In this study accomplished of thyroxine baths with 0.1, 0.5 and 1 ppm (with 3 repeat). The other phase, thyroxine injected to females grass carp, silver carp, rainbow trout and barbell of Caspian Sea with different doses (1, 10 and 100 g/g B.W.). Tehn survival of development of embryo and larval and precent of fertilization were studied. Also, the percent of mortality were compared in two phases in stages of development. Results show that: 1) Trout: a) Phase of thyroxine bath: The number of hatching eggs and survival of larval in 0.5 ppm were increased to other treatment. b) Phase of hormone injection: The survival of larval in treatment of 10 g/g was 8.58% that was meaningful difference to other treatment (P

The effects of creosote on stellate sturgeon (Acipenser stellatus) juveniles each weighing 3.6 ±1 grams was evaluated. Acute toxicity test was undertaken in static water quality at 22 degree C plus or minus 1 according to the OECD method at the Caspian Sea Ecology Institute in 2005. The effect was assessed based on the results of the acute toxicity test. For the test, the hematological and biochemical properties of one control and five experimental groups of the fish juveniles what were exposed to creosote were compared. The acute toxicity test lasting 96 h was performed in fully static water condition with aeration.

This study aimed to investigate the toxic effects of atrazine herbicide on the fry of Caspian kutum (Rutilus frisii kutum, Kamensky, 1901). First the 96-h LC50 of the fry were exposed to atrazine at the concentration of 24.95 ppm was determined. Then the toxicity of this herbicide on Caspian kutum fry exposed to the concentration of 12.47ppm (1/2 LC50), for four days was measured and compared with a control group. Comparison of the length, weight and condition factor showed no significant differences between atrazine exposed and control group. The concentration of Na+, K+, Ca2+, Mg2+ and Cl- in the whole body of fry in control and atrazine exposure groups were as the following order: Ca2+>K+>Na+>Cl->Mg2+ and Ca2+>Na+>K+>Mg2+>Cl-, respectively. Results showed that the concentration of all these ions were higher in atrazine exposure group than control group, except for Cl-, and the only significant differences was found in Na+ concentration. Major histopathological effects of atrazine on the gills were hyperplasia and thickening of the filaments, separation of the pavement cells of the lamellae epithelium from the pillar cells and swelling of the epithelial cells. Results of the present study showed that atrazine could affect the ion composition of the body, and caused major damages in gill epithelium even at sublethal concentration and acute exposure, but had no effects on the growth parameters.