Description of the biology of Caspian vimba,Vimba vimba(Linnaeus,1758),in Gorgan Bay-Miankaleh Wildlife Refuge(southeast Caspian Sea)

We collected Vimba vimba throughout the spawning season （mid April to mid June, 2007） in Gorgan Bay （south-western Iran） and investigated its age, growth, and reproductive traits. The maximum age was 5＋ years. Both sexes grew allometrically （positive for males： b=3.140 9 and negative for females： b=2.791 4）. The von Bertalanffy growth functions were described by the formulae Lf=32.565（1-e-0.184（t＋0.530）） for males and Lt=35.950（1-e-0.179（t＋0.529）） for females. The overall sex ratio was balanced, but males were predominant in the smaller size classes and females in the larger size classes. Based on the gonadosomatic index （GSI） values, spawning appears to occur between late April and late May in the bay. The highest mean GSI was 6.44 for males in early May and 20.36 for females in late April Absolute fecundity varies from the minimum of 5 436 eggs for age 3＋ fish to the maximum of 36 141 eggs for age 5＋ fish. Fecundity was also positively correlated with fish size （length and weight）. Egg diameter ranged from 1.05 to 1.70 nun in the mean of 1.42 mm. There was no correlation between female size and ova diameter.

Life history pattern of mosquitofish Gambusia holbrooki (Girard, 1859) in the Tajan River (Southern Caspian Sea to Iran)

Investigation of the ecology of introduced species in new habitats can allow determinations of the degree, direction, and rate of evolutionary change. The introduction of Gambusia holbrooki in the southern Caspian Sea presents such a situation. We evaluated the life history traits of mosquitofish in the Tajan River basin. A total of 744 G. holbrooki specimens were collected between January and December 2008. The maximum observed ages are 0+ years for males and 1+ years for females. Both sexes grew allometrically (negative for males: b=2.442 and positive for females: b=3.232). The overall sex ratio is unbalanced and dominated by females. GSI values suggest that this population of G. holbrooki matures between February–July. The highest mean GSI value is 1.80 for males and 15.97 for females in May. Egg diameter ranges from 1.00 to 3.00 mm with a mean value of 2.098 mm. Absolute fecundity varied from 7 to 57 eggs. Both ova diameter and absolute fecundity were positively correlated to fish size (length and weight). Fecundity relative to total weight fluctuated from 34.44 to 582.64 eggs/g, and to total length from 2.33 to 12.95 eggs/cm. Both were negatively correlated with female size. The characteristics of this population are important with respect to life history of the species.

Effect of cooking conditions and oxygen-delignification on Bambusa tulda kraft pulping using experimental design and regression models

This study was concerned on the influence of cooking liquor parameters i.e. active alkali （AA） and sulfidity, on the properties of pulp produced from Thai bamboo by means of multivariate analysis. The investigated pulp properties were cooking yield and viscosity. The experiments were performed according to a face centered cube experimental design. Then, multiple linear regression （MLR） of independent and dependent variables were conducted with SPSS software using least square method. In order to optimize process, Pareto-Optimality method was employed. The obtained regression models were characterized by both descriptive and predictive ability （R^2 ≥ 95% and Rcv^2 ≥ 93%） and allowed the kraft pulping process with an acceptable viscosity （ 1110- 1 190 ml/g） and a total yield about 50% at a sulfidity level of 20-30% with 18% AA. Results indicated that high sulfidity at a lower AA could get high viscosity and relatively low kappa number for pulps. Also oxygen delignification was studied in this research.