Growth performance and age composition of Salmo trutta caspius in Iranian part of Caspian Sea

The aim of this project is to study the growth and age structure in the Caspian trout, comparison with other coldwater species and check the trend of these parameters in recent years. This study was conducted during 2013 till 2015. Totally, 43 specimens for back calculation and 101 specimens for biometrical study of the Caspian trout have been caught in two month period. Biometric parameters such as length, weight and age of the fish were recorded. Base on Back calculation method in 1393, the average length of fish at ages 1, 2 and 3 years old were 18.98 ± 3.5, 30.5 ± 7.24 and 41.7 ± 9.1 cm. So these age groups are under the adult age and don’t approaching to near the beach and rivers for spawning behavior. Therefore, these length groups cannot be observed in catch composition. The result showed, the mean of gonad weight in this fish was about 11 percent of total weight and number of eggs per gram of gonad calculated about 10.8 numbers. Minimum age and maximum age of this species determined 4 years and 7 years (mean = 5.6) and the most frequency allocated to 5 age group and the frequency of 6 and 7 years has been remarkable. The average length of salmon was 69.2 ± 6.2 cm (minimum 57 and maximum 81 cm) and the average weight was measured 3323 ± 677 g (2400 to 5600 g) in the catch composition. Growth parameters such as k, L_∞ and ø’ was measured 0.18, 104 cm and 3.289 respectively. The amount of b for relation length and weight was 2.9 which imply negative allometry. L_∞ and growth coefficient (K) on the Caspian trout were acceptable range, that it shows good growth the fish in the sea water. Most of the fishes were catched from Cheshmehkileh River. As at present Shilat uses just the broods of the Tonekaboon region for restocking of this species, we recommend using the broods of the western region separately for rehabilitation of the stocks of this region

The feasibility study for culture of Salmo trutta caspius by brackish water

Caspian trout is valuable, Commercial, anadromous and endemic fish species in the Caspian Sea so that, researchers attention have been focused on this species. At the moment, only pay attention to stocks rehabilitation that fisheries organization releases more than 300,000 fingerlings to the rivers ends to the Caspian Sea. Importance of this study consist (1) introducing a new species to the aquaculture system and (2) provide breeders in this research. we used from 2 treatments that consist with density of 10 kg/m^3 and 20 kg/m3 with 3 replication. Results showed, culture of Caspian trout is suitable with density 10 kg/m^3, so that weight gain, SGR and Daily growth mean are better than treatment 2(15-20 kg/m^3