Study the possibility of introducing sturgeon fingerlings in inland waters of Guilan province

The present study comprises the hydrological and hydrobiological investigation of three water bodies lying in the protected areas of the Gilan Province and includes: I. The Lahijan pond with a surface area of 14 hectares and an average depth of 2.2 m with 12 sampling stations. Hydrological and hydrobiological investigations were carried out from February 1999 through September 2001 (sampling conducted 32 times). 2. The Langarud pond with a surface area of about 8 hectares and an average depth of 2 m with 6 sampling stations. Sampling for hydrological and hydrobiological investigations were conducted 32 times starting from February 1999 through September 200 I. 3. The Bujagh Lagoon that lies in the Ziba Kenar region adjacent to the Caspian Sea, 15 m below sea level with a surface area of more than 8 hectares and an average depth of 2 m with 6 sampling stations. Samplings for hydrological and hydrobiologicai investigations were conducted 24 times staring from October 1999 through September 2001. Samplings from the three water bodies were conducted on a monthly basis throughout the study period. The present study comprises a physical and chemical analysis of various parameters in water samples such a water temperature, pH, dissolved oxygen orthophosphate, nitrate and ammonium and the identification and distribution of planktons and benthic organisms as well as nektons. Plankton specimens were collected using plankton nets and the Ruthner sampler, benthic organisms were collected using a grab and nekton specimens were collected using gillnets and waiting nets. The results obtained indicate that average dissolved oxygen concentration was 8.1 ± 0.2 mg/l in the Lahijan pond, 7.7 ± 0.5 mg/l in the Langarud pond and 8.1 ± 0.7 mg/I in the Bujagh Lagoon. Water temperature during the same period varied from 6.5 QC in January 1999 to 29.5 in August 2000 in the Lahijan Pond, 4.5 °C in January 1999 to 29 °C in August 1999,2000 and 2001 in the Langarud Pond and 6.2 °C in January 2001 to 29°C in August 2000 in the Bujagh Lagoon. Average pH recorded in the Lahijan, Langarud and Bujagh Ponds were 8 ± 0.8, 7.8 ± 0.3 and 7.6 ± 0.2, respectively. The abundance ofphytoplanktons was 9.5 x 103 cells mrl in the Lahijan pond that were comprised of28 genera and species, 8.7 x 103 cells mrl in the Langarud pond, comprised of 30 genera and species and 2 x 103 cells mr1 in the Bujagh Lagoon comprised of 22 genera and 3 species. The phytolanktons identified belonged to the five divisions chlorophyta, cyanophyta, chrysophyta, euglenophyta and chryptophyta. The mean biomass of zooplanktons was 31.97 g m-3 in the Lahijan pond comprised of 11 genera and 3 species, 17.78 g m-3 in the Langarud pond comprised of 6 genera and 2 species and 16.83 g m-3 in the Bujagh Lagoon comprised of 12 genera and 4 species. All zooplantons identified in the present study belonged to the phyla Arthropoda, Rotifera and Protozoa. Results obtained indicate that the maximum percentage frequency of zooplanktons in the surface and depths of the Lahijan Pond were 6.7 and 5.5 %, respectively and the minimum percentage frequency in the surface layers and depths of the same pond were lA and 0.8 %, respectively of the total abundance. In the Langarud Pond the maximum percentage frequency of zooplanktons in the surface layers and depths were 6.7 and 7A %, respectively while the minimum percentage frequencies were 1 and 1.2, respectively of the total abundance. In the Bujagh Lagoon maximum percentage frequency in the surface layers and depths were 7.1 and 9.6 %, respectively while the minimum percentage frequencies were 2.6 and 2.3 %, respectively of the total abundance throughout the study period. The mean biomass offbenthic organisms during the study period was estimated at 1.99 g m-2 in the Lahijan pond that was comprised of 1 genus and one species, 4.5 g m-2 in the Langarud pond comprised of 1 genus and one species and 2.13 g m-2 in the Bujagh Lagoon that was comprised of 6 genera and 4 species. The highest frequency of benthic organisms in all three water bodies belonged to the family Tubificidae that comprised 83A %, 60 % and 37 % of the total benthic organisms in the Lanhijan, Langarud and Bujagh Lagoon, respectively. The study of necktons in the Lahijan Pond indicated the presence of 6 fish species belonging to the Cyprinidae family dominated by Carassius auratus. The Langarud Pond consisted of 6 species from the Cyprinidae family dominated by Hyphothalmichthys molitrix while the Bujagh Lagocu consisted of 10 fish species belonging to the families Cyprinidae and Esoxidae. The dominant species in this lagoon was Carassius auratus. The Lahijan and Langarud Ponds lacked aquatic vegetation, however aquatic plants belonging to the families Ceratophlaceae, Potamogetonaceae, Lemnaceae, Fragmitidae and Haloracaceaea were identified in the study region of the Bujagh Lagoon. Based on the physical and chemical characteristics these three water bodies studied were found suitable for sturgeon culture. All three water bodies under study were classified as mesotrophic ecosystems. Therefore due to the lack of sufficient food supply, introducing sturgeons to these ecosystems will not be cost effective because of the costs involved in feeding them formulated diets.