The survey of vital condition on Sturgeon fry, when they were released into Tajan River by tagging
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AuthorRamezani Fokalaii, Hamid
MetadataShow full item record
AbstractThis Tajan river in / April/ 2000 and was followed to one year of Four stations selected from estuary to farah Abad station. Sampling occured to limited: (the survey of characteristic and choloride toxins in above limited in relative of three stations. Forty thousands species of Acipenser persicus fry with the different average weights were delivered fry were tagged and then the tagged fish were released in released stations in the different times. The fishing stations and the survival time in fry in the river, determination of upper and down streams in releasing area, Nutrition, Microbial diseases and estimation of catch populations in repeated fishing were evaluated. The physico - chemical characteristics of water and the evaluation of condamination were surveyed in the river. In addition, .the- evaluation of frequency and biomass (such as benthos and zooplankton were surveyed in the river). Finally, the effective factors in the mortality of fry in relative before and after releasing, the best place for releasing area of fry in the river was introduced into execution selection. The survival time of fry is low in the river and it depends on the distant between from the releasing area to estuary and the releasing time. Fry were passed from estuary after 24 hours and fry were approached to the sea after 48 hours and also the peak migration of them has been from 12 p.m to 3 a.m. The internal migrations don't have toward Upper River and these migrations have toward the sea. Fry haven't fed in survival time but after fourteen days, they caught in coastal section. The gammaridea and hypania (type of hypercilia) were fed by them. Before the releasing, fry have been contaminated by bacterial agents. The contamination rate was 3.3% but after releasing and passed from estuary have not been contaminated. The survey of the chemical and physical features in area indicated that the salinity was ascended higher than six ppt in third decade of April. The other factors indicated a healthy ecosystem. Of course, the increasing of salinity was related to Debi in water that approached to zero. The survey of choloride toxins in water indicated that were lack of difficult survey area in rivers. These toxins have been compared to another toxins such as hexa - choloro - benzen (a -HCB) that this concentration has a high in estuary. The evaluations the biomass of nutrition (Benthos and zooplankton) in the river indicated in the relative to benthic condition was included six classes. They contain bottom invertebrates, they have been identified 11 families and 9 species and so they consist of Insecta, Olighocheata class, Crustancea class, hypercilia class, Crustacea class, Bivalva class, Gastropoda class, it is obvious that the estuary station have a high biomass of benthic organisms and it has higher variation species than other stations. The zooplankton condition, In addition, it is belong to zooplankton that was identified to Rotatoria - Cladocera - Copepoda- Barnacles - Protozoa and forminofera as the beginning of spring season. Zooplanktons have a high variation but the end season, they have a below amount. Although, the gill net has one (cm) in mesh that sturgeon fry entrapped them the main effective factor of mortality about sturgeon's fry took place when sturgeon's fry entered into the sea. But the qoopegative company net of fishing, sturgeon's - fry caught in by catch that this agent were threatened when sturgeon's fry entered in to the sea. The evaluating of two stations for releasing the fry (research and farah Abad stations), the .research station (distance 500 m from estuary) has the best area for the releasing. the sturgeon's fry (fingerling) was introduced into the excution section . Key word Tajan river, Acipenser persicus (Sturgeon's fry gillnet) - nutrition, Microbal diseases, Choloride toxins.
Publisher or UniversityIranian Fisheries Science Research Institute
Series : NrOcr Translate Report (53);