Resource And Genetic Diversity Of Four Major Chinese Carps In The Xiajiang Reach Of Ganjiang River

The Ganjiang river locates at south shore of Yangtze River and originate from Ganyuandong in Yangdi township,Shicheng County, pour into Poyang lake at Wucheng town of yongxiu country, the main stem of Ganjiang river is Length 823 km, fringe by Ganzhou state and Xingan country, Ganjiang river is divided into upstream, midstream and the downstream, among which the upstream Length 312 km, midstream Length 303 km, downstream Length 208 km. The Xiajiang county locates at midstream of Ganjiang river, the Longitude east of Greenwich is from 114°53'to 115°31', and the Northern latiutde is from 27°27'to 27°45'. The river's noodles of the Ganjiang river in the Xiajiang reach is narrow, flowing water rapids, owning to its special geography position and complicated natural environment, it is abundant in fish resources. In the middle reach of Ganjiang river, the wan'an Dam was build up in 1993, in recent years, are starting to build Shihutang and Xiajiang Dam. These water facilities in the middle reach of Ganjiang river's fish resources constitutes a serious threat, resulting in a very negative impact.This paper study the fish resources, morphological characters of Four major Chinese carps'young fish, resources status of Four major Chinese carps and genetic diversity of Four major Chinese carps in Xiajiang reach of Ganjiang river. In addition, we studied spawning ground status of four major Chinese carps in the middle reach of Ganjiang river, Aim at reveal the resource status and breeding population of four major Chinese carps in Xiajiang reach of Ganjiang river, and offer scientific proof to the protection of four major Chinese carps'resource status, at the same time evaluate the influence by the water project of fish resources investigation in the future. The primary results were showed as follows:1. Investigated the fish resources in Xiajiang reach of Ganjiang river in December,2008 and April to June,2009.8134 specimens, including seventy-one species, belonging to fifty-eight genera, sixteen families and seven orders, were collected. Cypriniformes, including 46 species, is the most species-rich order, account for 70.42% of total stream fish. Six new records of fish fauna were found such as: Acheilognathus hypselonotus, Coilia brachygnathus, Acrossocheilus parallens, Erythroculter dabryi, Paracheilognathus himantegus, Hemirhamphus intermedius.2. Gather young fish of four major Chinese carps, we collected 4 black carp,47 grass carp,32 silver carp and 37 bighead carp. Measured the morphological characters of them, The results showing, intraspecific difference in 4 kinds of fishes is small and these population growing tidiness, but 4 kinds of fishes respectively express a special appearance of characteristics.3. Investigated the resource status of the four major Chinese carps in Xiajiang reach of Ganjiang river from April to June in 2008 and 2009, Collected 464 samples in all,including 49 Mylopharyngodon piceus,272 Ctenopharyngodon idellus,84 Hypophthalmichthys molitrix and 59 Aristichthys nobilis, each of them takes the proportion of 10.56%,58.62%,18.10%,12.72%. Among these carps, fewer sexual maturation individuals were found, which are 8 Mylopharyngodon piceus,5 Ctenopharyngodon idellus,1 in each of Hypophthalmichthys molitrix and Aristichthys nobilis, accounted 3.2%. Besides, the age structure of them are simple, mainly low age groups fish of age 1 and 2, which accounted over 80%. The results showed that the Xiajiang reach of Ganjiang river is lack in the resource of the four major Chinese carps and also less amount of reproduction groups.4. December,2008 and June,2009, through survey sampling analysis, questionnaire survey and enquiry fisherman etc. we investigated the status of in the middle reach of Ganjiang river, the result display the midddle reach of Ganjiang river's 12 tradition four major Chinese carps'spawning ground that has already disappeared gradually, the size of them has decreased. Only the chutan spawning ground and Xiajiang spawning ground keep better.5. The oclonial genetic variations in four major chinese carps were analyzed with ISSR. Which generate 47(black carp),74(grass carp),55(silver carp),59 (bighead carp)bands. The number of Polymorphic band was33,50,29,30, and the Pecerentage of Polmoryphism was 70.21%,67.57%,52.73%,51.72%. The index of Nei s gene diversity and Genetic diversity quantified by Shannon Index varied of black carp are 0.2606 and 0.3846, grass carp are 0.2391 and 0.3560, silver carp are 0.1858 and 0.2769, bighead carp are 0.1908 and 0.2827. The genetic similarity between populations and coefficient of gene differentiation are:black carp (0.7486,0.2514), grass carp(0.7700,0.2300), silver carp(0.8184,0.1816), bighead carp (0.8150,0.1850). The date above showing four major Chinese carps in Xiajiang reach of Ganjiang river is lower in it's coefficient of gene differentiation, the heredity and variation space is larger, they still keeping natural population's genetic character.