Duan Jinrong

Stress of hydraulic engineering on fisheries in the lower reaches of the Yangtze River and compensation

In the Low reaches of Yangtze River and the estuary region,there are rich fish species and high autochthonous species. The economic species that has an obvious fishing season characteristic almost distributes in this area,and the species number of the economic fish and fish catchability ranked first in the whole basin.In recent years the fishery ecological function has been weakened by many factors,such as river-lake disconnection,seawater intrusion,habitat fragmentation and hydrological changes due to the hydraulic engineering,and fish catchability,natural fishery resources,species diversity and idioplasm resources were also influenced seriously.In this paper,the development and status of hydraulic engineering and characteristics of fishery resources in the lower reaches of the Yangtze River have beea introduced,basing on some important hydraulic engineering,such as waterpower projects, migration engineering,navigation engineering,bridge construction,and sand digging.Existing and latent impacts of hydraulic engineering on fishery resources and fishery ecological environment have also been discussed.Suggestions on design of hydraulic engineering and compensation methods for fishery ecology have been given.Responsibilities and obligations that the fishery department should take were pointed out.At last the urgent research tasks of protection of fisheries resources and environments in lower reaches of the Yangtze River were put forward.

ANALYSIS OF GENETIC DIVERSITY OF FOUR TAKIFUGU OBSCURUS POPULATIONS USING SRAP MARKERS

Takifugu species(order: Tetradotiformes;family: Tetradontidae) have attracted attention among the scientific community for their peculiar biology,physiology and genomics.Obscure puffer(Takifugu obscurus) is an anadromous fish species in China.They usually grow in the sea before turning sexually mature,then migrate to freshwater rivers for reproduction during the spawning season.Obscure puffer is a popular fish in China for its high-quality meat.In 2002,annual production of obscure puffer was 2600 tons,and it has been continuing to rise owing to its large body size,rapid growth,and high market value of the fish.However,obscure puffer resource has sharply declined because of overfishing and water pollution.Previous studies have focused on the physiology and mitochondrial DNA.Analysis of the genetic diversity and structure of a fish species is an important prerequisite for conservation as it reflects the status and survival potential of this species.However,the genetic diversity among and within populations of obscure puffer populations remains unknown,thus it is difficult to implement effective conservation strategies.Molecular markers are useful for population genetic studies to assess the influence of various factors on genetic diversity and population structure.Among the many types of molecular markers,sequence-related amplified polymorphism(SRAP) has been recognized as a new and useful molecular marker system because of its simplicity,reproducibility and convenience.This method is based on two-primer amplification.The primers are 17 or 18 nucleotides long and consist of the following elements.SRAP amplifies open reading frames and is significant for gene and genetic diversity.It has been applied extensively in molecular identification,genetic linkage map construction,gene tagging,genetic diversity analysis and comparative genetics of different species.In this study,in order to investigate the genetic diversity and population structure among and within populations of obscure puffer,a SRAP marker was firstly used to analyze the genetic diversity of four obscure puffer populations.These populations included a captured population in the Yangtze Rive,a released population and two aquaculture populations.18 pairs of primer combinations,which were selected from 49 primer pairs,were applied to four populations.A total of 231 loci were detected,among which 156 were polymorphic.The proportion of polymorphic loci ranged from 54.98% to 58.87% in these four populations.The Nei’s genetic diversity(H) of the four populations were between 0.1992 and 0.2005,while the Shannon information index(I) were between 0.2953 and 0.3016.The gene flow(Nm) was 4.1291 among populations,of which,the proportion of polymorphic loci,the Nei’s genetic diversity(H) and Shannon information index(I) of the captured population were a little higher than the other three populations.Individual clustering showed that the Shanghai population formed an independent cluster and the other three populations belonged to another cluster.AMOVA analysis showed that 87.40% of variance was within population.These genetic statistics indicated there were a richer genetic diversity in four populations and a certain gene flow between them.

Preliminary study on the community structure and biodiversity of fishery resources in Xuliujing reach of Yangtze River,2005-2006

Based on the fishery resources surveys in the Xuliujing reach of the Yangtze River from December,2005 to March,2006,and July-September,2006,the community structure and biodiversity of fishery resources was preliminarily analyzed.The results indicated that,in this area,there were 48 species of fishes,3 species of shrimps,and 2 species of crabs collected,which belonged to 12 orders,20 families,44 genera.The index of rela- tive importance(IRI)was used in measuring ecological dominance of species to decide the role each species played in the community.The index of relative importance(IRI)above 1000 was defined as the dominant species.Only three dominant species,Macrobrachium nipponense,Synechogobius ommaturus,Parabramis pekinensis,accounted for 32.09% of the total catch in weight.Four diversity indexes,Wilhms index(H″),Margalefs index(R″),Pi- lous index(E″),McNaughtons index(D″),which were calculated by weight to analyze the characteristics of species diversity of fishery communities.The value of H″was 3 ,R″was 4.66,E″was 0.76 and D″was 0.22.The fishery community type in Xuliujing reach of the Yangtze River is the overlapping type of estuary fishery community and the fresh water fishery community.Compared with other sections of Yangtze River,the diversity of fishery com- munity in Xuliujing reach of the Yangtze River is in the medium level,while the community structure is unstable, and the community has the miniaturized tendency.根据2005-2006年间徐六泾河段进行的渔业资源调查，初步研究了徐六泾河段渔业群落结构和多样性。调查到鱼类48种、虾类3种、蟹类2种，分别隶属于12目20科44属，其中江湖半洄游性渔业生物（青鱼、草鱼等）6种、江海洄游性渔业生物（刀鲚、鳗鲡等）7种、近海河口类渔业生物（斑尾复缎虎、六带够等）9种，淡水定居性渔业生物31种。相对重要指数（IRI）大于1000的种类定为优势种，共有3种：日本沼虾、斑尾复缎虎、鳊．多样性特征值为：Wilhm改进指数（H〃）为3，Margalef指数（R〃）为4．66，Pilou指数（E〃）为0．76，McNaughton指数（D〃）为0．22．利用生态类型、个体生物学特征、多样性指数、相对重要指数等分析了徐六泾河段的渔业群落结构及多样性现状，表明徐六泾河段渔业群落属于河口渔业群落与淡水渔业群落交叉的类型，相比长江其他江段，多样性处于中等水平，但群落结构不稳定，有小型化趋势。