General Situation And Change Rule Of Main Economic Fish Resources In Dongjiang River Basin

Dongjiang river is one of the major rivers in the pearl river system.It originates from Xunwu town of Jiangxi province,which flows through Heyuan city of guangdong province,and goes to sea in Humen town.Dongjiang river has three large reservoir,as well as the Dongshen water supply project of water supply in Hong Kong,and there are many tributaries,for Jiangxi and Guangdong provinces with abundant water and fishery resources.This study in July 2013 to December 2016,the Dongjiang river to carry out the field data collection,gathering place respectively in the Dongjiang river,17 sampling points were set up,divided into five basin:Xunwu,Beiling,Heyuan,Humen,Zengcheng.Mainly collecting data for the local fish species,and the species composition,Seasonal dominant species of each basin,in order to understand the changing rule of Dongjiang river.Provide the basis for utilization and protection of fish resources.The results are as follows:1.In this survey,140 species of fish were found in the Dongjiang river basin,belonging to 14 contents,42 families and 108 genera.Among them,the most species are Cypriniformes,followed by Perciformes,and the third one is Siluriformes,while the remaining number is less than 10.2.From the composition of the fish,Beiling,Heyuan and Zengjiang are similar,The fish composition of Humen is the largest and most special among the other parts of the river.Due to its location in the mouth of the estuary,there are many species of fish in the estuary.3.There are 50 major economic fishes in Dongjiang basin,accounting for 35.71% of the total number of fish.Most economic fish ecological types belong to the sedentary nature;According to the food sex division,the omnivorous fish is the majority;According to the habitat environment division,there are more benthic fish.4.Based on the fish species data obtained in recent years,with Index of Relative Importance.The seasonal dominant species of five river segments were analyzed,and the variation patterns of fish dominant species in different seasons were analyzed by using the dominant species replacement rate(r).The results showed that the dominant species of fishes had obvious seasonal alternates.Among them,the change rule of Beiling,Heyuan and Humen are consistent;However,there is no obvious change rule of the seasonal change in the search for Xunwu and Zengjiang basin.5.The annual IRI value was calculated to determine the importance of fish in their community.And we found that there is an ecological phenomenon of miniaturization of economic fish in Dongjiang river basin.6.from the statistics of the ABC curve of the fish community structure in the east river,The structure of the fish community in Xunwu basin was undisturbed.The structure of fish community in Humen and Zengjiang basin was disturbed to a certain extent.7.According to the Comprehensive biological diversity index(H?)and other indicators,The index of Xunwu and Heyuan is relatively good.The biological diversity index(H?)and species richness index(D)of Beiling is the lowest.In Humen and Zengjiang basin,the uniformity index(J?)and the concentration index(C)are more than other basin.8.In recent years,the fish catches in each section of the river are counted.The value of fishing in Heyuan basin is the largest,and the fishery value of Humen basin is the lowest.The body length and weight of the main economic fish were basically the same.9.In comparison with historical data,there were 73 species of fish in the study.There were no 32 species in this survey,and 67 new species were added.It can be seen that as the environment changes,fish resources are affected,and there is a big change.10.By analyzing the influence of human activities on the ecosystem of Dongjiang river basin,the corresponding development and protection Suggestions are given:(1)Protect endemic species and maintain biodiversity.(2)We will ensure natural reproduction conditions and strengthen the work of artificial reproduction and release.(3)Control the pollution status and maintain the diversity of estuarine fish.(4)We will implement the ban on fishing and ban overfishing.(5)Scientific introduction to prevent biological invasion.