嫩江干流嫩江市段鱼类多样性调查OA

To clarify the current status of fish diversity and the changing trend of fishery resources in the Nenjiang River mainstream at Nenjiang City section,the survey team conducted two special investigations from September 13 to 17 and September 24 to 28,2024,covering the Bilianshan section,the back beach section behind Fanrong Vil-lage,and the Nenmo Floating Bridge section of this river section.Combining the methods of net fishing monitoring,market visits,and on-board observation,the specifications and layout plan of fishing nets were determined,and the Index of Relative Importance(IRI)and Shannon-Wiener diversity index were used to quantitatively analyze the community characteristics of fish.The results showed that a total of 34 fish species were recorded in the survey are-a,belonging to 4 orders,10 families,and 30 genera,with a cumulative catch of 948 individuals and a total weight of 59.89 kg,and an average catch of 28 individuals/1.78 kg per net operation.Cypriniformes accounted for 67.65%(23 species),which was the dominant group.The classification of IRI index showed that the dominant species in the first survey were Hemibarbus maculatusand Gobio cynocephalus(showing a miniaturization trend),while those in the second survey were Leuciscus waleckii and Opsariichthys bidens.The sectional diversity indices indicated that the Shannon-Wiener index(H′)ranged from 1.6 to 2.0,the Pielou evenness index(J′)from 0.52 to 0.63,and the Margalef richness index(D)from 4.21 to 4.87,all at a relatively low level.Compared with the historical record of 66 species,the number of species decreased by 48.48%,indicating a significant decline in fishery re-sources.