A Survey on Species Diversity in Elver Nets in Yangtze River Estuary
In order to explore the species composition of elver nets in the Yangtze River Estuary after the Yangtze River fishing ban,a total of 118 elver nets were collected in the waters outside the northern boundary of the Yangtze River Estuary Fishing Ban Area(31°42'N-31°43'N,122° 10'E-122° 16'E)from February to April 2023.A total of 5 482 bycatch fish were collected,belonging to 25 families,47 genera,and 64 species.Among them,there were 26 species of marine fish,31 species of estuarine fish,5 species of migratory fish,and 2 species of freshwater fish.The developmental stages included from the post-flexion stage to the adult stage,of which fish larvae accounted for 52.39％of the total number of bycatch fish,followed by juvenile fish 23.61％.According to the relative importance index(IRI)analysis results,the dominant species were Chaeturichthys stigmatias and Odontamblyopus lacepedii.The important species were Coilia nasus,Protosalanx hyalocranius,Neosalanx anderssoni,Cynoglossus lighti,Mugil cephalus,Thryssa kammalensis,Neosalanx tangkahkeii,Coilia mystus,and Collichthys lucidus.These 11 species accounted for 84.77％of the total number of bycatch fish,accounting for 87.51％of the total weight of bycatch fish.The number of bycatch fish was the highest in February,lowest in April.The weight of collected fish showed same tendency.There were 47 economic fish collected,44.13 ind./net.In addition,1 363 larval eels were collected.One larval eel in each 3.82 economic fish was collected.The results showed that the elver nets not only causes damage to target fish,but also caused serious damage to bycatch fish,as well as individuals in the early development stages of some economic fish.
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万方数据
