Study On Energy Density Of Potential Bait Fish Of Chinese White Dolphin In Sanniang Bay

With the frequent activities of human oceans,the environment of the estuary is deteriorating.The Chinese white dolphins that prefer the estuary habitat are on the verge of extinction.This study is mainly carried out in the Sanniang Bay-Dafeng River area of the activity area of the Chinese White Dolphin.According to the study of the four stations and the different seasons in the study area in 2017-2018.The species composition and dominant fish species in the sea area were counted.In the case of fish,the biodiversity of different stations was analyzed from the number of species,and the ABC curve was used to initially explore the degree of environmental disturbance caused by the stability of the biocommunity in the study.The results showed that a total of 35 species of fish were captured in this survey,belonging to 8 orders and 25 families,of which the most abundant perciformes was 57.1%of the total catch;the relative importance index of the dominant species in the sea area is the highest in IRI fish.Nematalosa japonic(IRI=4869.26)and Konosirus punctatus(IRI=4189.12);through the comparison of biomass at different sites,it is found that the reclamation will have a certain impact on the species of fish.Combined with the biomass curve and the quantitative curve in the ABC curve,the W value is 0.049,and the sea area is disturbed by moderate pollution.Strengthen the management of the Sanniang sea area to protect the population of Chinese white dolphins in the Sanniang Bay area.In this study,24 species of fish were collected from the Chinese white dolphins activity area in Sanniang Bay,and their nutrition and energy were measured.According to the fish’s different order,niche,season and station,the fish were mainly analyzed.Nutritional components of fat and protein were analyzed by univariate analysis.From the perspective of the known Chinese xwhite dolphin known bait fish,the energy density changes of the Chinese white dolphin eating bait fish were discussed.The main conclusions are as follows:The test results showed that there was no significant difference in energy density between the other orders except for Aulopiformes.Mugiliformes has the highest energy density(11.675 KJ/g),followed by the Perciformes(11.295 KJ/g);In terms of niche,the energy density of the demersal fish(11.483 KJ/g)is higher than that of the pelagicneritic(11.144 KJ/g)and the benthopelagic(6.683 KJ/g),respectively.In spring(11.336 KJ/g)and summer(11.384KJ/g),the energy density is higher in autumn(11.091 KJ/g)and winter(10.676 KJ/g),with the lowest in winter.The analysisfound that there is a significant difference between station Ⅰ-Ⅳ and Ⅱ-Ⅲ and the energy density of stationⅡ-Ⅲ is higher than that of Ⅰ-Ⅳ station.The energy density of station is related to land reclamation.In terms of protein and fat nutrients,Mugiliformes has higher protein and fat than other different orders.Between different niches,the range of fat is 13.9%～17.8%,the range of protein is between 11.6%～22.6.The protein and fat content are the highest in the demersal,and the benthopelagic is relatively low.In terms of fat,the order of fat is from Ⅱ>Ⅳ>Ⅲ>Ⅰ,and the fat content of the four stations is relatively close.In terms of protein,Ⅱ has the highest content,Ⅲ times,I has the lowest content,and the protein content between stations is not much different;In different seasons,the order of fat from big to small is spring>summer>winter,and the fat content in summer and close.In terms of protein,the content in summer is the highest,followed by spring and the lowest in winter.In the analysis of the known bait fish,Nematalosa japonica,Konosirus punctatus,Clupanodon thrissa,and Thryssa hamiltonii,the energy density of Japanese sea otters is generally higher than that of the other three types of fish,regardless of the location or season.