Study The Fish Resources In Jiulong River Estuary, Fujian

Estuary area which has complex physical and chemical conditions, is a suitable place forfishes breeding and nursery, and has an important impact on supplementting marine fishresources. Estuarine areas are also the areas with frequent human activity, it provides a greatnumber of goods and services. Jiu-long Jiang is the second largest river in Fujian Province, and itplayed an important role in economic development for Xia-men, Zhang-zhou and Long-hai City.Jiu-long Jiang estuary is an important fishing base for Xia-men and Long-hai city, which withabundant fish resources. Therefore the study on the fish resources of Jiu-long Jiang estuary hasan important practical significance: the survey results on estuarine fish resources provide advicefor the utilization of fish resources in the Jiu-long Jiang estuary, and provide a reference forlong-term study on the fishery resources of the Jiu-long Jiang estuary.This research was carried on the changes of fish resources in Jiu-long Jiang estuary fromSeptember2010to August2012. The sampling was operated in three sites of Jiu-long Jiangestuary monthly. In this paper, the changes of fish resource and the influence of water quality onfish community are studied, the results are as followed:1. There are210species of fish captured from Jiu-long Jiang estuary, belonging to145genus,73families and17orders.There are98species of fish captured in Zi-ni site,127speciescaptured in Fu-gong site and124species captured in Dao-mei site. This paper analyzed thechanges of dominant species in three sites: the season dominant species changes in the range of2-4species in Zi-ni site,3-5species in Fu-gong site and2-5species in Dao-mei site. Thenumbers of dominant species seasonly in Fu-gong site is more than in Zi-ni site and Dao-meisite.And the dominant species in Dao-mei site changes more frequently than other two sites.2. The changes of numbers in species, weight and number of catches are analysised in thispaper. The fishes captured from Fu-gong site has the most species numbers (23.1) than fromZi-ni site(18.1) and Daomei site(20.6). The average weight of fishes catched from Fu-gong site is22.07kg. It is more than the average weight in Zi-ni site (5.12kg) and Dao-mei site(1.53kg).Thebiggest catches are catched in summer and autumn in three sites.3. This paper analyzed the changes of biomass and bumbers of Stolephorus chinensis,Ambassis gymnocephalus, Sardinella zunasi, Tilapia mossambica, Coilia grayii, Mugilophuyseni and Clupanodon punctatus. Body length and weight of the7fishes are studied andfound that the dominant body length (and weight) team are young fishes. Based on measurement of body length and body weight data, the formula of realationship of body length and weight arecalculated. And the b value of Stolephorus chinensis, Ambassis gymnocephalus, Coilia grayii,Mugil ophuyseni and Clupanodon punctatus is smaller than3.0; the b value of Tilapiamossambica and Sardinella zunasi is close to3.0.The fishery biology parameters are calculated based on the data of body length of the7species. And the result shows that the exploitation rate (E value) of most the7fishes (exceptStolephorus chinensis) are bigger than0.5. The utilization of Stolephorus chinensis, Ambassisgymnocephalus and Tilapia mossambica are moderate. And Coilia grayii, Mugil ophuyseni andClupanodon punctatus are over-used.4. The effects of Water environmental on fishes are analyzed by CCA method based on thedata of fish abundance and water environmental factors. The results show that the mostimportant factors affected fish communities are salinity, temperature and melting oxygen. The7dominant fishes are influenced by different environmental factors: Sardinella zunasi is mostaffected by salinity and temperature, Tilapia mossambica is affected by the negative influence ofsalinity, Stolephorus chinensis is affected by salinity and DO, all the rest fishes are influenced bythe negative influence of salinity.