SPATIO-TEMPORAL DISTRIBUTION AND INFLUENCING FACTORS OF COILIA NASUS IN SEA AREAS OFF JIANGSU BEFORE FISHING BAN IN CHANGJIANG RIVER
To understand the resource status of Coilia nasus in the sea areas off Jiangsu,South Yellow Sea,and provide better supporting data for the evaluation of the effectiveness of the 10-year fishing ban plan in Changjiang River that started in January 1,2020.Four seasonal fishery resource surveys were conducted in the sea area(31°45′～35°00′N,119°30′～125°00′E)in May(spring),August(summer),November(fall)2017,and February(winter)2018.The distribution of stock resource density and weight resource density of the current situation of C.nasus resources was mapped using SPSS 26 software.Results show that the C.nasus populations distributed in the offshore areas of Jiangsu Province in the spring and summer or in the outside of the waters between the"line of closed fishing area for bottom trawed fishery by motorboat"and the coastline of Jiangsu Province in the fall and winter.In the spring,many environmental factors affected the distribution of C.nasus,including water temperature,salinity,dissolved oxygen,depth,and transparency because C.nasus were at the peak of spawning and were sensitive to environmental changes in spring.In the summer,the environmental constraint on the distribution of C.nasus in the study area was transparent,the species had just finished spawning and needed to replenish energy after returning to the offshore area,and thus nutrient-rich materials became the important constraint to the distribution.In the fall,water temperature decreased,and C.nasus began to migrate to the over-wintering ground,the water temperature became the main influencing factor.In the winter,the degree of sex maturity of C.nasus increased,a new round of spawning migration began,the depth of habitat layer of the species rose up,and thus the water depth became the key limiting factor.Compared in the size of C.nasus reported by other researchers after the fishing ban implementation in the Changjiang River,the species size of C.nasus showed a gradual increase trend,and the length and weight began to increase steadily,showing good outcome of resource recovery of C.nasus population in the river.
Coilia nasussea areas off Jiangsuspatio-temporal distributionenvironmental factorsthe effect of fishing ban
NETL
NSTL
万方数据
