Annual Change Of Temperature, Salinity, The Catch Composition And Fishing Ground Of Stow Net In The Southern Yellow Sea During Spring

Based on the oceanography and fisheries data collected from stow net located in the Lüsi, Dasha fishing ground in the southern Yellow Sea in April ~ May in 2006 ~ 2009, the yield,composition of the catch,fishing ground distribution and their relationships with the environmental factors were analysed. The amount of Yangtse River runoff and the relevant SST and SSS in the fishing ground could be the important reference for fisheries forcasting. We summarized the profile of anchor fishing net in Lüsi, Dasha fisheries,then clarified the the relationship the annual change of the composition of the catch and environmental factors, environmental factors refer to Lüsi, Dasha fisheries distribution of fishing ground in the Lüsi, Dasha spring fisheries, to provide theoretical basis for Lüsi, Dasha fisheries management.The results were as follows:1. Sea surface temperature(SST) were 9.6℃,11.9℃,11.7℃,11.1℃in spring of 2006 ~ 2009 respectively. In the same period sea surface salinity(SSS) and the amount of Yangtse River runoff changed every year. Salinity range were 31.2‰～34.8‰,28.7‰～32.6‰in spring of 2007 ~ 2008 respectively. The Yangtze river runoff each years flat in January~ February in 2006 ~ 2009. The size of the Yangtze river runoff in turn were 2009≥2006>2008>2007 in April ~ May in 2006 ~ 2009.2. Distribution of Fishing effort amount had certain changes with time extending in different voyage in the same year,but the changes tend to disaccord in spring of 2006 ~ 2009.3. The voyage catch were 933.8kg,1278.4kg,1086.9kg and 1369.1kg per net in spring of 2006 ~ 2009 respectively. The percentage of economical fishes in catch were 21.09%,5.84%,8.71%,1.11% for Pseudosciaena polyactis,Pampus argenteus,Lophius litulon and Scomberomorus niphonius respectively, followed by 10.15% for crab, and 53.09% for Setipinna taty and other low-quality yield altogether.4. Annual change of composition of the catch appeared marked in spring of 2006 ~ 2009. Catch of Pseudosciaena polyactis maintained higher yield in early April 2006 and in late April of 2007 ~ 2009. Catch of Pampus argenteus increased generally in early May,but declined in 2009. Catch of Scomberomorus niphonius appear sporadic after early April,composition of its catch was low.5. The fishes tend to nearshore gradually when SST increased in spring every year; and in different years, the main fishing location became more inshore when SST increased and offshore when the amount of Yangtse River runoff rised. It could lead to SSS's decreasing and main fishing location'moving offshore for about 20～50 n mile that the amount of Yangtse River runoff increased from 17000 m~3/s to 24000 m~3/s in April.