Analysis of variation of yield value by set net fishing boat in Shanghai Fengxian District

Abstract:

Sea area along Fengxian District is located in the northern Hangzhou Bay,where the migratory fish such as Coilia mystus,Pampus argenteus, etc must pass through for spawning and feeding migration.Set net is the only way for fishing in this sea area,so studying on the variety of yield and yield value from a set net fishing boat is very helpful to evaluate the current fishing income on the sea along Fengxian District.As no study has been carried out investigating the variation of yield value and value per unit effort (VPUE) from set net fishing boat on the sea along Fengxian District, the methods of curve estimation and cluster analysis were applied in this study to evaluate the variation of yield value and VPUE,which may be helpful to find out the relationship among yield, yield value and VPUE from a set net fishing boat in Fengxian District(from May 2009 to October 2012).The results indicated that yield value and VPUE from set net fishing boat increased year by year,yield value and VPUE in 2009 was 205.7 thousand yuan and 44.59 yuan per net respectively,and in 2012 increased to 313.5 thousand yuan and 61.98 yuan per net respectively.Yield and VPUE had no significant correlation (P=0.501>0.05),but yield value and VPUE had significant correlation(P=0.008<0.05),and the relationship between yield value and VPUE can be expressed as following equation: y= 33.812lnx + 5.3808.In seasonal variation of VPUE,there was no significant correlation between spring and summer(P=0.093>0.05),there was also no significant correlation between spring and autumn(P=0.165>0.05),but there was significant correlation between summer and autumn(P=0.008<0.05).The research showed that it was inadvisable for fishman to pursue profits by maximizing total catch and they should increase yield and proportion of commercial fishes,which can not only increase fishing income,but also promote protection of juvenile fish and recovery of fishery resources.