Assessment Of Important Fishery Resources In The South Offshore Of Shandong From 2010 To 2017

Due to factors such as overfishing and environmental pollution,the deline of fishery resources in China is extremely serious.In August of 2010 to 2017,42 stations in the southern part of Shandong Province were surveyed by single trawl sampling.The composition of species,quantity and weight,and dominant species,stock assessment,ecological characteristics were studied using methods of comparative analysis.Quantity,and weight distribution were analyzed by Arc GIS 10.0 software.The results are as follows:1.There were 73 species of fishery resources captured in the offshore survey in southern Shandong,including 47 species of fishes,19 species of shrimps and crabs,and 7species of cephalopods.The species with high economic value are composed of a maximum of 25 species of fish,13 species of shrimps and crabs,and 7 species of cephalopods.According to the proportion of the economic quality of fishery resources,the proportion of fishery resources with high economic value is relatively large revealing the high economic value of fishery resources in the offshore waters of southern Shandong.2.In August of 2010 to 2017,the number of species whose proportion of annual quantity reached more than 1%is 11 including Engraulis japonicus,Metapenaeopsis dalei,Trachypenaeus curvirostris,Oratosquilla oratoria,Enedrias fangi,Scomber japonicus,Loligo japonica,Chelidonichthys kumu,Charybdis bimaculata,Fenneropenaeus chinensis,Konosirus punctatus,accounting for 15.07%of the total number of fishery species.Due to the short life cycle,strong ability of adaptability and reproduction,and the implementation of the stock enhancement and releasing project in each summer of shrimps and crabs in recent years,shrimps and crabs trend to become the main economic category to replace the status of high quality fishes.3.There are 20 fishery species captured in August of 2010 to 2017 that accounted for more than 1%of the total annual weight including Engraulis japonicus,Metapenaeopsis dalei,Rhopilema esculehtum,Trachypenaeus curvirostris,Oratosquilla oratoria,Scomberomorus niphonius,Lepidotrigla micropterus,Setipinna taty,Enedrias fangi,Scomber japonicus,Loligo japonica,Todarodes pacificus,Conger myriaster,Portunus trituberculatus,Octopus variabilis,Lophius litulon,Apogon sp.,Chelidonichthys kumu,Larimichthys polyactis,Konosirus punctatus.These species account for 27.40%of the total number of fishery species.From 8 years of survey data,fishes are still the main economic category,followed by shrimps and crabs,and the proportion of cephalopods is the smallest.Only 30%of the pelagic fishes are captured in the fishery resources,and 70%are found in benthic fishes,shrimps and crabs,and cephalopods.4.In August of 2010 to 2017,the survey investigated five dominant species in the southern coastal waters of Shandong Province,including Engraulis japonicus,Metapenaeopsis dalei,Conger myriaster,Enedrias fangi,Oratosquilla oratoria.At present,there are too few dominant species of fishery resources,and the summer fishing moratorium provides guarantee for the sustainable use of fishery resources.The relevant departments should strengthen the monitoring of the summer fishing moratorium,reduce the occurrence of poaching,and ensure that the summer fishing moratorium will achieved its expected results.5.In August of 2010 to 2017,the existing fishery resources in the southern part of the Shandong Peninsula are 2.32×10~6t,1.67×10~6t,3.55×10~6t,3.49×10~6t,3.76×10~6t,1.46×10~6t,3.78×10~6t,2.65×10~6t,respectively.In Shandong's offshore fisheries,the composition of catches tends to be low-value,small-scale individuals and invertebrate resources.The value of fishery resources is decreasing,and the economic value structure of fishery resources is becoming increasingly low.6.According to the survey data of offshore fish in the southern part of Shandong from 2010 to 2017,the species richness index of this area is between 1.03±0.24 and1.82±0.54,and the species diversity index is between 1.01±0.16 and 1.67±0.46.The evenness index is between 0.43±0.31 and 0.64±0.23.There are some interannual differences in the ecological characteristics of fish in the offshore areas of southern Shandong,but the interannual variation is relatively small.7.The relative quantity densities of fishery resources are relatively high in 2010,2013,and 2016,and the lowest in 2011.In geographical distribution,the relative quantity density of Qinghai fishing area near Qingdao is relatively high,and fishery resources are abundant.The relative weight density of fishery resources was relatively high in 2012,2013,2014 and 2016,and low in 2011 and 2015.The distribution of relative weight density and quantity density in some years is inconsistent,which is related to the migration of large pelagic migratory fishes and the level of primary productivity in some regions.