| Chelidonichthys kumu,commonly known as green-winged fish,belonging to genus Chelidonnichthy of family Triglidae,is a secondary economic species in the East China Sea.The taste of C.kumu is firm and delicious,and it has high economic values,which leads to a certain market shares.In this paper,the author used monitoring data of single trawl fishery from 2017 to 2018 plus investigation data from 2008 to 2009 to understand the status quo of fishery resources,the resource structure,reproductive characteristics,feeding habits and spatial and temporal distributions of C.kumu in the East China Sea.The main results are list as follows:1.The length of C.kumu varied from 65 mm to 346 mm,and individuals with body length ranging from 150 to 240 mm accounted for 79% of the total.The weight varied from6 g to 798 g,and individuals with weight ranging from 1g to 300 g accounted for 90% of the total.According to the uniformed body-weight growth equation,the species allometric growth.The average catch rate of C.kumu in spring,autumn and winter was 0.22 kg/h,23.40 kg/h and 2.69 kg/h,respectively.The CPUE varies with seasons: CPUE reached highest in autumn and lowest in spring.2.In fertility samples,the minimum body length was 134 mm and the minimum body weight was 44.2g.In April,the female were with the highest sexual maturity index,reaching 8.9.According to the study,the breeding season is from March to May,and the peak period is from April to May.The absolute fecundity Emean ranged from 19,305 to126,878 eggs,and the average absolute fertility Emean ranged from 2,787 to 10,592 eggs.The individual relative fertility of unit length(F/L)fluctuated between 59 and 379 eggs,and the individual relative fertility of unit weight(pure weight,F/W)fluctuated between 69 and 612 eggs.The diameters of 154 fish eggs with IV~V ovarian were measured,and results showed that the egg diameter ranged from 0.31 to 0.74 mm.From the distribution diagram of egg diameters,it only had one peak: the egg diameter between 0.43 mm and0.49 mm in the ovary of stage IV~V took up the highest proportion accounting for 40.26%,from which it can be inferred that the C.kumu spawns once a year.3.The food species of C.kumu are abundant.In general,there are 15 types including Euphausiacea,Natantia,Pisces,Mysidacea and Stomatopoda.Among them,Euphausiacea,Natantia and Pisces,are the most important bait groups.The dominant bait are Euphausia pacifica,Parapenaeopsis tenella,Crangon affinis and Chaeturichths hexanema.In terms of food composition,the main ingestion of the C.kumu in each body length group differs,but main species are Natantia,Mysidacea,Euphausiacea and Pisces.The feeding habits with length ranging from 39 to 432 mm changed significantly.In winter,the feeding intensity gradually decreased to 0(i.e.,the empty stomach)and the empty stomach proportion accounting for 43.97%,which was significantly higher than rest seasons(28.47% and 40.54% in spring and autumn respectively).4.The C.kumu mainly distribute in the south-east part of the Yangtze estuary fishing ground and north-east and south east part of Zhoushan fishing ground.It can be inferred that the sea environment in these areas are suitable for the growth and reproduction of C.kumu.The inhabiting depth of the C.kumu is about 30 to 80 m,the temperature is between 11 to 18°C,and the salinity is between 32 to 34.Thus,C.kumu belongs to high salinity type.Finally,according to biological characteristics and resource status of the C.kumu,the author proposes the suggestion to rationally develop and utilize resource,which may provide a scientific reference for the sustainable use of fishery resources in near future. |
