Comparisions Of Fishery Biology For Boreopacific Arm Book Squid,Gonatopsis Borealis In The West Northern Pacific Ocean Based On Statolith And Beak Microstructure

The Boreopacific armhook squid,Gonatopsis borealis is a commercial species with a wide distribution throughout the northwestern Pacific Ocean,and it plays an important role in the local marine ecological system.Understanding its fishery biology of Cephalopods is the basic of the scientific fishery resource development.In order to develop and management more efficient and scientific,in this study,biological characteristics,age and growth of G.borealis were studied by the relationship between microstructure and mantle length,body weight of statoliths,beaks.Based on the samples collected by Chinese jigging vessels in 2019 off the northwestern Pacific Ocean,we the estimated age of G.borealis by analyzing the relationships between morphology and individual size or age of statolith and beak microstructure.And comparision the microstructure,age,and growth of G.borealis were studied using statolith and beak microstructure.The results of this study could be summarized as follows:(1)Preliminary study on the biological characterisitics of G.borealis.The results indicated that the mantle length(ML)ranged from 212 to 314mm with high concentrations in 230mm to 290mm and 230mm to 270mm accounting for 88.69%and 88.24%for females and males,and the body weight(BW)ranged from 327g to 859g with dominative weights for 370g to 670g and 370g to 570g accounting for about 83.47%and 86.96%for females and males,respectively.The relationships between ML and BW for female and male were best described by the power and exponential function by the AIC(Akaike’s information criterion),respectively.The ratio of females and males was 1:0.5,and the samples were mostly composed of Ⅲindividuals accounting for more than 60%.The feeding stage was mainly in 1,2 and 3 grades accounting for about 95%of all the samples.(2)The relationships between statolith morphology and age,ML.The total statolith length(TSL),rostrum lateral dome length(RLL),lateral dome length(LDL),and wing length(WL)are considered as the indicators of dome growth.There were different sexes between RLL,TSL,WL and age by the analysis of variance(ANOVA).The relationships between MW,LDL,WL and age also exist differences for females and males.The relationships between statolith morphology and age were best described by linear and logarithm function,whereas between morphology and ML were power and exponential function.There were no sex differences between LDL,MW and absolute growth rate(AGR),instantaneous relative growth rate(IRGR).(3)The relationships between beak morphology and age,ML.The upper hood length(UHL),upper crest length(UCL),upper wing length(UWL),lower crest length(LCL),lower lateral wall length(LLWL),and lower wing length(LWL)are considered as the indicators of beak morphology.There were different sexes between morphology and ML by the analysis of variance(ANOVA),whereas no differences BW and age.The relationships between beak morphology and ML,BW and age were best described by linear and logrithm function.(4)The relationship between age and ML,BW based on statolith microstructure.The results indicsted that the average increments for female and male were 275.9d and 256.3d.There were different sexes between age and ML,BW by the analysis of variance(ANOVA).The relationship between age and ML was best described by power function,others were linear function.The AGR for ML and BW was decreased at early growth stage,and then increased,wheras IRGR was fluctuated.(5)The relationship between age and ML,BW based on beak microstructure.The results indicsted that the average increments for female and male were 266.4d and 243.3d.There were different sexes between age and ML,BW by the analysis of variance(ANOVA).The relationships between age and ML,BW were best described by linear function.The AGR and IRGR for ML were increased at early growth stage,and then decreased,wheras AGR and IRGR for BW was fluctuated.(6)A comparative study on the age and growth of G.borealis based on the microstructure of statoliths and beak.The increments of statoliths were similar to beak,the number of beak was lower than statolith.There were day increments and sub-day increments in statoliths and beak.The average increments of statolith and beak was 253 and 235.The relationship between increments and ML was best described by logrithmn exponential function,and BW was linear and logrithmn function.The AGR and IRGR were fluctuated with increments increased.Compared with the growth increments of the statolith,the overlapping of the increments of beak is difficult to observe due to the small size of G.borealis.Therefore,the statolith is more suitable for study of age and growth of G.borealis.