| The study were based on Chinese squid jigging vessel during January to April of 2018 in the eastern equatorial Pacific.In this paper,the combination of CTD and NASA satellite remote sensing was used to study the fishery environment,and the relationship between source with environmental factors of the fishing ground was analyzed by using GAM model and SI model.The effects of temperature,fishing techniques and la Nina on the habitat environment were studied.The distribution of mantle length(ML),body weight(BW),maturity stages and stomach stages from February to April were studied by method of frequency distribution.And the relationship between ML to BW and the first mature mantle length were obtained by fitting.The differences in growth of female and male squids between different months in the samples were discussed according to the remote sensing temperature based on sampling location.(1)2018 is the year of la Nina.Compared with the same period in 2017,the temperature of D.gagas's fishing ground in the eastern Pacific equatorial decreased by 1 to 2.5 degrees Celsius,and there was a significant difference in the two-year temperature change(P<0.001).In the first quarter of both 2017 and 2018,the sea surface temperature showed an upward trend.In 2017,the center of fishing ground was gradually approaching the eastern part of the Pacific and the coast of America with the increase of time and temperature.The center of fishing ground in 2018 is about eastward migration of 2° W.The days of the lunar calendar have a great influence on the harvest of the D.gaigas.there are two optimum temperature in both hemispheres,infer that there may be two stem Dosidicus gigas populations.(2)The result indicated that the ranges of both ML and BW in female squids were from 20 to 46.7 cm and from 240 to 3420 g respectively,and the average were(30.6±4.47)cm and(939.07±460.02)g respectively;while in males,the vales were from 22.2 to 42.5 cm ML and from 310 to 2270g BW respectively,and the average were(31.3±3.93)cm and(925.57±358.6)g respectively.The equation of the relationship between ML and BW was fitted by power exponent.The effect of gender on the exponent "b" of the BW-ML relationship was significant in the March,suggesting that there was a significant difference in the body growth between female and male individuals by the analysis of covariance(ANCOVA)(P3<0.01).There were also significant differences in the body growth among three months in the same gender(P2-3<0.01,P3-4<0.05).From February to April,the stomach stages of both males and females were mainly 1 to 2 with the ratio of higher stomach stages decreased month by month.The sexual ratio of female to male was 2.04:1.The maturity stages of males were mainly ? with the ratio of maturity increased month by month.The ML at first maturity of males is 32.72 cm.The maturity stages of females were mainly ? with ratio of immature accounted for more than 97%.The linear relation is suitable for ML and BW to maturity stages for both male and female squid.Based on the study of all results,the time from February to March is the period of rapid growth and development,especially for male individuals.However,after reaching April,the dominant group no longer grows.It is suggested that the maturity stages of males are quite earlier than the maturity stages of females,males matured individuals are highly possible leaving the equatorial waters and starting to migrate.(3)The equatorial stem and squid fishing in the East Pacific Ocean uses sea anchors to keep the hull at a basic rest on the sea surface and uses light to lure fish.The main fishing object of equatorial stem and squid fishing in the East Pacific Ocean is that there is basically no concurrent catch object for equatorial stem and squid fish,and the fishing object is less.The main fishing area is relatively fixed.But the area is huge,And there are a lot of fishery resources,so there is less competition.Squid fishing vessels not only need advanced fishing gear and fishing methods to increase production,but also need the support of related equipment.Existing squid fishing vessels,although the operation technology is advanced,But there are still some problems,there is some room for improvement. |
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