Habitat model optimization of purpleback flying squid inhabiting South China Sea and its seasional change
FAN Jiangtao
FENG Zhiping
YU Wei
MA Shengwei
CHEN Xinjun
Abstract：Purpleback flying squid(Sthenoteuthis oualaniensis)is a cephalopod species with high eco-nomic values.It is largely exploited by Chinese fishing vessels in the South China Sea.The location of fishing ground showed seasonal differences,which may be related to habitat distribution of this squid species.Based on the fisheries data of S.oualaniensis in the South China Sea from Spring to Autumn,2014-2017,and by combining with key environmental factors each season including water temperature at 50 m(Temp_50 m),chlorophyll-a concentration(Chla)and mixed layer depth(MLD)in spring,sea surface temperature(SST),Chla and water temperature at 100 m(Temp_100 m)in summer,and SST,Chla and MLD in autumn:,a weighted-based habitat suitability index(HSI)model was devel-oped in this study.The optimal HSI model was selected each season to predict the HSI value.The sea-sons,spring and autumn,were taken,for example,to compare the habitat patterns and further exam-ine the impacts of the strong El Nino events on S.oualaniensis habitat.The results suggested that the selected optimal HSI model can accurately predict the fishing ground of S.oualaniensis,with the mod-el precision of 86％in spring,75％in summer and 76％in autumn.The area of the suitable habitat with HSI＞0.6 and the optimal suitable habitat with HSI＞0.8 enlarged in spring comparing to the au-tumn,and the optimal habitats were widely distributed in the northern waters of the South China Sea.While the habitat suitability in autumn clearly decreased,the optimal habitats in Zhongsha and Nansha Island mainly disappeared,with a few occurred in the northeastern waters.From a spatial perspective,the latitudinal gravity centers of the optimal habitats in spring during 2014-2016 moved northeastward relative to the habitat in autumn,whereas the poor habitat with HSI＜0.2 shifted southwestward.Comparing the year of 2014 with normal climate condition with the year of 2015 with strong El Nino e-vent,it was found that the area of the optimal habitats significantly decreased and the poor habitats dramatically increased.Our findings suggested that the HSI model based on the weighted-based algo-rithm and key environmental factor could be applied to predict habitat hotspots of S.oualaniensis in the South China Sea.The habitat pattern showed seasonal difference,and the strong El Nino event yielded profound negative effects on habitat suitability of S.oualaniensis.
Keywords：Sthenoteuthis oualaniensiskey environmental factorweighted-based algorithmseasonal differencehabitat suitability index modelSouth China Sea
Publication Date：2024-10-28
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：10( 111-120 )