CATCH PER UNIT EFFORT(CPUE)STANDARDIZATION OF PURPLEBACK FLYING SQUID STHENOTEUTHIS OUALANIENSIS FOR CHINESE LARGE-SCALE LIGHTING NET FISHERY IN THE NORTHWEST INDIAN OCEAN
Catch Per Unit Effort(CPUE)is a fundamental premise and basis for fisheries resource assessment.To better evaluate the abundance of purpleback flying squid Sthenoteuthis oualaniensis in the Northwest Indian Ocean,understanding the relationships between squid resource distribution and spatio-temporal as well as marine environmental factors is crucial.Utilizing generalized linear models(GLM)and generalized additive models(GAM),this study standardized the CPUE for the Northwest Indian Ocean S.oualaniensis light purse seine fishery from 2015 to 2021,integrating these factors to assess their impact on CPUE.The GLM results indicated significant influences from six variables:Year,Month,Longitude,Latitude,Sea Surface Temperature(SST),and Chlorophyll a concentration(chl a).A GAM incorporating these six significant variables was constructed,and its optimality was confirmed by comparing the Akaike information criterion(AIC)values across different models,showing the lowest AIC and an explanatory rate of 37.80% for CPUE variability.The study reveals that high CPUE mainly occurs from September to March,between 13°N to 20°N and 58°E to 66°E,with SST ranging from 26.0 to 29.0 ℃ and chi a from 0.07 to 0.73 mg/m3.Overall,the GLM and GAM-based standardization studies of CPUE for the S.oualaniensis light purse seine fishery in the Northwest Indian Ocean effectively reflect the fluctuations in squid resource abundance.
Sthenoteuthis oualaniensisnorthwest Indian oceanlarge-scale lighting netCPUE standardizationgeneralized linear model(GLM)generalized additive model(GAM)