CPUE Estimation and Standardization Based on VMS: A Case Study for Squid-Jigging Fishery in the Equatorial of Eastern Pacific Ocean

Different fisheries, even the same fishery, use different ways of quantifying fishing efforts such as the number of vessels, days, voyages, and hooks. In squid-jigging fisheries, fishing hours, fishing days, and the number of vessels are valid units for calculating the catch per unit effort (CPUE). A vessel monitoring system (VMS) provides vessel position data with high spatial and temporal resolution and offers the possibility to quantify the CPUE at a finer scale. Using the squid fishery in the equatorial waters of the eastern Pacific as a case study, the CPUE was evaluated and standardized based on VMS data. The drifting operating points of the squid fishing vessels were filtered by the speed threshold, solar radiation, and operating time setting methods, leading to the number of fishing hours per day, and the nominal CPUE was calculated by combining the catch data obtained from logbooks. Then, the generalized linear model (GLM) and generalized additive model (GAM) were applied to conduct CPUE standardization considering spatiotemporal factors and environmental variables including sea surface temperature (SST), sea surface salinity (SSS), sea surface height (SSH), and chlorophyll-a (Chl_a). The results showed that month, latitude, SST, SSH, and Chl-a all have a high significant effect on CPUE as demonstrated through the significance test conducted by GLM. The GAM including the significant factors was judged to be the best model according to the AIC guidelines. The latitude range for high CPUE in the fishery was 3 degrees S similar to 0 degrees S, SST range 24 similar to 25 degrees C, SSH range 4 similar to 8 m, and Chl_a range 0.15 similar to 0.20 mg/m(3). In addition, the nominal and standardized CPUEs were compared based on fishing hours and fishing days. The results indicated that the two types of CPUEs were highly related hence there was no significant difference.

Automated summary

Different fishing efforts are quantified using various units such as vessel numbers, days, voyages, and hooks. In squid-jigging fisheries, valid units for calculating catch per unit effort (CPUE) include fishing hours, fishing days, and vessel numbers. Using a vessel monitoring system (VMS), CPUE in the equatorial waters of the eastern Pacific was evaluated and standardized based on factors like sea surface temperature and chlorophyll-a. The results showed significant effects of factors like latitude and sea surface temperature on CPUE, and the standardized CPUE was highly related to the nominal CPUE.