Influence of Peruvian upwelling on the anchoveta (Engraulis ringens) fishing ground

Anchoveta (Engraulis ringens) forms the largest production in the world’s single species fishery. Therefore, study of the relationship between the Peruvian upwelling and E. ringens fishing ground could help understand the mechanisms about the formation of this fish’s fishing ground. Therefore, Our study aims to summarize the regularity of the upwelling and temperature to the E. ringens fishing ground formation. In this study, we used the upwelling velocity (UV) as the index of Peruvian upwelling, and combined the temperature (T) and temperature anomaly (TA) data in the fishing ground from 2005 to 2009 to analyze their effects on the fishing ground which was indicated by the nominal catch per unit effort (CPUE). The results showed that UV, T and TA in the fishing ground was 1.42×10^–5—7.44×10^–5 m/s, 16.61~19.42 °C and 1.87—1.69 °C, respectively. In addition, we used the generalized additive model (GAM) to analyze the influence of environmental factors on CPUE. The GAM could explain the changing trend of nominal CPUE as 67%. The optimum range for each environmental factor based on GAM was UV: less than 4.5×10^–5 m/s; T: 18.4—19.5 °C and TA: –2—0.2 °C. When UV was lower than 4.5×10^–5 m/s, the CPUE nearly remained the same with UV. However, when UV was higher than this value, the GAM showed the decreasing trend of CPUE. The studies suggested that the upwelling's impact to the E. ringens fishing ground was not following the pattern " the higher, the better”. There was also optimum range of upwelling velocity for the fishing ground. the results indicated that the optimum sea surface wind, moderate upwelling and appropriate temperature condition were beneficial to the fishing ground formation.