Some correlations between CPUE series of hake (Northern Stock)

Abstract

This document describes results of computing correlations between different CPUE series of hake (Northern Stock). Results show that significant correlations between some series appeared when same lag was allowed between series. Lesconil artisans CPUE (fishing in division VIlla) in year t seems to be correlated to CPUE La Rochelle "artlsans" on the same year, to La Coruña trawlers fishing in subarea VII on year (t+1) and to La Rochelle "hauturiers" fishing in subarea VII on year (t+3) ; these "hauturiers" CPUE is correlated with Lorient trawlers CPUE fishing in divisions IVa + VIa two years later. These correlations allow to become more confident on these CPUE series. However, it is difficult to believe that plots like the one in fig. 7 can prove that there is a direct cause to affect relationship between hake CPUE from "artisans" in subareas VII and VIII and hake CPUE from "hauturiers" fishing in divisions IVa + VIa two years later.