Abstract. A group of small pelagic fish captured between 1981 and 2012 within El Niño area 1–2 by the Ecuadorian fleet was correlated with the oceanographic Multivariate ENSO Index (MEI), and the Oceanographic El Niño Index (ONI) referred to El Niño region 3–4. For the period 1981–2012, total landings correlated poorly with the indexes, but during 2000–2012 (cold PDO) they proved to have a 14–29 % association with both indexes; the negative slope of the curves suggested higher landing during cold events (La Niña) and also indicated a tendency to decrease at extreme values ( >  0.5 and  < −1.0). Round herring (Etrumeus teres) fourth-quarter (Q4) landings were related to the MEI in a nonlinear analysis by up to 80 %. During moderate or strong La Niña events landings noticeably increased. Bullet tuna (Auxis spp.) catches showed a negative gradient from cold to warm episodes with an R2 of 0.149. For Chilean jack mackerel (Trachurus murphyi) irregular landings between 2003 and 2007 were observed and were poorly correlated (R2 < 0.1) with ONI or MEI. Anchovy (Engraulis ringens) captured in Ecuadorian waters since 2000 had an R2 of 0.302 and 0.156 for MEI and ONI, respectively, but showed a higher correlation with the cold Pacific Decadal Oscillation (PDO). South American pilchard (Sardinops sagax) was higher than −0.5 for the ONI and MEI, and landings dramatically decreased; however, Q4 landings correlated with ONI and MEI, with R2 of 0.109 and 0.225, respectively (n = 3). Linear correlation of Q4 indexes against the following year's Q1 landings had a linkage of up to 22 %; this species could therefore be considered a predictor of El Niño. Chub mackerel (Scomber japonicus) landings did not have a significant linear correlation with the indexes for 1981–2012 and therefore could not be considered a valid predictor. Chuhueco (Cetengraulis mysticetus) is a local species with high landings during El Niño years and, conversely, remarkably low landings during La Niña years. Additionally, chuhueco availability and landings were negatively affected by cold PDOs. Pacific thread herring (Opisthonema spp.) showed a 24 and 36 % relationship between landings (Q1) and the MEI and ONI (Q4). Therefore, results suggest that the South American pilchard and Pacific thread herring could be considered good species to use as predictors of El Niño in region 1–2 (Ecuador), especially when average Q4 MEI ∕ ONI is used against the next trimester Q1 landing. All species were prone to lower landings and/or fishing availability during strong–extreme events (ONI/MEI,  >  1.0 and  <  −1.0), and were also shown to be affected by the PDO. In the long term, landings decreased under warm PDO and vice versa, and therefore PDO fluctuations could be used to help manage these fisheries and to help the industry in long-term planning.

Abstract. Skipjack (Katsuwunus pelamis), yellow fin (Thunnus albacares) and albacore (Thunnus alulunga) tunas landed in the Eastern Pacific Ocean (EPO) countries and Ecuador were correlated to the Indexes Oceanic El Niño (ONI) and Multivariate Enso Index (MEI). The temporal series 1983–2012, and 1977–1999 (warm Pacific Decadal Oscillation, PDO), and 2000–2012 (cold PDO) were analyzed. Linear correlation showed that at least 11 % of the total landings were associated with the MEI, with a slightly negative gradient from cold to warm conditions. When non-linear regression (n  =  6), the R2 was higher up to 0.304 (MEI, r =  0.551). The correlation shows high spread from −0.5 to +0.5 for both MEI/ONI; the highest landings occurred at 0.34–0.45; both indexes suggested that at extreme values < −1.0 and > 1.1 total landings tend to decrease. Landings were associated up to 21.9 % (MEI) in 2000–2012, 1983–1999 rendered lower R2 (< 0.09); i.e., during cold PDO periods there was a higher association between landings and oceanographic conditions. For the non-linear regression (n  =  6) a R2 of 0.374 (MEI) and 0.408 (ONI) were registered, for the 2000–2012, a higher R2 was observed in 1983–1999, 0.443 and 0.711 for MEI and ONI respectively, suggesting that is better to analyze split series (1983–1999, 2000–2012) than as a whole (1983–2012), due to noise produced by the transition from hot to cold PDOs. The highest landings were in the range −0.2 to 0.5 for MEI/ONI. The linear regression of skipjack landings in Ecuador gave an R2 of 0.140 (MEI) and 0.066 (ONI) and the non-linear were 0.440 and 0.183 respectively. Total landings in the EPO associated to oceanographic events of high and low frequencies could be used somehow as predictors of the high El Niño o La Niña. There is a clear evidence that tuna fish biomass are at higher levels when the PDO is on cold phase (2000–2030) and vice versa on warm phase (1980–1999). The analysis of the skipjack catch per unit effort (CPUE) on floating aggregating devices (FADs) suggests higher CPUE on FADs (around 20 mt set−1) when oceanographic indexes ONI/MEI are below −0.5. Findings of this work suggest that fishing and management of commercial fish must be analyzed under the light of oceanographic conditions.