Resumen del producto

The wahoo Acanthocybium solandri is a piscivorous, epipelagic and highly migratory species distributed in tropical and subtropical waters worldwide, representing a high economic and ecological value resource. It is caught incidentally mainly by the international tuna fleet that operates in the Eastern Tropical Pacific Ocean, recording a high catch variability. Changes in distribution patterns and abundance of various pelagic species have been related to the presence of climatological events, such as El Niño-Southern Oscillation (ENSO). Investigating and predicting these changes can help to reducing bycatch and conserving species. Therefore, the main objective of this research is to determine ENSO (cold and warm phases) impact, as well as in normal conditions, on wahoo distribution and relative abundance and predict its behavior. The oceanographic variables analyzed were monthly average of Sea Surface Temperature (SST), Chlorophyll-a (Chl-a) concentration and Sea Surface Height (SSH), all derived from satellite remote sensing. As an indicator of ENSO presence, the Oceanic El Niño Index (ONI) was used. Fishing data corresponded to incidental catch recorded by the Inter-American Tropical Tuna Commission (IATTC) Observer Program from 2002-2015. The monthly average incidental catch per unit effort (CIPUE) was determined as an index of relative abundance by one-degree squares. The study area is characterized by average SST values from 24-26 °C, Chl-a from 0.16-0.23 mg/m3 and SSH from 0.007-0.12 m, with a statistically significant interannual and seasonal variability in all the variables. About 99% of the captured organisms were associated with floating objects. The CIPUE values recorded a significant interanual and seasonal variability with minimum values in 2011 and from February-March and maximum values in 2007 and from September-November, respectively. A differential distribution was observed in incidental catches, effort and CIPUE during the three phases with higher CIPUE average values during El Niño. Spatial prediction models showed that the highest incidental wahoo catches takes place in oceanic waters southward from the equator during El Niño phase with sea surface temperatures close to 25 °C and low Chl-a concentration (< 0.23 mg/m3). During La Niña phase spatial distribution was more dispersed.

Palabras clave: Wahoo; incidental catch; ENSO; eastern tropical Pacific Ocean

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