Variation in yellowfin tuna catches related to El Nino-Southern Oscillation events at the entrance to the Gulf of California

• Published in: Fishery bulletin (Washington, D.C.) Vol. 104; no. 2; pp. 197 - 203
• Main Authors: Torres-Orozco, Ernesto, Muhlia-Melo, Arturo, Trasvina, Armando, Ortega-Garcia, Sofia
• Format: Journal Article
• Language: English
• Published: National Marine Fisheries Service 01.04.2006
• Subjects: Environmental aspects; Fish industry; Fisheries; Marine; Statistics; Thunnus albacares; Yellowfin tuna; IS, Tropical Pacific; ISE, Mexico, California Gulf
• ISSN: 0090-0656; 1937-4518

Fishery catch data on yellowfin tuna (Thunnus albacares) were examined to study the effects of El Nino events between 1990 and 1999 for an area in the northeastern tropical Pacific (18-24 degree N, 112-104 degree W). The data were extracted from a database of logbook records from the Mexican tuna purse-seine fleet. Latitudinal distribution of the catches increased from south to north for the 10-year period. Highest catches and effort were concentrated between 22 degree N and 23 degree N. This area accumulated 48% of the total catch over the 10-year period. It was strongly correlated with El Nino-Southern Oscillation (ENSO) events. At least two periods of exceptionally high catches occurred following El Nino events in 1991 and 1997. Peaks of catches were triggered by the arrival of positive anomalies of sea surface temperature (SST) to the area. A delay of two to four months was observed between the occurrence of maximum SST anomalies at the equator and peaks of catch. Prior to these two events, negative SST anomalies were the dominant feature in the study area and catch was extremely low. This trend of negative SST anomalies with low catches followed by positive SST anomalies and high catches may be attributed to northward yellowfin tuna migration patterns driven by El Nino forcing, a result that contrasts with the known behavior of decreasing relative abundance of these tuna after El Nino events in the eastern Pacific. However, this decrease in relative abundance may be the result of a local or subregional effect.