Spatial and seasonal variation of relative abundance of the skipjack tuna Katsuwonus pelamis (Linnaeus, 1758) in the Eastern Pacific Ocean (EPO) during 1970-1995

To determine the spatial and seasonal variation of the catch-per-unit-effort of the skipjack tuna as an index of abundance, the logbook records of the international purse-seine tuna fleet that operated in the Eastern Pacific Ocean during 1970-1995 were used. Data were provided by the Inter-American Tropical Tuna Commission (IATTC). The catch-per-standard-day fishing (CPSDF), by year, quarter, and type of indicator was estimated for the operational area. The interannual and seasonal variation were significant, with two long periods in the fishing yields (1970-1982 and 1983-1995). In the first period, the highest yield was 1971 and the lowest in 1982. In the second period, the highest yield was in 1995, and the lowest 1983. Seasonally, the highest yields were obtained in the first half of the year, and the lowest during the third quarter. As result of the CPSDF distribution, the most productive areas are south of 10°N and east of 135°W.