Relationship between climatic factors and distribution and abundance of skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) in the Western and Central Pacific Ocean

Abstract

Distribution and abundance of two commercial species skipjack (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) are highly sensitive to environmental variances, in particular the rising sea surface temperatures and enhanced levels of CO2 in the atmosphere. In order to ascertain a relationship between these factors, tuna catch data were obtained from the Western & Central Pacific Fisheries Commission (WCPFC) during 1997 ？ 2007 to identify the relationship between the wild stock population of the two tuna species and environmental variability in particular Southern Oscillation Index (SOI), Pacific Decadal Oscillation (PDO), Aleutian Low Pressure Index (ALPI) and sea surface temperatures (SST). El Ni？o and La Ni？a events of 1997/1998 and 1998/1999 respectively were used, to evaluate the intensified climatic impacts on the fishery compared to that of a normal situation, which also leads to implications of ocean acidification and the prolonged changes over a period of time. Evidently, climate indices SOI and ALPI were shown to be generally related and catch yields of both species were directly related to ocean temperatures, reaching 1.4 million MT, as opposed to 600,000 MT in unfavorable temperature ranges. Hence, an understanding of these causes and impacts is the key to better management and sustainability.