Effects of Sea Surface Temperature on Tuna Catch: Evidence from Countries in the Eastern Pacific Ocean

Tuna move towards higher latitudes or deeper waters in response to ocean warming. The spatial redistribution of tuna will affect countries in the Eastern Pacific Ocean (EPO). We apply a production function approach to establish the relationship between sea surface temperature (SST) and yellowfin and skipjack tuna catch of purse seines. We use data for 1° latitude/longitude grids within the exclusive economic zones of countries in the EPO. Catch of yellowfin and skipjack tuna increases with SST in all countries with high values recorded in the eastern coastal borders. The biggest increase in revenue from yellowfin and skipjack tuna as result on 1°C increase in SST is for Mexico while the smallest is for Kiribati. However, if we adjust these values by coastal population, highest values are for Kiribati and French Polynesia. The higher tuna catch due to ocean warming translates to higher government revenue from tuna fishing licenses and more jobs for tuna fishers and those in the tuna processing industry in the state. However, it is possible that the recorded positive effects on tuna catch will be offset by the reduction on catch of other species and may even result in negative net impact overall. We highlight the importance of conducting research on SST that must be species-,gear-,and location¬ specific to fully account for the impact of ocean warming.