EAPSI: Elucidating migration patterns of Pacific Bluefin Tuna using molecular analysis of stable isotopes

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Pacific bluefin Tuna are an important commercial fisheries species, often sold for thousands or millions of dollars in seafood markets. Due to extreme popularity, the species has been greatly overfished, and experienced declines in population of 96% in recent decades. Even though dramatic declines have been experienced, the migration patterns across the Pacific, as well as the life stages in which this migration happens is still unknown for the Pacific bluefin Tuna. This study will investigate the rate of Pacific bluefin Tuna migration through molecular analysis. This research will be conducted at the Fisheries Research Institute in collaboration with Dr. Chi-Lu Sun, who has a long history of research on billfish and other pelagic species as professor at National Taiwan University's Institute of Oceanography.This project will use stable isotope analysis to better understand Pacific bluefin tuna (PBFT) migration patterns in the North Pacific Ocean. In different ocean regions, local oceanographic conditions affect delta-15N values at the base of the food web (phytoplankton), and these differences propagate up food webs from plankton to prey to predators. Previous studies have demonstrated differences in baseline delta-15N between the eastern and western Pacific Ocean (EPO and WPO). Because of these differences, PBFT can be categorized as residents or recent migrants in the WPO based on low (resident) or high (migrant) delta-15N values. By analyzing samples of PBFT from the WPO, inferences about migration patterns, including the identification of western residents and eastern migrants across a range of size classes will be made. This NSF EAPSI award is funded in collaboration with the National Science Council of Taiwan.