Pacific bluefin tuna (Thunnus orientalis) are a top predator in the North Pacific Ocean. This species ranges from waters off Japan southeast Asia to waters off California and Mexico. Some adults also migrate to waters off Australia and New Zealand. Recent reports have shown this species has declined dramatically, with biomass at approximately 96% of pre-fished levels. New methods are necessary to elucidate migrations and facilitate international management of this iconic species.
Our lab uses Fukushima-derived radionuclides (134Cs and 137Cs) as novel tracers to track bluefin migrations. Since our discovery in 2011 that bluefin had carried radiocesium from Fukushima to California waters, we have studied hundreds of bluefin to create new migration models. We combine our Cs approach with stable isotopes of C and N and amino acid-compound-specific isotopic analyses to create a ‘chemical toolbox’ that can be used to study this and other migratory Pacific species.
Madigan DJ, Baumann Z and NS Fisher. 2012. Pacific bluefin tuna transport Fukushima-derived radionuclides from Japan to California. PNAS 109:9483-9486.
Madigan DJ, Baumann Z, Snodgrass OE, Ergül HA, Dewar H and NS Fisher. 2013. Radiocesium in Pacific bluefin tuna Thunnus orientalis in 2012 validates new tracer technique. ES&T 47:2287-2294.
Fisher NS, Beaugelin-Seiller K, Hinton TG, Baumann Z, Madigan, DJ and J Garnier-LaPlace. 2013. An evaluation of radiation doses and associated risk from the Fukushima nuclear accident to marine biota and human consumers of seafood. PNAS 110(26): 10670-10675.