Assessing the usefulness of trace elements for evaluating the spawning migration of Pacific cod Gadus macrocephalus in coastal areas of Aomori Prefecture, northern Japan

It is known that Pacific cod Gadus macrocephalus in coastal areas of Aomori Prefecture (Japan) migrate to Mutsu Bay for spawning, but it is not clear where the schools are from. We analyzed the concentrations of 29 elements (Li, Na, Mg, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Mo, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, Pb, Bi) in muscle of Pacific cod collected from coastal areas of Aomori Prefecture. Pacific cod collected from the Sea of Japan had higher levels of mercury than those from the Pacific Ocean. Using mercury level as a predictor variable, we demonstrated that a logistic regression model would discriminate between Pacific cod from the Sea of Japan and those from the Pacific Ocean. The model predicted that the majority of Pacific cod in Mutsu Bay had migrated from the Pacific Ocean.