Thirteen commonly consumed types of fish caught in the North Pacific and locally available in Hawai'i were analyzed using gamma spectroscopy to measure Fukushima-derived and historic Cs-134 and Cs-137 isotopes. All fish samples had detectable Cs-137 above 95% confidence intervals. Three out of the thirteen samples had Cs-134, an isotope indicative of Fukushima releases, detected above 95% confidence intervals. The highest Cs-134 and Cs-137 concentration in the examined species was in 'ahi tuna, carrying 0.10 +/- 0.04 Bq/kg and 0.62 +/- 0.05 Bq/kg, respectively. Other samples with Cs-134 activities found above their 2-sigma uncertainty were albacore tuna and swordfish. Historic and Fukushima-derived contributions were evaluated, and in several samples the Fukushima-derived radiocesium dominated the total radiocesium inventory with up to 61% contribution. All activities were below derived intervention limits of 1,200 Bq/kg, and the doses to humans from consuming the fish attributable to radiocesium were 0.02-0.2 mu Sv, in comparison to 6-20 mu Sv contributed by the natural K-40 present in the same fish.
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