Ll ACKNOWLEDGMENTS I wish to thank Dr. Institute of Health, Toshiharu Kawabata, Tokyo, National for obtaining the samples from the Japanese fishery; Mrs. Monica Depuy and Mr. Lewis Leuders for performing many of the iron-55 analyses; Dr. T. M. Beasley for analysis of the Bikini Atoll samples for iron-55, as well as running cross checks on the results of other analyses, and discussions of the data.