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ZINC‐65 AND MANGANESE‐54 IN ALBACORE THUNNUS ALALUNGA FROM THE WEST COAST OF NORTH AMERICA
Author(s) -
Pearcy William G.,
Osterberg Charles L.
Publication year - 1968
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1968.13.3.0490
Subject(s) - albacore , environmental science , oceanography , fishery , trophic level , manganese , tuna , chemistry , biology , ecology , geology , fish <actinopterygii> , organic chemistry
Zinc‐65 and manganese‐54 were the dominant artificial radionuclides in the livers of albacore collected along the coast of North America from Washington to Baja California during the summers 1962–1966. The concentrations and specific activities of these radionuclides changed considerably during summer, indicating rapid responses to different radioecological conditions. Off Oregon and Washington 65 Zn levels, as well as specific activities, in albacore increased markedly during summer months. Association of albacore with the effluent of the Columbia River accounted for this enhancement. The 6 5 Zn concentrations of albacore from southern and Baja California were about 10% of those off Oregon and Washington with no seasonal trends evident. Highest radioactivities per gram and specific activities of 6 5 Zn were found late in summer off Oregon. The 6 5 Zn concentrations off southern Oregon at this time were as high as those off northern Oregon near the mouth of the Columbia River, probably because of the southward drift of plume waters coupled with the lag time for accumulation of 6 5 Zn through several trophic levels. We have no evidence either for immigration of 65 Zn‐tagged albacore into the southern California fishery or for immigration of southern albacore, with low 65 Zn content, into the northern fishery during one season. Manganese‐54 enters the ocean primarily from fallout of nuclear weapons tests. Both the radioactivity and the specific activity of 54 Mn in albacore off Oregon and Washington decreased during summer. Thus 54 Mn appeared to be more available to albacore in offshore waters than in the nearshore waters. The levels of 5 4 Mn in albacore were rather similar during the years of this study; this was unexpected since all the 54 Mn presumably originated from 1961–1962 nuclear weapons tests.