DEVELOPMENT OF THE METHODOLOGY TO UNDERSTAND THE ECOLOGY OF MINKE WHALES USING ENVIRONMENTAL CONTAMINANTS AS CHEMICAL TRACERS

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The minke whale samples including about 500 individuals collected from the Southern Ocean in the period of 1981 to 1999 and about 160 individuals from the North Pacific during 1994 to 1998 under the special permit of Japanese Whale Research Program(JARPA)were employed for chemical analysis and obtained the following results ;1)The analytical systems for monitoring the concentrations of organochlorines, organotins and heavy metals in various organs and tissues of minke whales were examined and constructed. The results of body distribution of these contaminants suggested to use the blubber for organochlorines and the liver for heavy metals including organotins as a proper tissue/organ to elucidate the ecology and biology of minke whales.2)The residue levels of organochlorines and toxic elements were varied according to sex, feeding habit and age, which suggests the necessity of classification of samples in order to discriminate the population of minke whales.3)When estimating the discrim … More ination of population in minke whales of North Pacific using some heavy metals and organochlorines as chemical tracers, the animals from the Sea of Okhotsk were classified into two groups with significantly higher concentrations of DDTs and PCBs and lower concentrations of Hg and with apparently higher concentrations of Cd and lower concentrations on HCHs, suggesting that the former group is principally inhabiting in the Sea or Japan/Yellow Sea/East China Sea and the latter group is immigrated from the western North Pacific.4)The determination of drug-metabolizing enzyme activities in the liver indicated the induction of CYP1A with low residue levels of organochlorines in the Antarctic minke whales, which implies sensitive to the toxic effects of these contaminants in minke whales. The CYP1A genes in minke whales revealed the similarity of amino acid sequences on that genes in Dall's porpoise from the northern North Pacific.5)The attempt to discriminate the population of southern minke whales using 12 trace elements found in skin and liver by the principal component analysis showed the significant difference in the matrix of trace elements among male animals from Area III, IV and V in Antarctic Ocean. These populations seemed to be segregated in association with immigration, reproduction, feeding habit etc. Thisapproach using the trace elements in the skin of animals is evidenced to be an effective non-killing method to elucidate the ecology and biology of minke whales.Considering all these results, the present study concluded that the environmental chemicals such as organochlorines and heavy metals were useful chemical tracers to understand the ecological and physiological aspects of minke whales yet to be known. Less