Levels of Mercury in Muscle and Liver of Star-Spotted Dogfish ( Mustelus manazo ) from the Northern Region of Japan: A C
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Levels of Mercury in Muscle and Liver of Star-Spotted Dogfish (Mustelus manazo) from the Northern Region of Japan: A Comparison with Spiny Dogfish (Squalus acanthias) Tetsuya Endo • Yohsuke Hisamichi • Osamu Kimura • Hideki Ogasawara Chiho Ohta • Nobuyuki Koga • Yoshihisa Kato • Koichi Haraguchi
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Received: 20 September 2012 / Accepted: 3 December 2012 / Published online: 28 December 2012 Ó Springer Science+Business Media New York 2012
Abstract We analyzed mercury (Hg) concentrations in muscle and liver samples of star-spotted dogfish (Mustelus manazo) caught off the northern region of Japan and compared them with those of spiny dogfish (Squalus acanthias) caught in the same region. The average body length of male star-spotted dogfish specimens was significantly smaller than that of female specimens, reflecting the slower growth rate of male fish. Hg concentrations in liver and muscle increased with increases in body length and estimated age of both male and female star-spotted dogfish specimens. However, the relationships between Hg concentration in liver or muscle and body length or estimated age of male specimens differed markedly from those of female specimens, reflecting differences in growth rate and cessation of growth on reaching maturity. Marked increases in Hg concentration in liver of male and female star-
T. Endo (&) Y. Hisamichi O. Kimura Faculty of Pharmaceutical Sciences, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757, Ishikari-Tobetsu, Hokkaido 061-0293, Japan e-mail: [email protected] H. Ogasawara Sapporo Higashi-Tokushukai Hospital, Sapporo, Hokkaido 065-0033, Japan C. Ohta N. Koga Faculty of Nutritional Sciences, Nakamura Gakuen University, Fukuoka 814-0198, Japan Y. Kato Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan K. Haraguchi Daiichi College of Pharmaceutical Sciences, Minami-ku, Fukuoka 815-8511, Japan
spotted dogfish specimens were observed slightly later than increases in Hg concentration in muscle of those specimens due to growth cessation. These marked increases in Hg in liver may reflect increases in Hg due to the formation of mercury selenide. Similar results were previously reported in spiny dogfish specimens, except spiny dogfish showed only trace levels of Hg in liver (Endo et al., Chemosphere 77:1333–1337, 2009). The greater lipid content in liver and the larger liver size in spiny dogfish may explain the much lower levels of Hg observed in liver of spiny dogfish compared with those in the star-spotted dogfish.
The star-spotted dogfish (Mustelus manazo), also commonly known as the star-spotted smooth-hound, is a small shark that feeds on crustacea, crabs, and small fish (Taniuchi et al. 1983). This shark is fished in all regions of Japan, the East China Sea, and around Taiwan. Although the growth rate of this shark varies with habitat, the body length and life span of female fish are greater than those of male fish (Tanaka and Mizue 1979; Taniuchi et al. 1983). Star-spotted dog
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