Seasonal Vertical Migration within Sediment by the Brackish Water Clam Corbicula japonica

DOI Web Site 被引用文献5件 参考文献35件
  • Goshima Seiji
    Department of Marine Biological Science, Faculty of Fisheries, Hokkaido University
  • Ikegawa Masato
    Department of Marine Biological Science, Faculty of Fisheries, Hokkaido University
  • Sonoda Takeshi
    Department of Marine Biological Science, Faculty of Fisheries, Hokkaido University
  • Wada Satoshi
    Department of Marine Biological Science, Faculty of Fisheries, Hokkaido University

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Abstract: Many fishermen of the common brackish water clam Corbicula japonica report that in the warm season, the clams inhabit shallow depths of the sediment and are easily caught by scraping the sediment with fishing gear, but in the cold season, they burrow more deeply and become harder to catch. We examined, first, this seasonal pattern of burrowing of clams in Lake Ogawara, a mixo-oligohaline lagoon in northern Honshu (Japan), and showed that the clams perform a clear seasonal vertical migration; in cold months, the clams burrowed up to 12cm into the sand sediment, but in warm months, they occurred exclusively within 3cm of the sediment surface. Secondly, an experiment of clam burrowing was conducted at different temperatures in the laboratory. The results were similar to those of field experiment; burrowing depths were deeper at lower temperatures. This suggests that temperatures may be the proximate cause of the seasonal vertical migration. Possible ultimate factors include physical turbulence, such as rough wave action, freezing of the shallow sediment layer, and predation by birds in cold months. In cold months, when the clams may have a low activity level, they would avoid physical turbulence and birds' predation, and increase survival rates by burrowing deeper into the sediment. These results suggest that the lowered fishing efficiency for clams that occurs in winter is closely related to the observed deep burrowing within the sediment, and which becomes more compact and, hence, more difficult to dredge due to the scattered vertical distribution of clams in the sediment.

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  • BENTHOS RESEARCH

    BENTHOS RESEARCH 54 (2), 87-97, 1999

    日本ベントス学会

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