Distribution of the introduced spider crab, Pyromaia tuberculata, along the coast of Japan

Abstract

The introduced spider crab, Pyromaia tuberculata, was originally distributed along the Pacific coast of southern North America. Its occurrence in Japanese coastal areas was first recorded in 1970, in and near Tokyo Bay, on the Pacific coast of central Japan. Thereafter, increase of abundance in that bay and some additional collection record of the crab in other regions were reported. To ascertain recent state of geographical distribution of the crab, a questinnaire was sent to the laboratories and stations of marine biology and fishery science covering whole Japan in winter, 1984. Geographical distribution of the crab along Japanese waters was determined by the result of the questionnaire. The crab was distributed along the Pacific coast of central Japan, eastern part of Seto Inland Sea, and a small inlet on the western end of Honshu, faced to Japan Sea. It tended to be abundant in organically polluted, large and shallow bays e. g. Tokyo Bay, Ise-Mikawa Bay and Osaka Bay. The informations about the initial place and time of introduction of the species, and process of spreading along Japanese waters were not obtained.