Migratory history of the Japanese eeI Anguilla japonica, as revealed by otolith microchemistry and stable isotope markers

采用电子探针波长色散x射线光谱法测定了大村湾（54尾熊本县黄鳝）、熊马河河口（48尾长崎市黄鳝）和东海（7尾银鳝）日本鳗鲡耳石中的锶（Sr）和钙（Ca），研究了日本鳗鲡的环境史。耳石中Sr/Ca比值随个体发育和生境盐度的变化而变化。咸淡水和淡水的多样性有显著差异。淡水标记外Sr/Ca比值的格局变化表明：(A)河鳗、(B)河口鳗和(C)短周期河鳗的三种洄游历史类型。根据耳石Sr/Ca比值，A型的发生率在大村湾为14%，在熊河河口为15%，在东海和(B)为14%，在大村湾为74%，在熊河河口为62%，在东海和(C)为43%，在大村湾为12%，在熊河河口为23%，在东海为43%。各类型间生长无差异。

Environmental history of the Japanese eel Anguilla japonica collected from Omura Bay (54 Yellow eels, Kumamoto Pref.), Kuma River estuary (48 Yellow eels, Nagasaki Oref.), and East China Sea (7 Silver eels) were studied by examining strontium (Sr) and calcium (Ca) in their otoliths with wavelength dispersive X-ray spectrometry on an electron microprobe. The Sr/Ca ratios in the otoliths changes with both ontogenetic development and salinity of the habitat. The rarios significantly different between brackish and fresh water.The pattern change of the Sr/Ca ratios outside the freshwater mark indicated three types of migratory history : (A) river eels, (B) estuarines eels and (C) estuarine eeis with short period river life. According to the otolith Sr/Ca ratios, the occurrence of type A was 14% for Omura Bay, 15% for Kuma river estuary, and 14% for East China Sea and that of (B), 74% for Omura Bay, 62% for Kuma river estuary, 43% for East China Sea and that of (C), 12% for Omura Bay, 23% for Kuma river estuary, 43% for East China Sea. There was no difference in growth between each types.