Studies on the early life history of two Platycephalus fishes distributed in Ariake Sound

对分布于阿里亚克海峡的两种扁头鱼的幼鱼阶段、年龄和生长、成熟、早期形态、早期生态和耐盐性等方面进行了研究。对年龄和生长的研究确定了每个物种的Bertalanffy生长方程，而对它们繁殖的研究确定了每个物种的产卵季节和产卵场。通过对它们的卵和仔鱼的饲养试验，阐明了它们在卵、仔鱼和幼虫阶段的形态发育，确立了它们的育苗方法。虽然幼虫和幼虫幼虫和幼虫的形态比较不能区分a-种，但本研究建立的PRC RFLP分析技术成功地区分了不同物种。在有宅湾不同冲浪区的实地调查发现，流入有宅湾东部的河流入海口区域被一种扁头鱼(日语中称为Magochi)用作它们的苗圃。幼鱼来到河口的沙地底部，并在那里停留约一年。两种鱼幼鱼对低盐度的耐受性比较表明，扁头鱼(所谓的Magochi)比其他物种(所谓的yoshinogochi)对低盐度的耐受性更强。

On two Platycephalus fishes distributed in Ariake Sound, the discrimination of species in young stages, age and growth, maturation, early morphology, early ecology, and low salinity tolerance were investigated. Studies on the age and growth resulted in the determination of the Bertalanffy's growth equation for each species, and studies on their reproduction determined the spawning season and the spawning ground of each species. The rearing experiments of their eggs and larvae elucidated the morphological developments in egg, larval and juvenile stages of both species, and established the method of seedling production. Although the morphological comparison of larvae and juveniles between species in young stages failed in the discrimination of a-species from each other, a PRC RFLP analysis technique established in this study was successful in discriminating a species from each other. The field surveys in various surf areas in Ariake Sound have found that the mouth areas of rivers, which discharge themselves into the eastern part of Ariake sound, are used by a species of Platycephalus (so-called magochi in Japanese) as their nursery. The juveniles come to the sandy bottom of the river mouths, and stay there for about one year. A comparison of the tolerance to low salinity between juveniles of both species revealed that the species of Platycephalus (so called magochi) is more tolerant to low salinity than the other species (so-called yoshinogochi).