Physiological and ecological characteristics of diadromous fish in islands of the Pyukyus

普丘斯群岛产鱼的生理和生态特征

基本信息

批准号：
08456100
负责人：
TAKANO Kazunori
金额：
$ 3.39万
依托单位：
University of the Ryukyus
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08456100/
关键词：
Ryukyu-ayu Flagtail Tilapia reproduction sea water adaptability diadromy

项目摘要

This study was carried out to clarify the physiological and ecological characteristics of some selected diadromous fish inhabiting sround the island of the Ryukyus.1.Ryukyu-ayu (Plecoglossus altivelis ryukyuensis) : The structure of mature spermatozoon of this species was characterized by a symmetric nucleus and asymmetric arrangement of two centrioles unlike Ayu, P.altivelis. Scales, comb-like teenth, alimentary canals and skeleton developed earlier than Ayu. Upstream migration also occurred earlier (February-March) and smaller in size (av. 32.3 mm) than Ayu.2.Flagtail (Kuhlia marginata) : Based on the histological observations and gonad-somatic index, it was estimated that females spawn repeatedly during the spawning period from April to September. Number of ovarian eggs varied between 70,000 to 360,000 with an increase of BL.After young migrated from sea to rivers at av. 20mm BL,during March to July, females grew faster than males. The average longevity of female and male was estimated 6 and 2, respectively, and the ratio of female to male resulted in 3 : 1. The change in plasma Na and C1 after trasfer to sea water revealed that the fish have the high ability of tolerance to environmental salinity.3.Tilapia (Oreochromis mossambicus) : The species O.mossambicus is the dominant fish occupying the estuaries of Okinawa Island. The average fertile span of this fish was estimated to be 2-9 years. Annual spawing period lasts from May through September, and females may spawn several times during this season. Although the analysis of the verious physiological parameters such as oxygen consumption rates, plasma constituents and plasma hormone levels under the different salinity conditions showed that sea water may be favorable environment to the fish, they might selsct estuaries as their habitat on the basis of the causes of reproductive strategy of the species.

进行这项研究是为了澄清居住在ryukyus岛的某些选定的生物学和生态特征。 p.altivelis。比例比Ayu早出的鳞片，梳子状的圆形，消化道和骨骼。上游迁移也发生在早期（2月3日）和大小（AV。32.3毫米）的较小。卵巢卵的数量在70,000至360,000之间变化，BL的增加。年轻人从AV迁移到河流。 20毫米BL，在三月至七月期间，女性的增长速度比男性快。 The average longevity of female and male was estimated 6 and 2, respectively, and the ratio of female to male resulted in 3 : 1. The change in plasma Na and C1 after trasfer to sea water revealed that the fish have the high ability of tolerance to environmental salinity.3.Tilapia (Oreochromis mossambicus) : The species O.mossambicus is the dominant fish occupying the estuaries of Okinawa Island.这种鱼的平均肥沃跨度估计为2 - 9年。每年的产卵期持续时间为5月至9月，在这个季节，女性可能会多次产卵。尽管对不同盐分条件下的氧气消耗率，血浆成分和血浆激素水平等鲜明的生理参数的分析表明，海水可能对鱼类是有利的环境，但它们可能是基于生殖策略的基础的栖息地。