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Studies of the population dynamics of edible giant jellyfish in relation to environmental changes in Ariake Sea

有明海食用巨型水母种群动态与环境变化的关系研究

基本信息

批准号：
17510009
负责人：
UYE Shin-ichi
金额：
$ 2.3万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

The Ariake Bay, western Kyushu, harbors two edible giant jellyfish species, Rhopilima eschulentum (locally called as Akakurage) and R. hispidum (called as Shirokurage), which have traditionally been harvested and processed for food. In spite of remarkable decrease in catch of fin-and shell-fish catch, the catch of these jellyfish are relatively stable and show an increasing tendency in recent years. The objective of this study is to elucidate the population dynamics of these jellyfish in relation to recent changes in the environmental factors of the bay. Since another giant jellyfish Nemopilema monural appeared for the first time in the bay in 2005, its dynamics is also investigated.(1) According to the annual amount of jellyfish on sales of Yanagawa Fish Market between 2001 and 2006, R. hispidum was mach fewer but stable (range: 33-45 tons of processed wet weight) compared to R. eschulentum (range: 115-526 tons). The latter showed a remarkable increase in 2005 and 2006 (526 and 447 tons, respectively) compared to 2001-2004 (115-285 tons).(2) Their ephyrae are released in April-May, grow to medusae of 20-30 kg in wet weight in July, and attain the maximum (ca. 30-40 kg) in August. They sexually mature in September.(3) In 2006, two N. nomurai medusae were confirmed to occur in the Ariake Sea, the first one on July 10th (bell diameter : 60 cm) and the second one on August 1st (bell diameter : 80 cm), suggesting that this species may establish the life cycle in this shallow bay.(4) The water content of fresh jellyfish is, on average, 95% and that of processed jellyfish is 87%. The carbon and nitrogen contents are 15% and 3.5%, respectively, of dry weight.

九州西部的有明湾有两种可食用的巨型水母，Rhopilima eschulentum（当地称为Akakurage）和R。hispidum（称为Shirokurage），传统上被收获和加工为食物。尽管鳍贝类的渔获量显著下降，但这些水母的渔获量相对稳定，近年来有上升的趋势。本研究的目的是阐明这些水母的种群动态与海湾环境因素的最近变化。自2005年首次在该海湾发现另一种大型水母Nemopilema monural以来，对其动态也进行了研究。(1)根据2001 - 2006年柳川鱼市的海蜇销售量，R。hispidum与R. eschulentum（范围：115-526吨）。与2001-2004年（115-285吨）相比，后者在2005年和2006年（分别为526吨和447吨）显著增加。(2)4 - 5月放出水母，7月生长到20-30公斤湿重，达到最大值（约100公斤）。8月30-40公斤。9月性成熟。(3)2006年，两个N.在有明海发现了第一条水母（钟形直径60 cm），第二条水母（钟形直径80 cm），第一条水母出现在7月10日，第二条水母出现在8月1日，表明该种可能在该浅海湾建立了生活史。(4)新鲜海蜇的含水量平均为95%，加工海蜇的含水量为87%。碳和氮含量分别为干重的15%和3.5%。