BASIC STUDIES FOR TECHNICAL DEVELOPMENTS ON SEED PRODUCTION IN AQUACULTURE

本研究的主要目的是获得关于仔鱼早期死亡的原因和机制的基本信息，以及以水产养殖为种子的幼鱼。我们从病原学、诊断学、免疫学、生理学、营养学和环境学的角度进行了调查，得到了以下结果。在种子生产过程中，由于传染病，有大量的死亡。其中，条纹叶枯病、黄尾叶枯病等病毒病是目前较为严重的问题。很明显，sJnnv(幼虫中的病毒性神经坏死)的可能病程是它们的亲代产卵者。在卵黄吸收之后或期间的一段时间内，鱼苗遇到食物颗粒，正常生长。如果长时间得不到合适的食物，幼虫可能会达到不可逆转的饥饿状态，最终发生死亡。进入这一末期的幼虫被称为…更多的人已经到达了PNR(不返回点)。在实际应用中，PNR可被定义为首次摄食仍能使50%的幼虫存活的最大延迟。列举了一些不同鱼种的饥饿致死和PNR的例子。成功地将臭氧用作水产养殖系统的消毒剂。所有鱼类病原菌的细菌数量每升下降超过0.04-0.06 mg的总残留氧化物(Tro)。这一结果表明，在tro/1浓度大于1.0 mg/l的情况下，臭氧处理几分钟就可以有效地消毒海水养殖。4)为了提高种子的遗传特性，对鲑鱼卵进行了转基因试验，证实了卵期引入的外源基因在后代中变得活跃。同时进行了倍性操作，得到了以下结果：每个细胞的最大核仁数目的变化与其年龄有关。用雌性虹鱼与其他鲑科鱼类杂交，获得了12个组合的二倍体和三倍体杂交种。此外，还产生了青冈属3个种的杂交雌株(三倍体异源三倍体)。较少

The main purposes of this study are to obtain basic informations about the causes and mechanism of early death during larval and young fish used aquaculture as the seed for aquaculture. We have investigated from pathogenic, diagnostic,immunological, physiological, nutritional and environmental points of view and obtained the following results.1). There are mass mortalities during seed production due to infectious diseases. Among these problems, the viral diseases such as SJNNV in the striped jack and YAV in the yellowtail are serious problem at present. It has become clear that possible courses of the sJnnv( viral nervous necrosis in larval striped jack) are their parental spawners.2). fish larvae encountering food particles some time after or during the period of yolk absorption grow normally. If suitable food is not available for longer periods, the larvae may attained state of irreversible inanition, at the end of which mortality occurs. Larvae entering this terminal phase are said … More to have reached the PNR( point-of-no-return). For practical purposes, PNR may be defined as the maximum delay in first feeding that still enables 50 % of the larvae to survive. Some examples of starvation-induced mortality and PNR in various fish species are presented.3). Successful use of ozone as a disinfectant for aquaculture system was developed. Bacterial counts of all fish pathogens decreased at more than 0.04-0.06 mg of total residual oxidans(TRO) per liter. This result indicates that ozone treatment at more than 1.0 mg of TRO/1 for several minutes is able to disinfect seawater for mariculture efficiently.4).In order to augment the genetic properties of the seed, transgenenic method has been tried on trout eggs and confirmed that foreign genes introduced during egg stage become active in the offsprings. At the same time,ploidy manipulations have been done and got the following results; the variation in the maximum number of nucleoli per cell is related to their age. Diploid and triploid hybrids with 12 combinations have been produced by the crosses between female rainbow trout and another salmonids fishes. In addition, hybrids females among 3 species of medaka have been produced( trigenomic allotriploids). Less