Latitudinal comparison in the carrying capacity and function of nursery grounds for juvenile Japanese flounder using ecophysiological modeling

采用生态生理学模型研究了日本鲽幼鱼苗圃承载能力和功能的纬向变化。1. 在日本西部若狭湾和日本北部仙台湾采集了鲽鱼的中上层幼虫和底栖幼鱼。若浅湾比目鱼的幼虫密度是仙台湾的3-9倍，幼鱼密度是仙台湾的30-60倍，说明日本北部比目鱼的存活率较高。2. 在日本南部和北部地区采集了比目鱼幼鱼和作为其主要猎物的蝇蛆，并对其胃内容物进行了检查。东北地区比目鱼幼鱼密度明显低于西南地区，mysid丰度明显高于西南地区。因此，日本东北部的摄食率和生长率较高，从而导致比目鱼幼鱼的生产力较高。3. 研究了牙鲆生产生态，将牙鲆生产模块纳入牙鲆亚种群生长模型。4. 以生态生理学模型为基础，建立了比目鱼幼鱼亚种群生产模型。利用该模型，我们估计了放养比目鱼幼鱼的最佳放养密度，在此密度以上，当食物供应开始限制亚种群的产生时，放养比目鱼幼鱼将限制同种野生幼鱼的生长。该模型预测日本东北部的最佳放养密度更高。然而，预计在日本东北部的几个地区也会出现库存过剩的情况。

Latitudinal variation in the carrying capacity and function of nursery grounds for juvenile Japanese flounder, Paralichthys olivaceus, was studied using ecophysiological modeling. 1. Pelagic larval and benthic juvenile Japanese flounder were collected in Wakasa Bay western Japan and Sendai Bay northern Japan. Flounder density was higher in Wakasa Bay than in Sendai Bay by 3-9 times in larvae and 30-60 times in juveniles indicating higher survival rate in northern Japan for larval flounder. 2. Flounder juveniles and mysids as the main prey of flounder juveniles were collected from southern to northern Japan and stomach contents of juveniles were examined. There was a clear tendency of lower juvenile flounder density and higher mysid abundance in northeastern areas than in southwestern areas. As a result, feeding rates and growth rates were higher in northeastern Japan, resulting in greater productivity of flounder juveniles. 3. The production ecology of mysids was studied to incorporate mysid production module into flounder sub-population growth model. 4. We developed a sub-population production model for juvenile flounder with the basis of an ecophysiology model. Using this model, we estimated the optimum stocking density above which the release of hatchery-raised juvenile flounder would restrict the growth of conspecific wild juveniles as food availability will begin to limit sub-population production. The model predicted a higher optimum stocking density in northeastern Japan. However, over-stocking was predicted to have occurred in several areas even in northeastern Japan.