At river mouths, where salty and fresh water mix, there are ample nutrients from the upstream parts of the rivers as well as from the sea to support a large amount of sea life. Yet there are relatively few predators. Thus these are places where the young of sea creatures--such as the eel--congregate.
而全省各鹹淡水交接的河口，因為匯聚河川上游及海洋的各種營養鹽，供給著浮游生物大量繁生，加上少有掠食性動物定居，成為各種海鮮幼苗聚集的場所，像是仔魚或是鰻魚苗等。