現存臺灣櫻花鉤吻鮭族群只分布在雪霸國家公園境內的七家灣溪大約八公里長的河段，自1996年起已規劃為櫻花鉤吻鮭野生動物保護區之範圍。由於這個區域的族群然有嚴密的保護措施，但是整個櫻花鉤吻鮭的族群數量，一直都未能有顯著的增加，因此這項問題頗受各界的重視。本報告嘗試分析過去十餘年間的族群調查以及環境監測結果，以了解這個區域裡的櫻花鉤吻鮭族群數量變動狀況，探討可能的影響因子，以及尋求正確的保育策略。 七家灣溪的櫻花鉤吻鮭族群數量與分布情形自1994年開始有全面性的系統調查，結果發現族群數量的變動相當劇烈，甚至整個族群分布狀況的變化也非常明顯。族群總數最少的時候是在1995年夏季，只有554尾，最多的時候數量則有2,495尾，數量相差四倍以上。族群變動原因主要為每年十月前後繁殖期的氣候狀況，尤其是颱風豪雨對於產卵場的危害導致繁殖失敗等因素，影響隔年幼魚加入各河段族群的比例。族群數量的波動與氣候狀況有非常明顯的相關性。 攔砂壩分割整個櫻花鉤吻鮭族群，使得櫻花鉤吻鮭在遭受境壓力之下無法自行逃避。因此在還沒能夠有效改善攔砂壩所導致櫻花鉤吻鮭區域洄游問題之前，以人工繁殖的方法改善二號壩以下的成魚繁殖問題，並經由將新生復育的幼魚放流至上游河段，以維持基因多樣性，並確保上游隔離族群的有效數量，在現階段是有效的策略之一。

　　　　　The existing Formosan landlocked Masu Salmon (Oncorhynchus masou formaosanus) has distributed only in a protected eight-kilometer section of the Chi-Chia-Wan River located in the Sheh-Bah National Park. Although the Masu Salmon in this area has been well protected, its population size has not distincitively enlarged. Therefore, it is a significant object to increase the population of the Masu Salmon. This report has revealed the investigation of the Masu Salmon during the past decade and analyzed the monitoring results of the surroundings. It has also described the fluctuation status of the Masu Salmon's population size in this area and discussed the possible influence factors and the methods of the conservation. Since 1994, the population and distribution of the Masu Salmon in the Chichiawan Stream has systematically investigated. It has revealed that not only the population of the Masu Salmon has violently fluctuated; its distribution status has also been distinctively changed. The minimum of its total amount of population was only 554 (in 1995 summer), however, the maximum 2,495 (in 1995 winter). Their difference is over four times. From the analysis of its fluctuations, it can be found that the weather status of the breeding seasons, from early October till late November, plays a significant factor. The floods of typhoon will destroy the breeding habitats. This weather factor is strongly relative to the population size of the Masu Salmon. Salmon breeding habitats destroyed by Typhoon will affect the recruitment of the population. Before being able to solve the problems of the partition of salmon population caused by the dam, it is suggested that artificial breeding be adopted in order to move larva salmon to suitable upstream habitat to keep from the extinction of the upstream salmon population. This method might be the efficient strategy at this monment.