臺灣博碩士論文加值系統

日本禿頭鯊（Sicyopterus japonicus）是台灣東部溪流中常見的兩棲洄
游型(Amphidromy）蝦虎科（Gobiidae）魚類，洄游於海洋和淡水之間，
而洄游的目的和生殖無關。本研究於1995年9月至1997年4月，於台灣東北
部隆隆溪及其河口域採集日本禿頭鯊之標本。利用耳石的微細構造（日周
輪、變態輪及鹽度輪等）及耳石微化學（鍶鈣比）所提供之訊息，配合環
境因子，來研究日本禿頭鯊之初期生活史及加入動態。

由耳石鍶鈣比之變化以及耳石微細構造之特徵，發現稚魚進入淡水之後2
星期左右形成變態輪，之後耳石的成長速率急速變快。上顎結構之改變可
能是造成成長加速的原因。日本禿頭鯊稚魚到達河口時的平均體長
為33.95mm（範圍30-38mm, n＝384），平均日齡為163.72天（範
圍125-212天, n＝277）。其加入期與回推之產卵期似乎和降雨量及水溫
有關。經周期性迴歸分析（periodic regression analysis）結果顯示，
日本禿頭鯊加入時的體長和日齡有一季節性之週期變化，兩 者周期性之
相位相反。加入期稚魚的體長和日齡之周期性變化可能與其後期仔魚
階段的海洋浮游期的餌料生物量的季節性變化有關。

Sicyopterus japonicus, a common species of amphidromous Gobiidae
fish, widespread in the stream of eastern Taiwan. In this
study we used theinformation achieved from otolith
microstructure and microchemistry ( Sr:Ca ) of the fish
collected in the Long-Long brook and its estuaryfrom September
1995 through April 1997 as well as environment factors to
investigate the early life history and recruitment dynamics.

Changes in otolithChanges in otolith microchemistry and
microstructure suggest that metamorphosis
check is deposited at the time approximately two weeks after
migration from sea water into freshwater. The growth of otolith
dramatically increasesafter metamorphosis. The change of jaw
structure of the fish may contribute to the dramatic growth. The
total lengths of Sicyopterus japonicus juvenilesat recruitment
to the Shung-Chi River estuary were 33.95mm in average (range
30-38mm, n=384) and daily age were 163.72 days in average(range
125-212days,n=277). The timing of recruitment of the juvenile
fish and their spawningseason back-calculated from sampling date
are correlated with precipitationand water temperature. Both
length and age of the juvenile at recruitment tothe estuary
show a periodic change and the peak phase of change is
reversebetween length and age. The periodic change in both
length and age depends onthe seasonal change of productivity
during their postlarval stage in the ocean.