飯島氏銀鮈Squalidus iijimae（Oshima, 1919）人工繁養殖及幼苗發育

Induced Spawning and Larval Development of the Taiwan Gudgeon Squalidus iijimae (Oshima, 1919)

飯島氏銀鮈Squalidus iijimae（Oshima, 1919）為台灣特有種，僅分布於台灣中北部的後龍溪水系，屬於小型淡水魚類，兼具生態與觀賞價值，由於近年來棲地破壞及環境汙染的問題，使其族群分布範圍與數量減少，已逐漸成為罕見魚種。本研究利用注射土虱魚（Clarias sp.）腦下垂體研磨液與促黃體釋放激素類似物（luteinizing hormone-releasing hormone analogue, LRH-A）混合液，進行人工催熟與自然產卵方式，進行繁殖與育苗試驗，以瞭解飯島氏銀鮈之生殖習性與魚苗發育過程，期望逐步建立飯島氏銀約之繁殖與幼苗發育的基礎生物學資料，並應用於種原庫的建立及自然環境中之復育。研究結果顯示，飯島氏銀鮈主要將卵產於水生植物的沈水部位，魚卵卵徑平均1.11 mm，呈透明、光滑、沈性且帶黏性，在水溫24-26℃的環境中約產出後5 hr（5HAS）進入原腸期，12HAS可觀察到肌節，13-14 HAS可觀察到心跳與耳石，39-48HAS孵化。初孵化魚苗全長平均為3.4 mm，孵出第5天可開始攝食餌料，第9天觀察到感覺芽，第11天背鰭發育完全，第15天臀鰭發育完全，第23天腹鰭發育完全，第31天鱗片發育完全，此時與成魚的外表形態類似。 The Taiwan gudgeon Squalidus iijimae (Oshima, 1919) is a small native freshwater fish, inhabiting in brooks and small lakes of the North-western Taiwan. Due to environmental deterioration resulted from habitat destruction and water pollution, its population has been gradually declining and becoming rare or extinct in many parts of its original ranges. We induced spawning of the fish in the laboratory with injecting a mixed solution of LRH-A and grounded pituitary glands of walking catfish (Enctkcu sp.), observed its spawning habit, and examined its embryonic and larval developments at water temperatures of 24-26℃. The fertilized eggs had an average diameter of 1.11 mm. They developed to the stages of gastrula at about 5 HAS (hours after spawning), and of embryos with myotomes at about 12 HAS and with heart beats and otoliths at 13-14 HAS. The larvae were hatched at 39-48 HAS. Newly hatched yolk-sac larvae had total lengths at an average of 3.4 mm. The larvae started feeding on 5 DAH (days after hatching), and developed sensory buds on 9 DAH, dorsal fin on 11 DAH, anal fin on 15 DAH, pelvic fins on 23 DAH, and scales on 31 DAH.