この文献の参照には次のURLをご利用ください : https://doi.org/10.15027/40804
広島大学水畜産学部紀要 8 巻 1 号
1969-07-30 発行
実験動物としてのブルーギルサンフィッシュに関する研究 : I. 産卵習性について
Studies on the usefulness fo the bluegill sunfish, Lepomis macrochirus rafinesque, as an experimental standard animal : I. On the breeding habits
中村 中六
笹原 正五郎
矢田 敏晃
Abstract
bluegill sunfish (Lepomis macrochirus Rafinesque) を実験動物として用いるための研究の一部としてその周年探苗を目的とした研究を行なっているが，そのための基礎資料として3才魚を1対ずつ収容した場合の産卵習性について詳細な観察を行なった.
1) 雄は雌にくらべ魚、体がやや大きい上，吻端のまるみが強く胸部の黄燈色が鮮かである.
2) 産卵床は雄が尾鰭を強く振り池底の砂礫を繰り返し堀りおこすことにより作成され，直経30~70cm ，深さ2.5~10cm の浅いすりばち状を呈する.
3) 底質として同一池に3段階の粒度組成の砂礫を用いた場合，産卵床は最も粗い場所として2.0~9. 5 mm 径)にのみ作られたが，次段階の粗砂(主として0.4~4.8 mm径)でもそれを単一に用いた場合には産卵床の作成は支障なく行なわれた.ただ前者では産卵床が産卵の都度新設されたのに対し，後者では同じものが反復使用された.
4) 雄の求愛行動は，産卵が行なわれるまで産卵床作成と平行して続けられ，雌の鰓蓋部や生殖孔付近をつつきながら追尾し産卵床に誘引する.
5) 各産卵に 要する時間は約2 時間であり，その開始時刻は午前9~10時 頃ならびに夕方5時頃が多かった.産卵の際は，つねに雌が雄の内側になり産卵床を共lこ廻りながら，随時休を横にして雄の下にもぐり込み，その休を左右に振って放卵する.
6) 雄は仔魚、の浮上まで産卵床にとどまって卵および卿化仔魚を保護し，産卵した雌を含め侵入者に対し激しく攻撃する.
7) 産卵期は6 月から9 月(水温20~28℃ー午前10 時) にわたり， その間同一親魚が4，5回の産卵を行なう1回の産卵数は約21,000~36,000 (平均26,000) 枇であり，産卵の回数が進むに従いその産卵数が減少する傾向がある.
1) 雄は雌にくらべ魚、体がやや大きい上，吻端のまるみが強く胸部の黄燈色が鮮かである.
2) 産卵床は雄が尾鰭を強く振り池底の砂礫を繰り返し堀りおこすことにより作成され，直経30~70cm ，深さ2.5~10cm の浅いすりばち状を呈する.
3) 底質として同一池に3段階の粒度組成の砂礫を用いた場合，産卵床は最も粗い場所として2.0~9. 5 mm 径)にのみ作られたが，次段階の粗砂(主として0.4~4.8 mm径)でもそれを単一に用いた場合には産卵床の作成は支障なく行なわれた.ただ前者では産卵床が産卵の都度新設されたのに対し，後者では同じものが反復使用された.
4) 雄の求愛行動は，産卵が行なわれるまで産卵床作成と平行して続けられ，雌の鰓蓋部や生殖孔付近をつつきながら追尾し産卵床に誘引する.
5) 各産卵に 要する時間は約2 時間であり，その開始時刻は午前9~10時 頃ならびに夕方5時頃が多かった.産卵の際は，つねに雌が雄の内側になり産卵床を共lこ廻りながら，随時休を横にして雄の下にもぐり込み，その休を左右に振って放卵する.
6) 雄は仔魚、の浮上まで産卵床にとどまって卵および卿化仔魚を保護し，産卵した雌を含め侵入者に対し激しく攻撃する.
7) 産卵期は6 月から9 月(水温20~28℃ー午前10 時) にわたり， その間同一親魚が4，5回の産卵を行なう1回の産卵数は約21,000~36,000 (平均26,000) 枇であり，産卵の回数が進むに従いその産卵数が減少する傾向がある.
Abstract
As part of research-work on the usefulness of the bluegill sunfish ， Lepomis macrochirus Rafinesque， as an experimental standard animal in fisheries research， we have tried to find out a way of obtaining its fingerlings throughout the year-curriculum. As the first stage for this study， observations have been conducted on the breeding habits of this species， using specimens of full three years old in rearing tanks - 3 × 1.5 m, 0.3-0.5 m (depth) and 1 × 0.5m, 0.7 m (depth). The results so far obtained are as follows:
1) The male fish is slightly larger than the female. The tip of the snout is somewhat rounded indorsal view in case of the male, while slightly pointed in the female. No definite difference is found in other external characters between the two sexes, except that in the breeding season the color of the breast is brighter in the male than in the female.
2) In the present observations, the breeding season lasted from June until middle September. During this period, water temperature measured at 10 a. m. varied between 20,C and 28,C.
3) The male fish forms the nest by excavating through flipping and fanning out the sand and gravel with his tail. The nest is a shallow bowl-like depression of 30-70cm in diameter and 2.5-10cm in depth.
4) When the bottom of the tank is divided into three even parts respectively covered with a layer (about 15 cm thick) of gravel (mainly 2-9 mm in diameter); gravelly sand (mainly 0.4-4,8 mm); and coarse sand (mainly 0.25-2.0 mm), the nest is made exclusively at the portion covered with gravel. However, a similar nest is made on the gravelly sand when a part of the bottom of the tank is covered with this material and the other part is left nake. The nest is formed anew at each spawning in the prior case, while it is repeatedly used again in the latter.
5) The male continues to prepare the nest until the spawning begins. Meanwhile, he follows the female, kisses her near her genital pore and compells her to come to the nest.
6) The spawning act took place in daytime, often beginning at about 9 a.m or 5 p.m. The usual span of spawning takes about 2 hours. The male swims in circles around the nest side by side with the female, always on the outside of the female. Eggs are laid when the female reclines on her side and vibrates her body, while the male continues the upright posture.
7) The eggs and newly hatched larvae in the nest are guarded by the male. When other fish or animals approach the nest, he vigourously drives the invadors away from it.
8) A pair of the bluegill spawn 4 or 5 times in one breeding season. The number of eggs in one spawning varies from 21,000 to 36,000. The number of spawned eggs progressively tends to decrease by repeated spawning.
1) The male fish is slightly larger than the female. The tip of the snout is somewhat rounded indorsal view in case of the male, while slightly pointed in the female. No definite difference is found in other external characters between the two sexes, except that in the breeding season the color of the breast is brighter in the male than in the female.
2) In the present observations, the breeding season lasted from June until middle September. During this period, water temperature measured at 10 a. m. varied between 20,C and 28,C.
3) The male fish forms the nest by excavating through flipping and fanning out the sand and gravel with his tail. The nest is a shallow bowl-like depression of 30-70cm in diameter and 2.5-10cm in depth.
4) When the bottom of the tank is divided into three even parts respectively covered with a layer (about 15 cm thick) of gravel (mainly 2-9 mm in diameter); gravelly sand (mainly 0.4-4,8 mm); and coarse sand (mainly 0.25-2.0 mm), the nest is made exclusively at the portion covered with gravel. However, a similar nest is made on the gravelly sand when a part of the bottom of the tank is covered with this material and the other part is left nake. The nest is formed anew at each spawning in the prior case, while it is repeatedly used again in the latter.
5) The male continues to prepare the nest until the spawning begins. Meanwhile, he follows the female, kisses her near her genital pore and compells her to come to the nest.
6) The spawning act took place in daytime, often beginning at about 9 a.m or 5 p.m. The usual span of spawning takes about 2 hours. The male swims in circles around the nest side by side with the female, always on the outside of the female. Eggs are laid when the female reclines on her side and vibrates her body, while the male continues the upright posture.
7) The eggs and newly hatched larvae in the nest are guarded by the male. When other fish or animals approach the nest, he vigourously drives the invadors away from it.
8) A pair of the bluegill spawn 4 or 5 times in one breeding season. The number of eggs in one spawning varies from 21,000 to 36,000. The number of spawned eggs progressively tends to decrease by repeated spawning.
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