アオリイカの多回産卵について

概要

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We reared the oval squid Sepioteuthis lessoniana in pens from June 3 to July 31 1992. The eggs spawned by these squid were reared in a tank to hatch. A female reared with a male in a pen spawned 11 times at intervals of 1-9 days from June 11 to July 30. This female laid 1, 540 egg capsules containing 7, 780 eggs in total (55 to 302 capsules containing 231 to 1, 388 eggs at one spawning). The hatchability of the eggs at each spawning ranged from 66.7 to 97.8%. Another female reared without a male in a pen spawned more than four times, but the hatchability rate of the eggs was lower than the former female. The female with a male had spermatophores when she died, while the female without a male had no spermatophores after several spawnings (both females had spermatophores at the beginning of the experiment). These results suggest that the oval squids copulated over the period from the previous spawning to the next. The number (Y) of eggs in one capsule was related to the water temperature (X, °C) on the day of spawning. This relation was expressed by the following equation. Y=15.1-0.426X.