Effect of rearing temperature on growth and maturation of black rockfish Sebastes schlegeli
2007
Nakagawa, M.(National Center for Stock Enhancement, Goto, Nagasaki (Japan). Goto Station)
Effects of rearing temperature on growth and maturation of black rockfish Sebastes schlegeli were examined in captivity. Rockfish were reared in three different temperature conditions: natural temperature (control), natural temperature +12 deg C in winter-spring (12 deg C) and natural temperature +15 deg C in winter-spring (15 deg C), during the period from 7 months after birth (MAB) in December 1997 to 48 MAB in May 2001 (4-year-old). Rockfish reared at higher temperatures in winter-spring showed significantly greater TL as 15 deg C 12 deg C control up to 15 MAB. Significant differences in TL between treatments were not found after 16 MAB because of the higher growth rate of control 12 deg C 15 deg C during the subsequent warm period of 13-18 MAB. This phenomenon is thought to be compensatory growth of fish whose growth was limited because of low temperature in the winter-spring season. Female fish grew faster in the higher temperature treatment up to 2.5 years old, but no difference was found in the growth rate among treatments for male. A slightly higher maturation rate was apparent at higher temperature treatments in males, but no temperature effect was seen for maturation in female fish. Four-year-old control and 12 deg C female bore healthy larvae. However, those at 15 deg C had abnormal parturition. Within the present experimental conditions, the artificial increase of winter-spring temperature from a natural one to 12 deg C or 15 deg C is inferred to be of no use to enhance growth and maturation of black rockfish.
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