Metamorphosis induction and postlarval growth of the red abalone (Haliotis rufescens) were evaluated in a commercial farm of Baja California, México. This hatchery settles larvae with gamma-aminobutyric acid (GABA, 1-μM final concentration) and culture postlarvae in 250-L tanks placed in a four-story structure inside a building with artificial illumination. Eight tanks (four at the top and four at the bottom of a culture structure) were sampled during four months after settlement. Upper tanks received more light than the lower tanks (means of 727 and 217 lux, respectively) and had a higher mean water temperature (14.9°C and 14.4°C, respectively). Estimates of metamorphosis induction were highly variable (37% to 99%) and mean values were higher in lower (76%) than in higher (54%) tanks. Potential causes of this unexpected variability are discussed. There was a significant positive linear relationship between metamorphosis induction and early (7-day) postlarval survival. Average postlarval growth rates were also highly variable among tanks (37–63 μm/day) and slightly higher in upper than in lower tanks (60 and 52 μm/day, respectively). During the sampling period, growth variability was positively associated with water temperature changes, especially after the formation of the first respiratory pore when growth increased abruptly.
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Vol. 26 • No. 3