Temperature can have wide-ranging effects on the early development of marine fish. In aquaculture, higher larval rearing temperatures can accelerate development and thus shorten the intensive and expensive larval rearing period. In a previous study with larval sablefish (Anoplopoma fimbria), time between first feeding on live prey and weaning onto artificial diets was shortened when larval rearing temperatures were increased from 12 degrees C to 15 degrees C or 18 degrees C. However, those higher temperatures may induce delayed or persistent effects that may not be detected until the fish are older. In this study, we took weaned fish from the above previous study and reared them for up to nine months at a common, naturally fluctuating temperature (mean 11 degrees C, SD 2.3, range 7.9-13.6 degrees C) to learn about effects of prior larval rearing temperature on future growth, flesh firmness, deformities, and phenotypic sex. At the beginning of this study, soon after weaning onto prepared feeds, larvae that had been previously reared at 18 degrees C were larger than larvae that had been previously reared at 12 degrees C or 15 degrees C. However, 15 degrees C juveniles caught up in size to the 18 degrees C juveniles by 3.5 months after removal from the temperature exposures and rearing at common temperature, and surpassed them in size by nine months (weights at nine months for 12 degrees C: 438 +/- 12 g, 15 degrees C: 530 +/- 15 g, and 18 degrees C: 472 +/- 11 g). Survival rates from weaning to the end of the nine-month common-temperature rearing period were greater for fish previously reared at 15 degrees C (92.3%) than for fish previously reared at 12 degrees C (83.9%) or 18 degrees C (82.6%). After the nine-month common-temperature rearing period, raw flesh from 15 degrees C fish was slightly softer than flesh from 18 degrees C fish, but neither treatment differed from 12 degrees C fish. Spinal deformities were highest in 12 degrees C fish, maxilla deformities were highest in 15 degrees C fish, and pelvic fin deformities were highest in 18 degrees C fish. Some deformities were associated with decreased growth. Broodstock crosses significantly differed in frequencies of isthmus, pelvic fin, and maxilla deformities, indicating possible genetic, maternal, and/or early environmental effects. Phenotypic sex matched genetic sex in all treatments; therefore, none of the prior temperature treatments induced sex reversal. This study shows that larval sablefish can be reared at temperatures > 12 degrees C without inducing severe long-term effects, and that warmer larval rearing temperatures-particularly 15 degrees C-may have benefits to rates of survival, deformity, and growth that do not become evident until long-term rearing after the temperature exposure period. Statement of relevance: Larval rearing temperature can have long-term effects.
