Effects of rearing temperature on growth and survival of larval sablefish (Anoplopoma fimbria)

The effects of three different rearing temperatures (12, 15 and 18°C) on growth and survival of sablefish larvae (Anoplopoma fimbria) were examined from 5 days poststocking to weaned subjuveniles. First‐feeding larvae were stocked into 960‐L circular tanks at a density of 15 larvae/L (n = 3 per temperature treatment). Feeding, increases in light and water flow and other changes during the experiment were based on a degree‐day (°Cday) schedule to adjust for time and temperature. The larvae were weaned on calendar day 41, 34 and 30 in the 12, 15 and 18°C treatments respectively. Survival to weaning was greater at 15 than 12 or 18°C. Calendar day and degree‐day length and dry weight were greater in the 18°C treatment. The larvae were weaned 7 days earlier at 15°C and 11 days earlier at 18°C compared to larvae at 12°C. Sablefish larvae can be reared at 15°C with faster growth and good survival compared to 12°C and at an approximately 17% reduction in cost and labour. Sablefish grew even faster but had higher mortality rates at 18°C compared to 15°C. Results from genotyping strongly suggest that there is a genetic basis for performing differentially at varying rearing temperatures and would also suggest that selection for faster growth and higher survival could be accomplished in a broodstock programme.