Experimental rearing of juvenile New Zealand turbot Colistium nudipinnis (Waite 1910): a potential new aquaculture species

Investigations into factors affecting the growth of the first hatchery-produced juvenile New Zealand turbot Colistium nudipinnis (Waite 1910) showed that this endemic flatfish can be reared in raceways and tanks. After initial high mortality (> 60%) in the post-weaning period (to 120 days post-hatch), the juveniles showed high survival over the grow-out period. Growth of the juveniles was better at lower (16–18 °C) than at higher (> 20 °C) water temperatures, and better in a deep tank than in shallow raceways. Under the experimental rearing conditions, growth (to mean weight of 0.2 kg in 20 months) was relatively slow and food conversion (FCRs > 1.4) relatively high, both factors being related to the feeding behaviour of this species. C. nudipinnis feeds directly from the bottom, and this behavioural characteristic influences aspects of fish farming practice, such as stocking density and feeding strategy, that are critical to its economic viability. There is potential to improve the growth by optimizing the rearing conditions, so that it may not be unrealistic to achieve the maximum growth reached in these trials commercially and produce marketable farmed turbot, of over 400 g weight, within 2 years.