Novel effects of salinity and water reuse on growth of juvenile New Zealand turbot, Colistium nudipinnis (Waite 1910), a potential aquaculture species

Juvenile New Zealand turbot, Colistium nudipinnis (Waite 1910), produced during the first aquaculture development project for this endemic flatfish, were reared at ambient and reduced salinities to determine the effect of salinity on growth and survival and the possible implications for aquaculture. Juveniles aged from 176 days to 17 months showed a high level of salinity tolerance, with minimal mortality attributable to salinity reduction over the range 33–18 g L^?1. Growth rate was slightly increased at the slightly reduced salinity of 28 g L^?1 (5 g L^?1 below ambient) but was significantly decreased at the markedly reduced salinity of 18 g L^?1. The growth response at 23 g L^?1 was markedly different between ‘new’ water and water that was recycled from a previous set of rearing tanks, with juveniles reared in 23 g L^?1‘new’ having a mean growth rate that was 29% lower than that of the control juveniles (in 33 g L^?1‘new’ water), whereas juveniles in 23 g L^?1‘reused’ water grew 45% faster than the controls. The implications of this novel effect are discussed in relation to the aquaculture potential of the New Zealand turbot.