Effects of reduced salinities on growth, food conversion efficiency and osmoregulatory status in the spotted wolffish

No significant differences in mean mass between groups were found at any ti me in spotted wolffish Anarhichas minor, mean (+/- S.D.) initial mass 76 (/- 21) g, reared at salinities of 12, 17, 25 and 34%, for 12 weeks at 8 deg rees C. Salinity did not have a significant effect on daily Feeding rates, total food consumption, food conversion efficiency and protein efficiency r atio. Growth trajectories varied between groups, but no overall difference in growth was found. Plasma osmolality and plasma chloride levels decreased with salinity in a 48 h abrupt exposure trial, and in the growth experimen t the low salinity groups (12 and 17 parts per thousand) exhibited signific antly lower values compared with 25 and 34%, The decrease was moderate and concentrations were well within the range described for other marine specie s. The results indicate that the spotted wolffish is a strong osmoregulator which could be reared at various salinity levels. (C) 2001 The Fisheries S ociety of the British Isles.