The effects of temperature and size on growth and mortality of cod larvae

The optimal temperatures for growth of four groups of hatchery-reared cod larvae (geometric mean weight: 73, 191, 249 and 251 μg), reared on rotifers at four or five constant temperatures between 4 and 16° C for 14, 12, 9 and 16 days were 9.7, 12.3, 12.7 and 13.4° C, respectively. The maximum growth rate also increased with size and was 6.5, 9.6, 11.7 and 11.3% day -1 for the respective size groups. The optimal temperature for survival was 8.5-8.8° C for all size groups. The results indicate an opposite relationship between (1) size and optimal temperature for growth and (2) size and maximum growth rate of cod larvae, to that observed for juvenile and immature cod.