Temperature dependent otolith growth of larval and early juvenile Atlantic cod (Gadus morhua)

The otolith (lapillus) size-fish size relationship was examined for offspring of two Atlantic cod stocks, reared Lit different temperatures. Larvae and early juveniles reared Lit high temperatures (fast growing), had larger otoliths Lit a given length than fish reared Lit low temperatures (slow growing). Within a given temperature group. however. faster growing cod tended to have proportionally smaller otoliths, although the difference was not always significant. Moreover, the otolith radius of Norwegian coastal cod was larger, Lit given fish lengths. compared to that of the northeast Arctic cod. An ontogenetic shift in the allometric otolith size-fish size relationship Occurred Lit onset of metamorphosis ( 12 mm). Mean daily otolith growth of the lapillus radius increased with increasing temperature from 4 to 14degreesC and was size dependent and peaked Lit a larval length of about 25 mm. The radius of the lapillus at hatching was poorly correlated with larval length Lit day 56 for both stocks, suggesting, that the potential for fast growth may not necessarily be reflected in traits present Lit hatching. The effects of temperature, stock and ontogeny are discussed with regard to the assumption of constant proportionality between otolith growth and fish growth. (C) 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.