Temperature- and size-dependent growth of larval and early juvenile Atlantic cod (Gadus morhua): a comparative study of Norwegian coastal cod and northeast Arctic cod

Norwegian coastal (NC) and northeast Arctic (NA) Atlantic cod (Gadus morhua ) larvae were reared on live zooplankton to investigate temperature- and si ze-specific growth. Larval and juvenile growth was temperature and size dep endent. Growth in length and weight increased with increasing temperature f rom 4 to 14degrees C, with a corresponding reduced larval stage duration. M aximum growthrate occurred at a larval size of 0.1-1.0 mg dry weight, follo wed by a declining trend during the juvenile stage. The temperature optimum of larval cod fedin excess is estimated to be between 14 and 16 degrees C, with a maximum weight-specific growth potential exceeding 25%.day(-1). Tem perature- and stock-specific growth curves of dry weight at age are well de scribed by a generalized Gompertz model. A stock-specific difference in mea n weight at age was observed, with NC growing better than NA. Neither count ergradient latitudinal variation in growth capacity of the two larval cod s tocks nor temperature adaptation across latitudes was indicated. A stock-sp ecific difference in weight at length was observed in early juveniles, with NC being heavier than NA. Overall, a positive correlation between temperat ure and condition level was found. No distinct temperature- or stock-specif ic differences in survival were observed.