Biochemical indices for instantaneous growth estimation in young cephalopod Sepia officinalis L.

Aspartate transcarbamylase (ATCase) activity was used to estimate instantan eous growth in young cuttlefish (Sepia officinulis) reared under different diet conditions, and compared with estimation obtained by RNA concentration . During the first month of life, the changes in ATCase activity and RNA co ntent of muscle are related to growth. ATCase appears to be a good index of growth during the first stage of intense cell multiplication. ATCase activ ity is correlated to food intake lip to a maximum ration, but decreases whe n animals are more than 40 days old. The approach of using ATCase activity as a biochemical index for estimating short-term change in growth rates of young cuttlefish in experimental rearing could be extended to young cephalo pods collected in the field, and used to predict the effect of biotic facto rs in recruitment. (C) 2000 International Council for the Exploration of th e Sea.