NUCLEIC-ACIDS AND ENZYMES IN ATLANTIC COD (GADUS-MORHUA) DIFFERING INCONDITION AND GROWTH-RATE TRAJECTORIES

Atlantic cod (Gadus morhua) were exposed to one of four feeding regime s, 16 weeks of food deprivation (U) or satiation feeding (F) or two 8- week periods of food deprivation followed by satiation feeding (UF) or vice versa (FU), to determine whether relationships between nucleic a cids or enzymes and growth rates result from a general enhancement of individual condition or are a direct result of enhanced growth rates. Final condition factor (K) differed between treatments, but did not di ffer between the mixed treatments after either 8 weeks of negative gro wth (FU) or 8 weeks of positive growth (UF). Intestinal cytochrome c o xidase activity matched the expected short-term growth rates, not only in fed and unfed fish but also in cod exposed to the mixed treatments (FU and UF). White muscle lactate dehydrogenase activity reflected gr owth rates, but initial levels were not reached within 8 weeks in FU c od. The liver glutamate pyruvate transaminase : DNA ratio reflected di fferences in K, hut not differences in recent growth rates. Myofibrill ar proteins decreased in unfed cod, while sarcoplasmic proteins follow ed changes in K more closely. The RNA:DNA ratio in white muscle did no t reflect changes in K or changes in growth rates.