Early weaning of Atlantic cod (Gadus morhua) larvae onto a microparticulate diet

A microparticulate diet was introduced on 8, 15, 22, 29 and 29 days post-hatch (dph) (with Artemia). Larvae were weaned from rotifers directly onto the diet in the first four treatments. Artemia were used in the fifth treatment and were fed for a period of 10 days. The microparticulate diet was able to completely replace live prey long before metamorphosis and larvae were weaned by 8.5 mm standard length. With the earliest introduction of the microparticulate diet on 8 dph, we observed 35% survival through 71 dph (21 mm). The survival of larvae from the other treatments was not significantly different and ranged from 32.7% to 39.4%. Weaning time did not have a significant affect on growth of cod larvae, as there were no differences when introducing the microparticulate diet on 8 or 29 (without Artemia) dph. However, supplementation of Artemia for 10 days had a growth-promoting effect. Larvae were larger than individuals from the other four treatments beginning on 29 dph and continued throughout the experiment. By 71 dph, they were 24 mm and weighed 20 mg (dry weight). Successful culture of many finfish species is dependent on the use of live prey during the larval period. Early introduction of a microparticulate diet reduces the quantity of rotifers required and makes Artemia nonessential. This lowers production costs considerably by reducing the number of live animal cultures that must be maintained. However, until better diets are produced, careful consideration should be given to how early weaning affects production cost vs. growth rate of the larvae. (C) 2000 Elsevier Science B.V. All rights reserved.