© 2005 International Council for the Exploration of the Sea
Growth, survival, and development of Atlantic cod (Gadus morhua L.) weaned onto diets containing various sources of marine protein
a Institute of Marine Research Austevoll, N-5392 Storebø, Norway
b Institute of Marine Research Matre, 5984 Matredal, Norway
c Norwegian Institute of Fisheries and Aquaculture Research Kjerreidviken 16, 5141 Fyllingsdalen, Norway
*Correspondence to I. Opstad: tel: +47 56182267; fax: +47 56182222. e-mail: ingegjerd.opstad{at}imr.no.
We studied the effects of partial or complete substitution of fishmeal with alternative sources of marine protein (amphipod or krill meal) on growth, survival, liver index, and deformities of juvenile cod (Gadus morhua L.). The diets contained either 100% fishmeal or fishmeal that was replaced with 25%, 50%, or 100% amphipod meal or 50% or 100% Antarctic krill meal. Cod larvae were start-fed on rotifers and weaned directly to one of the six formulated feeds at a mean wet weight of 28 mg, 40 days post first-feeding. The mean weight of fish reared on different diets at the end of the experiment ranged from 0.92 to 2.52 g. The best growth was obtained by cod fed 100% fishmeal and 50% krill meal. There was a trend in the direction of slower growth with increasing levels of amphipod meal in the diets. Survival ranged from 87% to 79%, and there was a tendency for higher mortality with increasing content of amphipod meal. The liver index varied between 11.7% and 9.9%. The composition of the diets also had a significant influence on the occurrence of skeletal deformities. The highest proportion of deformities (16% of all fish) was in fish fed 100% amphipod meal, decreasing as the proportion of amphipod meal in the diets declined. A similar effect was not seen with Antarctic krill meal. The amphipod meal had a high content of ash, fluoride, cadmium, and mercury, which may have caused the deformities.
Keywords: alternative protein sources, cod, weaning
Received 21 September 2004; accepted 14 November 2005.