The intensive tearing of juvenile cod, Gadus morhua L. In: The propagation of cod Gadus morhua L.: an international symposium, Arendal, 14 - 17 June 1983

Cod were reared in the laboratory from the egg to marketable size using cultured live foods for the early stages and then artificial diets. Survival to metamorphosis was about 10%; subsequent mortalities were negligible. The techniques developed for rearing larval turbot were broadly applicable to the cod. The larvae were fed initially on rotifers, with frequent additions of lsochrysis to the tanks, and then on Artemia. Nauplii freshly hatched from San Francisco eggs were inadequate as food but were improved when fed for 2 days on lsochrysis before being offered. No such treatment was necessary for nauplii hatched from Brazilian eggs. Post-metamorphosis growth rates varied from 1.9 to 2.8 cm/month at mean temperatures ranging from 6 to 17 degrees C. The optimum temperature for growth appeared to be around 10-12 degrees C. The prospects and problems of mass-producing juvenile cod in hatcheries are discussed