Disease Problems in Seawater Pen-culture of Salmonids

Abstract

Attempts have been done by the present author to improve the method for rearing and liberating chum salmon(Oncorhynchus keta)fry in Iwate Prefecture since 1967. As a result the return rate could be increased by liberating fry after being cultured in seawater for some time.
Vibriosis was noted to be the major problem in the culture of fry in seawater. It often occurred when water temperature rose rapidly to 11°C and above. A coho salmon(O. kisutch)culture using net pens set in the bay has been practiced commercially in recent years in the Northern Japan.Vibriosis is a serious problem in the culture of coho salmon fry, too. The matter that fish culturists most ardently hope is rapid development of effective vaccines and practical vaccine delivery systems against vibriosis.