Ichthyophonus hoferi disease in the herring in Norwegian waters
Original version
This report is not to be cited without prior reference to the authorsAbstract
After the discovery of I. hoferi disease in Norwegian spring
spawning herring in summer 1991, a program for systematic
surveillance of the disease in the herring in Norwegian waters
was developed. The programme, which aims primarily at
monitoring the prevalence of the disease, is described.
Macroscopic lesions in the heart emerged as the standard
diagnostic criterium. The results so far indicate that the
situation for Norwegian spring spawning herring is not
alarming, altohough it still deserves attention. For the North
Sea herring, the situation is less clear. The diseased herring
seem to be less prone to follow normal scooling behavior,
which causes sampling problems that must be taken into account
when interpreting prevalence results.