1992 ICES coordinated acoustic survey of ICES divisions IVa, IVb and VIa

This papers provides a report on the combined acoustic survey of herring stocks in the North Sea and ICES Division IVa in July 1992. Surveys by Norway, Scotland and the Netherlands are included covering the period 24 June to 31 July. The results and distributions of herring by age are given for area by 30 mile statistical squares. The results are expressed in biomass and numbers of fish. In addition data on ichthyophonus infection rates determined from trawl samples obtained on the survey are reported and the infected numbers and proportions of the population are estimated. A discussion of errors in the estimation of ichthyophonus infection are included in the report