Nr. 13: ICES co-ordinated acoustic survey on Herring and Sprat in the North Sea

Objectives for this survey with RV “Johan Hjort” were:
a) To conduct an acoustic survey to estimate the abundance and distribution of herring and sprat in the north-eastern part of the North Sea, between 57°00’and 62° N, and between 2° and 5° E.
b) To obtain biological samples. Herring were sampled for data on length, weight, age, sex, maturity and vertebrae count and infection by Ichthyphonus