Report of the Workshop on Herring Age Reading

Sixteen herring otolith readers from 10 different West-European countries met in IJmuiden to compare methods and to describe procedures for standardization and improved quality of herring age readings. Agreement between readers varied between 63% and 79%, depending on the racial composition of the sampies and the time of the year in which they were taken. A special problem was presented by the difference in timing of the formation of the new summer growth zone; in young herring (2-3 rings) this takes place earlier in the season than in older herring. The ageing of herring also depended on the ability to classify fish as an autumn or spring spawner. This classification is normally made on the basis of additional information on maturity stage.