Report of the mackerel age determination workshop

It is generally accepted that age determination of mackerel of the main stocks in the ICES area (the Western and the North Sea stocks) by the various otolith readers is sufficiently consistent and reliable for assessment  purposes  up to the age of ten.  Up to the present time it has been the normal practice of the ICES Mackerel Working Group to make age structured analytical assessments based on ages 1 to 10 with the older fish grouped as an 11+ group.  It could be an advantage for Virtual Population Analyses to work with an extended age range. Consequently at the 1984 meeting of the ICES Mackerel Working Group it was agreed  that an otolith exchange should be organised and the results examined before extending the range of ages used in the assessments.  The results of this otolith exchange were reported by Dawson (1986)and it was concluded that the level of agreement of fish older than 10 years was not satisfactory and it was suggested that convening an age determination workshop would be beneficial and hopefully would help to reduce the differences in otolith interpretation. Seven otolith readers from seven countries participated in the otolith exchange and five of these readers were able to attend the age determination workshop