Acoustic estimates of abundance-at-age of juvenile Norwegian spring-spawning herring (Clupea harengus L.) in the Barents Sea from 1983 to 1993

Precision and relevance of pre-recruit studies for fishery management related to fish stocks in the Barents Sea and adjacent waters. Proceeding of the sixth IMR-PINRO Symposium Bergen, 14-17 June 1994The first year-class of Norwegian spring-spawning herring to enter the Barents Sea in significant numbers since the stock collapse in the late 1960'ies was the 1983-cohort. Regular acoustic surveys have been carried out since then to assess the changes in abundance of recruiting year-classes in the area. In the following 11-year period several more cohorts of herring were distributed in the Barents Sea, and the development of the abundance of each t year-class has been followed in the same way. Altogether fifty acoustic estimates of the abundance of the first four age-groups of nine year-classes were obtained during this period. Standardised methods through the young life stages are in this context important to foresee the recruitment to the spawning stock and to make better medium term prognosis of the stock development. It is suggested that the data series presented here may be of use in shedding light on some of the processes determining the variability of year-class strength of Norwegian spring-spawning herring