Most herring populations are migratory and often congregate on feeding and wintering grounds where aggregations may consist of mixtures of individuals from several populations, thus the standard concept of 'a herring stock' within a geographical area such as a management unit is not straight-forward to assume. Morphometric analysis, analysis of calcified structures, and analysis of the genetic composition are among the most widespread tools available for stock identification of bony fish and a wide variety of methods have been used to separate herring into populations or stocks. A prevailing method is to relate population affiliation to spawning time of the individual herring and the current stock splitting procedure for NSAS and WBSS applied in the herring assessment working group in ICES (HAWG) assigns individual herring to stock based on spawning time based on either otolith microstructure, otolith shape or vertebrae count. These methods rely on updated baselines and inter-calibration between assigning laboratories in order to be as accurate and precise as possible. The last workshop was held between Sweden and Denmark in 1989. Since then, the methods have been implemented in several other countries and and new methods have been developed. In addition, Next Generation Sequencing (NGS) and Genotyping by Sequencing (GBS) based approaches have recently been developed and applied to e.g. cod (Gadus morhua), boarfish (Capros aper) and horse mackerel (Trachurus trachurus) for marker development and screening of spawning samples. Given all these developments, it is now highly appropriate to have an comprehensive workshop for herring stock identification methods. The workshop will cover the areas 2.a, 6.a+7.b-c, 4.a-c+7.d, 3.a, SD22+23+24 and the most common methods used to separate herring in those areas. The Workshop will be area-specific in terms of meth-ods, evaluations and output, but will also examine potential implementation of differ-ent methods for stocks new to the method. Manuals will be drafted, specifying the are-as relevant for the given method, hold details on minimum sampling size, stratifica-tion and other sampling related issues.