Workshop 3 on Stock Identification and Allocation of Catches of Herring to Stocks
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 concept of ‘a herring stock’ within a geographical area such as a management unit is not straight-forward and cannot be assumed. Genetic stock identification of herring has been recently examined by WKSIDAC2 in 2023 (ICES, 2023) and recommended methods for future stock identification. However, several caveats have been highlighted before these genetic methods can be fully implemented in the assessment of herring stocks.
Therefore, it is now timely to resolve these caveats following the recommendations of WKSIDAC2 in WKSIDAC3. The objectives of the workshop are to
- Review current sampling strategies and designs undertaken by laboratories and their surveys.
- Investigate the advantages and disadvantages of differing sampling strategies.
- Outline a common generic approach for sampling both surveys and commercial catches.
- Draft guidelines for the methods along with their uncertainties.
The workshop will cover the ICES subareas 2, 3, 4, 5, 6 and 7. A draft manual will be compiled, specifying the areas/surveys relevant to the given method, contain details on the minimum sampling size, stratification, and other sampling-related issues.
Where appropriate samples have or are being obtained it is possible to undertake ‘stock separation’ using e.g. genetics for the most recent period, and going forward with a new sampling protocol. Stock assessment, however, is reliant on a time-series of data where the stock information is known. Having the ability to retrospectively separate both survey and catch data to stock is important and this needs to predate any new genetic protocols which may be implemented.
The workshop will also consider a number of available data datasets which could be used to separate the historical survey and catch data into the various populations. These could include otolith archives, age and growth data etc.
