Workshop on Stock Identification and Allocation of Catches of Herring to Stocks (WKSIDAC)

The Workshop on stock identification and allocation of catches of herring to stocks (WKSIDAC) met on 20–24th November 2017 in Galway, Ireland. The workshop had several objectives; improve the accuracy and precision of the methods currently applied across laboratories by area; compare alternative available methods; outline a common generic approach in terms of methods; and draft guidelines for conducting stock-splits for assessment purposes. The meeting was co-chaired by Richard D.M. Nash, Norway and Martin Pastoors, The Netherlands. In total there were 26 participants in the meeting, of which two were present remotely, for their presentations. Participants were from 11 countries (representing 14 different institutes and three industry related organisations). 

A series of five ToRs were addressed which are summarized as follows:
At the outset of the meeting the key issues relating to stock mixes in each of the man-agement areas (2, 3, 5, 6 and 7) were outlined along with why the stock identification was important for the assessments of each of these stocks.
During the review of information on stock identification and validation work done so far it was apparent that there was no consistency between areas and in most either there was no validation or the validation needed to be updated. Only a few areas cur-rently utilise herring stock identification methodology for the assessments, namely areas 3.a and 4 for separation of WBSS from NSAS although the methodology was not ideal, Icelandic waters for separation of ISS from NSS and in Faroese waters for separating autumn from spring spawners.

The concept of this workshop was more on potential methods rather than a hands-on approach and as such the only material available to work on was the shape analyses approach. The attendees were able to capture images and the initial shape outlines un-dertaken with three different analytical techniques giving stable results. The rest of the workshop provided information on the available genetic, otolith-shape, -microstructure, - chemistry (including stable isotopes), morphometrics, and growth. The necessity of validation and Standard protocols or operating procedures was highlighted.  
The optimal allocation method for stock assessment purposes (as perceived by the Workshop members) varied by area. Otolith shape analyses appeared the most widely recommended, however, other techniques such as genetics and otolith microstructure and micro-chemistry would be necessary for validating the shape analyses results. In the Baltic separation based on the growth, through length-at-age was favoured and in Area 6.a a combined approach using genetics and morphology is preferred. Baselines would also need to be updated on a regular basis.

The Workshop was not able to provide an outline of a manual by method for stock identification of herring for implementation in individual laboratories nor provide guidance on retrospective corrections of herring survey time-series. These topics need to be taken up in some future Workshop/Meeting.