Report of the Workshop of National Age Readings Coordinators (WKNARC)

• Format: Report
• Language: English
• Published: 2011
• Subjects: Greenland; Norway; Iceland
• Online Access: https://archimer.ifremer.fr/doc/00049/16016/13477.pdf; https://archimer.ifremer.fr/doc/00049/16016/

The Workshop of National Age Readings Coordinators (WKNARC), chaired by Kélig Mahé, France and Willie McCurdy, UK, met in Boulogne-sur-Mer (IFREMER) France, 5–9 September 2011. 17 nations were represented by 27 participants. Age determina-tion is an essential feature in fish stock assessment to estimate the rates of mortalities and growth. Assessment of species/stocks using age structured models has proved useful in establishing a diagnosis of stock status. However, the approach has several limitations and shortcomings such as stock structure, natural mortality and growth. Age data is provided by different countries and are estimated using international ageing criteria which have not been validated. WKNARC was proposed by the Planning Group on Commercial Catches, Discards and Biological Sampling (PGCCDBS) 2010. Many activities in this group are closely linked to the activities of the Data Collection Framework (DCF). For the purpose of inter-calibration between ageing labs WKNARC reviewed preparation methods by species and areas, material and techniques development, methods in images process-ing, and the validation methods. WKNARC reviewed tools for the exchanges and workshops (WebGR, PGCCDBS Guidelines for Otolith Exchanges). The report contains a synthesis of 34 questionnaires (Belgium, Denmark, France, Germany, Iceland, Ireland, Netherlands, Norway, Sweden, UK England, UK-Scotland, UK-Northern Ireland, Slovenia, Spain, Portugal, Malta, Lithuania, Latvia, Greece, Finland, Cyprus, Italy, Romania, Greenland) presenting the species and the techniques of all these institutes. A list of all the publications concerning the age vali-dation studies is provided for ICES and GFCM areas. A summary of the status of quality management for age reading at MS institutes is presented. Good practice for age validations was identified. All Tools for the exchanges and workshops, in par-ticular the WebGR tool, are described in detail. Methods and usage of image process-ing at MS institutes are presented and an overview of methods in images processing is provided. The report recommends that a 3-point scale of age reading quality be used by all age readers who provide age data for stock assessments and that Age Calibration Workshops derive descriptors for the three scale points that are applica-ble to their species-stocks. The report presents the recommendations and the proposals to progress and stan-dardise age estimation within a Quality Control framework.