International Council for the Exploration of the Sea
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Report of the Sole (Solea solea) in the Bay of Biscay Otolith Exchange Scheme 2011

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posted on 2022-11-10, 11:08 authored by Kélig Mahé, Martine Moerman, Ilse Maertens, Anne Boiron-Leroy, Romain Elleboode

 There were an exchange and a workshop in 2002 of the sole in the Bay of  Biscay. The Otolith Exchange Scheme 2011 was the second exercise for the  sole in the Bay of Biscay. 5 readers participated in this exchange from  Belgium (2 readers), from France (2 readers) and from UK England (1  reader). The otolith collection (n=120) came from 3 samples realized at  the fishing port of La Cotinière during the month of June in 2010. For  each otolith, readers had the images of otolith section before and after  staining. This analyse presented the results of 8 readers (5 readings  of stained otoliths and 3 readings of unstained otoliths). Mean  precision of age estimate for individual fish were Coefficient of  Variation (CV) of 4.7% and percent agreement to modal age of 88.6%. On  120 otoliths, 67 were read with 100% agreement (56%) and thus a CV of  0%. There were only little variations in precision of age estimation  between individual fish, with CV ranging from 0 to 27% and percent  agreement range from 50 to 100%. There is no bias between the readers of  Belgium (Ilse Maertens and Martine Moerman), France (Anne Boiron and  Romain Elleboode) and the UK England (Ian Holmes). The Planning Group on Commercial Catch, Discards and Biological Sampling (PGCCDBS) meeting in 2011 recommended a small exchange : “ Bay of Biscay sole (Solea solea) The WGHMM identified a need to identify the cause of a discrepancy between French and Belgian weights at age. PGCCDBS recommends a small exchange in 2011 in order to clarify this issue and report back to WGHMM.”

Three countries took part in this exchange: Belgium, France, UK

The objectives of the exchange were to investigate the levels of agreement on age readings and to analyse the relative differences between age readers and techniques



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