Report of the Saithe (Polliachius virens, L.) Otolith Exchange 2013

The ICES Planning Group on Commercial Catch, Discards and Biological Sampling (PGCCDBS) identified the need of a Saithe (Polliachius virens) otolith exchange to take place in 2013. It was the second exchange after that’s of 2008. The IFREMER institute coordinated this exchange. A total of 295 fish was sampled from the Barent sea (ICES area : IIa, N=24), from the North Sea (ICES area : IV, N=34) and from the Western Scotland (ICES area : VIa, N=237). The length range of the fish was between 37 and 96 cm, with mean 60 cm. 13 readers from 5 countries (France, Germany, Iceland, Sweden & Norway) were participated. Mean precision of age estimate for individual fish were Coefficient of Variation (CV) of 6.2% and percent agreement to modal age of 85.9. Among 298 fish, 54 were read with 100% agreement (18%) and thus a CV of 0%. There were variations in precision of age estimate between individual fish, with CV ranging from 0 to 27% and percent agreement range from 40 to 100% (Tab. 2). Precision of Age estimation from the North Sea was not as good as than those of the others areas. However, the size and age of fish from the North Sea were bigger than those of the others areas. The differences are primarily explained by the position and the number of rings after the eighth and closed the edge