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.