Otolith Exchange Results Of European Anchovy (Engraulis encrasicolus) 2014

European anchovy (Engraulis encrasicolus) is a small pelagic species of high commercial importance in European waters, in both the Atlantic and the Mediterranean Sea.

Ages reading on anchovy are important input data for the assessment and carried out by number of laboratories using international ageing criteria. The report on the latest workshop on age reading of European anchovy (WKARA, ICES 2009) stated that the frequency of workshops and exchanges on age reading of anchovy in the past had been good for Atlantic areas (mainly for the Bay of Biscay), and had been very poor for the Mediterranean areas. As well as for the Bay of Biscay have been many exchanges and workshops since the 90s (Astudillo et al 1990; Villamor and Uriarte, 1996; Uriarte, 2002a; Uriarte et al., 2002, 2006 and 2007), and the Gulf of Cadiz (Garcia, 1998; Uriarte et al., 2002), only one has been done for the Mediterranean areas (ICES, 2009). In this latter was the first time that anchovy otoliths of Atlantic and Mediterranean were included together. All workshops discussed and made an effort to standardize age reading methods by preparing a manual and a reference collection of agreed age otoliths.

The overall result of the last exchange and workshop exercise in 2009 was that there were significant variations in anchovy age estimates between readers and areas. Low precision, and large relative biases between readers and areas were found. Most of the anchovy otoliths were not well classified by most of the readers during the 2009 exchange, excluding the results of the readers of the Bay of Biscay (BB readers), which seem to be satisfactory. Possibly the success of the readers of the Bay of Biscay set, compared with the other sets, is because exchanges and workshops have been conducted since 1990 in this area, and there are sufficient criteria for the interpretation of anchovy otoliths. Following these findings all participants in the workshop agreed to follow the guidelines of the WKARA report for the decided upcoming exchange of images to facilitate an evaluation of the guidelines.

The Planning Group on Commercial Catch, Discards and Biological Sampling (PGCCDBS, ICES 2014a) indicated that an otolith exchange on anchovy should be organized in 2014, in order to ascertain the current level of precision among institutes and the difficulties that the age reading of anchovy otoliths present. This report represents the results of this exchange summarizing the readings of 18 readers of 10 European laboratories in five countries. The exchange was carried out from November 2014 to March 2015, organized by IEO and AZTI (Spain).