Report of the second Workshop on Age Reading of Red Mullet and Striped Red Mullet. 2 - 6 July 2012 Boulogne-sur-Mer, France

Type Scientific report
Date 2012
Language English
Ref. ICES CM 2012 / ACOM: 60
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Author(s) ICES
Contributor(s) Mahe KeligORCID, Elleboode Romain, Bellamy Elise
Abstract The Planning Group on Commercial Catch, Discards and Biological Sampling (PGCCDBS) and the Planning Group of Mediterranean (PGMED) meetings in 2011 (ICES, 2011a) recommended an otoliths and scales exchange for Mullus species from Atlantic and Mediterranean sea. Workshop on Age reading red mullet (Mullus barbatus) and striped red mullet (Mullus surmuletus) (WKACM2, chair : K. Mahé, France) has been held in Boulogne sur Mer (France) from 2 to 6 July 2012. Five countries took part in this exchange (Spain, Greece, Cyprus, Italy, France, for a total of 8 partici-pants) during 2011, and 3 countries (Spain, Italy, France: 6 participants) have been involved in the workshop. Results of this exchange showed important problems between readers (Mahé et al., 2012). The aim of this workshop was to review the results of the exchange 2011 and compare them with those of the previous workshop, to review validation methods on these species, to clarify the interpretation of annual rings, to continue a reference col-lection of well defined otoliths and to improve the recommendations.This report presented a review of age validation studies and state-of-the-art on age-ing the two Mullus species. After the presentation of readings results (mean agree-ment percentage from 50.5% to 74.8%; mean CV from 29.7% to 61.7%) and the precision of age estimation, the participants identified the sources of bias in the interpretation of the Mullus age. In both species, the position of the first growth ring on the otolith was identified as most important problem especially for Mediterranean area. Regarding the age from scales and otoliths, the choice of calcified piece influenced the results. The participants agreed in indicating the otoliths as the best calci-fied structure to ageing Mullus species. After discussion, second reading was made with the new scheme. The precision increased specially for M. barbatus in the Mediterranean sea (mean agreement percentage from 58.7% to 76.5%; mean CV from 37.3% to 16.7%). Moreover, there were some advances on the guideline of age reading during this workshop but it could be necessary to continue to clarify this guideline especially in the Mediterranean sea for both species. In consequence, the participants of WKACM2 recommended study on validation methods for Mullus spp. ageing from otolith interpretation and also they indicated the proposals. Moreover, in 2014, new otoliths exchange will be organize. In 2015, the new workshop (WKCAM3; Palma de Mallorca; co–chairs : F. Ordines, Spain ; K. Mahé, France) will focus on the analysis of exchange results, validation studies and formalized guideline of ageing for Mullus surmuletus and M. barbatus.
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ICES (2012). Report of the second Workshop on Age Reading of Red Mullet and Striped Red Mullet. 2 - 6 July 2012 Boulogne-sur-Mer, France. ICES CM 2012 / ACOM: 60.