FN Archimer Export Format PT Rapport TI Update of whiting abundance indices from professional fishing data (2016-2018) BT AF CAILL-MILLY, Nathalie LISSARDY, Muriel BRU, Noëlle AS 1:1;2:1;3:2; FF 1:PDG-ODE-LITTORAL-LERAR;2:PDG-ODE-LITTORAL-LERAR;3:; C1 Ifremer, LITTORAL, LERAR, 1 allée du Parc Montaury, F-64600 Anglet, France Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, LMAP, Anglet, France C2 IFREMER, FRANCE UNIV PAU & PAYS ADOUR, FRANCE SI ANGLET SE PDG-ODE-LITTORAL-LERAR UR https://archimer.ifremer.fr/doc/00631/74350/74005.pdf LA English DT Report AB The ROMELIGO project included a proposal of abundance indicators for whg-89a stock using professional fishing data. The methodolgy is based on the selection of a sample of representative vessels grouped in a cluster with the same technical characteristics, taking into account their LPUE for specifed period and area. The analysis was conducted on an historical dataset from 2010 to 2015. To be able to update it, a conditional decision tree was used to find rules to assign any new vessels to one of the predefined OTB clusters. Then, the trends of LPUE on the overall period were considered. In recent years, the north shows low levels, but the decrease is not significant over the whole period (Pearson test). For the south, no trend emerges. Professionals identified two management measures likely to affect the indicators. After analysis, they did not impact the trends of the series. Due to the characteristics of the southern indicator, the possibility of retaining only the northern one in future years is raised. PY 2020 PD MAY ID 74350 ER EF