Reference fleets identification by LPUE data filtering applied to the striped red mullet (Mullus surmulletus) in the Bay of Biscay
|Ref.||Working Document for the Working Group on Widely Distributed Stocks (WGWIDE). 28 August - 3 September 2018, The Faroe Islands|
|Author(s)||Caill-Milly Nathalie1, Lissardy Muriel1, Bru Noelle2, Dutertre Marie-Adèle2, Saguet Cassandre3|
|Affiliation(s)||1 : Ifremer, ODE/UL/LERAR, France
2 : UPPA, LMAP, France
3 : Ifremer, ODE/UL/LERLR, France
The striped red mullet (Mullus surmuletus) is a species for which ICES advances individualization of stocks in Western Europe. One of them concerns the Bay of Biscay, the waters bordering the Iberian Peninsula as well as the Celtic Sea, namely striped red mullet in Subareas and Divisions 6, 7a-c, e-k, 8, and 9a (Mur. 27.67a it-k89a). This stock is part of the Data Limited Stocks (DLS) and is currently classified in Category 5 (ICES, 2016); it is a stock for which only landings data are available. Such knowledge is insufficient to apply the ICES MSY approach and the advice rule on fishing possibilities is therefore based on the precautionary approach. For this stock, this approach is applied since 2012. For 2013 and 2014, ICES has recommended reducing landings by 20% compared to 2009-2011. In the absence of new information on stock biomass or exploitation level, the precautionary approach was applied again in 2017 (ICES, 2017). It led to a landing advice of a maximum of 1600 tonnes in 2018, 2019, and 2020.
It is in this context that the ROMELIGO project (Improvement of the fishery knowledge of striped red mullet, whiting and pollack of the Bay of Biscay) was conducted. A first step consisted of an update of the bibliographic review on the biology of the species and analyse the catches and the activity of the French professional fishery (composition and evolution of catches, seasonality, spatial distribution, gear used and discards). This work was the subject of a first WD transmitted and used by WGWIDE in 2017 (Caill-Milly et al, 2017).
This second WD concerned the Landings Per Unit of Effort (LPUE) of French vessels and proposes a data filtering method to identify vessels of interest (reference fleet) whose LPUEs can be considered as proxies of abundance indices of this resource. According to the landing distribution per “grouped gears” from 2000 to 2015 (Caill-Milly et al, 2017), five fleets are identified as potentially interesting: fleets using OTB (otter bottom trawls); OTT (otter twin trawls); GNS (set gillnets); GTR (trammel nets) and SDN (Danish seines).
The final objective is to strengthen expertise on this stock by providing data for the abundance and if possible move away from category 5 in the future.