The Fourth Workshop on Designing an Eel Data Call (WKEELDATA4)

The fourth Workshop on Designing an Eel Data Call (WKEELDATA4), chaired by Hilaire Drouineau (France) and Tea Bašić (UK), met virtually from 9 May–13 May 2022 to design a Data Call to all countries having natural production of European eel. Thirteen scientists from seven countries participated in this meeting, along with one participant from ICES.

The life cycle of the European eel is complex, with a unique spawning area in the Sargasso Sea and growth areas widely distributed across Europe and Northern Africa. The stock is genetically panmictic, but the continental eel stock shows strong local and regional differences in population dynamics and local stock structures (sex ratio, length and age distributions). Local impacts by fisheries vary from almost nil to heavy exploitation. Other forms of anthropogenic mortality (e.g. hydropower, pumping stations) impact on eel, with varying distribution and local relevance. Data on stock and impacts are reported to the Working Group on Eels (WGEEL), which supports the official recurrent ICES Advice on the stock. Data correspond to several different life stages, from juveniles to prespawning eels, in different habitats (from freshwater to saltwater environments).

To collect those data more efficiently, ICES and GFCM started a Data Call process in 2017. The ICES Workshop on Designing an Eel Data Call (WKEELDATA) generated the first version of the Data Call, improved the WGEEL database to host the collected data and integrated first data into the database. The Data Call and several related tools have then been progressively improved and developed during different successive workshops (WKTEEL, WKEELDATA2, WKEELDATA3). Currently, the Data Call relies on (1) a postgresql/postgis database that stores the collected data, (2) excel templates sent to data providers to collect the data, (3) a shiny application used to transfer the data between the template excel files and the database, while ensuring data integrity (that is also guaranteed by the relational database structure), and (4) a shiny application used to facilitate the visualisation of the data in the database. 

Following the roadmap implemented during the recent Workshop on the Future of Eel Advice (WKFEA), this workshop has prepared the collection of biometric data collected under programmes such as EU DCF in the upcoming Data Call (Subgroup 1). Such data will complement biometric data originating from sites monitoring glass eel recruitment and yellow and silver eel abundance, that were already collected by WGEEL. The possible decrease in eel quality (e.g. contamination/diseases) was recognized as a serious threat in various WGEEL reports and at WKFEA. To address this point, the workshop proposed to set up a pilot Data Call on eel quality (Subgroup 3) alongside biometric data. Furthermore, WGEEL started working on the analysis of time series of yellow and silver eel abundance and pointed out some limitations in the meta-information available, especially regarding data reliability/quality. The workshop has proposed different modifications to the Data Call to address these problems, following WGEEL recommendations in 2021 (Subgroup 2). Finally, the workshop has updated all pre-existing templates files (Subgroup 2), developed new templates to collect the new types of data (Subgroup 1 and 3) and adapted the database and the shiny tool used to integrate the data (Subgroup 4).