Joint EIFAAC/ICES/GFCM Working Group on Eels (WGEEL)

Elsa Amilhat, Tea Basic, Laurent Beaulaton, Claude Belpaire, Priit Bernotas, Cédric Briand, Andreas Bryhn, Fabrizio Capoccioni, Eleonora Ciccotti, Willem Dekker, Estibaliz Diaz, Isabel Domingos, Hilaire Drouineau, Caroline M. F. Durif, Derek Evans, Lukasz Giedrojc, Matthew Gollock, Tessa van der Hammen, Reinhold Hanel, Lisa HornKatarzyna Janiak Observer, Kenzo Kaifu Observer, Chiara Leone, Linas Lozys, Lasse Marohn, Tomasz Nermer, Ciara O’Leary, Michael Ingemann Pedersen, Jan-Dag Pohlmann, Russell Poole, Justas Povliūnas, Robert Rosell, Mehis Rohtla, Argyris Sapoundis, Janek Simon, Josefin Sundin, Arvydas Svagzydys, Eva B. Thorstad, Sami Vesala, Alan M. Walker, Håkan Wickström

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The WGEEL has this year adjusted the manner in which it reports data in time-series. First, readers should note that some data reported to the WGEEL in the most recent year are always provisional but are then finalised in the report of the following year. Where data have been updated from those reported in the 2018 report this is indicated in the 2019 report; and provisional data are similarly highlighted. Second, the mean of the previous 5 years data is also presented to help place the data from the most recent year(s) in context of this most recent period.
The recruitment of European eel from the ocean remained low in 2019. The glass eel recruitment compared to the 1960–1979 in the ‘North Sea’ index area was 1.4% in 2019 (provisional), 1.9% in 2018 (finalised) and the previous 5-year mean was 1.7% (2012-2016); and in the ‘Elsewhere Europe’ index series it was 6.0% in 2019 (provisional), 8.9% in 2018 (final) and the previous 5-year mean was 8.7%, based on available dataseries. For the yellow eel dataseries, recruitment for 2018 was 26.4% of the 1960–1979 level and the previous 5-year mean was 16.6% (2013–2017); 2019 data collection is ongoing so data not available at time of writing.
Statistical analyses of time-series from 1980–2019 show that there was a change in the trend of glass eel recruitment indices in 2011; the recruitment has stopped decreasing and has been increasing in the period 2011–2019 with a rate statistically significantly different from zero. The highest point during the period from 2011–2019 was in 2014.
Landings data were updated according to those reported to the WGEEL, either through responses to the 2019 Data call or Country Reports, or integrated by the WGEEL using data from its previous reports. When data are absent and presumed missing for a country or year, a predicted (reconstructed) catch is used to account for non-reporting, but this is not a complete solution and therefore even the raised estimates should be considered as minima. Here we present both reported and reconstructed values.
Glass eel fisheries within the EU take place in France, UK, Spain, Portugal and Italy. Glass eel landings have declined sharply from 1980, when reported and reconstructed landings were larger than 2000 tonnes, to 62.2 t in 2018 (final, full reporting), 58.6 t in 2019 (provisional, no reconstruction), and a mean for the previous 5 years (2013–2017) of 56.5 t (full reporting).
Yellow and silver eel landings are not always reported separately, so are combined here. The WGEEL has reconstructed the time-series to fill in some gaps in reporting. Reconstructed total commercial landings of yellow and silver eels were around 20 000 t in the 1950s to 2000–3500 t around 2009, most recently being 2393 t in 2017 (final), 2694 t in 2018 (provisional) and a mean of 2729 t for the preceding 5 years (2012–2016). The reported landings were around 10 000 to 12 000 t in the 1950s, declining to 2000 to 3000 t around 2009, and more recently being 2249 t in 2017 (final), 2375 t in 2018 (provisional, only 14 countries reported) and a mean of 2729 t for the preceding 5 years (2012–2016).
Recreational catches and landings are poorly reported, so amounts must be treated as minima. Spain reports a recreational fishery for glass eel, with landings estimated as 0.9 t for 2019 (provisional), with a mean of 2 t for the preceding 5 years (2014–2018). Recreational landings for yellow and silver eel combined were 543 t for 2016 (ten countries reporting), 195 t for 2017 (eight countries reported) and 148 t for 2018 (five countries reported). Overall, the impact of recreational fisheries on the eel stock remains largely unquantified although landings can be thought to be at a similar order of magnitude to those of commercial fisheries.
Aquaculture production of eel is presented from 1984 onwards. It increased until the mid-2000s, peaking around 8000 t. Production was reported in 2017 (the most recent year of most countries reporting: 10) as 5497 t in 2017 and the preceding 5-year mean was 6429 t (2012–2016). It should be noted that eel aquaculture is based on wild recruits, and part of the production is subsequently released as on-grown eel for stocking.
Restocking (the process of capture, translocation and restocking to new locations in the wild) of eel increased after the implementation of management plans in EU Member States in 2009. Although the definition of restocking is clear, the process is complex with a varied and broad sequence of steps and even life stages. As there is still some variation in the way that countries report some of these actions, the WGEEL broadly categorises them as RELEASES, though the term RESTOCKING is still used here for some circumstances. Most recent relatively complete data show 36.3 million glass eel (2017, 15 countries), 14 million yellow eels (2016, six countries) and about 0.25 million silver eels (2018, three countries) were restocked or released (combined).
The WG has made substantial progress in developing the use of the Data call and database to refine data submission, checking, analyses and reporting. The Data call for 2020 will request updates for recruitment, landings, aquaculture and releases, plus abundance indices for yellow and silver eels.
The emerging threats and opportunities reported by WGEEL in each of the last three years continue to develop/evolve from their initial reporting. In addition, a new eel virus (picornavirus EPV-1) has been detected in eels in several German waters.
The WG has a new standing annual activity to examine quantification of the impacts of nonfishery factors, and to review methods for reducing these mortalities. A crude estimate of loss to all non-fishery anthropogenic factors (largely hydropower and pumps) of eel was estimated from reported mortality indicators from approximately half of countries reporting to WG. This amounted to 1625 tonnes annually. Given better and more consistent data, this estimate could be improved in the future.
Evidence on the impacts of hydropower facilities and water pumps was reviewed, with new studies ranging from direct measurements of eel mortality at individual facilities, through models to extend empirical data at individual sites to estimate impacts to regional levels, to overarching reviews and national and international advisory reports. Ranges of mortality as eel pass by or through hydropower stations are highly variable, and within previously published ranges. Mitigation measures to reduce eel losses from hydropower and pumping facilities provide clear technical scope for individual site and collective actions to reduce current losses.
The WG considered the potential impact of changes to fishery regulations on the time-series used in support of the ICES advice. Many fishery-based time-series are used to assess temporal trends in recruitment and escapement. This is especially true for recruitment in the so-called ‘Elsewhere Europe’ area. New fishery regulations might introduce biases in those time-series and compromise their use in the analyses. Losing fishery-based indices would increase the noise in the stock assessment. As such, it seems worthwhile implementing new fishery-independent time-series.
The WG considered the consequences of the Precautionary Approach on advice for European eel. Based on the FAO Code of Conduct, the ICES form of advice, and the EU Eel Regulation, the WG developed a proposal for a coherent framework for advice on eel, consisting of a doubletiered approach: an international tier focused on the status of the whole stock and the long-term objectives (overall stock status, recruitment trends, biomass reference points), and a national (or lower) tier focused on mortality levels and related management actions, addressed per management unit. This proposal suggests adoption of the reference point of the Eel Regulation, as Bmgt = 40% escapement of pristine, and a corresponding mortality limit of ΣAmgt = 0.92. Below Bmgt, mortality should be reduced further, to allow recovery of the stock. It is suggested to adopt a provisional time frame in terms of number of generations for this, which would translate into a corresponding mortality limit for each management unit. Noting that the proposed comprehensive framework for advice deviates from conventional ICES approaches, it is concluded that a followup workshop convened by ACOM might be appropriate, to discuss and evaluate the proposed framework and consider any now unforeseen or unintentional consequences. An international process of Quality Assurance of national assessments and stock indicators is also required as a matter of urgency.
The WG considered the challenge of quantifying the effort that is undertaken in the commercial eel fisheries around Europe, based on new data provided by countries through the Data call. It was concluded that for many countries, the licensing of commercial eel fisheries needs to be improved in order to supply fishery managers and WGEEL with the appropriate information to assess the state of the stock. Difficulties encountered include inadequate reporting of levels of effort, lack of recording on number of gears per licence and generic multispecies licensing. The level of reporting can be at the national, regional or local level and this has resulted in some countries having different licence requirements per waterbody. The WGEEL has recommended a workshop on harmonising the reporting of fishing effort.
Original languageEnglish
PublisherInternational Council for the Exploration of the Sea (ICES)
Number of pages187
Publication statusPublished - 2019
SeriesICES Scientific Report

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