@article {9085, title = {Biogeographical snapshot of life-history traits of European silver eels: insights from otolith microchemistry}, journal = {Aquatic Sciences}, volume = {85}, year = {2023}, month = {Jan-04-2023}, abstract = {Life-history traits of eels display a high level of phenotypic plasticity in response to large-scale biogeographical drivers, as well as local conditions encountered during the continental phase. Here, we provided a biogeographical snapshot of the variability of life-history traits of eels (Anguilla anguilla), across a large proportion of their natural distribution range. Silver eels (n = 99) were collected across eleven European catchments to investigate how life-history traits vary along geographical and saline habitats, as it was inferred from the Sr:Ca ratio in otoliths. Among 13 life-history traits tested, 3 of them such as total length, body or liver weight were related to geographical coordinates. Overall, eels grow faster in southern Europe and migrate earlier suggesting that the silvering process is related to the local growth conditions more than fish age. The salinity profiles revealed by the otoliths{\textquoteright} Sr:Ca ratios indicate that eels with a brackish life-history generally grow faster, reach larger size-at-age, and have a better condition than eels living in freshwater. This observation associated with the lower abundance of the sanguivorous swimbladder nematode, Anguillicola crassus, confirms the importance of brackish areas for sustaining the eel production. A large proportion of the observed variation of life-history traits remained unexplained by the biogeographical trends and salinity condition, which suggests that other drivers act at the catchment scale.
}, keywords = {Anguilla anguilla, Biogeography, Brackish habitat, otolith, phenotypic plasticity, Sr:Ca ratio}, issn = {1015-1621}, doi = {10.1007/s00027-023-00940-4}, url = {https://link.springer.com/10.1007/s00027-023-00940-4}, author = {Teichert, Nils and Bourillon, Bastien and Suzuki, Kyoko and Acou, Anthony and Alexandre Carpentier and Kuroki, Mari and Righton, David and Thomas Trancart and Virag, Laure-Sarah and Walker, Alan and Otake, Tsuguo and Eric Feunteun} } @article {7773, title = {Assessment of the quality of European silver eels and tentative approach to trace the origin of contaminants {\textendash} A European overview}, journal = {Science of The Total Environment}, volume = {743}, year = {2020}, month = {Jan-11-2020}, pages = {140675}, issn = {00489697}, doi = {10.1016/j.scitotenv.2020.140675}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0048969720341978}, author = {Bourillon, Bastien and Anthony Acou and Thomas Trancart and Belpaire, Claude and Covaci, Adrian and Bustamante, Paco and Faliex, Elisabeth and Amilhat, Elsa and Malarvannan, Govindan and Virag, Laure and Aarestrup, Kim and Bervoets, Lieven and Boisneau, Catherine and Boulenger, Clarisse and Gargan, Paddy and Becerra-Jurado, Gustavo and Lob{\'o}n-Cervi{\'a}, Javier and Maes, Gregory E. and Pedersen, Michael Ingemann and Poole, Russell and Sj{\"o}berg, Niklas and Wickstr{\"o}m, H{\r a}kan and Walker, Alan and Righton, David and Eric Feunteun} } @article {7116, title = {Development of an accurate model to predict the phenology of Atlantic salmon smolt spring migration}, journal = {Aquatic Conservation: Marine and Freshwater Ecosystems}, year = {2020}, month = {Apr-07-2021}, abstract = {Changes in migration timing, resulting from the alteration in river continuity or the effect of climate change, can have major consequences on the population dynamics of diadromous fish. Forecasting the phenology of fish migration is thus critically important to implement management actions aimed at protecting fish during their migration.
In this study, an 11-year monitoring survey of Atlantic salmon smolts (Salmo salar\ ) from the Ourthe River, Belgium, was analysed within a European Special Area of Conservation to improve the understanding of environment-induced spring migration. A logistic model was fitted to forecast smolt migration and to calculate phenological indicators for management, i.e. the onset, end, and duration of migration, while accounting for the influence of photoperiod, water temperature, and hydrological conditions.
The results indicated that the photo-thermal units accumulated by smolts above a 7{\textdegree}C temperature threshold was a relevant proxy to reflect the synergistic effect between temperature and photoperiod on smolt migration. After integrating the effect of river flow pulses, the model accurately explained the inter-annual changes in migration timing (R2\ = 0.95). The model predictions provide decisive management information to identify sensitive periods during which mitigation measures (e.g. hydropower turbine shutdown, river discharge management) should be conducted to promote smolt survival.
The model was used to predict phenological characteristics under future scenarios of climate change. The results suggest a joint effect of hydrological alterations and water warming. Temperature increases of 1{\textendash}4{\textdegree}C were associated with earlier initiation of migration, 6{\textendash}51 days earlier, and spring flood events greatly influenced the duration of the migration period. Accordingly, the combined effects of human-induced modifications of the hydrological regimes and increasing temperatures could result in a mismatch between the smolt and favourable survival conditions in the marine environment.}, issn = {1052-7613}, doi = {10.1002/aqc.3382}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aqc.3382}, author = {Teichert, Nils and Benitez, Jean-Philippe and Dierckx, Arnaud and T{\'e}tard, St{\'e}phane and Oliveira, Eric and Thomas Trancart and Eric Feunteun and Ovidio, Micha{\"e}l} } @article {7777, title = {Resolving the trade-off between silver eel escapement and hydropower generation with simple decision rules for turbine shutdown}, journal = {Journal of Environmental Management}, volume = {261}, year = {2020}, month = {Jan-05-2020}, pages = {110212}, issn = {03014797}, doi = {10.1016/j.jenvman.2020.110212}, url = {https://linkinghub.elsevier.com/retrieve/pii/S030147972030147X}, author = {Teichert, Nils and T{\'e}tard, St{\'e}phane and Thomas Trancart and Eric Feunteun and Anthony Acou and de Oliveira, Eric} } @article {6736, title = {Resolving the trade-off between silver eel escapement and hydropower generation with simple decision rules for turbine shutdown}, journal = {Journal of Environmental Management}, volume = {261}, year = {2020}, pages = {110212}, abstract = {Hydropower plants are commonly reported as a major cause of the worldwide decline of freshwater eels (Anguillidae), so that management solutions are urgently needed to mitigate their impacts. Where downstream passage solutions are complex to develop, turbine shutdown appears as an effective management solution to protect silver eels during their river migration toward spawning areas. However, the definition of operational decision rules for turbine shutdown is challenging due to the duality between the benefit for eel conservation and the concomitant cost in term of hydropower production. Here, we proposed a decision framework for turbine shutdown based on simple hydrological criteria to guide negotiations between stakeholders toward a trade-off between silver eel escapement and hydropower generation. Eel migration was assumed to be triggered by a minimum river flow associated with a minimum discharge pulse, so that threshold values can be directly implemented as decision rules for turbine shutdown. To estimate relevant thresholds, a generic methodological framework was developed to generate alternative decision rules from data collected at hydropower plants, which can include telemetry surveys and estimates of eel abundance. A multiple-criteria decision analysis was then conducted to rank alternatives and to determine the best compromise between promoting silver eel escapement and limiting turbine shutdown duration. Graphic outputs can help stakeholders to understand the competitive interests between eel conservation and hydropower production, while visually identifying a range of consensual alternatives to support negotiations in the choice of operational thresholds. The method was illustrated for three river systems in Europe featured by distinct hydrological conditions and can be applied in other areas, providing that eel monitoring surveys and flow data are available.}, keywords = {Conservation policy, Decision rules, Multiple-criteria decision, Turbine shutdown}, issn = {0301-4797}, doi = {https://doi.org/10.1016/j.jenvman.2020.110212}, url = {http://www.sciencedirect.com/science/article/pii/S030147972030147X}, author = {Teichert, Nils and St{\'e}phane T{\'e}tard and Thomas Trancart and Eric Feunteun and Anthony Acou and Eric de Oliveira} } @article {7026, title = {Towards transferability in fish migration models: A generic operational tool for predicting silver eel migration in rivers}, journal = {Science of The Total Environment}, volume = {739}, year = {2020}, month = {Jan-10-2020}, pages = {140069}, abstract = {In the global context of river fragmentation, predicting fish migration is urgent to implement management actions aimed at protecting and promoting the free movement of diadromous fish. However, large-scale applicability of conservation measures requires transferable models that enable prediction of migration even in data-poor regions. Here, we surveyed 12 contrasted European river sites to predict the activity peaks of silver eels (Anguilla anguilla) during river migration towards spawning areas through an ensemble modelling approach. Site-specific Boosted Regression Tree (BRT) models were adjusted using standardized hydrological variables to predict migration probability, which were aggregated in consensus predictions. Results of independent cross-validations demonstrated that silver eel migration runs were accurately predicted in response to changes in river discharge. Transferability and predictive performance were improved by considering catchment-size dissimilarity between river sites (85 to 109 930 km{\texttwosuperior}) when combining the site-specific predictions. Nevertheless, we provided two examples for which the effects of human actions on flow conditions were so high that they prevented reliable predictions of migration runs. Further contributions should thus take advantage of the flexibility of our approach for updating model collection with new sites to extend the predictive performance under a larger range of ecological conditions. Our transferable hydrological-based modelling framework offers an opportunity to implement large-scale management strategies for eel conservation, even in rivers where eel monitoring data lack. The BRT models and prediction functions were compiled in an R package named {\textquoteleft}silvRpeak{\textquoteright} to facilitate operational implementation by end-user managers, which can determine when mitigation measures should be implemented to improve river continuity (e.g. turbine shutdown and sluice gate opening) and balance their economic activity towards eel conservation. The only input required is discharge records that are widely available across European hydrological stations.}, keywords = {eel runs prediction, ensemble modelling, European eel management, fish migration, model transferability, river obstacle}, issn = {00489697}, doi = {10.1016/j.scitotenv.2020.140069}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0048969720335890}, author = {Teichert, Nils and T{\'e}tard, St{\'e}phane and Thomas Trancart and de Oliveira, Eric and Anthony Acou and Alexandre Carpentier and Bourillon, Bastien and Eric Feunteun} } @article {6730, title = {When {\textquotedblleft}safe{\textquotedblright} dams kill: Analyzing combination of impacts of overflow dams on the migration of silver eels}, journal = {Ecological Engineering}, volume = {145}, year = {2020}, pages = {105741}, abstract = {1. The drastic decline in European eel\ Anguilla anguilla\ stock is now widely recognized. However, while various causes for this decline have been identified, the relative importance of each cause remains unclear.

2. During the catadromous migration of silver eels, the negative impact of dams is frequently highlighted, but mainly for powered dams (with turbines) or where connectivity is completely ruptured. Mechanical impact due to turbine blades is often considered the most important cause of mortality of silver eels during downstream migration. Consequently, non-powered dams equipped with spillways are often considered safe for the passage of migrating silver eels.

3. We hypothesized that, to understand the negative impacts of dams, a much wider context must be considered than turbine mortality alone. Using an acoustic telemetry survey of silver eels, we demonstrated the negative effects of non-powered dams on downstream migration.

4. Five main impacts on eel populations were highlighted: (i) the attenuation or loss of triggering factors, leading to an absence of or delay in migration; (ii) extra delays and extra distances travelled when crossing the dam; (iii) extra energetic costs of the additional distance travelled as result of exploring the dam and the reservoir to find other escape passages; (iv) the selection of a more risky behavioral phenotype, i.e., bold eels; and (v) direct blocking once migration has started. Mortality was evaluated as a supplementary impact. Some of these effects (attenuation of triggers, extra delays to cross the dam) might be more important than the same effect from powered dams, probably due to the constant high water discharge required for turbines that facilitate the passage of eels.

5. As these {\textquotedblleft}safe{\textquotedblright} dams are very widespread, they must be considered a potential threat to effective eel conservation.}, keywords = {Acoustic telemetry, Migration, mortality, Non-powered dams, Silver eels, Turbines drinking water intake}, issn = {0925-8574}, doi = {https://doi.org/10.1016/j.ecoleng.2020.105741}, url = {http://www.sciencedirect.com/science/article/pii/S092585742030029X}, author = {Thomas Trancart and Alexandre Carpentier and Anthony Acou and Fabien Charrier and Virgile Mazel and Valentin Danet and Eric Feunteun} } @article {6742, title = {Behaviour of endangered European eels in proximity to a dam during downstream migration: Novel insights using high accuracy 3D acoustic telemetry}, journal = {Ecology of Freshwater Fish}, volume = {29}, year = {2019}, pages = {266-279}, abstract = {River infrastructures such as weirs, hydropower stations or water reservoirs represent obstructions to migration for diadromous fish. Knowledge of accurate behaviour of fish in front of such structures is required to protect migrants from hazardous areas, guide them towards safe passage or adapt structure to improve the escapement. We developed and made available a method to process acoustic telemetry data based on Time Difference Of Arrival analysis to accurately locate tagged fish. Improved accuracy allows the detection of escape routes and description of dam-crossing tactics. Sixteen tagged eels were tracked with high accuracy (1{\textendash}2\ m) and 1 location min-1 frequency during their exploration period on reaching the dam. Two migration routes (spillways and bottom compensation flow pipe) were used by 77\% and 23\% of eels respectively. Spillways were the preferred route, but a median of 16\ days were required to pass the dam versus 1.1\ days via the compensation pipe. A minimal water crest of 40\ cm was required for passage via spillways. Eels passing through the compensation pipe were exclusively nocturnal and mainly explored the bottom of the dam. Eels passing through spillways explored the whole dam area by night and day, and were not attracted to the compensation pipe entrance. With global warming, more frequent drought periods are expected, potentially leading to decreased opportunities for eels to migrate across safer dams by spillways. To conserve this endangered species, dam management strategies that account for expected hydrologic conditions and distinct exploration behaviours are needed.}, keywords = {3D acoustic telemetry, dam, diadromous fish, downstream migration, European eel}, doi = {10.1111/eff.12512}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/eff.12512}, author = {Thomas Trancart and Alexandre Carpentier and Anthony Acou and Danet, Valentin and Elliott, Sophie and Eric Feunteun} } @article {6734, title = {Distribution and life history trait models indicate vulnerability of skates}, journal = {Progress in Oceanography}, volume = {181}, year = {2019}, pages = {102256}, abstract = {Elasmobranchs are k-strategy species with low reproduction rate and slow growth lending to increased anthropogenic vulnerability. Specific management measures to improve the conservation of elasmobranchs can be problematic due to insufficient information on their biology and ecology. Here, three sympatric skates occupying north-eastern Atlantic waters, which have differing conservation status were studied within ICES divisions 4.c, 7.d{\textendash}e, 7.f{\textendash}h and 8a{\textendash}b and d. Fisheries-dependent data on skate bycatch and a series of environmental variables were used to model spatio-temporal differences in habitat use between the three species. Raja undulata, the undulate ray (IUCN red listed as {\textquoteleft}Endangered{\textquoteright}) was observed to have a coastal distribution within the English Channel and the Bay of Biscay (ICES division 7.d{\textendash}e and 8.a{\textendash}b). Raja clavata, the thornback ray ({\textquoteleft}Near threatened{\textquoteright}), had a broader distribution with higher presence in the eastern English Channel and the southern North Sea (ICES division 7.e and 4.c). Raja montagui, the spotted ray{\textquoteright}s probability of presence ({\textquoteleft}Least concerned{\textquoteright}) was higher off the coast of southern Ireland (ICES division 7.g). Seasonal and life-history trait differences were also observed. From the fisheries-dependent data, wider skate distributions than previously studied were modelled. Although the species do co-occur, spatio-temporal differences between these species were observed. This study contributes to a greater understanding of skate habitat during their different life history stages, and indicates reasons for R. undulata{\textquoteright}s increased vulnerability than R. clavata and R. montagui. Information from the distribution models could be used for specific spatio-temporal management measures. Better understanding of the distribution of species can also help reduce bycatch of protected species such as R. undulata.}, keywords = {Distribution modelling, Elasmobranchs, Fisheries management, Habitat, IUCN red list species, Life history traits}, issn = {0079-6611}, doi = {https://doi.org/10.1016/j.pocean.2019.102256}, url = {http://www.sciencedirect.com/science/article/pii/S0079661119304367}, author = {Sophie A.M. Elliott and Alexandre Carpentier and Eric Feunteun and Thomas Trancart} } @article {6751, title = {Migration behaviour and escapement of European silver eels from a large lake and wetland system subject to water level management (Grand-Lieu Lake, France): New insights from regulated acoustic telemetry data}, journal = {Ecology of Freshwater Fish}, volume = {27}, year = {2018}, pages = {570-579}, abstract = {Current knowledge about the downstream migration of sexually mature European eels (Anguilla\ anguilla) remains incomplete, particularly in still water habitats such as lakes and wetlands subject to water level management. However, for the management of this endangered species, it is important to understand migration dynamics, and contribution to the breeding stock. This study aimed to assess the parameters that trigger and guide the migration of silver eels in the largest floodplain lake and associated wetlands in France (the sluice regulated Grand-Lieu Lake). A telemetry survey of 50 acoustic and PIT-tagged female silver eels was performed during the 2015{\textendash}2016 migration period. We deployed a novel telemetric approach, using receivers to delimit several restricted virtual boxes to determine the instantaneous location of individuals and to transform simple discrete telemetric data into presence/absence data. The low numbers leaving the lake centre are probably explained by the lack of orienting water flows or other environmental clues, but whilst the fate of 34\% (17/50) of the tagged eels is unknown, 18\% (9/50) were caught by commercial fishermen. Modelling showed that detections were not clearly associated with environmental factors typically involved in riverine migrations (e.g. current velocity, atmospheric pressure and temperature) but they were particularly associated with higher and increasing water levels and, for eels exiting the lake, a sharp increase when sluice gates were opened to an effective gap of \>75\ cm. It is concluded that management of water levels and sluice gate opening during the migration period might aid escapement of silver eels.}, keywords = {Anguilla~anguilla, cues, silver eel migration, triggers}, doi = {10.1111/eff.12371}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/eff.12371}, author = {Thomas Trancart and Eric Feunteun and Danet, Valentin and Alexandre Carpentier and Mazel, Virgile and Charrier, Fabien and Druet, Morgan and Anthony Acou} } @article {6752, title = {Silver eel downstream migration in the River Rhine, route choice, and its impacts on escapement: A 6-year telemetry study in a highly anthropized system}, journal = {Ecological Engineering}, volume = {123}, year = {2018}, pages = {202 - 211}, abstract = {Several routes are available for the downstream migration of silver eels in the river Rhine system. Very different effects on migration success can result from this choice, such as speed and migration duration or escapement rate. We studied the downstream migration of silver eels in a river section with two different routes. The first route is the initial and old riverbed, with two dams equipped with two rather small or medium sized hydropower plants (HPPs) located at the beginning and at the exit of the bypass stretch. Both HPPs have small bar spacing (10 mm and 20 mm, respectively) and the second HPP has two downstream bypasses. The second route is a power canal, supplying four major HPPs (maximum discharge capacity = 1400 m3 s-1) and a nuclear power plant with cooling water. Firstly, this study focused on highlighting the factors influencing route choice. Secondly, we focused on the consequences of this choice. We demonstrate that water current management in the old riverbed at the study site had a 40\% higher negative effect on eel survival than that by a consecutive passage in four turbines.}, keywords = {Escapement, Migration, Path selection, Rhine river, Silver-eel, Telemetry}, issn = {0925-8574}, doi = {https://doi.org/10.1016/j.ecoleng.2018.09.002}, url = {http://www.sciencedirect.com/science/article/pii/S0925857418303318}, author = {Thomas Trancart and St{\'e}phane T{\'e}tard and Anthony Acou and Eric Feunteun and Fr{\'e}d{\'e}ric Schaeffer and Eric de Oliveira} } @article {Trancart20169, title = {Difference in responses of two coastal species to fluctuating salinities and temperatures: Potential modification of specific distribution areas in the context of global change}, journal = {Estuarine, Coastal and Shelf Science}, volume = {173}, year = {2016}, note = {cited By 3}, pages = {9-15}, doi = {10.1016/j.ecss.2016.02.012}, url = {https://www.sciencedirect.com/science/article/pii/S0272771416300555} } @article {Besson2016779, title = {Disrupted downstream migration behaviour of European silver eels (Anguilla anguilla, L.) in an obstructed river}, journal = {Environmental Biology of Fishes}, volume = {99}, number = {10}, year = {2016}, note = {cited By 13}, pages = {779-791}, doi = {10.1007/s10641-016-0522-9}, url = {https://link.springer.com/article/10.1007/s10641-016-0522-9} } @article {4803, title = {Empirical observations of the spawning migration of European eels: The long and dangerous road to the Sargasso Sea.}, journal = {Science Advances}, year = {2016}, abstract = {The spawning migration of the European eel (Anguilla anguilla\ L.) to the Sargasso Sea is one of the greatest animal migrations. However, the duration and route of the migration remain uncertain. Using fishery data from 20 rivers across Europe, we show that most eels begin their oceanic migration between August and December. We used electronic tagging techniques to map the oceanic migration from eels released from four regions in Europe. Of 707 eels tagged, we received 206 data sets. Many migrations ended soon after release because of predation events, but we were able to reconstruct in detail the migration routes of \>80 eels. The route extended from western mainland Europe to the Azores region, more than 5000 km toward the Sargasso Sea. All eels exhibited diel vertical migrations, moving from deeper water during the day into shallower water at night. The range of migration speeds was 3 to 47 km day-1. Using data from larval surveys in the Sargasso Sea, we show that spawning likely begins in December and peaks in February. Synthesizing these results, we show that the timing of autumn escapement and the rate of migration are inconsistent with the century-long held assumption that eels spawn as a single reproductive cohort in the springtime following their escapement. Instead, we suggest that European eels adopt a mixed migratory strategy, with some individuals able to achieve a rapid migration, whereas others arrive only in time for the following spawning season. Our results have consequences for eel management.}, doi = {10.1126/sciadv.1501694}, url = {https://advances.sciencemag.org/content/2/10/e1501694}, author = {D. Righton and H. Westerberg and Eric Feunteun and F. Okland and P. Gargan and E. Amilhat and J. Metcalfe and J. Lobon-Cervia and N. Sj{\"o}berg and J. Simon and Anthony Acou and M. Vedor and A. Walker and Thomas Trancart and U Br{\"a}mick and K. Aarestrup} } @article {T{\'e}tard2016216, title = {Poor oxic conditions in a large estuary reduce connectivity from marine to freshwater habitats of a diadromous fish}, journal = {Estuarine, Coastal and Shelf Science}, volume = {169}, year = {2016}, note = {cited By 7}, pages = {216-226}, doi = {10.1016/j.ecss.2015.12.010}, url = {https://www.sciencedirect.com/science/article/pii/S0272771415301670} } @article {Trancart2015168, title = {The effect of thermal shock during diel vertical migration on the energy required for oceanic migration of the European silver eel}, journal = {Journal of Experimental Marine Biology and Ecology}, volume = {463}, year = {2015}, note = {cited By 2}, pages = {168-172}, doi = {10.1016/j.jembe.2014.12.004}, url = {https://www.sciencedirect.com/science/article/pii/S0022098114003190} } @article {Boulenger2015427, title = {Length-weight relationships of the silver European eel, Anguilla anguilla (Linnaeus, 1758), across its geographic range}, journal = {Journal of Applied Ichthyology}, volume = {31}, number = {2}, year = {2015}, note = {cited By 3}, pages = {427-430}, doi = {10.1111/jai.12685}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jai.12685} } @article {Josset2015150, title = {Pre-release processes influencing short-term mortality of glass eels in the French eel (Anguilla anguilla, Linnaeus 1758) stocking programme}, journal = {ICES Journal of Marine Science}, volume = {73}, number = {1}, year = {2015}, note = {cited By 6}, pages = {150-157}, doi = {10.1093/icesjms/fsv074}, url = {https://academic.oup.com/icesjms/article/73/1/150/2458188} } @article {Trancart2014181, title = {Modeling marine shad distribution using data from French bycatch fishery surveys}, journal = {Marine Ecology Progress Series}, volume = {511}, year = {2014}, note = {cited By 6}, pages = {181-192}, doi = {10.3354/meps10907}, url = {http://www.int-res.com/abstracts/meps/v511/p181-192/} }