A complete check-up of European eel after eight years of restocking in an upland river: Trends in growth, lipid content, sex ratio and health status

Matondo, Billy Nzau; Delrez, Natacha; Bardonnet, Agnès; Vanderplasschen, Alain; Joaquim-Justo, Célia; Rives, Jacques; Benitez, Jean‐Philippe; Dierckx, Arnaud; Séleck, Emilie; Xavier, Raquel; Ovidio, Michaël

doi:10.1016/j.scitotenv.2021.151020

Cited by 7 publications

(29 citation statements)

References 112 publications

(160 reference statements)

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“…Hence, the stocking of eels relies on wild‐caught individuals, which are directly implemented into the environment or are grown before stocking as farmed eels (Cabezas et al, 2006; Pedersen et al, 2017). Recent studies provide evidence for successful adaptation, survival, dispersal, growth and silvering of restocked eels in inland freshwaters and there are suggestions that eels will probably disappear without restocking (Félix et al, 2021; Nzau Matondo et al, 2019; Nzau Matondo et al, 2020; Nzau Matondo et al, 2021). However, in addition, a number of publications raised questions about the way in which the stocking measures are carried out and emphasized the importance of detailed planning and precise control of eel stocking.…”

Section: Discussionmentioning

confidence: 99%

Identification of virus infections of European eels intended for stocking measures

Danne

Adamek²,

Wonnemann³

et al. 2022

Journal of Fish Diseases

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The spread of viral diseases in eels is suggested to severely affect the European eel (Anguilla anguilla) panmictic population. The European Commission has initiated the Eel Recovery Plan (Council Regulation No. 1100/2007) to try to return the European eel stock to more sustainable levels within that measures eel restocking. However, scientific evidence evaluating the efficacy of stocking remains scarce. In addition, knowledge about the impact and contribution of eel stocking on the distribution of infectious diseases is insufficient. In this study, we aimed to investigate virus infections in batches of eels intended for restocking. We analysed samples of glass eels from certified fisheries and farmed European eels from different aquaculture farms. All analysed eels were purchased within a North Rhine Westphalian conservation program. Via a combination of cell culture and qPCR‐based techniques, we detected infections of glass eels with the rhabdovirus Eel Virus European X and anguillid herpesvirus 1 infections in farmed eels (10–15 cm).

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Section: Discussionmentioning

confidence: 99%

Identification of virus infections of European eels intended for stocking measures

Danne

Adamek²,

Wonnemann³

et al. 2022

Journal of Fish Diseases

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“…Eel restocking is applied in many European countries [1][2][3][4][5][6][7]. It corresponds to the reallocation of naturally recruited eels from high-density zones to recipient freshwater habitats where there is poor or no natural colonisation [8][9][10]. The utility of restocking is debated, but it is the only solution to enhance riverine eel stocks in countries that are far from the sea and located within the natural distribution area of the species [7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…The utility of restocking is debated, but it is the only solution to enhance riverine eel stocks in countries that are far from the sea and located within the natural distribution area of the species [7][8][9][10][11][12]. Some studies have demonstrated its effectiveness [1,[9][10][11][12]. However, the practice is still dependent on wild-caught glass eels and elvers, as reproduction of the species in captivity has not yet been achieved [5].…”

Section: Introductionmentioning

confidence: 99%

“…In the Belgian Meuse River basin (>320 km upstream of the North Sea), the state of local eel stocks is critical as they have drastically declined. The number of wild yellow eels ascending the Meuse River from the North Sea via the Dutch Meuse has decreased by about 3.6% per year from 1992 to 2020; in 2020, this number was 0.6% of the level recorded in 1992 [9,10,12,23,27,28]. Several rivers that have hosted abundant stocks of eels in the past are currently emptied of their eels.…”

Section: Introductionmentioning

confidence: 99%

“…This decline is due to the decrease in glass eel recruitment in the North Sea, which fell in 2019 to 1.4% of the mean level of 1960-1979 [29]. Without restocking, eels will probably disappear from the Belgian Meuse basin within the next decade [9,10,27]. It is therefore urgent to optimise the eel restocking practice, but also to understand the biological benefits associated with this practice.…”

Section: Introductionmentioning

confidence: 99%

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Space and Time Use of European Eel Restocked in Upland Continental Freshwaters, a Long-Term Telemetry Study

Matondo

Backory

Dupuy

et al. 2023

Fishes

Self Cite

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There is a lack of information on many biological and ecological aspects of the critically endangered European eel during its growth phase in inland waters, such as when the sedentary life stage begins, mobility according to age and response to habitat alteration. We used mobile radio frequency identification (RFID) telemetry technology to track tagged eels over 6 years after their restocking as glass eels in six typologically different rivers. We also cross-referenced telemetry data with those of several electrofishing monitoring sessions to better understand the mobility and behaviour of eels. The relative abundance (maximum 52 individuals km−1) and detection rate (maximum 28%) of eels were not significantly correlated with the time/age after restocking. Eels were present in all restocked rivers, but their abundance was low and mobility was high in a slightly acidified, oligotrophic river that had experienced a great loss of fish habitat heterogeneity. This loss of habitat heterogeneity was due to flooding events and machinery works in riverbeds to restore the altered riverbanks. Four years after glass eel release, restocked eels became sedentary and moved from shallow to deep microhabitats with riverbeds dominated by blocks as the bottom substrate. After this age, they exhibited high fidelity to the residence site. This study provides new insights concerning the biology and ecology of eels restocked as glass eels in freshwaters, which should lead to improved management plans for the species through the implementation of more effective conservation measures and strategies.

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Eel translocation from a conservation perspective: A coupled systematic and narrative review

Froehlicher,

Kaifu,

Rambonilaza

et al. 2023

Global Ecology and Conservation

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A complete check-up of European eel after eight years of restocking in an upland river: Trends in growth, lipid content, sex ratio and health status

Cited by 7 publications

References 112 publications

Identification of virus infections of European eels intended for stocking measures

Identification of virus infections of European eels intended for stocking measures

Space and Time Use of European Eel Restocked in Upland Continental Freshwaters, a Long-Term Telemetry Study

Eel translocation from a conservation perspective: A coupled systematic and narrative review

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