Mass-marking of farmed European eels (Anguilla anguilla (Linnaeus, 1758)) with alizarin red S

Abstract

The Working Group on Eel of the International Council for the Exploration of the Sea (ICES) regularly reports that a significant amount of stocked eels in Europe was pregrown in aquaculture farms prior to stocking-so called "farmed eels." The ICES advices chemical marking of stocked recruits to ensure their traceability throughout all life stages. To date, however, there was a lack of knowledge concerning the most suitable chemical substance and its application on farmed eels. The aim of this study was to fill this gap by presenting successful attempts of marking those eels with alizarin red S (ARS). An ARS concentration of 150 mg L −1 buffered with 150 mg L −1 Tris(hydroxymethyl)aminomethane applied as an immersion bath over 9 h was sufficient to mark a total of 3572 kg of farmed eels (6.5-8.0 g mean body weight). The marking success was 100% on otoliths and highest stocking density of up to 67.1 kg m −3 (corresponding 54.0 kg m −2 ) turned out to have no effect on mortality which was consistently below 1%.

Research and Monitoring plan Fish Migration River (FMR)

“…Mark-recapture techniques are present in various forms and differences among these methods include group (mass) or individual marking, tag retention and the necessity to kill glass eels to identify recaptures. Examples are methods such as alizarin red S (Kullmann et al 2017, Kullmann et al 2018, Diekmann et al 2019, oxytetracycline (Simon and Dörner 2005), vital dyes (Briand et al 2005), coded wire tags (Simon and Dörner 2005), PIT tags ) and visible implant elastomer (VIE) tags (Imbert et al 2007, Griffioen et al 2022a) are all used in the field for various purposes. To answer the research questions of passage success (Q2) and bottleneck analysis (Q3), marking method that can discriminate between groups, affecting neither behaviour nor survival, are preferred.…”

Guidelines for Uncertainty Analysis: Application of the respective Documents of EFSA and BfR for Exposure Assessments

“…Regarding the ARS/SC concentration, the following values seem to be widely used: 150 mg/l ARS ( (Simon et al, 2009), (Neukamm, 2009), (Caraguel et al, 2015), (Kullmann et al, 2017)) and 1g/l strontiumchloridhexahydrat ( (Wickstrom & Sjoberg, 2014), (Neukamm & Hempel, 2017)), which translates to 328.6 mg/l strontium. Regarding the ARS/SC concentration, the following values seem to be widely used: 150 mg/l ARS ( (Simon et al, 2009), (Neukamm, 2009), (Caraguel et al, 2015), (Kullmann et al, 2017)) and 1g/l strontiumchloridhexahydrat ( (Wickstrom & Sjoberg, 2014), (Neukamm & Hempel, 2017)), which translates to 328.6 mg/l strontium.…”

“…The cumbersome task remains to determine the maximal possible intake. Regarding the ARS/SC concentration, the following values seem to be widely used: 150 mg/l ARS ( (Simon et al, 2009), (Neukamm, 2009), (Caraguel et al, 2015), (Kullmann et al, 2017)) and 1g/l strontiumchloridhexahydrat ( (Wickstrom & Sjoberg, 2014), (Neukamm & Hempel, 2017)), which translates to 328.6 mg/l strontium. In one source, different experimental designs regarding the amount of water and number of eels were tested with ARS (Kullmann et al, 2017).…”

“…Regarding the ARS/SC concentration, the following values seem to be widely used: 150 mg/l ARS ( (Simon et al, 2009), (Neukamm, 2009), (Caraguel et al, 2015), (Kullmann et al, 2017)) and 1g/l strontiumchloridhexahydrat ( (Wickstrom & Sjoberg, 2014), (Neukamm & Hempel, 2017)), which translates to 328.6 mg/l strontium. In one source, different experimental designs regarding the amount of water and number of eels were tested with ARS (Kullmann et al, 2017). The design that maximises the amount of water per eel was 10 m 3 water with 200 kg eel (8g per eel), which translates to 0.4 l per eel and therefore a maximal intake of ARS of 60 mg per eel.…”

Does tagging transparent fish increase predation risk? A laboratory study with glass eel (Anguilla anguilla) and sea bass (Dicentrarchus labrax)

“…The relative proportion of glass eel predated by piscivorous fish in relation to local abundance can be estimated by mark‐recapture techniques. To estimate local abundance, mark‐recapture methods such as alizarin red S (Caraguel et al ., 2015 ; Diekmann et al ., 2019 ; Kullmann et al ., 2017 ), oxytetracycline (Simon & Dörner, 2005 ), vital dyes (Briand et al ., 2005 ), coded wire tags (Simon & Dörner, 2005 ) and visible implant elastomer (VIE) tags (Imbert et al ., 2007 ) are used. Differences between these methods include group or individual marking, tag retention and the necessity to kill glass eels to identify recaptures (Briand et al ., 2005 ; Imbert et al ., 2007 ; Simon & Dorner, 2011 ; Simon & Dörner, 2005 ).…”