Study

Density‐dependent growth, survival, and biomass production of stocked glass eels (Anguilla anguilla) in seminatural ponds

  • Published source details Pedersen M.I., Rasmussen G. & Jepsen N. (2023) Density‐dependent growth, survival, and biomass production of stocked glass eels (Anguilla anguilla) in seminatural ponds. Fisheries Management and Ecology, 00, 1-7.

Actions

This study is summarised as evidence for the following.

Action Category

Change capture, transport or release methods to increase survivorship of translocated (‘stocked’ or ‘restocked') eels

Action Link
Eel Conservation in Inland Habitats
  1. Change capture, transport or release methods to increase survivorship of translocated (‘stocked’ or ‘restocked') eels

    A replicated, randomised study in 2013–2016 in eight experimental ponds in central Jutland, Denmark (Pedersen et al. 2023) found that releasing translocated wild European glass eels Anguilla anguilla at low densities resulted in higher survival rates, body mass, length and condition compared to eels released at higher densities. After 18 months, eels released at the lowest density (0.5 eels/m2) had the highest survival rates (44–84%) average body mass (9–12 g) and body condition (data reported as condition factor) compared to eels released at 1 eel/m2 (survival: 22–52%, mass: 7–11 g), 1.5 eels/m2 (survival: 32–48 %, mass: 68 g) and 2 eels/m2 (survival: 13–36 %, mass: 6–7 g). In addition, eels released at 0.5 eels/m2 grew to greater average lengths (1620 cm) than those released at 2 eels/m2 (1516 cm). Glass eels were captured from streams using electrofishing and kept in a mesh bag within the stream for 1–2 nights before being transferred to one of eight 200-m2 shallow open ponds. Eels were released in the ponds at 0.5, 1, 1.5 and 2 eels/m2 (3–5 ponds/density). Surviving eels were recaptured and measured after 18 months via pond draining and electrofishing. The study was run over two 18-month periods: June 2013 to November 2014 and June 2015 to November 2016.

    (Summarised by: Sam Reynolds)

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