Study

Temporal changes in European eel, Anguilla anguilla , stocks in a small catchment after installation of fish passes

  • Published source details Laffaille P., Acou A., Guillouët J. & Legault A. (2005) Temporal changes in European eel, Anguilla anguilla , stocks in a small catchment after installation of fish passes. Fisheries Management and Ecology, 12, 123-129.

Actions

This study is summarised as evidence for the following.

Action Category

Install fish elevators/lifts

Action Link
Eel Conservation in Inland Habitats
  1. Install fish elevators/lifts

    A study in 1995–2002 in a river in northern Brittany, France (Laffaille et al. 2005) found that, 10 years after installing a fish lift at a dam, along with eel passes in three other dams, European eel Anguilla anguilla density, biomass and length declined in river sections furthest upstream of the lift, but did not change in all other upstream and downstream sections along the river. During 310 years after installation of a fish lift and eel passes, average eel density did not change significantly in each of two river sections downstream of the lift (year 3: 0.1 eels/m2, year 10: 0.1–0.2 eels/m2) or five of six river sections upstream of the lift (year 3: 0.1–0.4 eels/m2, year 10: 0.1–0.7 eels/m2).  In the other section, located furthest upstream, average eel density declined (year 3: 0.4 eels/m2, year 10: 0.1 eels/m2). Over the same period, average eel biomass and length declined in two river sections upstream of the lift, but did not change significantly in the four other sections upstream or two sections downstream (see paper for data). In 1992, a fish lift was installed in a 14-m high impassable dam in the river Frémur. In 1996, eel passes (details not provided) were installed in two 4–6-m high, partially impassable dams (previously only eels <120 mm could pass) downstream of the fish lift. Each September from 1995–2002, eels were captured by electric fishing (net mesh size 3mm) in eight river sections (each 430–1,500 m2), 4–17 km upstream of the estuary (two sections downstream and four upstream of the fish lift). In total, 7,079 eels were weighed, measured and released. 

    (Summarised by: Vanessa Cutts)

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