Fish capture rates of little egrets Egretta garzetta are significantly reduced by raising fish pond water turbidity, southern France

  • Published source details Cezilly F. (1992) Turbidity as an ecological solution to reduce the impact of fish-eating colonial waterbirds on fish farms. Colonial Waterbirds, 15, 249-252


This study is summarised as evidence for the following.

Action Category

Increase water turbidity to reduce fish predation by birds

Action Link
Bird Conservation
  1. Increase water turbidity to reduce fish predation by birds

    A randomised trial in southern France found that little egret Egretta garzetta foraging efficiency (capture rate) declined significantly in turbid water, under captive conditions (Cezilly 1992). A 3 x 6 m pool (water depth 10 cm) was used. Nine adult egrets either foraged alone or in threes. Three trials were undertaken using clear or turbid water, with three densities of prey i.e. mosquito fish Gambusia affinis (1, 2, and 4/m²). Treatment order was randomised and trials lasted 5 min. Turbid water was created by adding clay (Secchi disc lost from view at 10 cm depth).


Output references

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, terrestrial mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 18

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust