Increased abundance of European eel (Anguilla anguilla) in acidified Norwegian rivers after liming

Published source details Larsen B.M., Hesthagen T., Thorstad E.B. & Diserud O.H. (2015) Increased abundance of European eel (Anguilla anguilla) in acidified Norwegian rivers after liming. Ecology of Freshwater Fish, 24, 575-583.
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This study is summarised as evidence for the following.

	Action	Category
	Add lime to water bodies to reduce acidification  Action Link

Add lime to water bodies to reduce acidification 

A replicated, before-and-after study in 1987–2005 in 13 rivers in southern Norway (Larsen et al. 2015) found that adding lime to reduce acidification led to an increase in the abundance of European eels Anguilla anguilla. Eel abundance was greater 10 years after liming of rivers began compared to before liming (data reported as statistical model results). The proportion of sampling stations at which eels were recorded was also greater 10 years after liming began than before (data reported as statistical model results). In 1987–1997, liming of 13 acidified rivers began. Limestone powder was continuously added by dosers controlled by water flow and pH (11 rivers) or lime was added to lakes within the river systems (two rivers). In 1987–2005, eels were sampled in each of the 13 rivers during one year before and 9–19 years after liming began. During August each year, backpack electrofishing was carried out three times at 4–18 stations/river (each 100–150 m2). Total numbers of yellow eels caught/100 m2 at each sampling station were recorded. 

(Summarised by: Anna Berthinussen)