Lake IJsselmeer This is an IBA in danger! 

Country/territory: Netherlands

IBA Criteria met: A1, A4i, A4iii, B1i, B2, B3, C1, C2, C3, C4, C6 (2016)
For more information about IBA criteria please click here

Area: 109,000 ha

Vogelbescherming Nederland
Most recent IBA monitoring assessment
Year of assessment Threat score (pressure) Condition score (state) Action score (response)
2018 very high not assessed medium
For more information about IBA monitoring please click here

Site description
Previously the Zuiderzee, this area is now a vast shallow freshwater lake, having been cut off from the Wadden Sea (001) by the Afsluitdijk (in 1932) and with 45% of its extent having been reclaimed. The original IJsselmeer was then bisected by a dyke in 1975, which separated it from the southern part now called Markermeer (038). This site adjoins three subsites 035, 036 and 037 (the figure for the area of this site excludes these subsites) which are located along the Frisian coast. The lake receives Rhine water through the IJssel river (046 and 047) via Lake Ketelmeer (039). The wetland habitat in the subsites is not included in the percentage cover for this site (to avoid overlap). Extraction of sand and water occurs, and natural-gas extraction is planned. Military training (artillery) occurs at Breezanddijk (Afsluitdijk). The lake has been locally deepened to over 25 m by sand extraction. This site, together with site 038, formed part of a single, larger site (former site NL030) in the previous pan-European IBA inventory (Grimmett and Jones 1989).

Key biodiversity
Numbers are based on aerial counts, which tend to underestimate those species with a scattered occurrence. This is the main moulting area for subadult Cygnus olor in the Netherlands, and the main feeding area for Phalacrocorax carbo from Oostvaardersplassen (066), although the actual numbers are poorly represented by the aerial counts. The number of Chlidonias niger is based on numbers flying to roost at Balgzand (013). Other species which do not fulfil IBA criteria include non-breeding Larus minutus (5,100 in January 1983).

Recommended citation
BirdLife International (2021) Important Bird Areas factsheet: Lake IJsselmeer. Downloaded from on 01/12/2021.