Sites - Important Bird Areas (IBAs)

Ornithological information 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).

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).

Populations of IBA trigger species

Protected areas

Protected area	Designation	Area (ha)	Relationship with IBA	Overlap with IBA (ha)
De Ven	Nature Conservation Law	17	protected area contained by site	45
De Ven	Nature Reserve	17	protected area contained by site	17
Friese IJsselmeerkust - NL1000002	Habitats Directive	2,526	protected area contained by site	2,526
Friese IJsselmeerkust I	Natural Monument	4,800	protected area overlaps with site	88
Friese IJsselmeerkust II	Natural Monument	120	protected area overlaps with site	12
IJsselmeer	Wetlands of International Importance (Ramsar)	108,000	protected area overlaps with site	108,000
IJsselmeer - NL9803028	Birds Directive	113,290	is identical to site	109,000
Onderdijken	Nature Reserve	100	protected area contained by site	100
Stoenckherne	Natural Monument	40	protected area contained by site	40
Stoenckherne II	Natural Monument	100	protected area contained by site	100

Habitats

Land use

Management considerations The main problems are over-fishing, water management (level deliberately kept high during summer to supply water for farming), pollution by nutrients from the River Rhine/IJssel and by trace pollutants such as cadmium, mercury and DDT (`Other' threat, above), entanglement in fishing nets (involving thousands of birds), and recreation (leisure boating).

Protection status National Low International Low88 ha of IBA covered by Natural Monument (Friese IJsselmeerkust I, 4,800 ha). 12 ha of IBA covered by Natural Monument (Friese IJsselmeerkust II, 120 ha). 45 ha of IBA covered by Natural Monument (De Ven, 45 ha). 40 ha of IBA covered by Natural Monument (Stoenckherne, 40 ha). 100 ha of IBA covered by Natural Monument (Stoenckherne II, 100 ha). 17 ha of IBA covered by Nature Reserve (De Ven, 17 ha). 100 ha of IBA covered by Nature Reserve (Onderdijken, 100 ha). 240 ha of IBA covered by Special Protection Area (Friese IJsselmeerkust, 5,130 ha).

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Recommended citation  BirdLife International (2013) Important Bird Areas factsheet: Lake IJsselmeer. Downloaded from http://www.birdlife.org on 19/06/2013

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