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Dieren en planten

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Other seabed products   Shell extraction   

Shell extraction

Shells were being extracted already in the 10th century, particularly from the exposed seabed where they were raked together and collected. Shells are presently mined by companies which have specialized in extracting clean shells (originating from sand sedimentation) or clay shells (originating from clay sedimentation). Even shellfish restaurants supply shells, although it is a by-product for them, their main product being the meat of the shellfish. Shells are used for drainage, paving bicycle paths, grit production, mashed foods industry, insulation under floors etc.

  • Wadden Islands
    Shell extraction on the Wadden Sea, Ecomare

    'Wadden shells' have been popular since the 1980s as insulation material under the floor. They are mostly made up of fossilized cockle shells (75%) which are fished up from old cockle banks. Baltic tellins make up 4%.
    In earlier days, shell extraction was a way of life for residents of the islands. The majority of the shells was sold to the mainland, where for example, it was burned in ovens for producing lime.

  • Policy

    Quota have been established in order to prevent excessive amounts of extraction. Shell miners in the Wadden Sea were permitted to extract 178,000 cubic meters annually till 1998. The quota was then raised to 200,000 cubic meters, based upon calculations made by the NIOZ, which showed that the annual accretion of cockle shells is approximately 250,000 cubic meters. Despite the larger quota, only 160,000 cubic meters of shells were extracted then.
    Present policy for mining shells was drafted in the document Shell Extraction Policy at the end of 1998 and evaluated in 2004. At the moment, shells are being mined in the Wadden Sea, the Westerschelde, the Voordelta and the North Sea. 290,000 cubic meters of shells are allowed to be mined per year, of which 210,000 cubic meter shells coome from the Wadden Sea region (90,000 cubic meter in the PKB region) and 80,000 cubic meter in Zeeuws waters. Shell mining in the Wadden Sea is concentrated in three channels (Marsdiep, Vlie and Frisian Sea Channel).
    Shell mining is forbidden in the German National Parks and the Danish section of the Wadden Sea.

  • Regulations for shell extraction

    The Waddenvereniging (an environmental lobby group for the wadden region) as well as Greenpeace are afraid that there will be negative effects for the Wadden Sea by increasing the quota. The fishermen could disturb the birds and seals in the region and the extraction could make the water turbid affecting the development of the sea plants. The oyster, which used to be numerous in the tidal flat region, needs a hard underground to live, such as the shell banks. Shell fishermen could have contributed to the decline. The organizations wanted to maintain the old quota.
    In the North Sea and the waters around Zeeland, a total of 80,000 cubic meters of shells per year are extracted. Extraction is forbidden in the Oosterschelde. This region is still suffering from the effects of the closure. Extracting shells could lead to a further decrease in the number of shell banks.

  • Coastal erosion from shell extraction?
    Mountain of mussel shells, Ecomare

    At the end of 1999, the Wadden Adviesraad ('Advice Council') (WAR) commissioned a study of the possible influence of shell extraction on the behaviour of the Wadden island coasts. The most important conclusion of the study was that the effects of shell extraction are marginal, at the present, allowed amounts. For the western Wadden Islands, extra coastal erosion of a maximum 18 centimeters per year was calculated, for the eastern islands was this 8 centimeters per year. With concentrated exploitation, or exploitation lasting several years at the same place, noticeable effects could occur on the coasts of the Wadden Islands.

    Even shellfish dishes produce a large amount of shells

  • Wadden Islands

    'Wadden shells' have been popular since the 1980s as insulation material under the floor. They are mostly made up of fossilized cockle shells (75%) which are fished up from old cockle banks. Baltic tellins make up 4%.
    In earlier days, shell extraction was a way of life for residents of the islands. The majority of the shells was sold to the mainland, where for example, it was burned in ovens for producing lime.

  • Policy

    Quota have been established in order to prevent excessive amounts of extraction. Shell miners in the Wadden Sea were permitted to extract 178,000 cubic meters annually till 1998. The quota was then raised to 200,000 cubic meters, based upon calculations made by the NIOZ, which showed that the annual accretion of cockle shells is approximately 250,000 cubic meters. Despite the larger quota, only 160,000 cubic meters of shells were extracted then.
    Present policy for mining shells was drafted in the document Shell Extraction Policy at the end of 1998 and evaluated in 2004. At the moment, shells are being mined in the Wadden Sea, the Westerschelde, the Voordelta and the North Sea. 290,000 cubic meters of shells are allowed to be mined per year, of which 210,000 cubic meter shells coome from the Wadden Sea region (90,000 cubic meter in the PKB region) and 80,000 cubic meter in Zeeuws waters. Shell mining in the Wadden Sea is concentrated in three channels (Marsdiep, Vlie and Frisian Sea Channel).
    Shell mining is forbidden in the German National Parks and the Danish section of the Wadden Sea.

  • Regulations for shell extraction

    The Waddenvereniging (an environmental lobby group for the wadden region) as well as Greenpeace are afraid that there will be negative effects for the Wadden Sea by increasing the quota. The fishermen could disturb the birds and seals in the region and the extraction could make the water turbid affecting the development of the sea plants. The oyster, which used to be numerous in the tidal flat region, needs a hard underground to live, such as the shell banks. Shell fishermen could have contributed to the decline. The organizations wanted to maintain the old quota.
    In the North Sea and the waters around Zeeland, a total of 80,000 cubic meters of shells per year are extracted. Extraction is forbidden in the Oosterschelde. This region is still suffering from the effects of the closure. Extracting shells could lead to a further decrease in the number of shell banks.

  • Coastal erosion from shell extraction?

    At the end of 1999, the Wadden Adviesraad ('Advice Council') (WAR) commissioned a study of the possible influence of shell extraction on the behaviour of the Wadden island coasts. The most important conclusion of the study was that the effects of shell extraction are marginal, at the present, allowed amounts. For the western Wadden Islands, extra coastal erosion of a maximum 18 centimeters per year was calculated, for the eastern islands was this 8 centimeters per year. With concentrated exploitation, or exploitation lasting several years at the same place, noticeable effects could occur on the coasts of the Wadden Islands.

    Even shellfish dishes produce a large amount of shells