Invasive alien species – North Holland Province

The province protects the flora and fauna of northern Holland, among other things, by combating invasive alien species. These are animals and plants that did not originally come from here and can spread very quickly. Once in nature, these exotic species can displace native species and affect our local nature.

Invasive alien species pose a threat to biodiversity in nature reserves. “Often these types of plants and animals end up in our nature as a result of human activity,” says Karlin van der Pan, a green policy advisor for Noord-Holland province. “A tropical aquatic plant that people throw into the water. A type of turtle from the garden center is released into nature because its owner allows animal freedom. Or little monsters that travel from distant lands via container and truck trade routes.”

Watercrassula on Texel

There are many different types of invasive alien species, from the Egyptian goose to the giant hogweed. Each type requires a different control method. Sometimes this can be done with relative ease. In the case of minor infestation, removal of invasive alien species is primarily preventive. But it is sometimes a widespread problem that is difficult to contain. For example, the invasive aquatic plant Cabomba has been a threat to aquatic recreation and nature in the eastern Vechtplassen for years.

Click on the image to watch the video on water weed control on Texel (YouTube).

In Texel, the aquatic crassiola has once again become unsightly to the eye. Van der Baan: “It’s an aquatic plant that is originally from Australia and is used here in aquariums. Then some people dump those plants in nature. With all its consequences. Even a 3 millimeter piece of the plant under the sole of a shoe can lead to a real plague in a reserve. Natural.In no time they grow into huge, dense mats on the water that do not allow sunlight to pass through and make other life forms impossible, such as the netterjack frog, shore grass and dwarf linen.So it is a real threat to our nature and our biodiversity.You must intervene quickly in case of fire, Otherwise, the costs will rise significantly and the fight will not be possible.”

Spanish white-headed duck

Sometimes two species of animals meet face to face, such as the reddish spiny tail that can cross with the white Spanish duck. This threatens the white-headed duck. In order to protect the native flora and fauna, the member states of the European Union have concluded agreements among themselves on the approximately 70 invasive species of plants and animals that occur in Europe. This list is constantly expanding. Van der Pan: “Nature simply does not respect borders, so European countries must work together to ensure that native species such as the Spanish white duck are protected.”

Under the Nature Protection Act, the control of species identified by the European Union has been transferred to the provinces. The exceptions are the Chinese mitten, non-native lobster, and quipu. Van der Baan: “It is subject to fisheries legislation and is therefore the responsibility of the Ministry of Agriculture, Nature and Fisheries (LNV). In the case of the beaver and musk, it is the role of water boards. This makes dealing with sometimes invasive alien species very complex and difficult.”

American lobster
Photo: American lobster (Source: – Anneke van Lijnschoten)


The Natura2000 regions of northern Holland are particularly vulnerable to these “foreign invaders”. So the province wants to preserve and protect these areas of special natural value. However, combating invasive alien species can harm nature in some cases. “Sometimes doing nothing is the best option,” says van der Pan. “When you think of invasive alien species, you quickly think of controlling and eliminating them, but sometimes this is at the expense of our vulnerable nature reserves. In some cases, we haven’t It is possible to remove it completely. Then it is better to accept that alien species are now part of our nature and focus on enhancing the surroundings and biodiversity. Thus, controlling alien elements is a tailor-made thing: we look at what is needed for each area.”

Together with municipalities and administrators

When making agreements about approach, county, municipalities, and nature managers work together. For example, a province could order the control of certain alien species or establish a nature promotion policy (as in the Biodiversity Master Plan). The county can also make a financial contribution or help share knowledge. Van der Pan: “Unfortunately, there is still no national structural monitoring of invasive aliens. So it is difficult to define the problem. As a county, we are thus dependent on officials. They know their area better and therefore are our eyes on the field.”

Population and pedestrian observations are also important in mapping and combating invasive alien species. For example, they can help by posting strange pictures on the website.

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