Providing a home for sharks, rays and crabs

Almost twice a month, the sea creatures in Rotterdam Zoo’s Oceanium are provided with fresh ocean water transported from their original habitat by Maersk vessels. A special collaboration is required before the animals can take a happy and healthy swim in their home away from home.

Once back at the Zoo, the water is transferred to the Oceanium’s aquariums through an underground pipeline system. This only happens once the samples, taken during the collection of the water, have undergone extensive testing and received approval.

Few tourists visiting the Rotterdam Oceanium will be able to imagine the journey the oceanium’s water has travelled before it provides a natural resource for the stunning marine habitats and displays.

It all starts with a call from Rotterdam Zoo to Maersk Line requesting that one of its vessels take in water at specially designated areas in the Atlantic Ocean or the Gulf of Biscay.

“Taking in some extra ballast water is quite simple for us”, says Maersk Line captain Otto Janssen. “We pass by the area anyway, so we don’t have to deviate from our route, and we don’t have to stop the vessel, so there’s no delay. To store the water designated for the Zoo, we use two side tanks that are not normally in use.

Once the water has been taken in, the vessel continues its normal route to the port of Rotterdam”.

Pumping the water from the vessel into the barge takes about three hours and takes place while the vessel is already moored for the offload of containers.

What sounds simple is rendered quite special by the key anchor at Rotterdam Zoo:

“In my entire life, I have never witnessed such a special collaboration. Each and every person or company involved is working on the joint project on a voluntary basis, just for one very important purpose: a sustainable future for all animals, living in our Oceanium”, says Mirsada Mutapcic, Water Quality Manager at Rotterdam Zoo (‘Blijdorp’) in the Netherlands.

From one boat to the other

 As the water is being stored by Maersk in the middle of the Atlantic Ocean, activities are likewise high in ­Rotterdam Zoo, where preparatory work is being carried out on-board the old ‘Haaibaai’ barge.

Aboard are two very dedicated and enthusiastic men, Captain Willem Lodder and First Officer Piet de Bruin. Both of them actually retired quite some years ago, but they still make the journey along the Maas river every fortnight to collect the special cargo.

“The Haaibaai can carry about 300 tons of water, which is the equivalent of approximately fifteen filled 40-foot containers”, explains Lodder. “Once we arrive at the vessel, Piet jumps on board and, together, we connect the vessel and the barge”.

An important part of Piet de Bruin’s job is to check the water’s salinity:

“If we’re above a thirty-four salinity percentage, we’re good. If not, the water is rejected and we don’t take it on-board. Fortunately, this almost never takes place”.
Pumping the water from the vessel into the barge takes about three hours and takes place while the vessel is already moored for the offload of containers.

Home away from home

Ballast water discharge typically contains a variety of biological materials, including plants, animals, viruses, and bacteria – which is exactly why the Zoo is interested in getting the water from natural environments. However, these materials can also be a nuisance and cause ecological damage to aquatic ecosystems.

“Extensive screening is carried out by the Rotterdam Zoo laboratory. We maintain a high quality standard for the water that goes into the homes of our animals, as it can easily affect their well-being”, explains Mirsada.

The Haaibaai can carry about 300 tonnes of water, which is the equivalent of approximately fifteen filled 40-foot containers


Ballast water is regularly pumped into tanks on board a ship in order to maintain stability and improve handling when it is empty or only partially laden. Due to the various microorganisms carried from one ocean to another, the discharge of ballast water is normally only considered as having a negative impact on the marine environment.

This is an issue that the Maersk Group takes very seriously:

“By treating ballast water with UV light, Maersk aims to limit the spread of invasive species across seas. This is one of our technologies that we are currently applying to minimise the environmental impact”, says Lasse Emil Andersen, an in-house specialist on ballast water at Maersk Maritime Technology.

But for this specific task, the microbial ballast water is exactly what Rotterdam Zoo – and the sharks, king penguins, sea lions and jellyfish – are looking for.