German Federal Agency for Nature Conservation (BfN)



Container ship. Photo: BfN
Container ship. Photo: BfN

Marine traffic continues to grow around the world as vessels increase in numbers, speed and size. The North Sea and the Baltic Sea are no exception to this trend. Shipping routes in the North Sea and especially in the German Bight are among the world’s busiest. The Baltic Sea is no different: This again is an area with among the heaviest shipping traffic in the world. In German waters, two-thirds of all shipping vessels land at North Sea ports, the majority in Hamburg. There is scarcely any area left free of shipping in the North Sea and the Baltic Sea.

Heavily trafficked shipping lanes

Big ships mostly keep to recommended lanes. In narrow or very heavy traffic areas, traffic separation schemes regulate shipping with clearways of precisely specified widths. In the Baltic Sea, there are traffic separation schemes for areas including the Fehmarn Belt and the Kadet Trench north-west of the Darss peninsula – the main route between the Baltic Sea, the Danish Belt Sea and the North Sea beyond. In the North Sea, the approach to Hamburg with northern and southern clearways through the German Bight is one of the busiest waterways in the world.

Table 1 gives an impression of the numbers of ships in the German merchant fleet:

Number of ships in the German merchant fleet
Type of vesselNumberGross tonnage (GT)
Passenger transport96296.470
Dry cargo ships3.14883.064.453
Other vessels594764.631

Table 1: Number of ships in the German merchant fleet, comprising vessels under the German flag, vessels in the International Shipping Register (ISR) and vessels under foreign flag; the gross tonnage (GT, replacing the earlier gross register tonnage or GRT) is the volume of all enclosed spaces of the ship times a multiplier based on the ship’s volume.

Information as of October 2013 (BSH)

Though 2009 saw cargo transshipment decrease for the first time in many years (by 18 percent), experts predict a long-term return to growth – especially in container shipping – once the slump has been overcome. 2013 already brought a slight increase of 2.1%.

Looking at oil transportation, this has doubled in the last ten years in terms of both the quantity of oil carried and the number of tankers. Today’s biggest tankers carry some 450,000 tonnes of crude oil.

Larger ships with increasing draughts have made it necessary to dredge deeper and deeper channels to ports. There are current plans to upgrade parts of the Ems, the Weser, the Elbe, the Kiel Canal and the Rostock Sea Canal.

It is clear from these developments that impacts on marine ecosystems and the marine environment are set to increase.

Impacts in coastal waters

Indirect impacts in coastal waters include changes in the hydrological situation caused by the widening and deepening of rivers and estuaries, such as lower river flow velocities and changes in salinity or tidal amplitude in North Sea currents.

Maintaining the upgraded channels in some cases requires very major dredging work, which in turn has further impacts such as turbidity plumes, remobilisation of nutrients and loss of habitat. Such disturbances take place on a recurrent basis.

Upgrading channels naturally leads to an increase in shipping traffic.

Vessels also pose a further threat to coastal habitats through wash, undertow and sediment resuspension.

Impacts on marine diversity

An increase in the number of ships using shipping lanes also amplifies the direct impacts of shipping on the marine environment. Besides maritime accidents (most of all with oil tankers), chronic pollution such as oily residues, ships’ waste (litter), fecal matter, and toxic anti-fouling paint has a negative impact on numerous species and habitats. Examples include the potential damage caused by anti-fouling paint to the eggs and larvae of species such as whelks and the ingestion of plastic waste by sea birds.

Another serious problem is the introduction of alien species (see Non-indigenous species).

Shipping also affects marine mammals by causing death and injury in collisions and by continuously increasing underwater background noise levels (see
Underwater noise). Sensitive sea bird species are scared away from their accustomed resting and feeding grounds. Research has shown that some species of sea birds avoid resting in the clearways of large traffic separation schemes in the German Bight.

Oil-contaminated, enfeebled Eider duck (Somateria mollissima). Photo: S.E. Arndt
Oil-contaminated, enfeebled Eider duck (Somateria mollissima). Photo: S.E. Arndt

Discharges of oily waste and tank wash water are a major source of pollution. This results in oil slicks that most of all can adhere to the plumage of sea birds and poison them with fatal effect. In some parts of the North Sea, for example, oiled birds account for over 50 percent of common guillemots washed up dead.

This makes it especially important to improve the control of and apply strategies to prevent discharges of oily water.