Scientists in Germany have developed a new map of shipping networks that they say will act as a useful tool in preventing the threat of invasive species.

During 2007, Bernd Blasius at Carl Von Ossietzky University in Oldenberg, Germany, and his colleagues analysed the routes of over 16,000 cargo ships through onboard automatic transmitters to map the links between the ports they visited.

With data from the shipping routes Blasius was able to draw up a list of the ports with the highest risk for the introduction of invasive species.

The top ports at risk were the Panama Canal, followed by the Suez Canal, Shanghai, Singapore, and Antwerp. The list also featured Piraeus, Houston, Santos, Tianjin, Hamburg, and Barcelona.

The results showed that container ships sail along a largely predictable route, whereas bulk carriers and tankers were less predictable as a result of current market-trends.

Dry bulk carriers and oil tankers were also often sailing empty after offloading their goods and taking on large amounts of ballast water for trim.

When ballast water is pumped into the ship at a port, it includes organisms found in that port. The organisms that survive the trip are then released when the ballast water is discharged at the final port destination, often resulting in invasive species thriving in non-native waters.

"The model allows for identification of bioinvasion hot-spots, high risk routes and major source regions from which bioinvasion is most likely to occur and thus enables the identification of high risk scenarios, which are necessary for the development and implementation of effective prevention and management programmes," said Blasius.

The study was also able to track the speeds of the ships and found that container ships travelled at between 20 and 25 knots, whereas bulk carriers and tankers travelled at slower speeds of 13 to 17 knots.

Latest reports revealed that operating at 17 to 19 knots, considered super-slow steaming, instead of full speed of 23 to 25 knots, can not only can save 5 to 7% on total operating costs of long-haul loops but also substantially reduces emissions of carbon dioxide (CO2) and nitrogen oxides (NOx).

The Complex Network of Global Cargo Ship Movements has been released by Britain's Journal of the Royal Society Interface.