The establishment of alien species (bioinvasion) is regarded as one of the major threats to biodiversity with global shipping being the main vector of introduction. Alien species can hitchhike as stowaways on cargo ships attached to the hull of the ship, inoculated in ballast tanks or hidden in containers. Globalisation with its ever increasing demand for cargo transport has accelerated the global spread of species during the last decades.

Based on the network of global cargo ship movements we developed a model to quantify the probability of invasion by ballast water releases. At each port of call of a vessel the model integrates data about ballast water releases, environmental heterogeneity, biogeography, and the full history of the ship journey. The model allows the determination of the highways and hot spots of marine bioinvasion and the source regions from where invasive species are likely to be introduced. The results are published in Ecology Letters.

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