B11 The increase in the transport and introduction 
of invasive alien species worldwide is primarily 
influenced by economic drivers, especially the 
expansion of global trade and human travel 
(Figure SPM.5) (well established) {2.1.2, 3.1.1, 
3.2.3}. There has been a fivefold increase in the size of the 
global economy over the last 50 years (well established)
{3.1.1}. International trade, which has increased nearly 
tenfold over the same period, represents the most important 
pathway through which invasive alien species are 
transported worldwide (Figure SPM.5) (well established)
{3.1.1, 3.2.3.1}. There is a strong link between the volume 
of commodity imports and the number of invasive alien 
species in a region, and patterns in the global spread of 
species mirror shipping and air traffic networks (well 
established) {3.2.3.1}. The construction of shipping canals 
(e.g., Suez, Panama) has connected previously separated 
marine and freshwater regions, facilitating the spread of 
invasive alien species through species migration, ballast 
water transfers (Box SPM.2) and biofouling (well 
established) {3.2.3.1, 3.3.1.3}. For example, 150 years after 
the opening of the Suez Canal, marine alien species are still 
being newly recorded in the Mediterranean Sea (well 
established) {Box 3.7}. Biosecurity measures at international 
borders have not kept pace with the growing volume, 
diversity and origins of global trade (including e-trade) and 
SUMMARY FOR POLICYMAKERS
19SUMMARY FOR POLICYMAKERS
BACKGROUND
A GLOBAL DISTRIBUTION OF ESTABLISHED ALIEN SPECIES 