AIS/Ballast Background and Research
Advances in shipbuilding technology have created larger and faster ships, which in turn, have increased survival rates of transported species between regions. Coupled with this has been a long-term steady increase in global shipping, such that today, more than 35,000 vessels are at sea at any given time. These facts may account for the almost exponential increase in observed species introductions during the past 200 years (Ruiz et al. 2000). In the year 2000, for example, 2.1 million metric tons of foreign ballast water was discharged into the San Francisco Bay-Delta (Falkner, 2001). This input of foreign ballast water presents significant opportunity for new AIS to invade, and once a species is established in a new area it is very difficult to manage and nearly impossible to eliminate.
Once AIS have been introduced, they can be spread by several vectors, including recreational boaters and fishers. Read the short Guide to Preventing AIS Spread to find out how to prevent the further spread of AIS.