In these situations, adult organisms may reproduce and release larvae into ballast water while adults remain in the sediment. This pathway leads to the release of the same nonindigenous species into multiple ports. Stopping invasions before they occur is the more practical and economical solution in the long term. In order to stop an invasion, organisms must not be discharged from ballast tanks. This can be achieved by not taking organisms into ballast tanks, killing organisms during the voyage, or not discharging organisms when ballast water is released.
More research needs to be conducted on methods to prevent introductions of unwanted species.
Unfortunately, no ballast water treatment method can completely eliminate the risk of introducing exotic species. The goal of managing ballast water is to minimize the risk, possibly by targeting species that are known to have the potential to cause ecological and economic harm. The United States requires all ships traveling in the Great Lakes or the Hudson River above the George Washington Bridge to exchange ballast water in the open ocean prior to entering these waterways. With the exception of these two waterways, no mandatory regulations exist for minimizing the risk of exotic species introductions in the ocean or other waterways in the United States. Because the transfer of nonindigenous species via ballast water is an international issue, regulations for the management of ballast water to prevent introductions will be most effective if applied internationally.