Likely Sources of Marine Introductions
•Ship hull fouling 
•Ballast water dumping
•Escapes from field aquaculture
•Escapes or release of aquarium pets
•Incidental w/ aquaculture packing material
•Bait bucket
•Intentional stocking to start a fishery
•
Here is a short list of pathways which could lead to the introduction of exotic organisms.  I don’t want to forget to mention the rate of introductions steadily increase as commerce and free-trade increase as well.  New pathways for the possible introduction are also occurring.