For the most part, they come here accidentally, but some are introduced deliberately. Congress has asked the Coast Guard to develop a prevention policy, but more is needed. Real control of invaders requires total population involvement. Here s why.
Natural movement is one of the most obvious accidental vectors.
To survive and reproduce, animals, plants and pathogens all move by wind, water. Less obvious but equally important, sometimes species are moved naturally but by unusual vectors such as storms, other times by unnatural vectors such as clothing, people or other animals, boats, ships, planes, trains, boxes, almost anything. New or developed species migrate deliberately for survival. They are also introduced deliberately by agriculture strategies to improve food supply, and by aquaculture strategies to improve fish stocks. Some species are introduced in strategies to improve recreation for anglers and boaters.