Introduced marine species may enter through a variety of pathways (also referred to as vectors). These include shipping (ballast water, hull fouling, drilling platforms and docks), live seafood releases, marine bait discards, recreational activities, release of live animals from internet sales, canal construction, and research and educational releases. This web site focuses on ballast water, hull fouling and other shipping-related vectors, marine bait and hitchhikers, and live seafood releases. Links to information on other vectors and ways to prevent or minimize new introductions are provided.
| PATHWAY |
SPECIES THAT MAY BE INTRODUCED |
EXAMPLES AND IMPACTS |
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| SHIPPING |
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| Ballast and other discharges |
Planktonic and nektonic organisms, including microbes |
Zebra and quagga mussels (Dreissena spp.) that block intake and outflow pipes, |
| Hulls and hard surfaces (e.g. anchors, propellers, live wells, sea chests). |
Attached and free-living organisms |
Barnacles that foul docks and hard surfaces, sea squirts that impact aquaculture |
| Recreational boats and equipment (diving and trailers) - hulls and hard surfaces |
Attached, free-living, and planktonic organisms |
Sea squirts (e.g. Didemnum vexillum) and alga (e.g. Grateloupia turuturu) attach to hulls and trailers and impact aquaculture and marinas |
| Drilling platforms, docks |
Planktonic, attached, and free living organisms |
May serve as a stepping stone for many species, e.g. a mussel on a derelict navy vessel in Hawaiian waters transfers to other locations |
| Canals and irrigation ditches |
Movement of plants, animals, and diseases |
Live seafood (Tilapia sp.) has escaped into irrigation ditches; jumping carp in the Great Lakes |
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| LIVE RELEASES |
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| Live seafood releases |
Release of fish and other species |
Snakehead fish (Channa sp.) and Chinese mitten crabs (Eriocheir sinensis) are examples |
| Bait |
Sea worms and small fish and packing materials with stowaways |
The European Green crab (Carcinus maenas) may have arrived in California by discarded bait packages |
| Aquaculture |
Macroinvertebrates and macroalgae, fish, and diseases |
The European oyster (Ostrea edulis) has spread throughout the northeast from aquaculture |
| Aquarium industry |
Primarily fish, but also algae, diseases, and hitchhikers |
The lion fish (Pterois spp.)is a marine example, the common goldfish (Carassius gibelio) is found in New England waters |
| Research and public aquaria |
Free-living and attached organisms and diseases |
The green alga Caulerpa taxifolia was released by an Oceanarium and outcompeted native species |
| Internet |
Virtually all organisms can be purchased and sent by air express |
"Living rocks" that have attached to plants and animals are used for aquariums |
