Vessel Fouling

Vessel Fouling. Courtesy of Steve Mercer.

Vessel Fouling (aka biofouling or hull fouling) refers to marine organisms (including AIS) that attach themselves to objects immersed in salt water, including the hulls and ancillary gear of yachts and other vessels. AIS, including small fish, barnacles, mussels, sponges, algae, crabs, and sea squirts, can attach themselves to ships, fouling the wetted surface areas (WSA), or live within the matrix of the fouling community and protected nooks and crannies such as Sea Chests and Anchor Systems (anchor, chain, locker), as well as the areas highlighted in the diagram below. These organisms then colonize the hull and "hitch a ride" from one port to the next. Invasions can occur when these fouling organisms come in contact with structures in a new port or release
their larvae into its waters, possibly establishing themselves in the
new port and spreading to nearby areas.

High risk areas on a recreational vessel, which are similar to those on a commercial vessel. Diagram courtesy of AQIS.

While ballast water is often the primary vector of transer for many species/regions, hull fouling is now recognized as an important AIS vector, introducing more AIS than ballast water in some regions. Hull fouling as a serious problem is not surprising, considering:

The WSA that arrives into the U.S. annually is equivalent to 2.5 times the area of Washington, D.C. (438 sq km). ¹
67% percent of this WSA comes from outside the U.S.¹
70% of the 250 Australia's AIS² and 74% of Hawaii's AIS³ arrived via biofouling.
Vessels may contain large amounts biofouling - up to 90 tons.
Simply cleaning the ship is not enough, as live organisms are often released into the water during this process (image at right).

1 Smithsonian Environmental Research Center
2 Australian Quarantine and Inspection Service. 2005. AQIS Fact Sheet.
3 Godwin, L Scott (2003). Hull Fouling of Maritime Vessels as a Pathway for Marine Species Invasions to the Hawaiian Islands. Biofouling, 19 (1), 0892-7014.