Pathways and Prevention : ShippingShipping is often considered the major pathway for marine introductions. Commercial shipping (both international and within the country), recreational boating, cruise ships, and small commercial vessels (such as fishing, barges, and ferry boats), can all serve as pathways for the movement and introduction of species. The most common shipping-related pathways for introduction of non-native marine species include via ballast water, hull fouling, sea chests, other seawater discharges, and other areas of ships where plants or animals can attach. Click a pathway for more information ...
What is the Problem? The hulls of privately-owned boats used in brackish, estuarine, or ocean waters are not immune to the settlement, attachment, and growth of marine organisms, both native and introduced. Given enough time, organisms will begin to cover any below-water surface of a boat, including the hull, propeller, propeller shaft, seawater intake, keel, rudder, and bow thruster. A fouled hull increases the boat's drag in the water, reducing fuel efficiency and speed. The fouling organisms may even damage the engine. If boats are moved between ports, such as winter and summer ports along the eastern seaboard, the likelihood that those with fouled hulls will also transport living organisms is greatly increased. Some organisms can survive the transit and when introduced into the waters of the new port, become established. If they then become invasive, the problem is magnified. What are we concerned about? The results of a research study examining the extent of hull fouling on more than 100 privately-owned powerboats and sailboats in ports along the eastern seaboard showed that ~75% of sailboats and ~55% of the powerboats examined had medium to heavy fouling (1% to >50% fouling by macroorganisms, Whitlatch et al. 2007). These boats were examined in both winter (southern) and summer (northern) ports, as well as at stopover ports in-between. The highest degree of fouling was typically found on rudders, seawater intakes, keels, propellers, and propeller shafts. The hulls of sailboats were slightly more heavily fouled than power vessels. The researchers also found a generally poor correlation between the degree of fouling estimated from surface inspections and diver inspections.  Photo: Team Benthos, University of Connecticut What are the solutions? Maintenance of hulls through regular cleaning will minimize the number of fouling organisms present. This is especially important prior to moving the boat from a port in one area of the country (or world) to a port in another area. The fouling of a boat hull and other below-water surfaces can be reduced through the use of protective coatings applied to the hull. These coatings usually contain a toxic chemical (such as copper) or an irritant (such as pepper) that discourages organisms from attaching. Other coatings, such as those that are silicone-based, provide a surface that is more difficult to adhere to firmly, making cleaning of the hull less laborious. The type and concentration of coatings that can be applied to a boat hull is regulated, and can vary from state to state. It is important to be aware of what is approved for use in your state. Hull cleaning can take place on land or in-water. In both cases, care should be taken to prevent the organisms from being released into the water. Hull cleaning practices may be regulated at the state level to prevent paint chips and their associated chemicals from getting into the water. By following best management practices, the impact of the cleaning procedure on the environment will be minimized. Fact Sheets Rock the Boat! Balancing Invasive Species, Antifouling and Water Quality for Boats Kept in Saltwater. Leigh Johnson and Jamie Gonzalez. California Sea Grant College Program Report No. T-064. 2007 West Coast Ballast Outreach Project: Ballast water and hull fouling; two vectors for aquatic invasive species to invade CaliforniaClean Boater Programs California Clean Marina Programs Connecticut Other Links National Clean Boating Campaign Best Management Practices |
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