Management options for vessel hull fouling: an overview of risks posed by in-water cleaning

Abstract

Hopkins, G. A., and Forrest, B. M. 2008. Management options for vessel hull fouling: an overview of risks posed by in-water cleaning. – ICES Journal of Marine Science, 65: 811–815. Hull fouling has been identified as an important pathway for the spread of non-indigenous marine species. However, the management of associated biosecurity risks has proven challenging. Left unmanaged, a fouled vessel can pose a biosecurity risk through the detachment and dispersal of viable material, and through spawning by adult taxa upon arrival in a recipient port or region. These risks can be managed effectively through the removal of the vessel to land for defouling (e.g. dry-docking). However, alternative methods are needed for small (e.g. recreational) vessels, as well as for large vessels fouled outside their dry-docking schedule. Among the various treatment options, in-water cleaning is relatively common, although some countries have placed restrictions on this method because of perceived biosecurity risks. Here, we present a conceptual framework that identifies risks posed by in-water cleaning compared with alternatives, including no management. Decisions on the appropriate management option will be influenced by many factors, including the species present, the level of fouling, and the time a vessel spends in a recipient region. It is important that any regulatory changes regarding in-water defouling be supported by relevant research that quantifies the risks associated with the various management options.

Indications of marine bioinvasion from network theory

“…The discussion about how to most effectively manage marine bioinvasion [23,24] has been clarified somewhat. Which of the several techniques and treatments to clean ballast water and the large selection of antifouling-paints is most effective to slow down bioinvasion?…”

“…The European Physical Journal B discussed more or less controversially [23,24]. Ballast water may e.g.…”

Interrupting a multi-species bioinvasion vector: The efficacy of in-water cleaning for removing biofouling on obsolete vessels

“…Additional components in the obsolete vessel transfer process could include some hull husbandry during the preceding lay-up time, salinity or temperature treatments en -ro ute, and/or post-transit management (e.g. docking, beaching or additional targeted scrubbing with suction/retention capability; Coutts and Forrest, 2007;Hopkins and Forrest, 2008) upon arrival at the destination port. These would combine to reduce propagule supply, which we would expect to reduce the invasion risk from obsolete ships.…”

Marinas may act as hubs for the spread of the pseudo-indigenous bryozoan <em>Amathia verticillata</em> (Delle Chiaje, 1822) and its associates

“…In the Galveston Bay (Texas, USA), A. verticillata was listed as having the highest ecological risk score and least feasibility for control and/or eradication (Gosset et al 2004). Although its soft colonies can be easily detached from hulls by mechanical removal, stolons are likely to persist and regenerate new colonies, whilst viable fragments dislodged during manual removal may survive and subsequently reattach once the environmental conditions become favourable (Hopkins and Forrest 2008).…”