Setting a New Benchmark in Managing Biofouling on Vessels in a Sensitive Marine Environment

Abstract

Abstract The water surrounding Barrow Island (BWI), Western Australia is an internationally significant marine protected area for coral and turtle conservation. A key commitment of the Gorgon Project is that no marine pests be introduced to island waters. A comprehensive quarantine strategy has been developed to prevent the introduction of marine pests, monitor for any that have penetrated the quarantine barriers, and respond to any introductions of such pests. All vessels mobilising to Barrow Island must be free of secondary biofouling (barnacles, bryozoans, hydroids and worms) at the time of mobilisation. In meeting this criterion, all vessels undergo an initial risk assessment to determine the risk of being infected with marine pests and measures are taken to remediate or mitigate such risks. A preference exists to drydock vessels. In-water inspections and cleaning are also undertaken for vessels that remained in high risk areas following drydocking. The key question "How long can vessels remain in-water and still be considered to be free of secondary biofouling?" is ecologically and economically significant. To address this, the results of 32 vessel inspections were analysed, including vessels commencing, ongoing and departing from Gorgon service. A range of vessels were considered: offshore support vessels, landing craft tankers, dredges, barges, utility vessels and crew transport vessels. The results have significant implications for all vessel owners that work in sensitive marine areas. It is also an important indication that the current risk assessment methods underestimate the risks vessels present to marine ecosystems, more so when vessels operate in marine protected areas. To date, quarantine measures to prevent the introduction of marine pests to Barrow Island from overseas have been effective.