Tens of thousands of vessels operate annually in the Great Barrier Reef World Heritage Area. Any vessel, including commercial ships, fishing vessels, and recreational craft can strike dugongs and marine turtles. Animals may be struck when they are unaware of or fail to avoid an oncoming vessel, or the driver of the vessel is not aware of or cannot avoid the animal. These species can be seriously injured by boat hulls and propellers if struck at high speed. The animal may sustain fractures and damage to internal organs. In severe cases, cuts caused by propellers can lacerate organs killing the animal outright, or lead to serious infection or disability that may also result in death. The Queensland Parks and Wildlife Service (QPWS) StrandNet database recorded seven dugongs being struck in the Great Barrier Reef between 1996 and 2003. There are also concerns that frequent boat activity can displace dugongs from their preferred habitats, although this appears to be a less serious problem than the mortality resulting from boat strikes.

Reported turtle strandings show human activities accounted for between 78 per cent and 81 per cent of mortality where the cause of death can be identified.  Boat strike is a primary cause of mortality accounting for up to 60 per cent of reported human caused deaths.

Actions

• Voluntary vessel transit lanes and speed restrictions have been established in waters known around Hinchinbrook Island to be important dugong habitat
• The Hinchinbrook Local Marine Advisory Committee, in conjunction with the Great Barrier Reef Marine Park Authority(GBRMPA), has produced several boat ramp signs and a brochure aimed at reducing the risk of dugong and turtle collisions
• Recommended Reef Practices have been promoted to boat users
• The GBRMPA is working with other agencies to collect information about the risks and incidence of boat strikes on dugongs and turtles. A tri-agency programme facilitates public reporting of marine wildlife strandings, recording of data and detailed examinations of dugong and turtle carcasses to identify causes of mortality. Data from the programme are released in annual reports. The GBRMPA website enables the general public to subscribe to an Email List Server called Stranding Announce, that posts notices about each stranding soon after it is investigated
• A Code of Practice has been adopted by the peak recreational fishing group to minimise boat strikes
• GBRMPA has funded research into boat traffic effects on marine mammals and turtles in the Hinchinbrook Dugong Protection Area and published it as GBRMPA Research Publication no. 67
• Additionally, access to the waters surrounding critical turtle nesting sites is restricted under the Great Barrier Reef Marine Park Zoning Plan and through permits.