Assessing the risk of boat strike on Dugongs Dugong dugon at Burrum Heads, Queensland, Australia

Abstract

The risk of mortality due to boat strike is increasingly being recognized as an important management issue for marine wildlife, including Dugongs Dugong dugon. Ameliorating the effects of boat strike requires assessment of how that risk varies over the management area. This is dependent on the distribution and movements of both Dugongs and boats and on the physical characteristics of the area, particularly depth. In this study we assess these features for a small community that is dependent on tourism centred around recreational fishing and which is home to a regionally significant Dugong population. During one of the most popular holiday times, boats accessing the favoured fishing site pass directly through the core area of Dugong activity. Our data show that boat strike risk to Dugongs can be lowered significantly with minimal imposition on boaters. Boaters can avoid the area of highest risk by travelling around it in deeper water. However, this straightforward solution is only possible because of the restricted spatial scale of Dugong activity and the proximity of a deepwater channel enabling boaters to easily avoid shallow areas where boat strike risk is highest.