Distraction

Three vessel interaction critical issues were identified:

Critical issue 1: Vessels and swim-with activities within 300m disturb behaviours critical to survival

The current level of effort correlated with significant effects on all six behaviours. Overall, dolphins spent less time traveling, resting, and foraging in presence of vessels, which decreased by 70%, 133%, and 160%, respectively. In addition, dolphins generally spent more time socialising, milling and diving in presence of vessels, which increased by 126%, 248% and 300% respectively. Once disturbed, the time required to return to a given behavioural state was significantly affected by the presence of vessels for all behaviours. Primarily, when foraging or resting, bottlenose dolphins took significantly longer to return to these states in the presence of vessels, with time increasing by 262% and 726%, respectively.

Critical issue 2: High cumulative vessel effort exerted on local population

Dolphins in the BoI spent on average 86% of daylight hours with at least one vessel. Private vessels were the most prevalent type of vessels recorded in the area (36%, n=6,274). However, both permitted and un-permitted vessels also demonstrated a strong presence, accounting for 33% (n=5,752) and 31% (n=5,403) of the vessels observed, respectively. All vessel types exerted significantly more cumulative viewing effort in spring/summer than autumn/winter.

Critical issue 3: Poor compliance across all vessel types utilising BoI waters 

Poor compliance with MMPR (1992) was observed across all vessel types. Results indicate current mitigation efforts have not been successful.