Dolphin behavior vessel regulations

Vessels cause considerable disturbance to cetaceans world-wide, with
potential long-term impacts to population viability. Here we present a
comprehensive review of vessel impacts to cetacean behavior in Australian
waters (2003-2015), finding inadequate protections to be in place. The
majority of these studies found trends of decreased animal travel and
resting behavioral states as well as low compliance to regulations, and
they recommended further regulatory action such as greater enforcement or
monitoring, or passive management strategies. As a case study, we
conducted the first field assessment of vessel compliance with the
Wildlife (Marine Mammal) Regulations 2009 in Gippsland Lakes, Australia,
and provide the first assessment of the endangered Gippsland Lakes
Burrunan dolphin (Tursiops australis) population’s behavioral ecology.
Dolphin behavior and vessel regulation compliance data were collected
during boat-based surveys of Gippsland Lakes from July 2017 to January
2018, with a total of 22 dolphin group sightings resulting in 477
five-minute point samples. 77% of dolphin sightings involved vessel
interactions (within 400 m), and 56 regulation breaches were observed.
These breaches were most severe in summer (mean = 4.54 breaches/hour).
Vessels were found to alter dolphin behavior before, during, and after
interactions and regulation breaches, including increased mating (mate
guarding) and milling behavioral states, and increased ‘fish catch’, ‘high
leap’ and ‘tail slap’ behavioral events. These behavioral changes may
indicate masking of the dolphins' acoustic communication, disturbance
of prey, increased dolphin transition behaviors, and/or induced stress and
changes to group structure (including increased mate guarding). While our
results provide evidence of short-term altered behavior, the potential for
long-term effects on population dynamics for this threatened species is
high. In the context of reported inadequate cetacean protection
Australia-wide, our management recommendations include greater monitoring
and enforcement, and the utilisation of adaptive management.