Study

Acoustic alarms elicit only subtle responses in the behaviour of tropical coastal dolphins in Queensland, Australia

  • Published source details Soto A.B., Cagnazzi D., Everingham Y., Parra G.J., Noad M. & Marsh H. (2013) Acoustic alarms elicit only subtle responses in the behaviour of tropical coastal dolphins in Queensland, Australia. Endangered Species Research, 20, 271-282

Actions

This study is summarised as evidence for the following.

Action Category

Use acoustic devices on fishing vessels

Action Link
Marine and Freshwater Mammal Conservation

Use acoustic devices on fishing vessels

Action Link
Marine and Freshwater Mammal Conservation

Use acoustic devices on fishing gear

Action Link
Marine and Freshwater Mammal Conservation
  1. Use acoustic devices on fishing vessels

    A before-and-after study in 2007–2008 at a pelagic site in the Rainbow Channel, Queensland, Australia (Soto et al. 2013) found that during and after an acoustic device was deployed alongside a vessel, Indo-Pacific humpback dolphins Sousa chinensis spent less time foraging and had reduced surfacing and echolocation rates compared to before the device was deployed, but eight other types of behaviour did not differ. Three types of dolphin behaviour (percentage of time spent foraging, active surfacing rates, echolocation click rates) were reduced during and after an acoustic device was deployed compared to before (data reported as statistical model results). Eight other types of behaviour (percentage of time spent travelling, socializing or vocalizing; rate of blows, dives, whistles, burst pulses or other behaviours) did not differ significantly before, during or after an acoustic device was deployed. An acoustic device (Fumunda acoustic alarm) was deployed alongside a stationary research vessel during a total of 17 trials near 37 dolphin groups (1–3 dolphins/group). Each trial had three 10-minute periods with no device, an active device submerged (emitting 300 ms pulses every 4 seconds at 10 kHz), and the device removed from the water. Dolphin behaviour was observed from the vessel and vocalizations were recorded with a hydrophone submerged at a depth of 3 m during each of the 17 trials in September 2007–April 2008.

    (Summarised by: Anna Berthinussen)

  2. Use acoustic devices on fishing vessels

    A before-and-after study in 2007–2008 at a river mouth in Keppel Bay, Queensland, Australia (Soto et al. 2013) found that deploying an acoustic device alongside a vessel reduced the percentage of time Australian snubfin dolphins Orcaella heinsohni spent socializing compared to before a device was deployed, but 10 other types of behaviour did not differ. Snubfin dolphins spent less time socializing during and after an acoustic device was deployed compared to before (data reported as statistical model results). Ten other types of behaviour (time spent foraging, travelling or vocalizing; rate of active surfacing, blows, dives, whistles, burst pulses, clicks or other behaviours) did not differ significantly before, during or after an acoustic device was deployed. An acoustic device (Fumunda acoustic alarm) was deployed alongside a stationary research vessel during a total of 10 trials near 13 dolphin groups (1–5 dolphins/group). Each trial had three 5-minute periods with no device, an active device submerged (emitting 300 ms pulses every 4 seconds at 10 kHz), and the device removed from the water. Dolphin behaviour was observed from the vessel and vocalizations were recorded with a hydrophone submerged at a depth of 3 m during each of the 10 trials in September 2007–April 2008.

    (Summarised by: Anna Berthinussen)

  3. Use acoustic devices on fishing gear

    A randomized, controlled study in 2007–2008 at a pelagic site in the Rainbow Channel, Queensland, Australia (Soto et al. 2013) found that when a row of three active acoustic devices was deployed to simulate a fishing net, the number of Indo-Pacific humpback dolphin Sousa chinensis groups observed, the minimum surfacing distance of dolphins to a device and the number of days in which dolphins did not cross devices was similar to when three inactive devices were deployed. The number of dolphin groups observed did not differ significantly with active acoustic devices (average 4 groups/day) or inactive acoustic devices (5 groups/day). The same was true for the minimum distance between a surfacing dolphin and an acoustic device (active devices: average 41 m; inactive: 33 m) and the number of days in which dolphins did not cross the row of acoustic devices (active devices: 7 days; inactive: 3 days). A row of three acoustic devices (Fumunda acoustic alarms) was deployed across a channel to simulate a gill net. On randomly selected days, all three devices were either active (emitting 300 ms pulses every 4 seconds at 10 kHz; total 10 days) or inactive (silent; total 10 days).  Devices were attached to buoys anchored to the seafloor and submerged at a depth of 5 m in water 10–15 m deep. A total of 84 dolphin groups were observed from the shore during 20 days using a video camera attached to a theodolite in September 2007–April 2008.

    (Summarised by: Anna Berthinussen)

Output references

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