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Te Rūnanga Papa Atawhai o Tāmaki Makaurau Auckland Conservation Board
Hauraki Gulf
Globally significant marine mammal habitat
Member Te Rnanga Papa Atawhai o Tmaki Makaurau Auckland Conservation - - PowerPoint PPT Presentation
Member Te Rnanga Papa Atawhai o Tmaki Makaurau Auckland Conservation - - PowerPoint PPT Presentation
Andrew Jeffs, Member Te Rnanga Papa Atawhai o Tmaki Makaurau Auckland Conservation Board Hauraki Gulf Globally significant marine mammal habitat Whales & Dolphins Highly social animals Live in an acoustic world Sound
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- Highly social animals
- Live in an acoustic world
- Sound travels long distances underwater
- Echolocate – underwater radar
- Communicate – talk to one another
- Navigate – finding each other
- Environmental sound cues – dinner bells
- Stun prey – stun gun
Whales & Dolphins
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Human Underwater Sound
Vessel impacts on whales & dolphins:-
- Disturbance & avoidance
- Stop or reduce feeding
- Silenced or more frequent calling – “masking”
- Health effects
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LOUDNESS
Underwater Sound in the Gulf
Low - PITCH - High
Inner Gulf Outer Gulf Mid Gulf
- Low background noise
- Higher for inner Gulf
- Vessel sound 35.2% Bean Rock
versus – 1.9% Horn Rock
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Sound is additive
LOUDNESS
Underwater Sound in the Gulf
Low - PITCH - High
Inner Gulf Outer Gulf Mid Gulf
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Sound is additive
LOUDNESS
Underwater Sound in the Gulf
Low - PITCH - High
Inner Gulf Outer Gulf Mid Gulf
Tugs towing barges
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Estimated detection distance for dolphins for vessel of 178 dB re 1 µPa @ 1 m. Masking occurs at lower range
990 m 2800 m 3600 m
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Bryde’s Whale
- “Nationally Critical” species
- NZ population ~250 whales
- ~46 resident in the Gulf
- 44 deaths in the Gulf since 1989
- 85% known deaths ship strike
- Spends a lot of time on surface
- “Sleeps” on the surface at night
- Likely sensitive to low frequency sound
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Bryde’s Whale
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Other Species
Bigeye- nocturnal schooling fish Crayfish post-larvae
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Options
Marine Mammal Acoustic Thresholds :NOAA - Fisheries West Coast Region Only widely circulated threshold values, but some conjecture Behavioral disruption for continuous noise (e.g., vibratory pile driving, drilling) - Recommends threshold of 120 dBrms Problem: based on bowhead whales responding to drilling operations in the Arctic Ocean. i.e., very different acoustic environment, and assumes the hearing in all species is the same, which we know it is not. Possible Conditions: DMC could put a sound output limit on vessel-tug combination.