Member Te Rnanga Papa Atawhai o Tmaki Makaurau Auckland Conservation - PowerPoint PPT Presentation

Andrew Jeffs, Member Te Rūnanga Papa Atawhai o Tāmaki Makaurau Auckland Conservation Board

Hauraki Gulf Globally significant marine mammal habitat

Whales & Dolphins • 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

Human Underwater Sound Vessel impacts on whales & dolphins:- • Disturbance & avoidance • Stop or reduce feeding • Silenced or more frequent calling – “masking” • Health effects

Underwater Sound in the Gulf • Low background noise • Higher for inner Gulf • Vessel sound 35.2% Bean Rock LOUDNESS versus – 1.9% Horn Rock Inner Gulf Mid Gulf Outer Gulf Low - PITCH - High

Underwater Sound in the Gulf LOUDNESS Inner Gulf Mid Gulf Outer Gulf Low - PITCH - High Sound is additive

Underwater Sound in the Gulf Tugs towing barges LOUDNESS Inner Gulf Mid Gulf Outer Gulf Low - PITCH - High Sound is additive

2800 m 3600 m 990 m Estimated detection distance for dolphins for vessel of 178 dB re 1 µPa @ 1 m. Masking occurs at lower range

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

Bryde’s Whale

Other Species Bigeye- nocturnal schooling fish Crayfish post-larvae

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 dB rms 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.