Te Rūnanga Papa Atawhai o Tāmaki Makaurau

Auckland Conservation Board

Andrew Jeffs, Member

Hauraki GulfGlobally significant marine mammal habitat

• 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

Human Underwater Sound

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

LOU

DN

ESS

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

Sound is additive

LOU

DN

ESS

Underwater Sound in the Gulf

Low - PITCH - High

Inner Gulf

Outer Gulf

Mid Gulf

Sound is additive

LOU

DN

ESS

Underwater Sound in the Gulf

Low - PITCH - High

Inner Gulf

Outer Gulf

Mid Gulf

Tugs towing barges

Estimated detection distance for dolphins for vessel of178 dB re 1 µPa @ 1 m. Masking occurs at lower range

990 m

2800 m

3600 m

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 RegionOnly 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.