Investigating high frequency underwater vessel noise and potential masking of killer whale echolocation clicks Tim Hunt Beam Reach Marine Science and Sustainability School Fall beamreach.org/071 Flinders University of South Australia

Introduction The Southern Resident Killer Whale The Southern Resident Killer Whale Endangered Endangered Increase in WW boats over the years Increase in WW boats over the years ‘98-’05 consistently 20 vessels within ½ mile radius ‘98-’05 consistently 20 vessels within ½ mile radius Erbe (2002) - underwater noise study of WW boats Erbe (2002) - underwater noise study of WW boats My study expand on aspects of this – boater cooperation! My study expand on aspects of this – boater cooperation! Look at specific vessel types using HF hydrophone Look at specific vessel types using HF hydrophone Sample up to 30 kHz at 44.1k sampling rate - HF samples up to 90 kHz at 192k sampling rate WOW! Sample up to 30 kHz at 44.1k sampling rate - HF samples up to 90 kHz at 192k sampling rate WOW! Not done before measuring vessel noise new & novel! Not done before measuring vessel noise new & novel! Echolocation clicks in these higher frequencies Echolocation clicks in these higher frequencies Compare with boat noise to infer possible masking? Compare with boat noise to infer possible masking? Relate to County Law and WW guidelines Relate to County Law and WW guidelines

Spot the Orca

Echolocation clicks in killer whales What is an echolocation click? What is an echolocation click? What is it used for? What is it used for? What does it sound like? What does it sound like? High frequency, range up to 80 kHz High frequency, range up to 80 kHz Need a device to sample up to these high frequencies… Need a device to sample up to these high frequencies…

Killer whale audiogram 2 orcas in captivity Attached probes to melon Measured ABR Simplified from Szymanski et al Most sensitive kHz

Questions posed Is a vessel cruising at high speeds (>18 knots) at 400m “louder” that a vessel slow motoring at low speeds (5-8 knots) at 100m? Is a vessel cruising at high speeds (>18 knots) at 400m “louder” that a vessel slow motoring at low speeds (5-8 knots) at 100m? Is there is a difference in frequency spectrum levels between different vessel propulsion types? Is there is a difference in frequency spectrum levels between different vessel propulsion types? To what degree, if at all, do different vessel To what degree, if at all, do different vessel types mask echolocation clicks?

Methods Two speeds, two distances (relates to SJ County Law and BWW guidelines) Two speeds, two distances (relates to SJ County Law and BWW guidelines) Slow Motor (SM) = speed of 5-8 knots Slow Motor (SM) = speed of 5-8 knots When within 400m of whales When within 400m of whales Cruise (C) = knots Cruise (C) = knots When further than 400m When further than 400m Test SM and C at Test SM and C at 100m and 400m Record echolocation clicks Record echolocation clicks

Study site Sample sites

Materials

Sampling

Vessels measured Business names kept anonymous, vessel classification based on propulsion system Business names kept anonymous, vessel classification based on propulsion system Twin Inboard 400HP BioDiesel Twin Inboard 400HP BioDiesel Twin Outboard 150HP Twin Outboard 150HP Surface Piercing Surface Piercing Twin Inboard Diesel Twin Inboard Diesel Jet Drive Jet Drive Also measured Gato Verde Also measured Gato Verde catamaran, Washington State Ferry, cargo ship and dinghy

Results

More Results

Even more results No sig. difference b/w No sig. difference b/w SM 100m & C 400m 3/5 vessels had difference in RL of 10 dB or greater (C 400m > SM 100m) 3/5 vessels had difference in RL of 10 dB or greater (C 400m > SM 100m) Twin OB 150HP opposite Twin OB 150HP opposite Surface Piercing 1dB Surface Piercing 1dBdifference

A killer whale echolocation click What in the bloody hell do all these lines mean?! Sounds above echo, clicks masked Sounds below echo, clicks heard

Vessels vs. click vs. audiogram Higher spectrum level = higher mean RL? NO! Both dB 2 vessels below echo All vessels above echo MASKING

Discussion Peaks in Jet Drive vessel, & Twin IB 400HP BioDiesel. Mmm…. Peaks in Jet Drive vessel, & Twin IB 400HP BioDiesel. Mmm…. What is a significant dB difference? What is a significant dB difference? 6 dB = twice as loud in human ear 6 dB = twice as loud in human ear Gato Verde – EM vs G, just propeller noise? Gato Verde – EM vs G, just propeller noise? Echolocation click mean Echolocation click mean Bimodal distribution kHz Bimodal distribution kHz Similar to Au et al Similar to Au et al. 2003

Things to think about KW Audiogram – is it representative of wild orcas? KW Audiogram – is it representative of wild orcas? Individual tested reportedly partially deaf Individual tested reportedly partially deaf Busy day in the Haro Strait - individual vessel noise might be indistinguishable to an orca Busy day in the Haro Strait - individual vessel noise might be indistinguishable to an orca Hard to quantify difference in vessel type Hard to quantify difference in vessel type Can’t really say one is better/worse than another Can’t really say one is better/worse than another Can’t really say one is having more/less effect on echolocation Can’t really say one is having more/less effect on echolocation Personal observations – orcas swimming under ferries & riding bow wave of cargo ship Personal observations – orcas swimming under ferries & riding bow wave of cargo ship Does noise really bother them? Does noise really bother them?

Improvements/Future research Make sample size bigger! Make sample size bigger! Sample vessels on separate days Sample vessels on separate days More clicks, perhaps infer distance? More clicks, perhaps infer distance? Measure vessels at more distances, build database, compare, infer, legislate? Measure vessels at more distances, build database, compare, infer, legislate? Engine noise? Propeller noise? Combination? Engine noise? Propeller noise? Combination? Test these to aid in minimising underwater noise Test these to aid in minimising underwater noise More research = better understanding More research = better understanding

If we can lower noise of this

And better understand this

Then we can minimise impact on this

Acknowledgements Beam Reach and all the crew Beam Reach and all the crew Boat operators for driving-by Boat operators for driving-by Whale watch operators for the good times on the radio Whale watch operators for the good times on the radio Team VaTo for putting up with my singing Team VaTo for putting up with my singing Flight Of The Conchords for musical comic relief during times of hardship Flight Of The Conchords for musical comic relief during times of hardship

Questions?