investigating the effect of large vessel noise on southern resident killer whales
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Investigating the Effect of Large Vessel Noise on Southern Resident Killer Whales. Hilary B. Rollins UC Davis Beam Reach Marine Science and Sustainability School [email protected]. Introduction. Southern Resident killer whales depend on communication - PowerPoint PPT PresentationTRANSCRIPT
Investigating the Effect of Large Vessel Noise on Southern
Resident Killer Whales
Hilary B. RollinsUC Davis
Beam Reach Marine Science and Sustainability [email protected]
Introduction• Southern Resident killer whales
depend on communication• Anthropogenic noise can mask killer
whale calls• Large vessels (ships) produce the
majority of the background noise in Haro Strait
• Large vessel noise is very consistent and very loud and concentrated in low frequencies
Hypothesis• Whales will be forced to compensate
for ship noise to maintain necessary communication and will change their acoustic behavior
• This experiment will test changes in call duration, fundamental frequency, and power ratio depending on ship absence or presence
Methods
• Calibrated Labcore hydrophone array was towed and sounds were recorded on Sound Device 702s
• Ship absence/presence was monitored using AIS, recorded by Ship Locator software and determined by a range of 5 NM
• Behavior states, boats within .5 NM, and sea state were monitored
Methods•S1 calls measured for call duration, fundamental frequency, power ratio•0.5 seconds of background noise measured within 3 seconds of each call•141 calls measured
S1 Call Factors
Average Minimum Maximum
Duration (seconds)
1.00936 0. 704811 1.649056
Fundamental Frequency (Hz)
1061.667 572 1453
Power Ratio (relative dB)
0.06383 -20 13
Results
•Background noise varies significantly with ship absence/presence and boat count (P-value: 0.012149, 0.000394)
Absence Presence123.2123.4123.6123.8
124124.2124.4124.6124.8
125125.2
Background Noise vs. Ship Absence/Presence
Ship Absence/Presence
Back
grou
nd N
oise
(dB
re 1
micr
oPa)
0 2 4 6 8 10 12 14110
115
120
125
130
135
f(x) = 0.323886032986112 x + 123.539209661458R² = 0.0783896366786265
Background Noise vs. Vessel Count
Vessel Count within 0.5 NM
Back
grou
nd N
oise
(dB
re 1
micr
oPa)
ResultsBackground Noise
Boat Count Ship Absence/Presence
Duration No significance,P-value=0.543694
No significance,P-value=0.566138
No significance,P-value=0.841500
Fundamental Frequency
No significance,P-value=0.948566
No significance,P-value=0.828676
No significance,P-value=0.884519
Power Ratio No significance,P-value=0.412809
No significance,P-value=0.623204
No significance,P-value=0.693920
Results
116 118 120 122 124 126 128 130 1320
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
f(x) = − 0.00320533369154511 x + 1.40043218997713R² = 0.002903367256606
Call Duration vs. Background Noise
Background Noise (dB re 1 microPa)
Call
Dura
tion
(sec
s)
116 118 120 122 124 126 128 130 1320
200
400
600
800
1000
1200
1400
1600
f(x) = − 0.234056183378835 x + 1090.83823783443R² = 3.97088730215156E-05
Fundamental Frequency vs. Background Noise
Background Noise (dB re 1 microPa)
Fund
amen
tal F
requ
ency
(Hz)
Results
116 118 120 122 124 126 128 130 132
-25
-20
-15
-10
-5
0
5
10
15
f(x) = − 0.148822427683547 x + 18.6122995514518R² = 0.0052384244083068
Power Ratio vs. Background Noise
Background Noise (dB re 1 microPa)
Pow
er R
atio
(rel
ative
dB)
Discussion•Sample size•Total behavior comparison•AIS•Variation in ship noise depending on design•Alternate methods of vocal compensation
AcknowledgementsMany, many thanks to... Dr. Jason Wood, Dr. Val Veirs, Dr. Scott
Veirs, Erica Beneze, Hannah McGowan, Peter Valenzuela, Matt Williams,
Captain Todd Shuster, Captain Mike Kramer, and the captains of the whale watch fleet
Any Questions?