2. Defence Research and Development Canada Recherche et développement pour la défense Canada Canada The impact of noise on passive monitoring of marine mammals in the Bay of Fundy Francine Desharnais 1, Marjo H. Laurinolli 2, Alex E. Hay 3, and Douglas J. Schillinger 3 1 DRDC Atlantic 2 JASCO Research Ltd 3 Department of Oceanography, Dalhousie University

3. Defence R&D Canada R & D pour la défense Canada Outline Designing a system for the Bay of Fundy –Feasibility study for passive detection SE = SL - (TL + AN) –Transmission loss, source level –Ambient noise on the Scotian Shelf and the Bay of Fundy –Signal excess (some examples) Conclusions

4. Defence R&D Canada R & D pour la défense Canada The problem North Atlantic right whales Bay of Fundy –Deeper area of Bay –Clay on top drift –Summer/Fall Feasibility study with omnidirectional sensors (sonobuoys)

5. Defence R&D Canada R & D pour la défense Canada Sample Sounds - Eubalaena Glacialis moan trumpet down cry + harmonics low upsweep down cry gunshot dB

6. Defence R&D Canada R & D pour la défense Canada Localization methodology [Laurinolli, 2002] Aural detection Time delay estimates through spectrogram cross- correlation technique Localization with crossing of hyperbolae of equal time difference

7. Defence R&D Canada R & D pour la défense Canada Transmission loss Scotian Shelf drift over sandstone Layer of LaHave clay in deeper basin Source depth 3 m Receiver depth 30 m 180 m water depth 150 & 500 Hz

8. Defence R&D Canada R & D pour la défense Canada Source Level Determination Lower bound: –10-200 Hz: 175 dB re 1  Pa @ 1m –200-800 Hz: 160 dB re 1  Pa @ 1m A.E. Hay, M.H. Laurinolli, F. Desharnais, D.J. Schillinger, Source levels of North Atlantic right whale sounds in the Bay of Fundy (unpublished)

9. Defence R&D Canada R & D pour la défense Canada Ambient noise - Key references for Scotian Shelf Piggott –C.L. Piggott, “Ambient sea noise at low frequencies in shallow water of the Scotian Shelf,” J. Acoust. Soc. Am. 36, 2152-2163, 1964. –8.4 - 3100 Hz, 20 and 28 fathoms depths –Ship noise edited out –Main reference for Scotian Shelf

10. Defence R&D Canada R & D pour la défense Canada Key references - cont’d Wenz –G.M. Wenz, “Acoustic ambient noise in the ocean: spectra and sources,” J. Acoust. Soc. Am. 34, 1936-1956, 1962. –Increase by 2.5 dB for shallow water –2-7 dB lower than Piggott Knudsen et al. –Knudsen, V. O., Alford, R. S., and Emling, J. W., “Underwater ambient noise,” J. Mar. Res. 3, 410-429, 1948. –Agrees closely with Wenz >500 Hz –<500 Hz Wenz is closer to Piggott

11. Defence R&D Canada R & D pour la défense Canada Key references - cont’d Zakarauskas et al. –P. Zakarauskas, “Ambient noise in shallow water: a survey of the unclassified literature,” Defence Research Establishment Atlantic Technical Memorandum 86/207, 1986. –P. Zakarauskas, D.M.F. Chapman and P.R. Staal, “Underwater acoustic ambient noise levels on the Eastern Canada continental shelf,” J. Acoust. Soc. Am. 87, 2064-2071, 1990. <1 kHz Grand Banks, Scotian Shelf, Flemish Cap, Laurentian Channel Winter and summer

12. Defence R&D Canada R & D pour la défense Canada More references EC-SWAN (temporal and spatial fluctuations) Gully and Sable Bank Western Bank Bay of Fundy Classified literature

13. Defence R&D Canada R & D pour la défense Canada Scotian Shelf Rules of Thumb 20 Hz –Seasonal finback cycle (in excess of 25 dB in winter) Shipping band (10-200 Hz) –Moderate to high shipping on Wenz’ curves for shallow water –EC-SWAN dataset for specific areas –Short-term temporal fluctuations up to 10 dB, spatial fluctuations < 5 dB Wind band (>200 Hz) –Piggott is good guide, Wenz and Knudsen too low –Low fluctuations Very little data processed above 3 kHz Some information on temporal and spatial statistics Very little on depth dependence

14. Defence R&D Canada R & D pour la défense Canada Bay of Fundy - unpublished < 200 Hz: –Noise levels follow EC-SWAN data for moderate to heavy shipping. 200-800 Hz: –Amongst the highest levels measured on Scotian Shelf at these frequencies –Shallow water Wenz curves + 2 to 5 dB to account for spillage from high shipping noise Depth dependence –Little based on modelling (energy-flux model)

15. Defence R&D Canada R & D pour la défense Canada Examples of Signal Excess (10 km) Frequency band [Hz]100-200200-800 Source level [dB re 1  Pa @ 1 m] 175160 Ambient noise level [dB]8272 Transmission loss [dB]7085 Signal excess [dB]233

16. Defence R&D Canada R & D pour la défense Canada Range inferences

17. Defence R&D Canada R & D pour la défense Canada Conclusions Right whales can be detected well beyond 10 km in range in the 100-200 Hz band. Higher frequencies get lost in background noise ~10 km Shipping noise a significant factor - directional sensors desirable for added range

19. Defence R&D Canada R & D pour la défense Canada Eastern Canada Shallow Water Ambient Noise survey (EC-SWAN)

20. Defence R&D Canada R & D pour la défense Canada EC-SWAN 12 month survey at 4 sites on shelf Sonobuoy data No attempt to extract ship- contaminated samples 10-2500 Hz (some to 32 kHz) Spatial and temporal statistics