off Elephant Island, Antarctica

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Alfred Wegener Institute – Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany,

Thünen Institute of Sea Fisheries, Bremerhaven, Germany

Fin whale (Balaenoptera physalus) acoustic presence off Elephant Island, Antarctica

References:

Bioacustics Research Program 2014, Cornell Lab of Ornithology, Ithaca, NY

Burkhardt, E., and Lanfredi, C. (2012). "Fall feeding aggregations of fin whales off Elephant Island (Antarctica)," Paper SC/64/SH9 presented to the IWC Scientific Committee, 6. / Joiris, C. R., and Dochy, O. (2013). "A major autumn feeding ground for fin whales, southern fulmars and grey-headed albatrosses around the South Shetland Islands, Antarctica," Polar Biology 36, 1649-1658.

Širović, A., Hildebrand, J. A., Wiggins, S. M., McDonald, M. A., Moore, S. E., and Thiele, D. (2004). "Seasonality of blue and fin whale calls and the influence of sea ice in the Western Antarctic Peninsula," Deep Sea Research Part II: Topical Studies in Oceanography 51, 2327-2344.

Santora, J., Schroeder, I., and Loeb, V. (2014). "Spatial assessment of fin whale hotspots and their association with krill within an important Antarctic feeding and fishing ground," Marine Biology 161, 2293-2305.

Viquerat, S., and Herr, H. (2017). "Mid-summer abundance estimates of fin whales (Balaenoptera physalus) around the South Orkney Islands and Elephant Island.,"

Endangered Species Research 32, 515-524.

BREMERHAVEN

Am Handelshafen 12 27570 Bremerhaven Telefon 0471 4831-0 www.awi.de

In a nutshell:

• Visual sightings of large fin whale groups suggest Elephant Island may serve as an important feeding spot.

• PAM used to gather year round information of fin whale acoustic presence between Jan 2013 - Feb 2016.

• Data exhibit autumn increase in fin whale 20 Hz calls preceded by volume backscatter peaks in February.

• Lack of discernable diel cycle during peak call period (May-June).

Jan 2013-Feb 2016 - 5min/hr, Aural, data screening every second day.

Monthly statistics of hourly presence per day

Fin whale index and „calls per 10min“ for 24 hour intervals 2013 diel pattern 2013-2016 daily presence per month

Jan 2013 – Nov 2013 – continuous SonoVault data, screening every second day.

Calls

throughout the day

Acoustic Presence Analysis

Calls occasionally

Call rate Analysis

Jan 2013 – Nov 2013 – continuous SonoVault data, „Calls/10min“ continuous SonoVault data every 7th file on every 6th day.

Fin Index based on combination of SNRFL (13-22/84-89 Hz) and Entropy (13-22 Hz).

© M. Wurst AWI

Jan 2013 - Nov 2013 - continuous SonoVault data, every 7th file on every 6th daycalls/10 min.

Mean Volume Backscatter Strength 50-200m

Sea ice concentration r=30km

2013 – 2016 long-term spectrogram AURAL

2013 long-term spectrogram SonoVault Methods: ─ AURAL: 210m depth, 32kHz 16bit, duty cycle 8% (5 min every hour)

 SonoVault: 212m depth, 5.3kHz 24 bit, continuous sampling, duty cycle 100%

 Upward looking ADCP for backscattering strength, 314m depth, averaged 50-200m

 Sea ice data: Spreen, G., L. Kaleschke, and G.Heygster (2008), Sea ice remote sensing using AMSR-E 89 GHz channels J. Geophys. Res.,vol. 113, C02S03, doi:10.1029/2005JC003384.

Conclusions:

 Seasonality in acoustic presence, peaking in late autumn/early winter (April-July) for multiple years.

 Near constant high call rates throughout day during peak season.

 Fin whale calls increase subsequent to peaks in ADCP-MVBS (Mean Volume Backscatter Strength as proxy for food).

 Fin whale calls wane concurrent to onset and growth of sea ice → less calls or reduced range?

 2014 () high daily presence related to lesser sea ice?

 Time series of FI resembles manually logged time series of call rates.

 Fin whale index (FI) detects presence of calls even if fin whale calls are numerous and merging into a continuous band

rendering reliable manual counting impossible.

Fin Whale 20 Hz pulses March 21, 2012 61° 6.786‘S, 55° 54.117‘W

─── DAY 

Contact: elke.burkhardt@awi.de

= days not screend

= Fin Index

 = 24 hr intervalls screened

Acoustic mooring off Elephant Island

(61° 0.88‘S, 55° 58.53‘W, water depth 320m)

Fin whale upper call component 89 Hz