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Kate Stafford

Principal Oceanographer

Affiliate Associate Professor, Oceanography

Email

stafford@apl.washington.edu

Phone

206-685-8617

Department Affiliation

Acoustics

Publications

2000-present and while at APL-UW

Acoustic occurrence and behavior of ribbon seals (Histriophoca fasciata) in the Bering, Chukchi, and Beaufort seas

Frouin-Mouy, H., X. Mouy, C.L. Berchok, S.B. Blackwell, and K.M. Stafford, "Acoustic occurrence and behavior of ribbon seals (Histriophoca fasciata) in the Bering, Chukchi, and Beaufort seas," Polar Biol., EOR, doi:10.1007/s00300-019-02462-y, 2019.

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15 Feb 2019

Due to the difficulty of studying ice seals in their natural environment, distribution and movement patterns of ribbon seals (Histriophoca fasciata) over large spatio-temporal scales are poorly understood. In this study, we analyzed their distribution patterns in the Bering, Chukchi, and Beaufort seas, using passive acoustic data collected between August 2012 and July 2013 at 53 recording sites. Ribbon seal downsweeps were found using spectrogram correlation autodetection, at 30 of these recording sites. These detections were further manually analyzed to investigate the vocal repertoire and quantify the diel pattern in acoustic presence. We found that the Beaufort Sea shelf and the northern Bering Strait/southern Chukchi Sea are ecologically important for ribbon seals during the open-water season. Our results suggest that the northeastern Chukchi Sea serves as part of a migration corridor to and from the Chukchi Plateau and/or Beaufort Sea. In the Bering Sea, most detections occurred from February to June. Vocal activity was higher at nighttime than during the daytime prior to the peak calling period, while during the peak calling period, diel rhythm became less pronounced. The number of calls, proportional use of downsweeps, and bandwidth of downsweeps (estimated broadband source level 170–178 dB re 1 μPa-m) increased during the breeding period, from March to June, peaking in May. An additional call type, the "shuffle", was identified in this study. These results improve our understanding of the migration, occurrence, and acoustic behavior of ribbon seals in the Bering, Chukchi, and Beaufort seas.

Seasonal occurrence and diel calling behavior of Antarctic blue whales and fin whales in relation to environmental conditions off the west coast of South Africa

Shabangu, F.W., K.P. Findlay, D. Yemane, K.M. Stafford, M. van den Berg, B. Blows, and R.K. Andrew, "Seasonal occurrence and diel calling behavior of Antarctic blue whales and fin whales in relation to environmental conditions off the west coast of South Africa," J. Mar. Syst., 190, 25-39, doi:10.1016/j.jmarsys.2018.11.002, 2018.

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1 Feb 2019

Passive acoustic monitoring was used to detect the sounds of rarely sighted Antarctic blue and fin whales to investigate their seasonal occurrence (as presence or absence of whale calls) and behaviour (as determined from call rates) in the Benguela ecosystem. Data were collected using autonomous acoustic recorders deployed on oceanographic moorings for 16.26 months off the west coast of South Africa in 2014 and 2015. Satellite derived environmental variables were used as predictors of whale acoustic occurrence and behaviour. Migratory Antarctic blue and fin whales were acoustically present in South African waters between May and August with call occurrence peaks in July whereas some fin whales extended their presence to November. No whale calls were recorded in summer for either species, suggesting whales use the Benguela ecosystem as an overwintering ground and migration route. Antarctic blue whales produced both their characteristic Z-call and their feeding associated D-call. Fin whales produced calls characteristic of animals from the eastern Antarctic fin whale acoustic population. Random forest models identified environmental variables such as sea surface temperature anomaly, sea surface height, wind speed, months of the year, Ekman upwelling index and log-transformed chlorophyll-a as the most important predictors of call occurrence and call rates of blue and fin whales. Here we present the first acoustic recordings of Antarctic blue and fin whales in the Benguela ecosystem, and provide preliminary information to investigate seasonal abundance and distribution of these large baleen whale populations. This work demonstrates the feasibility of cost-effectively monitoring Antarctic top-consumer baleen whales in the Benguela ecosystem.

Broad-scale study of the seasonal and geographic occurrence of blue and fin whales in the Southern Indian Ocean

Leroy, E.C., F. Samarn, K.M. Stafford, J. Bonnel, and J.-Y. Royer, "Broad-scale study of the seasonal and geographic occurrence of blue and fin whales in the Southern Indian Ocean," Endangered Species Res., 37, 289-300, doi:10.3354/esr00927, 2018

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13 Dec 2018

The southern Indian Ocean is believed to be a natural territory for blue and fin whales. However, decades after commercial and illegal whaling decimated these populations, little is known about their current status, seasonal habitat or movements. Recent passive acoustic studies have described the presence of 4 acoustic populations of blue whales (Antarctic and 3 'pygmy' types), but are generally limited temporally and geographically. Here, we examine up to 7 yr of continuous acoustic recordings (2010–2016) from a hydrophone network of 6 widely spaced sites in the southern Indian Ocean, looking for the presence of Antarctic and pygmy blue and fin whales. Power spectral density analyses of characteristic and distinct frequency bands of these species show seasonal and geographic differences among the different populations, and the overall patterns for each display interannual consistencies in timing and occurrence. Antarctic blue and fin whales are recorded across the hydrophone network, mainly from austral autumn to spring, with peak intensity in winter. Pygmy blue whales show spatial variation: Madagascan pygmy blue whales are mainly present in the west of the network, while the Australian call type is heard at the eastern sites. Both populations share a common seasonality, with a presence from January to June. Finally, the Sri Lankan call type is recorded only on a single site in the northeast. These results confirm the importance of the southern Indian Ocean for several populations of endangered large whales and present the first long-term assessment of fin whales in the southern Indian Ocean.

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In The News

Meet the bowhead whale, the jazz singer of the deep

Science Friday

Kate Stafford joins host John Dankowsky on the radio program to talk about the diverse songbook of bowhead whales. Over a three-year period, Stafford recorded bowhead whales in the Fram Strait in the Arctic singing 184 different melodies. The whales also altered their songs from year to year.

6 Apr 2018

Bowhead whales, the 'jazz musicians' of the Arctic, sing many different songs

UW News, Hannah Hickey

"If humpback whale song is like classical music, bowheads are jazz," says Kate Stafford. "The sound is more freeform. And when we looked through four winters of acoustic data, not only were there never any song types repeated between years, but each season had a new set of songs."

3 Apr 2018

UW research: Listen to the 'crazy, crazy' songs of bowhead whales

Seattle Times, Sandi Doughton

Kate Stafford and her colleagues have been eavesdropping on the massive, mysterious beasts for a decade. Among their early discoveries was that the whales sing nearly nonstop throughout the dark Arctic winter, hidden beneath thick sea ice. Now, the researchers have published the largest set of bowhead recordings ever compiled, documenting an astonishing repertoire of vocalizations that may be among the most diverse in the animal kingdom.

3 Apr 2018

More News Items

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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