On behalf of the research team collaborating on the SOCAL-BRS project to study the behavior of marine mammals in southern California and their responses to human sounds including military sonar, I am pleased to report the completion of our 2014 annual research report. This includes some work that ran later in the season this year and we recently completed the report and are glad to make it publicly available.

The report is available at <>


Risso’s dolphins in social interactions off California (Credit: B. Southall; NMFS permit #14534)

Within this report we provide details on our activities and accomplishments in 2014. We also reference the increasing number of scientific publications the project has and continues to generate. A number of these papers are referenced in the report and available in our resources page here and linked from the main SOCAL-BRS page available at <>. Any of these are also available by email at


Southall, B. L., J. Calambokidis, P. Tyack, D. Moretti, J, Hildebrand, C. Kyburg, R. Carlson, A. Friedlaender, E. Falcone, G. Schorr, A. Douglas, S. DeRuiter, J. Goldbogen, J. Barlow. (2011). Project report: Biological and Behavioral Response Studies of Marine Mammals in Southern California, 2010 (SOCAL-10).

Southall, B. L., J. Calambokidis, P. Tyack, D. Moretti, J, Hildebrand, C. Kyburg, R. Carlson, A. Friedlaender, E. Falcone, G. Schorr, A. Douglas, S. DeRuiter, J. Goldbogen, J. Barlow. (2012). Project report: Biological and Behavioral Response Studies of Marine Mammals in Southern California, 2011 (SOCAL-11).

Southall, B. L., D. Moretti, B. Abraham, J. Calambokidis, P.L. Tyack. (2012). Marine Mammal Behavioral Response Studies in Southern California: Advances in Technology and Experimental Methods. Marine Technology Society Journal 46, 46-59.

Goldbogen J.A., Calambokidis J., Friedlaender A.S., Francis J., DeRuiter S.L., Stimpert A.K., Falcone E., Southall B.L. (2012). Underwater acrobatics by the world’s largest predator: 360° rolling manoeuvres by lunge-feeding blue whales. Biology Letters 9:20120986.

Southall, B. L., J. Calambokidis, P. Tyack, D. Moretti, J, Hildebrand, C. Kyburg, R. Carlson, A. Friedlaender, E. Falcone, G. Schorr, K. Southall, A. Douglas, S. DeRuiter, J. Goldbogen, J. Barlow. (2013). Project report: Biological and Behavioral Response Studies of Marine Mammals in Southern California, 2012 (SOCAL-12).

DeRuiter S.L., Southall B.L., Calambokidis J., Zimmer W.M.X., Sadykova D., Falcone E.A., Friedlaender A.S., Joseph J.E., Moretti, D., Schorr G.S., Thomas L., Tyack P.L. (2013). First direct measurements of behavioural responses by Cuvier’s beaked whales to mid-frequency active sonar. Biology Letters 9: 20130223.

Goldbogen J.A., Southall B.L., DeRuiter S.L., Calambokidis J., Friedlaender A.S., Hazen E.L., Falcone E.A., Schorr G.S., Douglass A., Moretti D.J., Kyburg C., McKenna M.F., Tyack P.L. (2013). Blue whales respond to simulated mid-frequency military sonar. Proceedings of the Royal Society B: 20130657.

Yack, T.M., J. Barlow, J. Calambokidis, B. Southall, S. Coates. (2013). Identification of previously unknown beaked whale habitat in the Southern California Bight using a towed hydrophone array. J. Acoust. Soc. Amer. 134, 2589-2597.

Southall, B. L., J. Calambokidis, P. Tyack, D. Moretti, A. Friedlaender, E. Falcone, G. Schorr, K. Southall, A. Douglas, S. DeRuiter, J. Goldbogen, J. Barlow. (2014). Project report: Biological and Behavioral Response Studies of Marine Mammals in Southern California, 2013 (SOCAL-13).

Friedlaender A.S., Goldbogen, J..A. Hazen E.L., Calambokidis, J.A., Southall, B.L. (2014). Feeding performance of sympatric blue and fin whales exploiting a common prey resource. Marine Mammal Science. DOI: 10.1111/mms.12134.

Goldbogen, J. A., A. K. Stimpert, S. L. DeRuiter, J. Calambokdis, A. S. Friedlaender, G. S. Schorr, D. J. Moretti, P. L. Tyack, B. L. Southall. (2014). Using accelerometers to determine the calling behavior of tagged baleen whales. The Journal of Experimental Biology, jeb-103259.

Stimpert, A. K., DeRuiter, S. L., Southall, B. L., Moretti, D. J., Falcone, E. A., Goldbogen, J. A., Friedlaender, A., Schorr, G.S., & Calambokidis, J. (2014). Acoustic and foraging behavior of a Baird’s beaked whale, Berardius bairdii, exposed to simulated sonar. Scientific Reports, 4: 7031. DOI: 10.1038/srep07031.

Goldbogen, J. A., Hazen, E. L., Friedlaender, A. S., Calambokidis, J., DeRuiter, S. L., Stimpert, A. K., & Southall, B. L. (2014). Prey density and distribution drive the three‐dimensional foraging strategies of the largest filter feeder. Functional Ecology. DOI: 10.1111/1365-2435.12395.

B. Southall Delivers Visionary Research Seminar on SOCAL-BRS at ONR S&T Expo


Dr. Brandon Southall gave an invited “Visionary Research” presentation at the recent ONR Science and Technology Expo in Washington D.C. This expo highlights cutting edge research and innovative technology supported by ONR. Given their long-standing support of marine mammal research in a wide variety of areas, including sound and it’s potential effects. Dr. Southall’s lecture covered a variety of these issues but focused primarily on the technological and methodological innovations made in the SOCAL-BRS project. More information on the S&T expo is available at <> and a .pdf of Dr. Southall’s presentation is available on request <>.

New SOCAL-BRS publication on foraging kinematics and prey distribution of blue whales


On behalf of the SOCAL-BRS project, I am happy to announce the publication of another paper resulting from our work. Lead by Dr. Jeremy Goldbogen of Stanford’s Hopkins Marine Station with a number of colleagues from the SOCAL-BRS team, this paper focuses on the fine-scale kinematics of foraging behavior in endangered blue whales and how they change as a function of prey distribution. These data provide both a better basic understanding of behavior in these remarkable, largest-ever animals, but also critical baseline information from which the potential consequences of disturbance from human activities may be determined. The reference for the paper is given below as well as the summary. The .pdf is available on request from

Goldbogen, J. A., Hazen, E. L., Friedlaender, A. S., Calambokidis, J., DeRuiter, S. L., Stimpert, A. K., & Southall, B. L. (2015). Prey density and distribution drive the three‐dimensional foraging strategies of the largest filter feeder. Functional Ecology. DOI: 10.1111/1365-2435.12395.


1. Despite their importance in determining the rate of both energy gain and expenditure, how the fine-scale kinematics of foraging are modified in response to changes in prey abundance and distribution remain poorly understood in many animal ecosystems.

2. In the marine environment, bulk-filter feeders rely on dense aggregations of prey for energetically efficient foraging. Rorqual whales (Balaenopteridae) exhibit a unique form of filter feeding called lunge feeding, a process whereby discrete volumes of prey-laden water are intermittently engulfed and filtered. In many large rorqual species the size of engulfed water mass is commensurate with the whale’s body size, yet is engulfed in just a few seconds. This filter-feeding mode thus requires precise coordination of the body and enlarged engulfment apparatus to maximize capture efficiency.

3. Previous studies from whale-borne tags revealed that many rorqual species perform rolling behaviours when foraging. It has been hypothesized that such acrobatic manoeuvres may be required for efficient prey capture when prey manifest in small discrete patches, but to date there has been no comprehensive analysis of prey patch characteristics during lunge feeding events. We developed a null hypothesis that blue whale kinematics are independent of prey patch characteristics.

4. To test this hypothesis, we investigated the foraging performance of blue whales, the largest filter-feeding predator and their functional response to variability in their sole prey source, krill using a generalized additive mixed model framework. We used a combination of animal-borne movement sensors and hydroacoustic prey mapping to simultaneously quantify the threedimensional foraging kinematics of blue whales (Balaenoptera musculus) and the characteristics of targeted krill patches.

5. Our analyses rejected our null hypothesis, showing that blue whales performed more acrobatic manoeuvres, including 180° and 360° rolling lunges, when foraging on low-density krill patches. In contrast, whales targeting high-density krill patches involved less manoeuvring during lunges and higher lunge feeding rates.

6. These data demonstrate that blue whales exhibit a range of adaptive foraging strategies that maximize prey capture in different ecological contexts. Because first principles indicate that manoeuvres require more energy compared with straight trajectories, our data reveal a previously unrecognized level of complexity in predatorprey interactions that are not accounted for in optimal foraging and energetic efficiency models.

New Publication on Detection of Complex Sounds in Seals and Sea Lions

Complex masking
On behalf of lead author Kane Cunningham, we would like to provide some information on our recent paper on the detection of complex sounds by seals and sea lions.  The goal of this study was to test how auditory data predict detection of complex sounds in quiet and noisy conditions.  Our results indicate that pinnipeds may utilize certain common features of natural sounds to enhance detectability (the key figure demonstrating these results is shown above).  We believe that this study is relevant given current efforts to predict the effects of anthropogenic noise on marine mammal species. This paper is available online through JASA or a .pdf may be obtained by request from
“Auditory sensitivity of seals and sea lions in complex listening scenarios.”
 Cunningham, K. A., Southall, B. L., & Reichmuth, C.
 The Journal of the Acoustical Society of America136(6), 3410-3421 (2014).
Standard audiometric data, such as audiograms and critical ratios, are often used to inform marine mammal noise-exposure criteria. However, these measurements are obtained using simple, artificial stimuli—i.e., pure tones and flat-spectrum noise—while natural sounds typically have more complex structure. In this study, detection thresholds for complex signals were measured in (I) quiet and (II) masked conditions for one California sea lion (Zalophus californianus ) and one harbor seal (Phoca vitulina ). In Experiment I, detection thresholds in quiet conditions were obtained for complex signals designed to isolate three common features of natural sounds: Frequency modulation, amplitude modulation, and harmonic structure. In Experiment II, detection thresholds were obtained for the same complex signals embedded in two types of masking noise: Synthetic flat-spectrum noise and recorded shipping noise. To evaluate how accurately standard hearing data predict detection of complex sounds, the results of Experiments I and II were compared to predictions based on subject audiograms and critical ratios combined with a basic hearing model.  Both subjects exhibited greater-than-predicted sensitivity to harmonic signals in quiet and masked conditions, as well as to frequency-modulated signals in masked conditions. These differences indicate that the complex features of naturally occurring sounds enhance detectability relative to simple stimuli.

New SOCAL-BRS Publication on Baird’s Beaked Whale Behavior

Baird's Beaked whale


We are pleased to announce a recent publication from the SOCAL-BRS project on the basic behavior and responses to simulated military sonar in a Barid’s beaked whale. These data were particularly significant in being the first high-resolution movement and acoustic measurements for any individual of this species. The photo above (Taken under NMFS permit #14534-2; credit A. Douglas) shows the subject described in the feature being tagged.  The reference for this paper and abstract are given below. A .pdf copy is available on request from: <> or <>.


Stimpert, A. K., Stacy Lynn DeRuiter, B. L. Southall, D. J. Moretti, E. A. Falcone, J. A. Goldbogen, Ari Friedlaender, G. S. Schorr, and John Calambokidis. “Acoustic and foraging behavior of a Baird’s beaked whale, Berardius bairdii, exposed to simulated sonar.” Scientific reports 4 (2014).

Beaked whales are hypothesized to be particularly sensitive to anthropogenic noise, based on previous

strandings and limited experimental and observational data. However, few species have been studied in

detail. We describe the underwater behavior of a Baird’s beaked whale (Berardius bairdii) from the first

deployment of a multi-sensor acoustic tag on this species. The animal exhibited shallow (23 +/- 15 m max

depth), intermediate (324 +/- 49 m), and deep (1138 +/- 243 m) dives. Echolocation clicks were produced with

a mean inter-click interval of approximately 300 ms and peak frequency of 25 kHz. Two deep dives included

presumed foraging behavior, with echolocation pulsed sounds (presumed prey capture attempts) associated

with increased maneuvering, and sustained inverted swimming during the bottom phase of the dive. A

controlled exposure to simulated mid-frequency active sonar (3.5–4 kHz) was conducted 4 hours after tag

deployment, and within 3 minutes of exposure onset, the tagged whale increased swim speed and body

movement, and continued to show unusual dive behavior for each of its next three dives, one of each type.

These are the first data on the acoustic foraging behavior in this largest beaked whale species, and the first

experimental demonstration of a response to simulated sonar.



20140919-JAC-0004 After a few rough weather days – hot and windy with high seas – we got a break on our last day for this phase of SOCAL-14. It was nice and calm as we worked back towards our end point near LA and we found a number of different animals feeding on some rich aggregations of krill near the oil rigs in the San Pedro Channel – sea lions, dolphins, birds, fish, and minke, humpback, and blue whales. We managed to get two blue whales in the same group tagged simultaneously and follow them for most of the day tracking their movements, behavior, and calling as well. One of these blue whales (a large female who was the lead animal in this pair shown above – taken under NMFS permit #14534, credit J. Calambokidis). We completed a successful experimental sequence with both whales who continued feeding, although it was halted slightly early when a sea lion swam close enough to the sound source that we had to terminate the experiment because of our permit mitigation requirements. Sea lions especially seem to be quite unaffected by and possibly even attracted to the sound source we use, which is an interesting observation even though they are not the direct subjects. We have an incredibly talented and dedicated group of professionals on this project. We cover a lot of water in sometimes rough seas and work with some of the most challenging animals on earth to study. We have tagged 18 animals of 4 different species with 21 tags of 3 types and conducted 10 complete experimental sequences in SOCAL-14 thusfar. The breadth and amount of new knowledge, publications, and guidance for management decisions regarding the conservation and protection of marine mammals that has come from this project is entirely the result of this remarkable team. Many of them are shown in the photo below and we encourage you to check out more of what many of these folks do outside of the BRS project by linking to some of the websites of all our partners (notably, but see the many other partners listed on and the partner links on the right hand side). We also want to acknowledge the support, cooperation, and willingness to ask hard questions by our sponsors at the U.S. Navy’s Living Marine Resources Program and the Office of Naval Research and our partners in various parts of the Navy. We have a two month hiatus until a final phase of SOCAL-14 in November. Thanks so much to those of you that have and continue to follow the blog and send feedback and questions. GroupPhoto_0019

Making the most of it…

As you may have heard, the (second) hurricane off the Pacific coast earlier this week hit parts of Baja pretty badly. While we aren’t getting any direct effects of that (but thanks for the few emails we have received asking), we are picking up some of the swell from it mixing in with some local swell for confused seas. The bigger issue is that we have just had some very strong offshore winds the last few days. We were really wanting to work offshore this last week of SOCAL-14 phase II but we have gotten progressively knocked backwards and are sitting in a port on the mainland tonight. Even in here at midnight I can hear the wind howling through the harbor and there is a small craft advisory in effect even close to shore. So, it’s been a little rough finding reasonable conditions in which to tag cetaceans. We did manage to tag and follow a fin whale yesterday (see photo below – taken under NMFS permit #14534, credit A. Friedlaender) and run a full experimental sequence as well as prey imaging measurements.

Tagged fin whale copy 2

Today we had a very interesting interaction with an unidentified cetacean swimming at quite high speed. Below is a photo of what most of the interaction looked like as the animal was throwing water strongly swimming at over 15 knots. We are still sorting through all the video and photos taken and piecing it together with the observations of our visual team and the tagging boat. From all accounts though, this was likely not one of the more common species we have seen and tagged out here. The current best guess is actually a Longman’s beaked whale (Indopacetus pacificus), but we are still trying to get some more insight into that. We will provide some better pictures and description of this as possible – most of what we saw looked like the below picture in the one interaction we had trying to deploy a tag (on pole in the foreground).



We have two more field days out here and will provide a final update and summary of this segment of our field work by the end of the week. Thanks for the interest and the comments and encouragement received. Again, we really are fine out here with the storm.


Rough Seas…

Angry SOCAL sea copy

It’s been a rough few days on the sea off southern California for the SOCAL-BRS effort. We need relatively calm seas (e.g, <10-15 kt winds and <3-4 ft seas) and if you check out the offshore actual weather and forecasts for the outer waters where we hope to work with beaked whales and other pelagic (open water) species more commonly occur you will see a lot of numbers higher than that. Most of the seas, especially in the afternoons, are looking more like the picture above snapped from the R/V Truth. But we did hear some beaked whales on our acoustic listening array today which was promising. We have another four days in the field and, while the forecast is largely the same this week, we will keep with it and hope to get tags deployed.


Double Tagged Blue Whale – Close Interaction with a Large Ship


Though we had planned on working nearshore today in SOCAL-BRS with some planned refueling and transfers of people and gear, the small craft advisory from large swell and 20+ knot winds in outer water ensured it. Knowing the weather would be poor we got an early start with the objective of getting a baleen whale tagged before the high winds made their way inshore. We worked out from San Pedro near LA and found several blue whales feeding along the shelf break south of Palos Verdes peninsula. This is a very common area for feeding baleen whales, though it overlaps with some of the main shipping lanes on the U.S. west coast. We attached two different acoustic and movement tags (a WHOI DTAG and a Mark-10 TDR – please see the detailed information and summary at for more details on these sensors). Both of  these tags are visible in the picture above (taken under NMFS permit #14534-2 by C. Casey) on the whale from today (who is still carrying both tags as of 2300 PDT!). This combination allows us to measure high resolution diving behavior, broadband sound, and GPS position in a complimentary way, which is accompanied by visual focal follow sampling of individual behavior.

After the controlled sound exposure experiment (fortunately) our tagged whale had a close interaction with a large commercial vessel in the shipping lanes in the San Pedro Channel. Below is a photo of the vessel with our tagging and focal follow small boat in the foreground – obviously it is the small boat in this interaction.


The whale came within just a few hundred meters of this vessel and based on the track and where the animal surfaced (about 100 meters on the other side of the track about a minute after it passed) we believe it went directly below it. John Calambokidis of Cascadia Research Collective has been leading some pioneering research and conservation efforts on the serious issues related to whales and the threats posed by ship strikes out here on the west coast. Please go to <> for much more information on these issues and on some of the innovative new technologies and measures being taken to try and understand and mitigate these risks.


Back From Offshore

9_8_14_blue whale

Apologies for those of you that have been following the SOCAL-BRS blog for our 2014 field efforts for the few days delay (and thanks for the emails checking in on us!). We have been well offshore working the last three days and out of cell and internet range to get updates posted. We had reasonably good offshore weather at least in the mornings and some of the focal species have been distributed a little further offshore. Despite a few equipment setbacks, we have managed to get a number of tags deployed and two experimental sequences conducted. So far we have managed to tag a blue whale (above) as well as several Risso’s dolphins (both taken under NMFS permit #14534-2, credit A. Friedlaender).

We are working out of LA tomorrow and then doing our mid-trip provisioning and re-fuel tomorrow to gear up for the second week. We will post some additional information and examples of some of the tag record data while inshore with a little better internet access over the next few days. Thanks again for the interest in following our work out here. Please do refer to some of the information we have on the project at <>. 025_tag on a Rissos dolphin_A Friedlaender copy


SOCAL-BRS is a study of basic behavior and responses to controlled sound exposures in a variety of marine mammal species.

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