Author: Dawn Barlow

New Zealand blue whale research in the time of COVID

By Grace Hancock, Undergraduate Student at Kalamazoo College MI, GEMM Lab Intern (June 2020 to present)

It feels safe to say that everyone’s plans for the summer of 2020 went through a roller coaster of changes due to the pandemic. Instead of the summer research or travel plans that many undergraduate students, including myself, expected, many of us found ourselves at home, quarantining, and unsure of what to do with our time. Although it was unexpected, all that extra time brought me serendipitously to the virtual doorstep of the GEMM Lab. A few zoom calls and many, many emails later I am now lucky to be a part of the New Zealand Blue Whale photo-ID team. Under Leigh’s and Dawn’s guidance, I picked up the photo identification project where they had left it and am helping to advance this project to its next stage.

The skin of a blue whale is covered by distinct markings similar to a unique fingerprint. Thus, these whales can have a variety of markings that we use to identify them, including mottled pigmentation, pock marks (often caused by cookie cutter sharks), blisters, and even holes in the dorsal fins and flukes.

Figure 1. Examples of skin conditions that help in matching demonstrated on a photo of NZBW052 on the 10/9/2015

True blue blog fans may remember that in 2016 Dawn began the very difficult work of creating a photo ID catalog of all the blue whales that the GEMM Lab had encountered during field work in the South Taranaki Bight in New Zealand. Since that post, the catalog has grown and become an incredibly useful tool. When I came to the lab, I received a hard drive containing all the work Dawn had done to-date with the catalog, as well as two years of photos from various whale watching trips in the Hauraki Gulf of New Zealand. The goal of my internship was to integrate these photos into the GEMM catalog Dawn had created and, hopefully, identify some matches of whales between the two datasets.  If there were any matches – and if I found no matches – we would gain information about whale movement patterns and abundance in New Zealand waters.

Before we could dive into this exciting matching work, there was lots of data organization to be done. Most of the photos I analyzed were provided by the Auckland Whale and Dolphin Safari (AWADS), an eco-tourism company that does regular whale watching trips in the Hauraki Gulf, off the North Island of New Zealand. The photos I worked with were taken by people with no connection to the lab and, because of this, were often filled with pictures of seals, birds, and whatever else caught the whale watcher’s eye. This dataset led to hours of sorting, renaming, and removing photos. Next, I evaluated each photo of a whale to determine photo-quality (focus, angle to the camera, lighting) and then I used the high-quality photos where markings are visible to begin the actual matching of the whales.

Figure 2. The fluke of NZBW013 taken on 2/2/2016 with examples of unique nicks and markings that could be used to match

Blue whales are inarguably massive organisms. For this reason, it can be hard to know what part of the whale you’re looking at. To match the photos to the catalog, I found the clearest pictures that included the whale’s dorsal fin. For each whale I tried to find a photo from the left side, the right side, and (if possible) an image of its fluke. I could then compare these photos to the ones organized in the catalog developed by Dawn.

The results from my matching work are not complete yet, but there are a few interesting tidbits that I can share with our readers today. From the photos submitted by AWADS, I was able to identify twenty-two unique individual whales. We are in the process of matching these whales to the catalog and, once this is done, we will know how many of these twenty-two are whales we have seen before and how many are new individuals. One of the most exciting matches I made so far is of a whale known in our catalog as individual NZBW072. Part of what made this whale so exciting was the fact that it is the calf of NZBW031 who was spotted eight times from 2010-2017, in the Hauraki Gulf, off Kaikoura, and in the South Taranaki Bight. As it turns out, NZBW072 took after her mother and has been spotted a shocking nine times from 2010 to 2019, all in the Hauraki Gulf region. Many of the whales in our catalog have only been spotted once, so encountering two whales with this kind of sighting track record that also happen to be related is like hitting the jackpot.

Figure 3. NZBW072 photographed on 11/8/2010 (top photo taken by Rochelle Constantine in the Hauraki Gulf) and on 10/3/2019 (bottom photo taken by the Auckland Whale and Dolphin Safari) with marks circled in red or yellow to highlight the matched features.

Once I finish comparing and matching the rest of these photos, the catalog will be substantially more up-to-date. But that is not where the work stops. More photos of blue whales in New Zealand are frequently being captured, either by whale watchers in the Hauraki Gulf, fellow researchers on the water, keen workers on oil and gas rigs, or the GEMM Lab. Furthermore, the GEMM Lab contributes these catalog photos to the International Whaling Commission (IWC) Southern Hemisphere Blue Whale Catalog, which compiles all photos of blue whales in the Southern Ocean and enables interesting and critical conservation questions to be addressed, like “How many blue whales are there in the Southern Ocean?” Once I complete the matching of these 22 individuals, I will upload and submit them to this IWC collaborative database on behalf of the GEMM Lab. This contribution will expand the global knowledge of these whales and motivates me to continue this important photo ID work. I am so excited to be a part of this effort, through which I have learned important skills like the basics of science communication (through writing this blog post) and attention to detail (from working very closely with the photos I was matching). I know both of these skills, and everything else I have learned from this process, will help me greatly as I begin my career in the next few years. I can tell big things will come from this catalog and I will forever be grateful for the chance I have had to contribute to it.

Five mind-blowing facts about sperm whales

By Solène Derville, Postdoctoral Scholar, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

Having worked almost exclusively on humpback whales for the past 5 years, I recently realized how specialized I have become when I was asked to participate in an expedition targeting another legendary cetacean, which I discovered I knew so little about: the sperm whale. On November 18th I boarded a catamaran with a team of 8 other seamen, film makers and scientists, all ready to sail off the west coast of New Caledonia in the search of this elusive animal. The expedition was named “Code CODA” in reference to the unique patterned series of clicks produced by sperm whales.

As I prepared for the expedition, I did my scientific literature homework and felt a growing awe for sperm whales. At every step of my research, whether I investigated their morphology, physiology, social behavior, feeding habits… everything about them appeared to be exceptional. Below is a list summarizing five mind-blowing facts everyone should know about sperm whales.

A sperm whale sketch I made on the boat in preparation for this blog post (Illustration credit: Solène Derville)

Sea giants

 Sperm whales are the largest of the odontocetes species, which is the group of “toothed whales” that also includes dolphins, porpoises and beaked whales. They show a strong sexual dimorphism, unusual for a cetacean, as adult males can be about twice as big as adult females. Indeed, male sperm whales can reach up to 18 m and 56 tons (approximately the weight of 9 elephants!). Their massive block-shaped head is perhaps their most distinctive feature. It contains the largest brain in the animal kingdom and as a comparison, it is claimed that an entire car could fit in it! By its morphology alone, the sperm whale hence appears like an all-round champion of cetaceans.

Abyssal divers

 Sperm whales are some of the best divers among air-breathing sea creatures. They have been recorded down to 2,250 m, and sperm whale carcasses have been found entangled in deep-sea cables suggesting that they can dive even deeper. In these dark and cold waters, sperm whales hunt for fish and squids (and sometimes check out ROVs, see videos of a surprising deep sea encounter made in 2015 off the coast of Louisiana, on Nautilus Live). They are renowned for attacking giant (Architeuthis spp) and colossal (Mesonychoteuthis hamiltoni) squids, which can reach more than 10 m in length. The squid sucker scars born by sperm whales give evidence of these titan combats. Because sperm whales only have teeth on the lower jaw, they cannot chew and may end up eating their prey alive. But every problem has its solution… sperm whales have evolved the longest digestive system in the world: it can reach 300 m long! Their stomach is divided into four compartments, the first of which is covered by a thick and muscular lining that can resist the assault of live prey.

Deluxe poopers  

The digestion of sperm whale prey happens in the next digestive compartments, but one component will resist: the squids’ beaks! As beaks accumulate in the digestive system (up to 18,000 beaks were found in a specimen!), they cause an irritation that is responsible for the production of a waxy substance known as ‘ambergris’. After a while, this substance is thought to be occasionally secreted along with the whale’s poop (although it has been speculated that large pieces of ambergris might be expelled by the mouth… charming!). Ambergris may be found floating at sea or washed up on coastlines, where it may make one happy beachcomber! The latest report of such a lucky finding of ambergris in 2016 was estimated at more than US$71,000 for a 1.57 kg lump. Indeed, ambergris is a valued additive used in perfume, although it has now mostly been replaced by synthetic equivalents. The use of ambergris in cooking, incense or medication in ancient Egypt and the Middle Ages is also reported.

Ambergris lump found in the UK in 2018 (photo credit: APEX, source: https://www.bbc.com/news/uk-england-devon-42703991)

Caring whales

Sperm whales are highly social animals. They are organized in “clans” with their own vocal repertoire and behavioral traits that differ geographically. Clans are formed by several connected social units, which are ruled by a complex matrilineal system. While adult males typically live solitary lives, females remain in family units composed of their close female relatives. Within these groups, females take communal care of the calves, even nursing the calves of other females. Every female can act as a babysitter to the group’s calves at the surface while the clan members perform deep foraging dives of approximately 40 min. Juvenile males may also provide care to the younger calves in the group as they remain in the group far past weaning, up to 9 to 19 years old. When attacked by predators (mostly killer whales), all the group members will protect the younger and most vulnerable individuals by adopting a compact formation, either the “marguerite” (facing inwards with their tails out and the young at the center for protection) or the “heads-out” version.

Social interaction in a pod of sperm whales… much like the whale version of a cuddle (photo credit: Tony Wu)

Powerful sonars

Like other toothed whales, sperm whales use sound to echolocate and communicate. But again, sperm whales stand out from the crowd with the unique spermaceti organ that allows them to produce the most powerful sound in the animal kingdom, reaching a source level of about 230 dB within frequencies of 5 to 25 kHz (this is louder than the sound of a jet engine at take-off). The spermaceti organ is a large cavity surrounded by a tough and fibrous wall called “the case”, and is filled with up to 1,900 liters of a fatty and waxy liquid called “spermaceti”. The spermaceti oil is chemically very different from the oils found in the melons (heads) of most other species of odontocetes, which also explains why sperm whales were particularly targeted by whalers of the 19th and 20th centuries. Indeed, the spermaceti oil has exceptional lubricant properties, and thus was used in fine machinery and even in the aerospace industry.

Original figure from Raven & Gregory 1933

Sperm whales are among the most widely distributed animals in the world, as they roam waters from the ice-edge to the equator. While pre-whaling global abundance is thought to have been 1,110,000 sperm whales, the most recent estimate suggests that only about a third of this number currently populates the ocean. It is our absolute duty to make sure that these marvelous, superlative animals recover from our past mistakes and that they can be admired by future generations.

Sources:

Gero, Shane, Jonathan Gordon, and Hal Whitehead (2013) “Calves as Social Hubs: Dynamics of the Social Network within Sperm Whale Units.” Proceedings of the Royal Society B: Biological Sciences 280 (1763). https://doi.org/10.1098/rspb.2013.1113

Graber, Cynthia (2007) “Strange but True: Whale Waste Is Extremely Valuable.” Scientific American. https://www.scientificamerican.com/article/strange-but-true-whale-waste-is-valuable/

Møhl, Bertel, Magnus Wahlberg, Peter T. Madsen, Anders Heerfordt, and Anders Lund (2003) “The Monopulsed Nature of Sperm Whale Clicks.” The Journal of the Acoustical Society of America, 114 (2): 1143–54. https://doi.org/10.1121/1.1586258

Raven, H C, and William K Gregory (1933) “The Spermaceti Organ and Nasal Passages of the Sperm Whale (Physeter Catodon) and Other Odontocetes.” American Museum Novitates, no. 677.

Whitehead, Hal (2018) “Sperm Whale.” Encyclopedia of Marine Mammals, 919–25. https://doi.org/10.1016/b978-0-12-804327-1.00242-9

A Multidisciplinary Treasure Hunt: Learning about Indigenous Whaling in Oregon

By Rachel Kaplan, PhD student, OSU College of Earth, Ocean, and Atmospheric Sciences and Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

At this year’s virtual State of the Coast conference, I enjoyed tuning into a range of great talks, including one by Zach Penney from the Columbia River Inter-Tribal Fish Commission. In his presentation, “More Than a Tradition: Treaty rights and the Columbia River Inter-Tribal Fish Commission,” Penney described a tribal “covenant with resources,” and noted the success of this approach — “You don’t live in a place for 15,000 years by messing it up.”

Indigenous management of resources in the Pacific Northwest dates back thousands of years. From oak savannahs to fisheries to fires, local tribes managed diverse natural systems long before colonial settlement of the area that is now Oregon. We know comparatively little, however, about how Indigenous groups in Oregon interacted with whale populations before the changes brought by colonialism and commercial whaling.

Makah hunters in Washington bring a harvested whale into Neah Bay (Asahel Curtis/Washington State Historical Society).

I’m curious about how this missing knowledge could inform our understanding of the coastal Oregon ecosystems in which many GEMM Lab projects take place. My graduate research will be part of the effort to identify co-occurrence between whales and fishing in Oregon, with the goal of helping to reduce whale entanglement risk. Penney’s talk, ongoing conversations about decolonizing science, and my own concerns about becoming the scientist that I want to be, have all led me to ask a new set of questions: What did humans know in the past about whale distributions along the Oregon coast? What lost knowledge can be reclaimed from history?

As I started reading about historical Indigenous whale use in Oregon, I was struck by how little we know today, and how this learning process became a multidisciplinary treasure hunt. Clues as to how Indigenous groups interacted with whales along the Oregon coast lie in oral histories, myths, journals, and archaeological artifacts. 

Much of what I read hinged on the question: did Indigenous tribes in Oregon historically hunt whales? Many signs point to yes, but it’s a surprisingly tricky question to answer conclusively. Marine systems and animals, including seals and whales, remain an important part of cultures in the Pacific Northwest today – but historically, documentation of hunting whales in Oregon has been limited. Whale bones have been found in coastal middens, and written accounts describe opportunistic harvests of beached whales. However, people have long believed that only a few North American tribes outside of the Arctic regularly hunted whales. 

But in 2007, archaeologists Robert Losey and Dongya Yang found an artifact that started to shift this narrative. While studying a collection of tools housed at the Smithsonian Institution, they discovered the tip of a harpoon lodged in a whale flipper bone. This artifact came from the Partee site, which was inhabited around AD 300-1150 and is located near present-day Seaside, Oregon.

A gray whale ulna with cut marks found at the Partee site (Wellman, et al. 2017).

Through DNA testing, Losey and Yang determined that the harpoon was made of elk bone, and that the elk was not only harvested locally, but also used locally. This new piece of evidence suggested that whaling did in fact take place at the Partee site, likely by the Tillamook or Clatsop tribes that utilized this area.

Several years later, this discovery inspired Smithsonian Museum of Natural History archaeologist Torben Rick and University of Oregon PhD student Hannah Wellman to comb through the rest of the animal remains in the Smithsonian’s collection from northwest Oregon. Rick and Wellman scrutinized 187 whale bones for signs of hunting or processing, and found that about a quarter of the marks they inspected could have come from either hunting or the opportunistic harvest of stranded whales. They examined tools from the midden as well, and found that they were more suited to hunting animals, like seals and sea lions, or fishing. 

However, Wellman and Rick also used DNA testing to identify which whale species were represented in the midden – and the DNA analyses suggested a different story. Genetic results revealed that the majority of whale bones in the midden came from gray whales, a third from humpback whales, and a few from orca and minke. Modern gray whale stranding events are not uncommon, and so it follows logically that these bones could have simply come from people harvesting beached whales. However, humpback strandings are rare – suggesting that such a large proportion of humpback bones in the midden is likely evidence of people actively hunting humpback whales.

Percentage of whale species identified at the Partee site and percentage of species in the modern stranding record for the Oregon Coast (Wellman, et al. 2017).

These results shed new light on whale harvesting practices at the Partee Site, and, like so much research, they suggest a new set of questions. What does the fact that there were orca, minke, gray, and humpback whales off the Oregon coast 900 years ago tell us about the history of this ecosystem? Could artifacts that have not yet been found provide more conclusive evidence of hunting? What would it mean if these artifacts are found one day, or if they are never found?

As this fascinating research continues, I hope that new discoveries will continue to deepen our understanding of historic Indigenous whaling practices in Oregon – and that this information can find a place in contemporary conversations. Indigenous whaling rights are both a contemporary and contentious issue in the Pacific Northwest, and the way that humans learn about the past has much to do with how we shape the present. 

What we learn about the past can also change how we understand this ecosystem today, and provide new context as we try to understand the impacts of climate change on whale populations in Oregon. I’m interested in how learning more about historical Indigenous whaling practices could provide more information about whale population baselines, ideas for management strategies, and a new lens on the importance of whales in the Pacific Northwest. Even if we can’t fully reclaim lost knowledge from history, maybe we can still read enough clues to help us see both the past and present more fully.

Sources:

Braun, Ashley. “New Research Offers a Wider View on Indigenous North American Whaling.” Hakai Magazine, November 2016, www.hakaimagazine.com/news/new-research-offers-wider-view-indigenous-north-american-whaling/. 

Eligon, John. “A Native Tribe Wants to Resume Whaling. Whale Defenders Are Divided.” New York Times, November 2019. 

Hannah P. Wellman, Torben C. Rick, Antonia T. Rodrigues & Dongya Y. Yang (2017) Evaluating Ancient Whale Exploitation on the Northern Oregon Coast Through Ancient DNA and Zooarchaeological Analysis, The Journal of Island and Coastal Archaeology, 12:2, 255-275, DOI: 10.1080/15564894.2016.1172382

Losey, R., & Yang, D. (2007). Opportunistic Whale Hunting on the Southern Northwest Coast: Ancient DNA, Artifact, and Ethnographic Evidence. American Antiquity, 72(4), 657-676. doi:10.2307/25470439

Sanchez, Gabriel (2014). Conference paper: Cetacean Hunting at the Par-Tee site (35CLT20)?: Ethnographic, Artifact and Blood Residue Analysis Investigation.

Boundaries in the dynamic ocean

By Dawn Barlow, PhD student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

The ocean is vast, ever-changing, and at first glance, seemingly featureless. Yet, we know that the warm, blue tropics differ from icy polar waters, and that temperate kelp forests are different from coral reefs. In the connected fluid environment of the global oceans, how do such different habitats exist, and what separates them? On a smaller scale, you may observe a current mixing line at the ocean surface, or dive down from the surface and feel the temperature drop sharply. In a featureless ocean, what boundaries exist, and how can we delineate between different environments?

These questions have been on my mind recently as I study for my PhD Qualifying Exams, an academic milestone that involves written and oral exams prepared by each committee member for the student. The subject matter spans many different areas, including ecological theory, underwater acoustics, oceanography, zooplankton dynamics, climate change and marine heatwaves, and protected area design. Yet, in my recent studying, I was struck by a realization: since when did my PhD involve so much physics? Atmospheric pressure differences generate wind, which drive global ocean circulation patterns. Density properties of seawater create structure in the ocean, and these physical features influence productivity and aggregate prey for predators such as whales. Sound propagates through the fluid ocean as a pressure wave, and its transmission is influenced by physical characteristics of the sound and the medium it moves through. Many of these examples can be distilled and described with equations rooted in physics. Physics doesn’t behave, it simply… is. In considering the vast and dynamic ocean, there is something quite satisfying in that simple notion. 

Circling back to boundaries in the ocean, there are changes in physical properties of the oceans that create boundaries, some stark and some nuanced. These physical features structure and partition the marine environment through differences in properties such as temperature, salinity, density, and pressure. Geographic partitions can occur in both horizontal and vertical dimensions of the water column, and on scales ranging from less than a kilometer to thousands of kilometers [1,2].

In the horizontal dimension, currents, fronts, and eddies mark transition zones between environments. In the time of industrial whaling, observations of temperature and salinity were made at the surface from factory whaling ships and examined to understand where the most whales were available for hunting. These early measurements identified temperature contour lines, or isotherms, and led to observations that whales were found in areas of stark temperature change and places where isotherms bent into “tongues” of interacting water masses [3,4] (Fig. 1). These areas where water masses of different properties meet are often areas of high productivity. Today, we understand that shelf break fronts, river plumes, tidal fronts, and eddies are important horizontal structures that drive elevated nutrient availability, phytoplankton production, and prey availability for mobile marine predators, including whales.

Figure 1. Surface temperature and salinity contour lines from measurements taken aboard a factory whaling ship in the Antarctic, reproduced from Nasu (1959).

In the vertical dimension, the water column is also structured into distinct layers. Surface waters are warmed by the sunlight and are often lower in salinity due to freshwater input from rain and runoff. Below this distinct surface portion of the water column, the temperature drops sharply in a layer known as the thermocline, and below which pressure and density increase with depth. The surface layer is subject to mixing from wind input, which can draw nutrients from below up into the photic zone and spur productivity. The alternation between stratification—a water column with distinctive layers—and mixing drives optimal conditions for entire food webs to thrive [1,2].

While I began this blog post by writing about boundaries that partition different ocean environments, I have continued to learn that those boundary zones are often critically important in their own right. I started by thinking about boundaries in terms of their importance for separation, but now understand that the leaky points between them actually spur ocean productivity. Features such as fronts, currents, mixed layers, and eddies separate water masses of different properties. However, they are not truly complete and rigid boundaries, and precisely for that reason they are uniquely important in promoting productive marine ecosystems.

Figure 2. Left: Some of the materials I am studying for my qualifying exams. Right: A blue whale surfaces in New Zealand’s South Taranaki Bight, the subject of my PhD and the lens through which I consider the concepts I am reading about (photo by L. Torres).

Many thanks to my PhD Committee members who continue to guide me through this degree and who I am lucky to learn from. In particular, the contents of this blog post were inspired by materials recommended by, and discussions with, Dr. Daniel Palacios.

References:

1.          Mann, K.H., and Lazier, J.R.N. (2006). Dynamics of Marine Ecosystems 3rd ed. (Blackwell Publishing).

2.          Longhurst, A.R. (2007). Ecological Geography of the Sea 2nd ed. (Academic Press).

3.          Nasu, K. (1959). Surface water conditions in the Antarctic whaling pacific area in 1956-57.

4.          Machida, S. (1974). Surface temperature fields in the Crozet and Kerguelen whaling grounds. Sci. Reports Whales Res. Inst. 26, 271–287.

Never a Straight Path

By Florence Sullivan, MSc, GEMM Lab Graduate

It’s rather amazing how, in a span of five years, the journey of your life can take twists and turns that you never expected. Long time blog readers may remember me as the graduate student who began this blog way back in February of 2015 with a recitation of our lab’s very first science outreach event. Since then, I completed my master’s thesis investigating gray whale foraging ecology (a project that just finished its 6th field season thanks to the excellent leadership of Lisa Hildebrand), fulfilled a dream of working as a marine mammal observer, and survived the existential crisis of graduation and job searching.

None of the species we study in this lab forage in straight lines.  If we consider a job (and salary) as the mechanism by which most of us put food on the table (i.e. foraging) why should our path be any less complex than theirs? By April 2018, I had moved back in with my parents in Seattle and was thoroughly heartsick about how long my job search was taking, so I jumped on the first field opportunity that came my way.  The project was billed as an attempt to pair discrete killer whale behaviors to specific call sequences, with collaborators from a variety of countries and backgrounds. In my enthusiasm, I ignored some red flags, and paid for it with a field season where I (1) experienced my first person-overboard situation, (2) witnessed steady verbal harassment, (3) was injured when our live-aboard trimaran was run aground on a clearly marked reef, and (4) ended up committing mutiny and leaving the project early.  There have been encouraging discussions in the marine science community recently about the barriers that women & early career scientists face while in the field, particularly with regard to accessibility, equity, and unpaid/underpaid internships. I will add some learned lessons to the list of things one should consider before embarking on a new research endeavor:

  • If someone says they are affiliated with a university, but will not give you a project or lab website because ‘the project is quite delicate, we don’t want other folks stealing our work’, check that they actually do have university affiliations and aren’t misrepresenting their connections. Do some homework.
  • Don’t cross a border without a contract, and when repeated attempts to secure a description of your responsibilities and payment are put off until later, consider that this might be a pattern of behavior.
  • If you were told that you would work under a senior bioacoustician, and you show up to find that your new colleague had been told the same thing, but neither of you has more than a MSc degree or much experience with acoustics, add this to your tally of red flags.
  • If basic safety standards (like wearing a life jacket on deck) are being ignored, hold yourself to a higher standard, and lead by example.
  • If sustained verbal and emotional abuse is occurring, you still have not been paid, and you’ve been asked to keep working after being injured in an accident caused by negligence, it is ok to break faith and leave a project.

Entering this project, I was very keen to learn new skills in acoustics, study a new species, and build partnerships with international researchers. Instead, I learned about interpersonal conflict and resolution strategies.  So, time for a new plan & another bend in my path. Thankfully, I have the immense privilege of a capable, employed husband who was able to support me while I recovered and began a new job search.

A pod of northern resident orcas resting during the rain, British Columbia. Photo credit: F. Sullivan
As salmon migrate upriver, their bodies undergo drastic changes in coloration, and once they spawn, they die. Their decomposing carcasses provide a critical influx of nutrients to the river and forest ecosystems of the Pacific Northwest. Photo credit: F. Sullivan

In the year that followed, I joined the team at the Environmental Science Center and taught 3rd -10th graders how to be “Salmon Heroes”. I explained salmon ecology, taking them on field experiences where we dissected salmon, measured oxygen and nitrogen levels in salmon streams, assessed habitat quality, observed migration and spawning behaviors (when fish cooperated), and brainstormed ways to protect these special (and delicious) fish. 

When salmon season came to an end, we transitioned to the “Beach Hero” program, targeted at K-3rd grade, where I became part of the classroom team, teaching intertidal ecology before bringing the kids to the beach where many of them experienced low tide for the first time.  In keeping with the education theme, I also worked with South Sound Nature School to provide kids with a forest-based after school program and was a summer camp counselor at Camp Long for several weeks. Still, I continued to try to find my way back to research and a data-driven career.

This is a sea star, it turns its stomach inside out to eat mussels! (we had awesome puppets for demonstration). Photo credit: Kharli Rose

Another bend in my ‘foraging’ job search happened when I stumbled across a short term data contract at my local election office while searching the state and county job boards. Washington State is a vote-by-mail state, and with a record turn-out in the 2018 mid-term elections they needed help updating everyone’s contact information & verifying signatures.  Let me tell you, staring at a computer screen, deciphering people’s handwriting to add emails and phone numbers to their voter registration for 8 hours a day for 6 weeks was not particularly fun. Yet, it gave me a little more experience in government databases, and gave me a lot of confidence in my election office for how transparent they are about every step of the voting process. I can’t speak for anywhere else, but in King County (Washington), you can go visit the election office & give yourself a self-guided walking tour of the whole ballot counting process from arrival to sorting to signature verification and opening to tallying. (There’s a hallway with massive windows surrounding the giant open concept floor space where everything happens, so you can observe without interfering). I’d never thought about what happens to my ballot after I mail it before, and its rather fascinating. Speaking of which, Please Vote!

Frustrated by a job search that failed to yield anything with health benefits or more than part-time hours, my Dad suggested that I apply to the University of Washington Continuing Education program, and enroll in a professional certificate to add another explicit skill to my resume. When enough pressure is applied to the system, something has to give eventually. The month where I was accepted to the UW Certificate in Statistical Analysis with R Programming was also the month I started interviewing for the Research Analyst Position at the Pacific Whale Foundation.  Partially because I could prove my data management experience, and that I was serious about continuing to hone my skiIls, I was offered, and accepted the position! Hilariously or stressfully, however you want to look at it, I moved to Maui, began my new position, and started my statistics with R programming coursework all in the same week – the learning curve was STEEP.

Amazingly, Leila (another GEMM Lab alumn) was visiting Maui the week I moved, and we were able to have dinner together my first night on-island! Photo credit: Leila Lemos

I completed my certificate in June, and hit my one-year work anniversary last month! I’m responsible for a good portion of our database management, and use R coding on a daily basis to pull data requests, tidy historical data, and add new information.  I’d never been to Maui before moving here, but now I’ve experienced the glory of Humpback whale breeding & calving season and heard whale song underwater. I’ve helped collect important life history data for false killer whales, spotted, spinner & bottlenose dolphins, and I’m looking forward to encountering more new-to-me odontocete species. It took months before I felt like I was past the ‘onboarding’ information stage, but now I’m collaborating with my colleagues on my first data analysis project (rather than simple data management) and loving my team despite the wrenches that the pandemic has thrown in our work. My job search = cetacean foraging analogy breaks down a little at this point, but my story still stands. I acknowledge my privilege of a good education and supportive husband, but I have this suggestion for job seekers: Don’t be afraid to get creative while you search for the right position, because you never know what you might stumble across and learn along the way. In the process, do your best to catch red flags, and keep yourself out of dangerous positions.  My job search hasn’t been a straight path, but that doesn’t mean it wasn’t full of small victories, and it did ultimately lead to a successful “prey patch”.

A pod of northern resident orcas traveling along the outer coast of British Columbia.

Marine mammals of the Northern California Current, 2020 edition

By Dawn Barlow, PhD student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

Clara and I have just returned from ten fruitful days at sea aboard NOAA Ship Bell M. Shimada as part of the Northern California Current (NCC) ecosystem survey. We surveyed between Crescent City, California and La Push, Washington, collecting data on oceanography, phytoplankton, zooplankton, and marine mammals (Fig. 1). This year represents the third year I have participated in these NCC cruises, which I have come to cherish. I have become increasingly confident in my marine mammal observation and species identification skills, and I have become more accepting of the things out of my control – the weather, the sea state, the many sightings of “unidentified whale species”. Careful planning and preparation are critical, and yet out at sea we are ultimately at the whim of the powerful Pacific Ocean. Another aspect of the NCC cruises that I treasure is the time spent with members of the science team from other disciplines. The chatter about water column features, musings about plankton species composition, and discussions about what drives marine mammal distribution present lively learning opportunities throughout the cruise. Our concurrent data collection efforts and ongoing conversations allow us to piece together a comprehensive picture of this dynamic NCC ecosystem, and foster a collaborative research environment.  

Figure 1. Data collection effort for the NCC September 2020 cruise, between Crescent City, CA, and La Push, WA. Red points represent oceanographic sampling stations, and black lines show the track of the research vessel during marine mammal survey effort.

Every time I head to sea, I am reminded of the patchy distribution of resources in the vast and dynamic marine environment. On this recent cruise we documented a stark contrast between  expansive stretches of warm, blue, stratified, and seemingly empty ocean and areas that were plankton-rich and supported multi-species feeding frenzies that had marine mammal observers like me scrambling to keep track of everything. This year, we were greeted by dozens of blue and humpback whales in the productive waters off Newport, Oregon. Off Crescent City, California, the water was very warm, the plankton community was dominated by gelatinous species like pyrosomes, salps, and other jellies, and the marine mammals were virtually absent except for a few groups of common dolphins. To the north, the plume of water flowing from the Columbia River created a front between water masses, where we found ourselves in the midst of pacific white-sided dolphins, northern right whale dolphins, and humpback whales. These observations highlight the strength of ecosystem-scale and multi-disciplinary data collection efforts such as the NCC surveys. By drawing together information on physical oceanography, primary productivity, zooplankton community composition and abundance, and marine predator distribution, we can gain a nearly comprehensive picture of the dynamics within the NCC over a broad spatial scale.

  • Northern fur seal
  • Humpback whales
  • Common dolphins
  • Humpback whale breaching
  • Blue whale
  • Risso’s dolphins
  • Pacific white-sided dolphins
A few images of marine mammals of the NCC. Click a photo to explore gallery. All photos by Dawn Barlow.

This year, the marine mammals delivered and kept us observers busy. We lucked out with good survey conditions and observed many different species throughout the NCC (Table 1, Fig. 2).

Table 1. Summary of all marine mammal sightings from the NCC September 2020 cruise.

Figure 2. Maps showing kernel densities of four frequently observed and widely distributed species seen during the cruise. Black lines show the track of the research vessel during marine mammal survey effort, white points represent sighting locations, and colors show kernel density estimates weighted by group size at each sighting.

This year’s NCC cruise was unique. We went to sea as a global pandemic, wildfires, and political tensions continue to strain this country and our communities. This cruise was the first NOAA Fisheries cruise to set sail since the start of the pandemic. Our team of scientists and the ship’s crew went to great lengths to make it possible, including a seven-day shelter-in-place period and COVID-19 tests prior to cruise departure. As a result of these extra challenges and preparations, I think we were all especially grateful to be on the water, collecting data. At-sea fieldwork is always challenging, but morale was up, spirits were high, and laughs were frequent despite smiles being concealed by our masks. I am grateful for the opportunity to participate in this ongoing valuable data collection effort, and to be part of this team. Thanks to all who made it such a memorable cruise.

Figure 3. The NCC September 2020 science team at the end of a successful research cruise! Fieldwork in the time of COVID-19 presents many logistical challenges, but this team rose to the occasion and completed a safe and fruitful survey despite the circumstances.

What makes a good meal for a hungry whale?

By Dawn Barlow, PhD student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

In the vast and dynamic marine environment, food is notoriously patchy and ephemeral [1]. Predators such as marine mammals and seabirds must make a living in this dynamic environment by locating and capturing those prey patches. Baleen whales such as blue and humpback whales have a feeding strategy called “lunge feeding”, whereby they accelerate forward and open their massive jaws, engulf prey-laden water in their buccal pouch that expands like an accordion, and filter the water out through baleen plates so that they are left with a mouthful of food (Fig. 1) [2]. This approach is only efficient if whales can locate and target dense prey patches that compensate for the energetic costs of diving and lunging [3]. Therefore, not only do these large predators need to locate enough food to survive in the expansive and ever-changing ocean, they need to locate food that is dense enough to feed on, otherwise they actually lose more energy by lunging than they gain from the prey they engulf.

Figure 1. Schematic of a humpback whale lunge feeding on a school of fish. Illustration by Alex Boersma.

Why do baleen whales rely on such a costly feeding approach? Interestingly, this tactic emerged after the evolution of schooling behavior of prey such as zooplankton and forage fish (e.g., herring, anchovy, sand lance) [4]. Only because the prey aggregate in dense patches can these large predators take advantage of them by lunge feeding, and by engulfing a whole large patch they efficiently exploit these prey patches. Off the coast of California, where krill aggregations are denser in deeper water, blue whales regularly dive to depths of 100-300 m in order to access the densest krill patches and get the most bang for their buck with every lunge [5]. In New Zealand, we have found that blue whales exploit the dense krill patches near the surface to maximize their energetic gain [6], and have documented a blue whale bypassing smaller krill patches that presumably were not worth the effort to feed on.

By now hopefully I have convinced you of the importance of dense prey patches to large whales looking for a meal. It is not necessarily only a matter of total prey biomass in an area that is important to a whale, it is whether that prey biomass is densely aggregated. What makes for a dense prey patch? Recent work has shown that forage species, namely krill and anchovies, swarm in response to coastal upwelling [7]. While upwelling events do not necessarily change the total biomass of prey available to a whale over a spatial area, they may aggregate prey to a critical density to where feeding by predators becomes worthwhile. Forage species like zooplankton and small fish may school because of enhanced food resources, for predator avoidance, or reproductive grouping. While the exact behavioral reason for the aggregation of prey may still only be partially understood, the existence of these dense patches allows the largest animals on the planet to survive.

Another big question is, how do whales actually find their food? In the vast, seemingly featureless, and ever-changing ocean environment, how does a whale know where to find a meal, and how do they know it will be worthwhile before they take a lunge? In a review paper written by GEMM Lab PI Dr. Leigh Torres, she suggests it is all a matter of scale [8]. On a very large scale, baleen whales likely rely on oceanographic stimuli to home in on areas where prey are more likely to be found. Additionally, recent work has demonstrated that migrating blue whales return to areas where foraging conditions were best in previous years, indicating a reliance on memory [9,10]. On a very fine scale, visual cues may inform how a blue whale chooses to lunge [6,8,11].

What does it matter what a blue whale’s favorite type of meal is? Besides my interest in foundational research in ecology such as predator-prey dynamics, these questions are fundamental to developing effective management approaches for reducing impacts of human activities on whales. In the first chapter of my PhD, I examined how oceanographic features of the water column structure krill aggregations, and how blue whale distribution is influenced by oceanography and krill availability [12]. Currently, I am deep into my second chapter, analyzing the pathway from wind to upwelling to krill to blue whales in order to better understand the links and time lags between each step. Understanding the time lags will allow us to make more informed models to forecast blue whale distribution in my third chapter. Environmental managers in New Zealand plan to establish a protected area to conserve the population of blue whales that I study [13] on their foraging grounds. Understanding where blue whales will be distributed, and consequently how their distribution patterns might shift with environmental conditions or overlap with human activities, comes down the fundamental question I started this blog post with: What makes a good meal for a hungry whale?

References

1.        Hyrenbach KD, Forney KA, Dayton PK. 2000 Marine protected areas and ocean basin management. Aquat. Conserv. Mar. Freshw. Ecosyst. 10, 437–458. (doi:10.1002/1099-0755(200011/12)10:6<437::AID-AQC425>3.0.CO;2-Q)

2.        Goldbogen JA, Cade DE, Calambokidis J, Friedlaender AS, Potvin J, Segre PS, Werth AJ. 2017 How Baleen Whales Feed: The Biomechanics of Engulfment and Filtration. Ann. Rev. Mar. Sci. 9, 367–386. (doi:10.1146/annurev-marine-122414-033905)

3.        Goldbogen JA, Calambokidis J, Oleson E, Potvin J, Pyenson ND, Schorr G, Shadwick RE. 2011 Mechanics, hydrodynamics and energetics of blue whale lunge feeding: efficiency dependence on krill density. J. Exp. Biol. 214, 131–146. (doi:10.1242/jeb.048157)

4.        Cade DE, Carey N, Domenici P, Potvin J, Goldbogen JA. 2020 Predator-informed looming stimulus experiments reveal how large filter feeding whales capture highly maneuverable forage fish. Proc. Natl. Acad. Sci. U. S. A. (doi:10.1073/pnas.1911099116)

5.        Hazen EL, Friedlaender AS, Goldbogen JA. 2015 Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density. Sci. Adv. 1, e1500469–e1500469. (doi:10.1126/sciadv.1500469)

6.        Torres LG, Barlow DR, Chandler TE, Burnett JD. 2020 Insight into the kinematics of blue whale surface foraging through drone observations and prey data. PeerJ (doi:10.7717/peerj.8906)

7.        Benoit-Bird KJ, Waluk CM, Ryan JP. 2019 Forage Species Swarm in Response to Coastal Upwelling. Geophys. Res. Lett. 46, 1537–1546. (doi:10.1029/2018GL081603)

8.        Torres LG. 2017 A sense of scale: Foraging cetaceans’ use of scale-dependent multimodal sensory systems. Mar. Mammal Sci. 33, 1170–1193. (doi:10.1111/mms.12426)

9.        Abrahms B et al. 2019 Memory and resource tracking drive blue whale migrations. Proc. Natl. Acad. Sci. U. S. A. (doi:10.1073/pnas.1819031116)

10.      Szesciorka AR, Ballance LT, Širovi A, Rice A, Ohman MD, Hildebrand JA, Franks PJS. 2020 Timing is everything: Drivers of interannual variability in blue whale migration. Sci. Rep. 10, 1–9. (doi:10.1038/s41598-020-64855-y)

11.      Friedlaender AS, Herbert-Read JE, Hazen EL, Cade DE, Calambokidis J, Southall BL, Stimpert AK, Goldbogen JA. 2017 Context-dependent lateralized feeding strategies in blue whales. Curr. Biol. (doi:10.1016/j.cub.2017.10.023)

12.      Barlow DR, Bernard KS, Escobar-Flores P, Palacios DM, Torres LG. 2020 Links in the trophic chain: Modeling functional relationships between in situ oceanography, krill, and blue whale distribution under different oceanographic regimes. Mar. Ecol. Prog. Ser. (doi:https://doi.org/10.3354/meps13339)

13.      Barlow DR et al. 2018 Documentation of a New Zealand blue whale population based on multiple lines of evidence. Endanger. Species Res. 36, 27–40. (doi:https://doi.org/10.3354/esr00891)

Inference, and the intersection of ecology and statistics

By Dawn Barlow, PhD student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

Recently, I had the opportunity to attend the International Statistical Ecology Conference (ISEC), a biennial meeting of researchers at the interface of ecology and statistics. I am a marine ecologist, fascinated by the interactions between animals and the dynamic ocean environment they inhabit. If you had asked me five years ago whether I thought I would ever consider myself a statistician or a computer programmer, my answer would certainly have been “no”. Now, I find myself studying the ecology of blue whales in New Zealand using a variety of data streams and methodologies, but a central theme for my dissertation is species distribution modeling. Species distribution models (SDMs) are mathematical algorithms that correlate observations of a species with environmental conditions at their observed locations to gain ecological insight and predict spatial distributions of the species (Fig. 1; Elith and Leathwick 2009). I still can’t say I would identify as a statistician, but I have a growing appreciation for the role of statistics to gain inference in ecology.

Figure 1. A schematic of a species distribution model (SDM) illustrating how the relationship between mapped species and environmental data (left) is compared to describe “environmental space” (center), and then map predictions from a model using only environmental predictors (right). Note that inter-site distances in geographic space might be quite different from those in environmental space—a and c are close geographically, but not environmentally. The patterning in the predictions reflects the spatial autocorrelation of the environmental predictors. Figure reproduced from Elith and Leathwick (2009).

Before I continue, let’s take a look at just a few definitions from Merriam-Webster’s dictionary:

Statistics: a branch of mathematics dealing with the collection, analysis, interpretation, and presentation of masses of numerical data

Ecology: a branch of science concerned with the interrelationship of organisms and their environments

Inference: a conclusion or opinion that is formed because of known facts or evidence

Ecological data are notoriously noisy, messy, and complex. Statistical tests are meant to help us understand whether a pattern in the data is different from what we would expect through random chance. When we study how organisms interact with one another and their environment, it is impossible to completely capture all elements of the ecosystem. Therefore, ecology is a field ripe with challenges for statisticians. How do we quantify a meaningful biological signal amidst all the noise? How can we gain inference from ecological data to enhance knowledge, and how can we use that knowledge to make informed predictions? Marine mammals are notoriously difficult to study. They inhabit an environment that is relatively inaccessible and inhospitable to humans, they occur in low numbers, they are highly mobile, and they are rarely visible. All ecological data are difficult and noisy and riddled with small sample sizes, but counting trees presents fewer logistical challenges than counting moving whales in an ever-changing open-ocean setting. Therefore, new methodologies in areas like species distribution modeling are often developed using large, terrestrial datasets and eventually migrate to applications in the marine environment (Robinson et al. 2011).

Many presentations I attended at the conference were geared toward moving beyond correlative SDMs. SDMs were developed to correlate species occurrence patterns with features of the environment they inhabit (e.g. temperature, precipitation, terrain, etc.). However, those relationships do not actually explain the underlying mechanism of why a species is more likely to occur in one environment compared to another. Therefore, ecological statisticians are now using additional information and modeling approaches within SDMs to incorporate information such as species co-occurrence patterns, population demographic information, and physiological constraints. Building SDMs to include such process-explicit information allows us to make steps toward understanding not just when and where a species occurs, but why.

Machine learning is an area that continues to advance and open doors to new applications in ecology. Machine learning approaches differ fundamentally from classical statistics. In statistics, we formulate a hypothesis, select the appropriate model to test that hypothesis (for example, linear regression), then test how well the data fit the model (“Is the relationship linear?”), and test the strength of that inference (“Is the linear pattern different from what we would expect due to random chance?”). Machine learning, on the other hand, does not use a predetermined notion of relationships between variables. Rather, it tries to create an algorithm that fits the patterns in the data. Statistics asks how well the data fit a model, and machine learning asks how well a model fits the data.

Machine learning approaches allow for very complex relationships to be included in models and can be excellent for making predictions. However, sometimes the relationships fitted by a machine learning algorithm are so complex that it is not possible to infer any ecological meaning from them. As one ISEC presenter put it, in machine learning “the computer learns but the scientist does not”. The most important thing when selecting your methodology is to remember your question and your goal. Do you want to understand the mechanism of why an animal is where it is? Or do you not need to understand the driver, but rather want to make the best predictions of where an animal will be? In my case, the answer to that question differs from one of my PhD chapters to the next. We want to understand the functional relationships between oceanography, krill availability, and blue whale distribution (Barlow et al. 2020), and subsequently we want to develop forecasting models that can reliably predict blue whale distribution to inform conservation efforts (Fig. 2).

Figure 2. An example predictive map of where we expect blue whales to be distributed based on environmental conditions. Warmer colors represent areas with a higher probability of blue whale occurrence, and the blue crosses represent locations where blue whales were observed.

ISEC was an excellent opportunity for me to break out of my usual marine mammal-centered bubble and get a taste of what is happening on the leading edge of statistical ecology. I learned about the latest approaches and innovations in species distribution modeling, and in the process I also learned about trees, koalas, birds, and many other organisms from around the world. A fun bonus of attending a methods-focused conference is learning about completely new study species and systems. There are many ways of approaching an ecological question, gaining inference, and making predictions. I look forward to incorporating the knowledge I gained through ISEC into my own research, both in my doctoral work and in applications of new methods to future research projects.

Figure 3. The virtual conference photo of all who attended the biennial International Statistical Ecology Conference. Thank you to the organizers, who made it a truly excellent and engaging conference experience!

References

Barlow, D.R., Bernard, K.S., Escobar-Flores, P., Palacios, D.M., and Torres, L.G. 2020. Links in the trophic chain: Modeling functional relationships between in situ oceanography, krill, and blue whale distribution under different oceanographic regimes. Mar. Ecol. Prog. Ser. doi:https://doi.org/10.3354/meps13339.

Elith, J., and Leathwick, J.R. 2009. Species Distribution Models: Ecological Explanation and Prediction Across Space and Time. Annu. Rev. Ecol. Evol. Syst. 40(1): 677–697. doi:10.1146/annurev.ecolsys.110308.120159.

Robinson, L.M., Elith, J., Hobday, A.J., Pearson, R.G., Kendall, B.E., Possingham, H.P., and Richardson, A.J. 2011. Pushing the limits in marine species distribution modelling: Lessons from the land present challenges and opportunities. doi:10.1111/j.1466-8238.2010.00636.x.

What we know now about New Zealand blue whales

By Dawn Barlow, PhD student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

For my PhD, I am using a variety of data sources and analytical tools to study the ecology and distribution of blue whales in New Zealand. I live on the Oregon Coast, across the world and in another season from the whales I study. I love where I live and I am passionate about my work, but I do sometimes feel removed from the whales and the ecosystem that are the focus of my research.

A pair of blue whales surface in the South Taranaki Bight region of New Zealand. Drone piloted by Todd Chandler during the 2017 field season.

Recently, I have turned my attention to processing acoustic data recorded in our study region in New Zealand between 2016 and 2018. In the fall, I developed detector algorithms to identify possible blue whale vocalizations in the recording period, and now I am going through each of the detections to validate whether it is indeed a blue whale call or not. Looking closely at spectrograms for hours and hours is a change of pace from the analysis and writing I have been doing recently. Namely, I am looking at biological signals – not lines of code and numbers on a screen, but depictions of sounds that blue whales produced. I have to say, it is the “closest” I have felt to these whales in a long time. Scrolling through thousands of spectrograms of blue whale calls leaves room for my mind to wander, and I recently had the realization that those whales have absolutely no idea that on the other side of the Pacific Ocean, there are a few scientists dedicating years of their lives to understand and protect them. Which led me to another realization: we know so much more about blue whales in New Zealand now than we did 10 years ago. In fact, we know so much more than we did even a year ago.

Screenshot of the process of reviewing blue whale D call detections in the acoustic analysis program Raven.

Nine years ago, Dr. Leigh Torres had a cup of coffee with a colleague who recounted observer reports of several blue whales during a seismic survey of the South Taranaki Bight region (STB) of New Zealand. This conversation sparked her curiosity, and led to the formulation of a hypothesis that the STB was in fact an unrecognized feeding ground for blue whales in the southern hemisphere (Torres 2013).

A blue whale surfaces in front of an oil rig in the South Taranaki Bight. Compiling opportunistic sightings like this one was an important step in realizing the importance of the region for blue whales. Photo by Deanna Elvines.

After three field seasons and several years of dedicated work, the hypothesis that the STB region is important for blue whales was validated. By drawing together multiple data streams and lines of evidence, we now know that New Zealand is home to a unique population of blue whales, which are genetically distinct from all other documented populations in the Southern Hemisphere. Furthermore, they use the STB for multiple critical life history functions such as feeding, nursing and calf raising, and they are present there year-round (Barlow et al. 2018).

Once we documented the New Zealand population, we were left with perhaps even more questions than we started with. Where do they feed, and why? Are they feeding and breeding there? Does their distribution change seasonally? What is the health of the population? Are they being impacted by industrial activity and human impacts such as noise in the region? We certainly do not have all the answers, but we have been piecing together an increasingly comprehensive story about these whales and their ecology.

For example, we now know that blue whales in New Zealand average around 19 meters in length, which we calculated by measuring images taken via drones and using an analysis program developed in the GEMM Lab (Burnett et al. 2018). The use of drones has opened up a whole new world for studying health and behavior in whales, and we recently used video footage to better understand the movement and kinematics of how blue whales engulf their krill prey. Furthermore, we know that blue whales may preferentially feed on dense krill aggregations at the surface, and that this surface feeding strategy may be an energetically favorable strategy in this part of the world (Torres et al. 2020).

We have also assessed one aspect of the health of blue whales by describing their skin condition. By analyzing thousands of photographs, we now know that nearly all blue whales in New Zealand bear the scars of cookie cutter shark bites, which they seem more likely to acquire at more northerly latitudes, and that 80% are affected by blister lesions (Barlow et al. 2019). Next, we are beginning to draw together multiple data streams such as body condition and hormone analysis, paired with skin condition, to form a detailed understanding about the health of this population.

Most recently we have produced a study describing how oceanography, prey and blue whales are connected within this region of New Zealand. The STB region is home to a wind-driven upwelling system that drives productivity and leads to aggregations of krill, which in turn provide sustenance for blue whales to feed on. By compiling data on oceanography and water column structure, krill availability, and blue whale distribution, we now have a solid understanding of this trophic pathway: how oceanography structures prey, and how blue whales respond to both prey and oceanography (Barlow et al. 2020). Furthermore, we are beginning to understand how those relationships may look under changing ocean conditions, with global sea temperatures rising and the increasing frequency and intensity of marine heatwaves.

The knowledge we have accumulated better enables managers to make informed decisions for the conservation of these blue whales and the ecosystem they inhabit. To me, there are several take-away messages from the story that continues to unfold about these blue whales. One is the importance of following a hunch, and then gathering the necessary tools and team to explore and tackle challenging questions. An idea that started over a cup of coffee and many years of hard work and dedication have led to a whole new body of knowledge. Another message is that the more questions you ask and the more questions you try to answer, the more questions you are often left with. That is a beautiful truth about scientific inquiry – the questions we ask drive the knowledge we uncover, but that process is never complete because new questions continue to emerge. Finally, it is easy to get swept up in details, outputs, timelines, and minutia, and every now and then it is important to take a step back. I have appreciated taking a step back and musing on the state of our knowledge about these whales, about how much we have learned in less than 10 years, and mostly about how many answers and new questions are still waiting to be uncovered.

A victorious field team celebrates a successful end to the 2017 field season with an at-sea sunset dance party. A good reminder of sunny, salty days on the water and where the data come from!

References

Barlow DR, Bernard KS, Escobar-Flores P, Palacios DM, Torres LG (2020) Links in the trophic chain: Modeling functional relationships between in situ oceanography, krill, and blue whale distribution under different oceanographic regimes. Mar Ecol Prog Ser.

Barlow DR, Pepper AL, Torres LG (2019) Skin Deep: An Assessment of New Zealand Blue Whale Skin Condition. Front Mar Sci.

Barlow DR, Torres LG, Hodge KB, Steel D, Baker CS, Chandler TE, Bott N, Constantine R, Double MC, Gill P, Glasgow D, Hamner RM, Lilley C, Ogle M, Olson PA, Peters C, Stockin KA, Tessaglia-hymes CT, Klinck H (2018) Documentation of a New Zealand blue whale population based on multiple lines of evidence. Endanger Species Res 36:27–40.

Burnett JD, Lemos L, Barlow DR, Wing MG, Chandler TE, Torres LG (2018) Estimating morphometric attributes on baleen whales using small UAS photogrammetry: A case study with blue and gray whales. Mar Mammal Sci.

Torres LG (2013) Evidence for an unrecognised blue whale foraging ground in New Zealand. New Zeal J Mar Freshw Res 47:235–248.

Torres LG, Barlow DR, Chandler TE, Burnett JD (2020) Insight into the kinematics of blue whale surface foraging through drone observations and prey data. PeerJ.

Snacks at the surface: New GEMM Lab publication reveals insights into blue whale surface foraging through drone observations and prey data

By Dawn Barlow, PhD student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

As the largest animals on the planet, blue whales have massive prey requirements to meet energy demands. Despite their enormity, blue whales feed on a tiny but energy-rich prey source: krill. Furthermore, they are air-breathing mammals searching for aggregations of prey in the expansive and deep ocean, and must therefore budget breath-holding and oxygen consumption, the travel time it takes to reach prey patches at depth, the physiological constraints of diving, and the necessary recuperation time at the surface. Additionally, blue whales employ an energetically demanding foraging strategy known as lunge feeding, which is only efficient if they can locate and target dense prey aggregations that compensate for the energetic costs of diving and lunging. In our recent paper, published today in PeerJ, we examine how blue whales in New Zealand optimize their energy use through preferentially feeding on dense krill aggregations near the water’s surface.

Figure 1. A blue whale lunges on a dense aggregation of krill at the surface. Note the krill jumping away from the mouth of the onrushing whale. UAS piloted by Todd Chandler.
Figure 2. Survey tracklines in 2017 in the South Taranaki Bight (STB) with locations of blue whale sightings, and where surface lunge feeding was observed, denoted. Inset map shows location of the STB within New Zealand. Figure reprinted from Torres et al. 2020.

To understand how predators such as blue whales optimize foraging strategies, knowledge of predator behavior and prey distribution is needed. In 2017, we surveyed for blue whales in New Zealand’s South Taranaki Bight region (STB, Fig. 2) while simultaneously collecting prey distribution data using an echosounder, which allowed us to identify the location, depth, and density of krill aggregations throughout the region. When blue whales were located, we observed their behavior from the research vessel, recorded their dive times, and used an unmanned aerial system (UAS; “drone”) to assess their body condition and behavior.

Much of what is known about blue whale foraging behavior and energetics comes from extensive studies off the coast of California, USA using accelerometer tags to track fine-scale kinematics (i.e., body movements) of the whales. In the California Current, the krill species targeted by blue whales are denser at depth, and therefore blue whales regularly dive to depths of 300 meters to lunge on the most energy-rich prey aggregations. However, given the reduced energetic costs of feeding closer to the surface, optimal foraging theory predicts that blue whales should only forage at depth when the energetic gain outweighs the cost. In New Zealand, we found that blue whales foraged where krill aggregations were relatively shallow and dense compared to the availability of krill across the whole study area (Fig. 3). Their dive times were quite short (~2.5 minutes, compared to ~10 minutes in California), and became even shorter in locations where foraging behavior and surface lunge feeding were observed.

Figure 3. Density contours comparing the depth and density (Sv) of krill aggregations at blue whale foraging sightings (red shading) and in absence of blue whales (gray shading). Density contours: 25% = darkest shade, 755 = medium shade, 95% = light shade. Blue circles indicate krill aggregations detected within 2 km of the sighting of the UAS filmed surface foraging whale analyzed in this study. Figure reprinted from Torres et al. 2020.
Figure 4. Kinematics of a blue whale foraging dive derived from a suction cup tag. Upper panel shows the dive profile (yellow line), with lunges highlighted (green circles), superimposed on a prey field map showing qualitative changes in krill density (white, low; blue, medium; red, high). The lower panels show the detailed kinematics during lunges at depth. Here, the dive profile is shown by a black line. The orange line shows fluking strokes derived from the accelerometer data, the green line represents speed estimated from flow noise, and the grey circles indicate the speed calculated from the vertical velocity of the body divided by the sine of the body pitch angle, which is shown by the red line. Figure and caption reprinted from Goldbogen et al. 2011.

Describing whale foraging behavior and prey in the surface waters has been difficult due to logistical limitations of conventional data collection methods, such as challenges inferring surface behavior from tag data and quantifying echosounder backscatter data in surface waters. To compliment these existing methods and fill the knowledge gap surrounding surface behavior, we highlight the utility of a different technological tool: UAS. By analyzing video footage of a surface lunge feeding sequence, we obtained estimates of the whale’s speed, acceleration, roll angle, and head inclination, producing a figure comparable to what is typically obtained from accelerometer tag data (Fig. 4, Fig. 5). Furthermore, the aerial perspective provided by the UAS provides an unprecedented look at predator-prey interactions between blue whales and krill. As the whale approaches the krill patch, she first observes the patch with her right eye, then turns and lines up her attack angle to engulf almost the entire prey patch through her lunge. Furthermore, we can pinpoint the moment when the krill recognize the impending danger of the oncoming predator—at a distance of 2 meters, and 0.8 seconds before the whale strikes the patch, the krill show a flee response where they leap away from the whale’s mouth (see video, below).

Figure 5. Body kinematics during blue whale surface lunge feeding event derived from Unmanned Aerial Systems (UAS) image analysis. (A) Mean head inclination and roll (with CV in shaded areas), (B) relative speed and acceleration, and (C) distance from the tip of the whale’s rostrum to the nearest edge of krill patch. Blue line on plots indicate when krill first respond to the predation event, and the purple dashed lines indicate strike at time = 0. The orange lines indicate the time at which the whale’s gape is widest, head inclination is maximum, and deceleration is greatest. Figure reprinted from Torres et al. 2020

In this study, we demonstrate that surface waters provide important foraging opportunities and play a key role in the ecology of New Zealand blue whales. The use of UAS technology could be a valuable and complimentary tool to other technological approaches, such as tagging, to gain a comprehensive understanding of foraging behavior in whales.

To see the spectacle of a blue whale surface lunge feeding, we invite you to take a look at the video footage, below:

The publication is led by GEMM Lab Principal Investigator Dr. Leigh Torres. I led the prey data analysis portion of the study, and co-authors include our drone pilot extraordinaire Todd Chandler and UAS analysis guru Dr. Jonathan Burnett. We are grateful to all who assisted with fieldwork and data collection, including Kristin Hodge, Callum Lilley, Mike Ogle, and the crew of the R/V Star Keys (Western Workboats, Ltd.). Funding for this research was provided by The Aotearoa Foundation, The New Zealand Department of Conservation, The Marine Mammal Institute at Oregon State University, Greenpeace New Zealand, OceanCare, Kiwis Against Seabed Mining, The International Fund for Animal Welfare, and The Thorpe Foundation.

Read Oregon State University’s press release about the publication here.