Marine Mammals – Page 8 – Geospatial Ecology of Marine Megafauna Laboratory

Putting Physiological Tools to Work for Whale Conservation

By Alejandro Fernandez Ajo, PhD student at the Department of Biology, Northern Arizona University, Visiting scientist in the GEMM Lab working on the gray whale physiology and ecology project

About four years ago, I was in Patagonia, Argentina deciding where to focus my research and contribute to whale conservation efforts. At the same time, I was doing fieldwork with the Whale Conservation Institute of Argentina at the “Whale Camp” in Península Valdés. I read tons of papers and talked with my colleagues about different opportunities and gaps in knowledge that I could tackle during my Ph.D. program. One of the questions that caught my attention was about the unknown cause (or causes) for the recurrent high calf mortalities that the Southern Right Whale (SRW) population that breeds at Peninsula Valdés experienced during the 2000s (Rowntree et al. 2013). Still, at that time, I was unsure how to tackle this research question.

Golfo San José, Península Valdés – Argentina. Collecting SRW behavioral data from the cliff’s vantage point. Source: A. Fernandez Ajo.

Between 2003 and 2013, at least 672 SRWs died, of which 91% were calves (Sironi et al. 2014). These mortalities represented an average total whale death per year of 80 individuals in the 2007-2013 period, which vastly exceeded the 8.2 average deaths per year of previous years by a ten-fold increase (i.e., 1993-2002) (Rowntree et al. 2013). In fact, this calf mortality rate was the highest ever documented for any population of large whales. During this period, from 2006 to 2009, I was the Coordinator of the Fauna Area in the Patagonian Coastal Zone Management Plan, and I collaborated with the Southern Right Whale Health Monitoring Program (AKA: The Stranding Program) that conducted field necropsies on stranded whales along the coasts of the Península and collected many different samples including whale baleen.

Southern Right Whale, found stranded in Patagonia Argentina. Source: Instituto de Conservación de Ballenas.

In this process, I learned about the emerging field of Conservation Physiology and the challenges of utilizing traditional approaches to studying physiology in large whales. Basically, the problem is that there is no possible way to obtain blood samples (the gold standard sample type for physiology) from free-swimming whales; whales are just too large! Fortunately, there are currently several alternative approaches for gathering physiological information on large whales using a variety of non-lethal and minimally invasive (or non-invasive) sample matrices, along with utilizing valuable samples recovered at necropsy (Hunt et al. 2013). That is how I learned about Dr. Kathleen Hunt’s novel research studying hormones from whale baleen (Hunt et al., 2018, 2017, 2014). Thus, I contacted Dr. Hunt and started a collaboration to apply these novel methods to understand the case of calf mortalities of the SRW calves in Patagonia utilizing the baleen samples that we recovered with the Stranding program at Península Valdés (see my previous blog post).

What is conservation physiology?

Conservation physiology is a multidisciplinary field of science that utilizes physiological concepts and tools to understand underlying mechanisms of disturbances to solve conservation problems. Conservation physiology approaches can provide sensitive biomarkers of environmental change and allow for targeted conservation strategies. The most common Conservation Physiology applications are monitoring environmental stressors, understanding disease dynamics and reproductive biology, and ultimately reducing human-wildlife conflict, among other applications.

I am now completing the last semester of my Ph.D. program. I have learned much about the amazing field of Conservation Physiology and how much more we need to know to achieve our conservation goals. I am still learning, yet I feel that through my research I have contributed to understanding how different stressors impact the health and wellbeing of whales, and about aspects of their biology that have long been obscured or unknown for these giants. One contribution I am proud of is our recent publication of, “A tale of two whales: putting physiological tools to work for North Atlantic and southern right whales,” which was published in January 2021 as a book chapter in “Conservation Physiology: Applications for Wildlife Conservation and Management” published by Oxford University Press: Oxford, UK.

This book outlines the significant avenues and advances that conservation physiology contributes to the monitoring, management, and restoration of wild animal populations. The book also defines opportunities for further growth in the field and identifies critical areas for future investigation. The text and the contributed chapters illustrate several examples of the different approaches that the conservation physiology toolbox can tackle. In our chapter, “A tale of two whales,” we discuss developments in conservation physiology research of large whales, with the focus on the North Atlantic right whale (Eubalaena glacialis) and southern right whale (Eubalaena australis), two closely related species that differ vastly in population status and conservation pressures. We review the advances in Conservation Physiology that help overcome the challenges of studying large whales via a suite of creative approaches, including photo-identification, visual health assessment, remote methods of assessing body condition, and endocrine research using non-plasma sample types such as feces, respiratory vapor, and baleen. These efforts have illuminated conservation-relevant physiological questions for both species, such as discrimination of acute from chronic stress, identification of likely causes of mortality, and monitoring causes and consequences of body condition and reproduction changes.

Link to this Book here: https://oxford.universitypressscholarship.com/view/10.1093/oso/9780198843610.001.0001/oso-9780198843610

Book chapter: https://oxford.universitypressscholarship.com/view/10.1093/oso/9780198843610.001.0001/oso-9780198843610-chapter-12

Book Overview:

This book provides an overview of the different applications of Conservation Physiology, outlining the significant avenues and advances by which conservation physiology contributes to the monitoring, management, and restoration of wild animal populations. By using a series of global case studies, contributors illustrate how approaches from the conservation physiology toolbox can tackle a diverse range of conservation issues, including monitoring environmental stress, predicting the impact of climate change, understanding disease dynamics, and improving captive breeding, and reducing human-wildlife conflict. The variety of taxa, biological scales, and ecosystems is highlighted to illustrate the far-reaching nature of the discipline and allow readers to appreciate the purpose, value, applicability, and status of the field of conservation physiology. This book is an accessible supplementary textbook suitable for graduate students, researchers, and practitioners in conservation science, ecophysiology, evolutionary and comparative physiology, natural resources management, ecosystem health, veterinary medicine, animal physiology, and ecology.

References

Hunt KE, Fernández Ajó A, Lowe C, Burgess EA, Buck CL. 2021. A tale of two whales: putting physiological tools to work for North Atlantic and southern right whales. In: “Conservation Physiology: Integrating Physiology Into Animal Conservation And Management”, ch. 12. Eds. Madliger CL, Franklin CE, Love OP, Cooke SJ. Oxford University press: Oxford, UK.

Sironi, M., Rowntree, V., Di Martino, M. D., Beltramino, L., Rago, V., Franco, M., and Uhart, M. (2014). Updated information for 2012-2013 on southern right whale mortalities at Península Valdés, Argentina. SC/65b/BRG/06 report presented to the International Whaling Commission Scientific Committee, Portugal. <https://iwc.int/home>.

Rowntree, V.J., Uhart, M.M., Sironi, M., Chirife, A., Di Martino, M., La Sala, L., Musmeci, L., Mohamed, N., Andrejuk, J., McAloose, D., Sala, J., Carribero, A., Rally, H., Franco, M., Adler, F., Brownell, R. Jr, Seger, J., Rowles, T., 2013. Unexplained recurring high mortality of southern right whale Eubalaena australis calves at Península Valdés, Argentina. Marine Ecology Progress Series, 493, 275-289. DOI: 10.3354/meps10506

Hunt KE, Moore MJ, Rolland RM, Kellar NM, Hall AJ, Kershaw J, Raverty SA, Davis CE, Yeates LC, Fauquier DA, et al., 2013. Overcoming the challenges of studying conservation physiology in large whales: a review of available methods. Conserv Physiol 1: cot006–cot006.

Hunt, K.E., Stimmelmayr, R., George, C., Hanns, C., Suydam, R., Brower, H., Rolland, R.M., 2014. Baleen hormones: a novel tool for retrospective assessment of stress and reproduction in bowhead whales (Balaena mysticetus). Conserv. Physiol. 2, cou030. https://doi.org/10.1093/conphys/cou030

Hunt, K.E., Lysiak, N.S., Moore, M.J., Rolland, R.M., 2016. Longitudinal progesterone profiles in baleen from female North Atlantic right whales (Eubalaena glacialis) match known calving history. Conserv. Physiol. 4, cow014. https://doi.org/10.1093/conphys/cow014

Hunt, K.E., Lysiak, N.S., Robbins, J., Moore, M.J., Seton, R.E., Torres, L., Buck, C.L., 2017. Multiple steroid and thyroid hormones detected in baleen from eight whale species. Conserv. Physiol. 5. https://doi.org/10.1093/conphys/cox061

Hunt, K.E., Lysiak, N.S.J., Matthews, C.J.D., Lowe, C., Fernández Ajó, A., Dillon, D., Willing, C., Heide-Jørgensen, M.P., Ferguson, S.H., Moore, M.J., Buck, C.L., 2018. Multi-year patterns in testosterone, cortisol and corticosterone in baleen from adult males of three whale species. Conserv. Physiol. 6, coy049. https://doi.org/10.1093/conphys/coy049

What makes a species, a species?

By Lisa Hildebrand, PhD student, OSU Department of Fisheries & Wildlife, Geospatial Ecology of Marine Megafauna Lab

Over the roughly 2.5 years that I have researched the Pacific Coast Feeding Group (PCFG) of gray whales, I have thought more and more about what makes a population, a population. From a management standpoint, the PCFG is currently not considered a separate population or even a sub-population of the Eastern North Pacific (ENP) gray whales. Rather, the PCFG is most commonly referred to as a ‘sub-group’ of the ENP. In my opinion, there are valid arguments both for and against the PCFG being designated as its own population. I will address those arguments briefly at the end of this post, but first, I want you to join on me on a journey that is tangential to my question of ‘what makes a population, a population?’ and one that started at the last Marine Mammal Institute Monthly Meeting (MMIMM).

During 2021’s first MMIMM, our director Dr. Lisa Ballance proposed that we lengthen our monthly meeting duration from 1 hour to 1.5 hours. The additional 30 minutes was to allow for an open-ended, institute-wide discussion of a current hot topic in marine mammal science. This proposal was immediately adopted, and the group dove into a discussion about the discovery of a new baleen whale species in the northeastern Gulf of Mexico: Rice’s whale (Balaenoptera ricei). Let me pause here very briefly to reiterate – the discovery of a new baleen whale species!! The fact that anything as large as 12 m could remain undiscovered in our oceans is really quite fascinating and shows that our scientific quest will likely never run out of discoverable subjects. Anyway, the discovery of this new species is supported by several lines of evidence. Unfortunately (but understandably), MMI’s discussion of these topics had to cease after 30 minutes, however I had more questions. I wanted to know what had sparked the researchers to believe that they had discovered a new cetacean species.

Scientific illustration of Bryde’s whale. Source: NOAA Fisheries.

I started my research by skimming through some news articles about the Rice’s whale discovery. In a Smithsonian Magazine article, I saw a quote by Dr. Patricia Rosel, the lead author of the study detailing Rice’s whale, that read: “But we didn’t have a skull.”. That quote made me pause. A skull? Is that what it takes to discover and establish a new species? This desired piece of evidence seemed rather puzzling and a little antiquated to me, given that the field of genetics is so advanced now and since it is no longer an accepted practice to kill a wild animal just to study it (i.e., scientific whaling). I backtracked through the article to learn that in the 1990s, renowned marine mammal scientist Dale Rice (after whom Rice’s whale was named) recognized that a small population of baleen whale occurred in the northeastern part of the Gulf of Mexico year-round. At the time, this population was believed to be a sub-population of Bryde’s whale. It wasn’t until 2008, that NOAA scientists were able to conduct a genetic analysis of tissue samples from this population, only to find that these whales were genetically distinct from other Bryde’s whales (Rosel & Wilcox 2014). Yet, this information was not enough for these whales to be established as their own species. A skull really was needed to prove that these whales were in fact a new species. Thankfully (for the scientists) but sadly (for the whale), one of these individuals stranded in Sandy Key, Florida, in 2019, and a dedicated team of stranding responders from Florida Fish and Wildlife, Mote Marine Lab, NOAA, Dolphins Plus, and Marine Animal Rescue Society worked tirelessly in difficult conditions to comprehensively document and preserve this animal. Through the diligent work of this, and previous, stranding response teams, Dr. Rosel and her team were provided the opportunity to examine the skull needed to determine population-status. The science team determined that the bones atop the skull around the blowhole provided evidence that these whales were not only genetically, but also anatomically, different from Bryde’s whales. It was this incident, triggered by that short quote in the Smithsonian article, that brought me to my journey of asking ‘what makes a species, a species?’.

Given that I had just read that Dr. Rosel needed a skull to establish Rice’s whale as its own species, I assumed that my search for ‘how to establish a new species’ would end quickly in me finding a list of requirements, one of which would be ‘must present anatomical/skeletal evidence’. To my surprise, my search did not end quickly, and I did not find a straightforward list of requirements. Instead, I discovered that my question of ‘what makes a species, a species?’ does not have a black-and-white answer and involves a lot of debate.

The skull of this stranded whale was a large piece of evidence in establishing Rice’s whale as its own species. Source: Smithsonian Magazine from NOAA / Florida Fish and Wildlife Commission

Kevin de Queiroz, a vertebrate, evolutionary, and systematic biologist who has published extensively on theoretical and conceptual topics in systematic and evolutionary biology, believes that the issue of species delimitation (‘what makes a species, a species?’) has been made more complicated by a larger issue involving the concept of species itself (‘what is a species?’) (De Queiroz 2007). To date, there are 24 recognized species concepts (Mayden 1997). In other words, there are 24 different definitions of what a species is. Perhaps the most common example is the biological species concept where a species is defined as a group of individuals that are able to produce viable and fertile offspring following natural reproduction. Another example is the ecological species concept whereby a species is a group of organisms adapted to a particular set of resources and conditions, called a niche, in the environment. Problematically, many of these concepts are incompatible with one another, meaning that applying different concepts leads to different conclusions about the boundaries and numbers of species in existence (De Queiroz 2007).

This large number of species concepts is due to the different interests of certain subgroups of biologists. For example, highlighting morphological differences between species is central to paleontologists and taxonomists, whereas ecologists will focus on niche differences. Population geneticists will attribute species differences to genes, while for systematists, monophyly will be paramount. It goes on and on. And so does the debate about the concept of species. It seems that there currently is not one clear, defined consensus on what a species is. Some biologists argue that a species is a species if it is genetically different, while others will insist that skeletal and morphological evidence must be present. From what I can tell, it seems that scientists describe and (attempt to) establish a new species by publishing their lines of evidence, after which experts in the field discuss and evaluate whether a new species should be established.

In the field of marine mammal science, the Society of Marine Mammalogy’s Taxonomic Committee is charged with maintaining a standard, accepted classification and nomenclature of marine mammals worldwide. The committee annually considers and evaluates new, peer-reviewed literature that proposes changes (including additions) to marine mammal taxonomy. I expect that the case of Rice’s whale will be on the committee’s docket this year. Given that Rosel and co-authors presented geographic, morphological, and genetic evidence to support the establishment of Rice’s whale, I would not be surprised if the committee adds it to their curated list.

After taking this dive into the ‘what makes a species, a species?’ question, let’s see if we can apply some of what we’ve learned to the ‘what makes a population, a population?’ question regarding the PCFG and ENP gray whales. Following the ecological species concept, an argument for the recognition of the PCFG as its own population would be that they occupy an entirely different environment during their summer foraging season than the ENP whales. Not only are the geographic ranges different, but PCFG whales also show behavioral differences in their foraging tactics and targeted prey. The argument against the PCFG being classified as its own population is largely supported by genetic analysis that has revealed ambiguous evidence that the PCFG and ENP are not genetically isolated from one another. While one study has shown that there is maternal cultural affiliation within the PCFG (meaning that calves born to PCFG females tend to return to the PCFG range; Frasier et al. 2011), another has revealed that mixing between ENP and PCFG gray whales on the breeding grounds does occur (Lang et al. 2014). So, even though these two groups feed in areas that are very far apart (ENP: Arctic vs PCFG: US & Canadian west coast) and certain individuals do show a propensity for a specific feeding ground, the genetic evidence suggests that they mix when on their breeding grounds in Baja California, Mexico. Depending on which species concept you align with, you may see better arguments for either side.

PCFG gray whale along the Oregon coast during the GEMM Lab’s 2020 GRANITE summer field season. Image captured under NOAA/NMFS permit #21678. Source: GEMM Lab.

You may be wondering why it is important to even ponder questions like ‘what makes a species, a species?’ and ‘what makes a population, a population?’. Does it really matter if the PCFG are considered their own population? Would anything really change? The answer is, most likely, yes. If the PCFG were to be recognized as their own population, it would likely have an immediate effect on their conservation status and subsequently on how the population needed to be managed. Rather than being under the umbrella of a large, (mostly) stable population of ~25,000 individuals, the PCFG would consist of only ~250 individuals. A group this small would possibly be considered “endangered”, which would require much stricter monitoring and management to ensure that their numbers did not decline from year to year, especially due to anthropogenic activities.

For a long time, I felt like taxonomy was a bit of an archaic scientific field. In my mind, it was something that biologists had focused their time and energy on in the 18^th century (most notably Carl Linnaeus, whose taxonomic classification system is still used today), but something that many biologists have moved on from focusing on in the 21^st century. However, as I have developed and grown over the last years as a scientist, I have learned that scientific disciplines are often heavily intertwined and co-dependent on one another. As a result, I am able to see the enormous value and need for taxonomic work as it plays a large part in understanding, managing, and ultimately, conserving species and populations.

Literature cited

De Queiroz, K. 2007. Species concepts and species delimitation. Systematic Biology 56(6):879-886.

Frasier, T. R., Koroscil, S. M., White, B. N., and J. D. Darling. 2011. Assessment of population substructure in relation to summer feeding ground use in the eastern North Pacific gray whale. Endangered Species Research 14:39-48.

Lang, A. R., Calambokidis, J., Scordino, J., Pease, V. L., Klimek, A., Burkanov, V. N., Gearin, P., Litovka, D. I., Robertson, K. M., Mate, B. R., Jacobsen, J. K., and B. L. Taylor. 2014. Assessment of genetic structure among eastern North Pacific gray whales on their feeding grounds. Marine Mammal Science 30(4):1473-1493.

Mayden, R. L. 1997. A hierarchy of species concepts: the denouement of the species problem in The Units of Biodiversity – Species in Practice Special Volume 54 (M. F. Claridge, H. A. Dawah, and M. R. Wilson, eds.). Systematics Association.

Rosel, P. E., and L. A. Wilcox. 2014. Genetic evidence reveals a unique lineage of Bryde’s whale in the northeastern Gulf of Mexico. Endangered Species Research 25:19-34.

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 18^th 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 19^th and 20^th 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

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 6^th 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 3^rd -10^th 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-3^rd 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.

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.

Cascadia 2020: Exploring Oregon via Zoom

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

As a newly-minted PhD student, starting graduate school has so far been everything I dreamt — and a bit more. I expected the excitement of meeting my cohort and professors, and starting classes. The apocalyptic drive to campus through a fiery sky as fires burned across Oregon, and the week after spent solely indoors, I did not.

When conditions allow, being in the field is one of my favorite parts of the scientific process!

As I’ve settled into Corvallis, my program, and navigating the roadblocks 2020 keeps throwing our way, I have been so grateful for the warm (virtual) welcome by my lab groups, professors, and fellow students. One of the most impressive displays of flexibility and adaptability so far is the ever-evolving field course I am currently taking.

Called “Cascadia,” this course provides an introduction to the range of geological, physical, ecological, and biogeochemical topics that exist within the Pacific Northwest, and explores the linkages between these areas. The course’s goal is to introduce incoming CEOAS (College of Earth, Ocean, and Atmospheric Sciences) students to the surrounding landscape, and to the ways that human systems interact with that landscape.

The professors teaching Cascadia — Drs. Frederick Colwell, Emily Shroyer, and George Waldbusser — have done an amazing job adapting the course to unprecedented circumstances. Over the summer, safety measures due to the pandemic required them to move the course to a largely online format, with only three planned day trips (typically the course is a full ten-day road trip around the state). Over the last week, the fires raging around Oregon have forced them to adapt the course repeatedly in real time, postponing field trips based on air quality forecasts and site closures.

During a typical year in the Cascadia course, the incoming students learn while exploring, camping, and hiking their way around a number of sites around Oregon. This year, our classmates are scattered around the country and our explorations have taken place in a Zoom room — but that hasn’t stopped the experience from being great.

Several professors shared their expertise with us through a series of talks that covered the ecology and history of the Willamette River, Pacific Northwest volcanoes, tsunami safety and preparation, and even wildfire ecology. In addition to talks by subject matter experts, each student delved into and presented on a topic of their choice, allowing us to learn from one another about everything from edible plants, to Oregon craft beers, to human movements throughout the Willamette River valley. We also enjoyed gorgeous pictures of Oregon’s mountains, coast, and desert, and received recommendations for trips and hikes that everyone is excited to explore.

As of the time of writing this blog, I’m excited to say that things may look a little different tomorrow — rain and improved air quality are in the forecast, and the Cascadia crew is planning to venture out to the coast for our first field trip! We’ll be learning on-site about the Oregon Coast Range and coastal dynamics, climate, and processes. This will actually be my first time on the Oregon coast, but definitely not my last.

For my PhD research, I will work with Dr. Leigh Torres and Dr. Kim Bernard (CEOAS) to understand how ocean conditions and prey distribution shape where whales are found in Oregon waters. Whale entanglements in Dungeness crab fishing gear have been on the rise since 2014, and we will collaborate with the Oregon Whale Entanglement Working group to look for solutions to this problem.

A big part of my excitement about this research project lies in the way it intersects natural and human systems, just as we have been exploring through the Cascadia course. I am interested in how marine mammal distribution and behavior intersect with human systems — and how understanding these interactions can inform management and conservation efforts. I am thrilled to be a new member of the GEMM Lab, and to be starting (remote) classes and this research. For now, I’m wishing everyone good air quality and a safe fall!

Update: The Cascadia class did make it the coast! We were even lucky enough to see gray whales here at Depoe Bay.

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)

“Do Dolphins Get Hives?”: The Skinny on Allergies in Cetaceans

By: Alexa Kownacki, Ph.D. Student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

While sitting on my porch and watching the bees pollinate the blooming spring flowers, I intermittently pause to scratch the hives along my shoulders and chest. In the middle of my many Zoom calls, I mute myself and stop my video because a wave of pollen hits my face and I immediately have to sneeze. With this, I’m reminded: Welcome to prime allergy season in the Northern Hemisphere. As I was scratching my chronic idiopathic urticaria (hives caused by an overactive immune system), I asked myself “Do dolphins get hives?” I had no idea. I know most terrestrial mammals can and do—just yesterday, one of the horses in the nearby pasture was suffering from a flare of hives. But, what about aquatic and marine mammals?

Springtime flowers blooming on the Central California Coast 2017. (Image Source: A. Kownacki)

As with most research on marine mammal health, knowledge is scare and is frequently limited to studies conducted on captive and stranded animals. Additionally, most of the current theories on allergic reactions in marine mammals are based on studies from terrestrial wildlife and humans. Because nearly all research on histamine pathways centers on terrestrial animals, I wanted to see what information exists the presence of skin allergies in marine mammals.

Allergic reactions trigger a cascade within the body, beginning with the introduction of a foreign body, which for many people is pollen. The allergen binds to antibodies that are produced to fight potentially harmful substances. Once this allergen binds to different types of cells, including mast cells, chemicals like histamines are released. Histamines cause the production of mucus and constriction of blood vessels, and thus are the reason your eyes water, your nose runs, or you start coughing.

Basic cartoon of an allergic reaction from exposure to the allergen to the reaction from the animal. (Image Source: Scientific Malaysian)

As you probably can tell just by looking at a marine mammal, they have thicker skin and fewer mucus membranes that humans, due to the fact that they live in the water. However, mast cells or mast cell-like cells have been described in most vertebrate lineages including mammals, birds, reptiles, amphibians, and bony fishes (Hellman et al. 2017, Reite and Evenson 2006). Mast cell-like cells have also been described in an early ancestor of the vertebrates, the tunicate, or sea squirt (Wong et al. 2014). Therefore, allergic-reaction cascades that may present as hives, red and itchy eyes or nose in humans, also exist in marine mammals, but perhaps cause different or less visible symptoms.

Skin conditions in cetaceans are gathering interest within the marine mammal health community. Even our very own Dawn Barlow, Dr. Leigh Torres, and Acacia Pepper assessed the skin conditions in New Zealand blue whales in their recent publication. Most visible skin lesions or markings on cetaceans are caused by parasites, shark bits, fungal infections, and fishery or boat interactions (Leone et al. 2019, Sweeney and Ridgway 1985). However, there is very little scientific literature about allergic reactions in marine mammals, let alone cetaceans. That being said, I managed to find a few critical pieces of information supporting the theory that marine mammals do in fact have allergies that can produce dermal reactions similar to hives in humans.

In one study, three captive bottlenose dolphins developed reddened skin, sloughing, macules, and wheals on their ventral surfaces (Monreal-Pawlowsky et al. 2017). The medical staff first noticed this atopic dermatitis in 2005 and observed the process escalate over the next decade. Small biopsy samples from the affected areas on the three dolphins coincided with the appearance of four pollens in the air within the geographic region: Betula, Pistacia, Celtis, and Fagus (Monreal-Pawlowsky et al. 2017). Topical prednisone treatments were applied to the affected areas at various dosages that slowly resolved the skin irritations. Researchers manufactured an allergy vaccine using a combination of the four pollens in hopes that it would prevent further seasonal outbreaks, but it was unsuccessful. In the coming years, the facility intends to adjust the dosages to create a successful vaccine.

In the three top images, visible skin irritation including redness, macules, wheals, and sloughing are present. In the image below, the above animal was treated with methylprednisolone and the skin irritation subsides. (Monreal-Pawlowsky et al. 2017)

In addition to the above study, there is an unpublished case of suspected allergic reaction to another pollen that produces a pruritic reaction on the ventral areas of dolphins on a seasonal basis (Vicente Arribes, personal communication). Although there are only a few documented cases of environmentally-triggered allergic reactions that are visible on the dermal layer of cetaceans, I believe this evidence makes the case that some cetaceans suffer from allergies much like us. So, next time you’re enjoying the beautiful blooms and annoyingly scratch your eyes, know that you are not alone.

Citations:

Barlow DR, Pepper AL and Torres LG (2019) Skin Deep: An Assessment of New Zealand Blue Whale Skin Condition. Front. Mar. Sci. 6:757.doi: 10.3389/fmars.2019.00757

Hellman LT, Akula S, Thorpe M and Fu Z (2017) Tracing the Origins of IgE, Mast Cells, and Allergies by Studies of Wild Animals. Front. Immunol. 8:1749. doi: 10.3389/fimmu.2017.01749

Leone AB, Bonanno Ferraro G, Boitani L, Blasi MF. Skin marks in bottlenose dolphins (Tursiops truncatus) interacting with artisanal fishery in the central Mediterranean Sea. PLoS One. 2019;14(2):e0211767. Published 2019 Feb 5. doi:10.1371/journal.pone.0211767

Monreal-Pawlowsky T, Fernández-Bellon H, Puigdemont A (2017) Suspected Allergic Reaction in Bottlenose Dolphins (Tursiops truncatus). J Vet Sci Ani Husb 5(1): 108. doi: 10.15744/2348-9790.5.108

Reite OB, Evensen O. Inflammatory cells of teleostean fish: a review focusing on mast cells/eosinophilic granule cells and rodlet cells. Fish Shellfish Immunol (2006) 20:192–208. doi:10.1016/j.fsi.2005.01.012

Sweeney, J. C., & Ridgway, S. H. (1975). Common diseases of small cetaceans. J. Am. Vet. Med. Assoc, 167(7), 533-540.

Wong GW, Zhuo L, Kimata K, Lam BK, Satoh N, Stevens RL. Ancient originof mast cells. Biochem Biophys Res Commun (2014) 451:314–8. doi:10.1016/j.bbrc.2014.07.124

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