Tag: Gray Whales

There she blows! Studying blow synchrony in blue and gray whale mother-calf pairs

Maddie Honomichl, CSUMB Undergraduate in Marine Science, 2025  NSF REU and TOPAZ/JASPER Intern

Hi everyone, my name is Maddie Honomichl, and I was one of the two NSF REU interns with the GEMM lab this summer. This fall will be my last semester at California State University, Monterey Bay (CSUMB), where I will receive my undergraduate degree in Marine Science. Growing up in the Arizona desert limited my exposure to large bodies of water but led to memorable family trips to San Diego. With each trip my adoration for the ocean and the vast marine ecosystem emerged, resulting in my choice to go to college at CSU Monterey Bay. During my time at CSUMB, I learned of what internships were and the magnitude of impact these experiences had on my peers. Naturally, I searched online for weeks for future summer internship openings available—eventually leading me to none other than the GEMM Lab’s TOPAZ/JASPER project.

Figure 1. A picture of me, Maddie Honomichl, in Redding, CA.

Celest Sorrentino, my amazing mentor, took me under her wing and helped me complete my very first research project: In sync? Studying blow synchrony in blue and gray whale mother-calf pairs using drone footage. The aim of my project is to understand more about calf development in gray and blue whales by investigating changes in mother-calf blow synchrony. But what is synchrony?

Synchrony can be defined as two individuals attempting to match each other’s behavior (Novotny & Bente 2022) and promote mimicry and learning. For example, humpback whales teaching their calves vocalizations and song patterns to communicate is an instance of synchrony and social learning (Anjara 2018). Another example of synchrony in wildlife is energetic transfer, where a whale calf will swim in alignment with its mother’s slipstream to expend less energy (Norris & Prescott 1961). Just like these behaviors, blow synchrony is a measure we can use in marine mammal mother-calf pairs to evaluate their relationship with each other.

Aside from the TOPAZ/JASPER project, you might already be familiar with two other incredible GEMM lab projects GRANITE and SAPPHIRE. During the years of 2016-2023, drone footage of the Pacific Coast Feeding Group of gray whales was collected along the Oregon coast for the GRANITE project. In 2016, 2017, 2024, and 2025, drone footage for the pygmy blue whales was collected in South Taranaki Bight, New Zealand, for the SAPPHIRE project. Large marine mammals, especially whales, are difficult to study for many reasons including their brief occurrences at the surface and the challenges of studying aquatic animals. However, the use of drones allows for a safer and non-invasive alternative method for marine mammal monitoring in their natural habitat (Álvarez-González et al., 2023).

Figure 2. Two still images taken from GRANITE drone footage. The left is of a mother gray whale blowing and the right is of a gray whale calf blowing

Baleen whale calves only have 6-8 months to learn everything they need to know before they wean and are sent off on their own (Lockyer 1984). I don’t know about you, but if my mom kicked me out after I turned 5 years old, I would be pretty lost. In American culture, the golden age for humans to be considered an adult is around 18 years old, when they finally leave the house and venture on their own. For humans, age is a cultural sign of independence, but not much is known about what factors influence what makes a calf ready to be independent. Blow synchrony between mother-calf pairs during the calf’s weaning period can be used as a metric for calf development, which is important to know more about as calf development and survival rates are critical factors to consider in population dynamics and management efforts.

When do whales eventually leave their mother? We frequently don’t know how old a calf is, so we use three different metrics as proxies of calf maturity. First, we use Total Length (TL), which is the length of the whale from rostrum to fluke (or nose to tail) (Pirotta et. al., 2023) and serves as an indicator of growth. Our next metric is Body Area Index (BAI), similar to BMI in humans, which is a score of body condition to understand how fat or skinny the whale calf is (Burnett et. al., 2019). Total Length and BAI measurements are derived from drone photogrammetry work conducted by the GEMM Lab and CODEX. Our last proxy is Day of Year (DOY), which is the day in the year we sighted the whales.

Figure 3. Demonstrating photogrammetry methods used to measure Total Length and Body Area Index (BAI). On the left is a drone image of a gray whale showing how we calculate Total Length (TL) from rostrum to fluke. This image is also divided into increments which are used to calculate Surface Area (SA), depicted by the green dashed box, and using the equation on the right with TL, BAI is calculated. 

The specific question I addressed was: Does mother-calf blow rate synchrony change as the calf’s Total Length and Body Area Index increase, and Day of Year increases? In other words, does synchrony change as calves become longer, healthier, and the year progresses. Meaning, as the calf grows in length, increases its body condition, and the day of year progresses, the calf will gain independence from its mother and become out of sync.

I analyzed blowhole rates of mother-calf gray and blue whales using  a program called BORIS (Friard & Gamba 2016). BORIS (Behavioral Observation Research Interactive Software) is an online free program where researchers can assign behavior states to animals in video. In BORIS, I watched the drone footage and marked a “blow” event for the mom and calf, recording a specific time stamp per event. I repeated this workflow for each video of both gray and blue whale mom-calf pairs. Once completed, I calculated the average difference of the calf’s timestamp from the mother’s timestamp per pair. The reason behind this approach is that  the larger the average difference, the more asynchronous the calf is with its mother, and the smaller the average difference the more synchronous they will become.

To evaluate the effect of our proxies for age, Total Length, BAI, and Day of Year, on mother-calf blow rate synchrony, I turned to my good friend RStudio. I created a scatterplot and regressions for these relationships (Figure 4). These results indicate that body condition (BAI) may be a better proxy of calf maturity and preparation for weaning in gray whales (p-value = 0.0064), whereas calf Total Length (TL) is more indicative of calf maturity in blue whales (p-value = 0.00097).

Figure 4. Scatterplot describing the relationship between the average difference in breath rate in seconds across our three proxies: (i) Average total length, (ii) Average BAI, (iii) Day of Year. The black line in the linear regression fit to the data produced by the linear model. The error bars around each point are the standard deviation or the variability in their blow synchrony. The bigger the error bars mean the more variation the mother and calf had in their blow rates, and the smaller the error bars means the less variation the mother and calf had in their blow rates. Ultimately to answer my question, for gray whales, blow synchrony between mother and calf decreases with increasing calf Body Area Index (BAI). For our blue whales, mother-calf blow synchrony decreases with increasing calf Total Length (TL).

As I end my 10-week internship summer filled with data collection and analysis, lots of laughs and inside jokes, I am proud to say I have learned so much about the research that goes into a project like mine. As someone who loves marine animals, especially whale sharks, I now have a newfound love for whales that will forever be in my heart. I am so incredibly grateful that I was able to work with the GEMM lab and the amazing team of researchers and scientists it encompasses. Being a first-generation college student comes with its challenges of learning how to navigate higher education without direct guidance of family who had been through the experience. But if there’s one thing I always tell myself, it’s that with a little bit of grit and hard work, you can do anything you put your mind to! Whatever my future holds for me, I hope it is filled with more research opportunities and the chance to work with marine mammals!

Figure 5. An image of Maddie Honomichl, presenting her research poster at the Hatfield summer coastal intern symposium remotely from Port Orford!

References:

Álvarez-González, M., Suarez-Bregua, P., Pierce, G. J., & Saavedra, C. (2023). Unmanned Aerial Vehicles (UAVs) in Marine Mammal Research: A Review of Current Applications and Challenges. Drones, 7(11), 667. https://doi.org/10.3390/drones7110667

Anjara Saloma. Humpback whales (Megaptera novaeangliae) mother-calf interactions. Vertebrate Zoology. Université Paris Saclay (COmUE); Université d’Antananarivo, 2018. English. ⟨NNT : 2018SACLS138⟩. ⟨tel-02869389⟩

Burnett, J. D., Lemos, L., Barlow, D., Wing, M. G., Chandler, T., & Torres, L. G. (2019). Estimating morphometric attributes of baleen whales with photogrammetry from small UASs: A case study with blue and gray whales. Marine Mammal Science, 35(1), 108–139. https://doi.org/10.1111/mms.12527

Friard, O., & Gamba, M. (2016). BORIS: A free, versatile open‐source event‐logging software for video/audio coding and live observations. Methods in Ecology and Evolution, 7(11), 1325–1330. https://doi.org/10.1111/2041-210X.12584

Huetz, C., Saloma, A., Adam, O., Andrianarimisa, A., & Charrier, I. (2022). Ontogeny and synchrony of diving behavior in Humpback whale mothers and calves on their breeding ground. Journal of Mammalogy, 103(3), 576–585. https://doi.org/10.1093/jmammal/gyac010

Lockyer, Christina. (1984). Review of Baleen Whale (Mysticeti) Reproduction and Implications for Management. Reproduction in whales, dolphins and porpoises. Proc. conference, La Jolla, CA, 1981. 6. 27-50.

Norris, K.S., & Prescott, J.H. (1961). Observations of Pacific cetaceans of Californian and Mexican waters. University of California Publications in Zoology, 63, 291- 402.

Novotny, E., & Bente, G. (2022). Identifying Signatures of Perceived Interpersonal Synchrony. Journal of nonverbal behavior, 46(4), 485–517. https://doi.org/10.1007/s10919-022-00410-9

Pirotta, E., Fernandez Ajó, A., Bierlich, K. C., Bird, C. N., Buck, C. L., Haver, S. M., Haxel, J. H., Hildebrand, L., Hunt, K. E., Lemos, L. S., New, L., & Torres, L. G. (2023). Assessing variation in faecal glucocorticoid co

Smultea, M. A., Fertl, D., Bacon, C. E., Moore, M. R., James, V. R., & Würsig, B. (2017). Cetacean mother-calf behavior observed from a small aircraft off Southern California. Animal Behavior and Cognition, 4(1), 1–23. https://doi.org/10.12966/abc.01.02.2017

Zoop Gone Missing: A Whale’s Dinner Dilemma

Dawson Mohney, TOPAZ/JASPER HS Intern, Pacific High School Graduate

My name is Dawson Mohney, I am a high school intern for the 2025 TOPAZ/JASPER team this field season. I first heard about the TOPAZ/JASPER internship from my friend Jonah Lewis, a previous intern from the 2023 field season. Coincidentally, Jonah and I both graduated this year from Pacific High School here on the coast—small world. I have called Port Orford my home for most of my life, and in recent years I discovered that a gray whale research project has been happening in my own backyard. Growing up less than a mile from the Oregon Coast, I’ve spent a lot of time looking out into the water. I always liked how, no matter what happened in my life, the ocean was always there. This interest is what encouraged me to apply for the internship with the hope of discovering more about the ocean, a substantial part of my home and family.

Fig 1: Picture fellow intern Maddie took of me (Dawson) during our trip to Natural Bridges.

A critical part of this project is understanding not only the magnificent gray whales but also the much less apparent zooplankton–after all, the whales need to eat a lot of zooplankton! Many different species of zooplankton—“zoop” for short—call the Oregon coast home. Each day, as we kayak to our 12 sample stations within the gray whale feeding grounds of Mill Rocks and Tichenor’s Cove, I find myself wondering which species of zoop I’ll get to identify later under the microscope.

Throughout the duration of this internship, our team has met to discuss a few research papers published by GEMM Lab members, including research produced from the TOPAZ/JASPER projects. Recently, I read, “Do Gray Whales Count Calories? Comparing Energetic Values of Gray Whale Prey Across Two Different Feeding Grounds in the Eastern North Pacific,” by Hildebrand et al. who describe the caloric content of different zooplankton species. Before reading this paper, I didn’t realize whale prey could vary in nutritional value – much like food for humans. This paper made it clear that each of the different species of zooplankton is just as important as the last, but consuming more of the higher caloric species such as the Neomysis rayii or the Dungeness crab larvae would certainly be a welcome meal. Seeing these “healthy” meals in the area makes me hopeful for the whales.

Fig 2: Image of a crab larvae in their megalopae stage.

From reading previous blog posts, the foraging habits of the whales this season appear to be unusual. In prior TOPAZ/JASPER field seasons, gray whales have often been tracked foraging near or around our Mill Rocks and Tichenor Cove study sites. This season, we haven’t tracked a single whale in Mill Rocks and only two in Tichenor Cove. Could there just not be enough good zoop?

Along with this lack of whales, there does seem to be a lack of these “high calorie zoop species”. Our team has most frequently collected samples primarily comprising of Atylus tridens, a lower calorie prey type. In fact, during one of our earlier kayak training days this field season we collected 2,019 individual A. tridens. However, since this day we have collected sparse amounts of zooplankton in our samples, ranging from zero to 121 in a given sample. Our total zoop count thus far is 2,524 zooplankton, a third of the total zooplankton collected last field season.

Fig 3: Image of an Atylus tridens under a microscope.

As for whale presence, we have been observing many whales blows near Hell’s Gate as mentioned in last week’s blog written by fellow intern Miranda Fowles. From our cliff site, it has been difficult to know whether these are gray whales or a different kind of whale, leading us to venture out to the Heads to get a better look. The persistence of whales in this area is certainly unusual, and perhaps it can be explained by a larger amount of higher calorie zooplankton species in the Hell’s Gate area.

Fig 4: Dawson tracking blows by Hell’s Gate with the theodolite.

Being part of the TOPAZ/JASPER project, I have become exposed to what the true meaning is behind “fieldwork,” including learning how to be flexible and adapt to new challenges every day. What I have most enjoyed is the team’s ability to overcome any new hurdle together as a unit.  My dad often says, “You learn something new every day,” and this internship couldn’t embody this quote more. In just these 5 weeks, it almost feels like my head is now a couple sizes bigger.

Before this experience, I never thought much about how one might track a whale or how different microscopic species could have such a profound impact on a whale’s decision to forage. Now I feel I understand just how important these less than obvious factors are and the effort which goes behind understanding these relationships. I can only hope future opportunities teach me as much as joining the TOPAZ/JASPER legacy has—it’s an experience that, even just a few days into the 2025 field season, I knew would be hard to match.

Fig 4: Dawson (navigator) and Miranda (sampler) during kayak training on their way to Mill Rocks.

Hildebrand, L., Bernard, K. S., & Torres, L. G. (2021). Do Gray Whales Count Calories? Comparing Energetic Values of Gray Whale Prey Across Two Different Feeding Grounds in the Eastern North Pacific. Frontiers in Marine Science, 8, 683634. https://doi.org/10.3389/fmars.2021.683634

Whales Off Course: Theodolite Tracking in an Unpredicted Area

Miranda Fowles, GEMM Lab TOPAZ/JASPER Intern, OSU Fisheries and Wildlife Undergraduate

Hello! My name is Miranda Fowles, and I am the OSU intern for the 2025 TOPAZ/JASPER project this summer! I recently earned my bachelor’s degree – almost, I have one more term, but I walked at commencement in June – from Oregon State University in Fisheries, Wildlife and Conservation Sciences and a minor in Spanish. My interest in whales began at a young age during a visit to SeaWorld. While I didn’t enjoy the killer whale shows for their entertainment aspect, this exposure allowed me to see a whale for the first time. From then on, I knew I wanted to contribute to understanding more about these animals, even if I wasn’t always sure how to make that happen. My decision to pursue Fisheries and Wildlife sciences was set from the beginning, however I wondered if there were actually opportunities to study whales.

Last summer, I was a MACO intern and stayed at the Hatfield Marine Science Center where I met last year’s TOPAZ/JASPER REU student, Sophia Kormann, and she raved all about her experience, so I just had to apply for this year’s internship! I remember feeling so nervous for the interview, but Dr. Leigh Torres and Celest Sorrentino’s kindness and inspiration quickly put me to ease. When I found out I was offered the position, I was just more excited than I’d ever been!

My day-to-day life as a TOPAZ/JASPER intern here at the Port Orford Field Station looks one of two ways: either on the kayak or the cliff site. When we are ocean kayaking, we go to our 12 sampling sites in the Mill Rocks and Tichenor Cove study areas (Fig. 1), where we collect zooplankton samples (Fig. 2) and oceanographic data with our RBR (an oceanographic instrument), as well as GoPro footage. When on the cliff site, we keep our eyes peeled for any whales to take pictures of them and mark their location in the water with a theodolite.

Fig. 1: Map of our study sites (Tichenor Cove and Mill Rocks) and where we have been seeing gray whales (Hell’s Gate) circled in green, and our Cliff Site.
Fig. 2: Miranda Fowles out on the kayak pointing at her zooplankton samples.

A theodolite is an instrument that is used for mapping and engineering; in our case it is used to track where a gray whale blows and surfaces (For more info, please see this blog by previous intern Jonah Lewis). Each time a whale surfaces, we use the theodolite to create a point in space that marks its location. Once we have multiple points, we can draw lines between each point to establish the track of the whale. These tracklines can then be used to make assumptions of the whales’ behavior. For example, if the trackline is straight, and the individual is moving at a consistent speed and direction, we can assume the whale is transiting. Whereas if the trackline is going back and forth in one small area, the whale is likely searching or foraging for food (Hildebrand et al., 2022).

In last week’s blog my peer Nautika Brown showed how photo ID is a critical part in our field methods. When theodolite tracking, we assign a number with each new individual whale observation. If the whale is close enough, we also capture photographs of the whale (Fig. 3) and match it up to its given number, allowing us to link the trackline to an individual whale so we can understand more about individual behavior. Documenting individual specific behavior is important because previous research has shown that age, size and the individual ID of a whale can all influence different foraging tactic use (Bird et al., 2024). Therefore, each season as we collect more and more data, we establish a repertoire of recurring or new behaviors to sieve for trends and patterns.

Fig. 3: Photo of a gray whale surfacing captured from our cliff site.

I find animal behavior to be an integral role in many ecological studies, and I am intrigued to explore this topic more. As marine mammals that spend most of their time underwater, cetaceans are quite an inconspicuous species to study (Bird et al., 2024), but by studying their ecology through photo ID and theodolite tracking we get insight into who they are, how they behave, and where they go.

Up until this point in the season, we have theodolite tracked gray whales for 12 hours and 3 minutes (woohoo). Interestingly, most of these tracks of whales have been near an area called “Hell’s Gate”, which is located around large rocks toward the far west of our study site (Figs. 2 and 4). We can assume, but cannot be sure, that the whales are feeding here because they spend so much time in the area, and return day after day. According to Dr. Torres, the consistent use of this area near Hell’s Gate by gray whales is unusual. In the prior 10 years of the TOPAZ project, few whales have been tracked foraging in this area near Hell’s Gate, but rather most whales have foraged in the Mill Rocks and Tichenor Cove areas. It is interesting to think about why the whales are behaving differently this year. Maybe this is due to variations in prey availability at these different sites. In recent years, Port Orford has been affected by a surge in purple sea urchin density, which have overgrazed the once prominent kelp forests here. A high urchin density decreases the kelp condition, which then leads to less habitat for zooplankton, creating a decline in prey availability for gray whales (Hildebrand et al., 2024). Upon reflection of my time on the kayak, I have noticed minimal kelp and low zooplankton abundance when conducting our zooplankton drops in our Mill Rocks and Tichenor Cove study sites. Additionally, I have also noticed many purple sea urchins in our GoPro videos. With the effects of this trophic cascade in mind, not observing any gray whales in our traditional study sites is understandable. With these gray whales more commonly seen near Hell’s Gate this year, I am curious to know what prey is attracting them there. Perhaps it is a different type of prey species or one that is high in caloric value than what is in the Mill Rocks and Tichenor Cove areas.

Fig. 4: Intern Nautika Brown looking at Hell’s Gate through the binoculars. Hell’s Gate is the passage between the two large boulders in the distance.

From actively observing whales and learning from my mentor, Celest, I have started to understand that behavior is a critical piece to any form of studying gray whales (and all species). By integrating photo-ID and theodolite tracking, we can learn so much about whale behavior, from where they eat, who is spending time where, and how they may adjust their behavior in response to a changing environment. The TOPAZ/JASPER internship has allowed me to truly comprehend what field research is like, how studying the behaviors of an individual is important, and how detail and patience are extremely necessary when collecting data. As this summer is continuing, I wonder if we will continue to see gray whales primarily feeding in the Hell’s Gate area, or if we will start to observe them more in the Mill Rocks and Tichenor Cove sites like previous years. The thrill of seeing gray whales is unlike any other, and I am so ready to see more whales this season!

References:

Bird, C. N., Pirotta, E., New, L., Bierlich, K. C., Donnelly, M., Hildebrand, L., Fernandez Ajó, A., & Torres, L. G. (2024). Growing into it: Evidence of an ontogenetic shift in grey whale use of foraging tactics. Animal Behaviour, 214, 121–135. https://doi.org/10.1016/j.anbehav.2024.06.004

Hildebrand, L., Derville, S., Hildebrand, I., & Torres, L. G. (2024). Exploring indirect effects of a classic trophic cascade between urchins and kelp on zooplankton and whales. Scientific Reports, 14(1), 9815. https://doi.org/10.1038/s41598-024-59964-x

Hildebrand, L, Sullivan, F. A., Orben, R. A., Derville. S., Torres L. G. (2022) Trade-offs in prey quantity and quality in gray whale foraging. Mar Ecol Prog Ser 695:189-201 https://doi-org.oregonstate.idm.oclc.org/10.3354/meps14115

A pinch of salty, silly, and science-y: meet Team Dabwich

Celest Sorrentino, GEMM Lab Master’s student, OSU Department of Fisheries, Wildlife and Conservation Sciences, Geospatial Ecology of Marine Megafauna Lab 

As a loyal and trusted GEMM Lab blog reader, I am sure you know just what time of year it is: the beginning of the 11th annual TOPAZ/JASPER field season where we study whales and their prey while also training the next generation of scientists. The start of the season has been kicked into high tail already and we have many updates to share. Fear not, dear reader, as I am here to release you from relentlessly refreshing your inbox for the long-awaited introduction of the TOPAZ/JASPER team that is taking the project into their second decade.

But first, to appreciate the present milestone, it’s worth revisiting the legacy of those who guided us to this moment. The TOPAZ/JASPER  projects began in 2015, with PI. Dr. Leigh Torres and master’s student Florence Sullivan (2015-2018), and continued forward with Lisa Hildebrand (2018-2021), and Allison Dawn (2022-2024). Now, as a new droplet in this stream of brilliant leaders before me, I feel immense gratitude to be the master’s student leading the TOPAZ/JASPER team this summer. Having been trained by Allison Dawn with Team Protein in 2024, and full unwavering support from Leigh and each leader before me, I enter this new role with confidence and excitement for the next six gray-whale-and-zooplankton filled weeks of data collection. Now, let’s meet the young scientist interns for 2025!

(Left picture) Maddie (right) with Nautika (top) and Celest (left) during their kayak training.
(Right picture) Photo Maddie took of a humpback in the Port Orford Bay.

Madison (Maddie) Honomichl is a senior wrapping up her last  semester of undergrad at CSU Monterrey Bay this fall to gain a degree in Marine Science. As the GEMM Lab’s REU intern this summer, Maddie began her internship in June by joining me in Newport to learn more about gray whale and pymgy blue whale mother-calf relationships. Without spoiling too much (you’ll hear more from her in her blog post in just a few weeks!) her project focuses on capturing mother-calf blow synchrony of gray and blue whales in drone footage. Now in Port Orford, her gifted talent for photography has been excellent in helping capture photos of traveling whales on the cliff.

(Left picture) Nautika finding a purple urchin after a successful zooplankton drop at our station MR 18.
(Right picture) Miranda(front) and Nautika(rear) after their first kayak training, where Nautika accidentally fell into the water but got back on the kayak in record breaking time, still in good spirits to dab!

Nautika Brown is one of our high school interns from Coulee Dam, Washington. Having just graduated, Nautika’s ambition and passion for studying wildlife lead her to apply to our TOPAZ/JASPER project and we are so happy she did. Accidentally hilarious, she has made everything from kayak training to zooplankton identification that much more enjoyable—reminding the team to have some fun while still getting the job done.

(Left picture) Dawson leading the team with the heavy theodolite stand up to the cliff.
(Right picture) The team hyper locked in on tracking a humpback whale in the bay, working together to describe the position of the whale for Dawson on the theodolite.

Dawson Mohney is our Port Orford local, having recently graduated from Pacific High School in May. Though he might not know the best spots around town, Dawson’s demeanor mirrors that of Port Orford itself: kind, welcoming, and always helpful. Always up for any task, he is the first to ask if anyone needs help with carrying equipment up to the cliff or cooking a ground beef refried beans mash for team dinner. Come fall Dawson is excited to start his first semester at Southwestern Oregon Community college.

(Left picture) Miranda enjoying an outdoor stroll of Port Orford beaches.
(Right picture) Miranda stoked on catching so many atylus tridens for her first kayak training day!

Miranda Fowles is a recent graduate at Oregon State University having completed her major in Fisheries, Wildlife, and Conservation Sciences with a minor in Spanish. Originally from Seattle, her childhood memories include kayaking with her family, so ocean kayaking has come naturally. Miranda’s genuine curiosity shines through in her eagerness to ask questions about whale life histories and their social dynamics. She’s expressed a clear passion for continuing her journey in marine science and academia.

We are now T-minus 2 days until the last of the team’s training period, and we couldn’t be more thrilled for the 4 more weeks to come. Through unexpected wildlife sightings and spontaneous team jokes, our team has only grown stronger and more connected. For all of the interns, this experience is not only their first experience with marine fieldwork, but also their longest. Training days have been both rewarding and physically strengthening; we’ve watched harbor seals lounging between Mill Rocks and tracked a particularly active humpback whale that keeps surfacing in the bay—all while developing what we now call our “ultimate kayak muscles.” By the time lunch rolls around, it feels like an ultimate power recharge, to continue forward with data processing. As any marine field scientist will tell you: there’s something deeply satisfying about coming back to shore and sinking your teeth into a handmade sandwich.

And speaking of our absolute craving for sandwiches, this team has unexpectedly brought back the 2010s dab—with such enthusiasm that it was only right to fuse “dab” with our love for chips-in-sandwiches. With this, I share with your our new, very official team name:

Team Dabwich.

With the right amount of salty, silly, and scienc-y, Team Dabwich is ready to crush the 11th TOPAZ/JASPER field season.

Team Dabwich dabbing right before a successful kayak training
ヽ(⌐_⌐ゞ)!

New GEMM Lab study indicates troubled times for PCFG gray whales

Dr. Enrico Pirotta (CREEM, University of St Andrews) and Dr. Leigh Torres (GEMM Lab, MMI, OSU)

The health of animals affects their ability to survive and reproduce, which, in turn, drives the dynamics of populations, including whether their abundance trends up or down. Thus, understanding the links between health and reproduction can help us evaluate the impact of human activities and climate change on wildlife, and effectively guide our management and conservation efforts. In long-lived species, such as whales, once a decline in population abundance is detected, it can be too late to reverse the trend, so early warning signals are needed to indicate how these populations are faring.

We worked on this complex issue in a study that was recently published in the Journal of Animal Ecology. In this paper, we developed a new statistical approach to link three key components of the health of a Pacific Coast Feeding Group (PCFG) gray whale (namely, its body size, body condition, and stress levels) to a female’s ability to give birth to a calf. We were able to inform these metrics of whale health using an eight-year dataset derived from the GRANITE project of aerial images from drones for measurements of body size and condition, and fecal samples for glucocorticoid hormone analysis as an indicator of stress. We combined these data with observations of females with or without calves throughout the PCFG range over our study period.

We found that for a female to successfully have a calf, she needs to be both large and fat, as these factors indicate if the female has enough energy stored to support reproduction that year (Fig. 1). Remarkably, we also found indication that females with particularly high stress hormone levels may not get pregnant in the first place, which is the first demonstration of a link between stress physiology and vital rates in a baleen whale, to our knowledge.

Figure 1. Taken from Pirotta et al. (2025), Fig. 5. Combined relationship of PCFG gray whale length and nutritional state (combination of body size and condition) in the previous year with calving probability, colored by whether the model estimated an individual to have calved or not at a given reproductive opportunity.

Our study’s findings are concerning given our previous research indicating that gray whales in this PCFG sub-group have been growing to shorter lengths over the last couple of decades (Pirotta et al. 2023), are thinner than animals in the broader Eastern North Pacific gray whale population (Torres et al, 2022), and show an increase in stress-related hormones when exposed to human activities (Lemos et al, 2022; Pirotta et al. 2023). Furthermore, in our recent study we also documented that there are fewer young individuals than expected for a growing or stable population (Fig. 2), which can be an indicator of a population in decline since there may not be many individuals entering the reproductive adult age groups. Altogether, our results act as early warning signals that the PCFG may be facing a possible population decline currently or in the near future.

Figure 2. Taken from Pirotta et al. (2025), Fig. 1. Age structure diagram for 139 PCFG gray whales in our dataset. Each bar represents the number of individuals of a given age in 2023, with the color indicating the proportion of individuals of that age for which age is known (vs. estimated from a minimum estimate following Pirotta, Bierlich, et al., 2024). The red line reports a smooth kernel density estimate of the distribution.

These findings are sobering news for Oregon residents and tourists who enjoy watching these whales along our coast every summer and fall. We have gotten to know many of these whales so well – like Scarlett, Equal, Clouds, Lunita, and Pacman, who you can meet on our IndividuWhale website – that we wonder how they will adapt and survive as their once reliable habitat and prey-base changes. We hope our work sparks collective and multifaceted efforts to reduce impacts on these unique PCFG whales, and that we can continue the GRANITE project for many more years to come to monitor these whales and learn from their response to change.

This work exemplifies the incredible value of long-term studies, interdisciplinary methods, and effective collaboration. Through many years of research on this gray whale group, we have collected detailed data on diverse aspects of their behavior, ecology and life history that are critical to understanding their response to disturbance and environmental change, which are both escalating in the study region. We are incredibly grateful to the following members of the PCFG Consortium for contributing sightings and calf observation data that supported this study: Jeff Jacobsen, Carrie Newell, NOAA Fisheries (Peter Mahoney and Jeff Harris), Cascadia Research Collective (Alie Perez), Department of Fisheries and Oceans, Canada (Thomas Doniol-Valcroze and Erin Foster), Mark Sawyer and Ashley Hoyland, Wendy Szaniszlo, Brian Gisborne, Era Horton.

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References:

Lemos, Leila S., Joseph H. Haxel, Amy Olsen, Jonathan D. Burnett, Angela Smith, Todd E. Chandler, Sharon L. Nieukirk, Shawn E. Larson, Kathleen E. Hunt, and Leigh G. Torres. “Effects of Vessel Traffic and Ocean Noise on Gray Whale Stress Hormones.” Scientific Reports 12, no. 1 (2022): 18580. https://dx.doi.org/10.1038/s41598-022-14510-5.

Pirotta, Enrico, K. C. Bierlich, Leslie New, Lisa Hildebrand, Clara N. Bird, Alejandro Fernandez Ajó, and Leigh G. Torres. “Modeling Individual Growth Reveals Decreasing Gray Whale Body Length and Correlations with Ocean Climate Indices at Multiple Scales.” Global Change Biology 30, no. 6 (2024): e17366. https://doi.org/https://doi.org/10.1111/gcb.17366. https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.17366.

Pirotta, Enrico, Alejandro Fernandez Ajó, K. C. Bierlich, Clara N Bird, C Loren Buck, Samara M Haver, Joseph H Haxel, Lisa Hildebrand, Kathleen E Hunt, Leila S Lemos, Leslie New, and Leigh G Torres. “Assessing Variation in Faecal Glucocorticoid Concentrations in Gray Whales Exposed to Anthropogenic Stressors.” Conservation Physiology 11, no. 1 (2023). https://dx.doi.org/10.1093/conphys/coad082.

Torres, Leigh G., Clara N. Bird, Fabian Rodríguez-González, Fredrik Christiansen, Lars Bejder, Leila Lemos, Jorge Urban R, et al. “Range-Wide Comparison of Gray Whale Body Condition Reveals Contrasting Sub-Population Health Characteristics and Vulnerability to Environmental Change.” Frontiers in Marine Science 9 (2022). https://doi.org/10.3389/fmars.2022.867258. https://www.frontiersin.org/article/10.3389/fmars.2022.867258

The Hitchhiker’s Guide to the Gray Whale: Cetacean Cyamid Coverage Explained

By Natalie Chazal, PhD student, OSU Department of Fisheries, Wildlife, & Conservation Sciences, Geospatial Ecology of Marine Megafauna Lab

When most people think about monitoring the health of a 40-ton gray whale, they picture blubber thickness, dive patterns, or perhaps growth rates. But what if some of the most telling signs are found not in the whale’s bulk, but right on the surface–embedded in its skin, and even crawling across it?

As part of the GRANITE project, my research focuses on using a long-term photographic dataset (>347,000 photos from 10 years!) to evaluate epidermal indicators of stress and health in Pacific Coast Feeding Group (PCFG) gray whales (Eschrichtius robustus) foraging off the Oregon coast. My central questions ask:

  • Can we use features visible on the skin like epidermal diseases, lesion severity, scarring from orcas, boats, and fishing gear, and potentially cyamid loads as biomarkers of physiological stress or nutritional status?
  • How do these skin-based indicators correlate with environmental variables, prey availability, fecal hormones, and overall body condition?

By tracking these patterns across individuals and years, my goal is to understand how gray whales are responding to a changing ocean and whether their skin can tell us more about what’s under the surface.

What are cyamids?

Cyamids, more commonly known as “whale lice”, are small crustaceans that live exclusively on marine mammals. Despite their nickname, cyamids are not true lice—they’re actually amphipod ectoparasites, more closely related to beach hoppers than anything you’d find in your hair. For gray whales (Eschrichtius robustus), these tiny passengers are a constant presence throughout their lives.

Figure 1. Gray whale blow hole area covered in barnacles and cyamids. The circle inset shows a zoomed in area where you can see the orange cyamids aggregating near the more yellow barnacles.

Each whale can host thousands of cyamids at a time, with individuals often clustering in specific areas of the body that provide physical refuge from the currents: around the blowhole, in the crevices of flukes, along the rostrum, genital slits, and especially around wounds or skin irregularities (Figure 1). Unlike barnacles, which attach directly to the skin and remain stationary while they feed on nutrients in the passing water, cyamids grasp onto the whale’s body using claw-like appendages, feeding on sloughed skin and bodily fluids. This relationship is generally not thought to be harmful to the whale, but high cyamid loads can be indicative of poor health, injury, or compromised immune function.

There are several species of cyamids, and many are host-specific—meaning they’ve evolved alongside particular whale species. In gray whales, the most common is Cyamus scammoni, which specializes on gray whales and is rarely found elsewhere. Other species found on gray whales include Cyamus kessleri, and the rarer Cyamus ceti. Cyamids are transmitted primarily from mother to calf, which helps explain their host fidelity, but horizontal transmission (between unrelated individuals) may also occur during close contact which can explain some rare occurrences of cyamids that are found outside of their general host species. In fact, Cyamus ceti was only found once on gray whales in 1861 but is generally thought to be specific to bowhead whales, giving us potential insight into interspecies interactions (bowhead and gray whales can spatially overlap on Arctic foraging grounds).

Figure 2. Cyamus scammoni close up photographs of (A) aggregation, (B) juvenile stage, (C) dorsal side of an adult, and (D) ventral side of an adult showcasing the cyamids corkscrew shaped gills (Takeda et al. 2005)

Because cyamids are permanent residents of the whale’s skin, they offer a unique window into both individual whale life histories and broader ecological trends. Their location, abundance, and distribution can potentially inform us about wound healing, residency duration in foraging areas, and even stress or health status—which makes them an unexpectedly valuable focal point in drone and photograph-based monitoring efforts like in the GRANITE project.

Cyamid Life History

Cyamids are obligate ectoparasites, meaning they spend their entire life on a whale and cannot survive independently in the open ocean. Unlike free-swimming crustaceans, cyamids are permanently attached to the skin or embedded within crevices of the whale’s body, often clinging to roughened areas, scars, embedded barnacles, or calloused skin where they can anchor themselves more securely.

They begin life as tiny juveniles, hatching from eggs carried in the brood pouch of a female cyamid. Rather than undergoing a larval phase in the water column like many marine invertebrates, cyamids develop directly into miniature versions of adults and remain on the whale from birth. This direct development is essential because there’s no safe habitat for a larval cyamid in the open ocean: the host whale is both nursery and home.

Most transmission occurs from mother to calf during the close physical contact of early life. Calves born in the warm lagoons of Baja California, Mexico where gray whales calve and nurse during the winter inherit their cyamid colonies during nursing, rubbing, and swimming alongside their mothers. These early colonizers will multiply as the calf grows and can remain with the whale for years, forming the basis of a persistent, host-specific population.

For Cyamus scammoni specifically (our gray whale specific cyamid), adults will breed in the summer just before the southbound migration. Females will have around 1,000 eggs in their brood pouch, although only about a 60% are fertilized (Leung, 1976). These eggs will hatch in the fall while the gray whales take on their southbound migration but they will stay in the safety of the brood pouch for around 2 to 3 months. The juveniles will be released in the winter, when gray whales arrive in the Baja lagoons where they will then find shelter within the crevices of their host gray whale. Juveniles reach maturity during the northbound migration and will be a full-grown brood upon arrival to summer grounds. While the cycle takes about 8 months to complete, there are juveniles found along the gray whales year-round, leading us to believe that there is likely overlap between broods. For our less abundant Cyamus kessleri, the life cycle is very similar, but the juveniles reach maturity before the gray whales northbound migration to summer feeding grounds. Also, there are around 300 eggs in the Cyamus kessleri brood pouches that have a higher rate of fertilization (75-80%) than Cyamus scammoni (60%) (Leung, 1976)

In short, the life of a cyamid is fully bound to the life of a whale. Every migration, dive, foraging event, and scar the whale experiences becomes part of the cyamid’s environment. By studying them, we gain another lens through which to interpret the health, behavior, and ecology of gray whales on the Oregon Coast.

Uses in Cetacean Health Assessments

As we’ve established, cyamids have unique life histories as ectoparasites and may be valuable indicators in cetacean health assessments across multiple whale species. Because they often congregate around wounds, lesions, and areas of poor skin integrity, their presence and distribution can reveal important clues about a whale’s physical condition, injury history, and immune response. However, studies that have made these connections have variable results.

In species like North Atlantic right whales (Pettis et al. 2004, Pirotta et al. 2023), harbor porpoises (Lehnert et al. 2021), and gray whales (Raverty et al. 2024), researchers have used visual surveys and photographic analysis to quantify cyamid loads in living, stranded, and hunted whales. Researchers can score cyamid presence by identifying attachment sites (e.g. blowhole, scar, dorsal ridge) and estimating the relative coverage by using standardized reference images to maintain consistency. In these studies, whales with heavy cyamid coverage, especially in sensitive regions like the blowhole, mouthline, and genital area, often show signs of poor health or stress, such as emaciation, scarring from entanglement, or chronic skin conditions. Cyamid coverage is sometimes used alongside body condition indices and lesion scoring to build a more complete health profile (Pirotta et al. 2023). There are also studies that show no connections, or even positive connections between body condition and cyamid coverage (Von Duyke et al. 2016).

While cyamids are often associated with injured, inflamed, or otherwise damaged skin, there is no evidence that points towards cyamids directly damaging the skin themselves. However, more work needs to be done to assess their role in the healing processes. Additionally, it’s been noted that more work is needed on the role of cyamids and disease spread (Overstreet et al. 2009). For the PCFG, there is an iconic whale we call “Scarlett” (also known as “Scarback”) who has a large scar on the right side of her back that is highly identifiable due to the orange swarm of cyamids that are constantly surrounding the edges of the wound. She has managed to survive and thrive, producing many calves over the years, but questions remain: How are the cyamids affecting the healing process? Are they increasing or decreasing the risk of infection? How does the frequency of large injuries like this on whales contribute to the cyamid population over evolutionary time?

Figure 3. Right side of PCFG icon, “Scarlett” showing her massive scar covered with orange aggregations of cyamids.

Because whales are complex, highly mobile, long-lived creatures with a constant population of cyamid hitchhikers their skin condition is likely representative of specific to life history, phylogeography, and demographic traits of individuals. While we know that cyamids generally eat sloughed or damaged skin on the whale, what this behavior and symbiosis means for each whale’s individual physiology can be highly complex. Through our high-resolution drone and lateral imagery of the same individuals over time paired with other data sources, such as body condition and prey availability, cyamid scores can offer key insights into how environmental stressors and foraging success affect individual and population-level whale health.

These tiny crustaceans, clinging to the folds and scars of their hosts, might seem like background noise in a study focused on body condition or foraging ecology—but they’re far from incidental. In my research, I’ve come to see cyamids as part of the bigger story: silent indicators of stress, recovery, movement, and resilience. By pairing imagery of PCFG gray whale skin with data on prey availability and environmental conditions, I’m working to understand how foraging success and anthropogenic stressors (such as vessel traffic and entanglements) manifest not just in a whale’s body condition, but in the skin itself. The presence, distribution, and density of cyamids may offer yet another layer of insight into how gray whales are coping with changing ocean conditions. It’s a reminder that even the smallest details, like a patch of whale lice, can help us ask bigger questions about the health, resilience, and future of these cetaceans.

References

Callahan, C.M., n.d. MOLECULAR SYSTEMATICS AND POPULATION GENETICS OF WHALE LICE (AMPHIPODA: CYAMIDAE) LIVING ON GRAY WHALE ISLANDS.

Lehnert, K., IJsseldijk, L.L., Uy, M.L., Boyi, J.O., van Schalkwijk, L., Tollenaar, E.A.P., Gröne, A., Wohlsein, P., Siebert, U., 2021. Whale lice (Isocyamus deltobranchium & Isocyamus delphinii; Cyamidae) prevalence in odontocetes off the German and Dutch coasts – morphological and molecular characterization and health implications. International Journal for Parasitology: Parasites and Wildlife 15, 22–30. https://doi.org/10.1016/j.ijppaw.2021.02.015

Leung, Y., 1976. Life cycle of cyamus scammoni (amphipoda: cyamidae), ectoparasite of gray whale, with a remark on the associated species. Scientific Reports of the Whales Research Institute 28, 153–160.

Overstreet, R.M., Jovonovich, J., Ma, H., 2009. Parasitic crustaceans as vectors of viruses, with an emphasis on three penaeid viruses. Integrative and Comparative Biology 49, 127–141. https://doi.org/10.1093/icb/icp033

Pettis, H.M., Rolland, R.M., Hamilton, P.K., Brault, S., Knowlton, A.R., Kraus, S.D., 2004. Visual health assessment of North Atlantic right whales (Eubalaena glacialis) using photographs. Can. J. Zool. 82, 8–19. https://doi.org/10.1139/z03-207

Pirotta, E., Schick, R.S., Hamilton, P.K., Harris, C.M., Hewitt, J., Knowlton, A.R., Kraus, S.D., Meyer-Gutbrod, E., Moore, M.J., Pettis, H.M., Photopoulou, T., Rolland, R.M., Tyack, P.L., Thomas, L., 2023. Estimating the effects of stressors on the health, survival and reproduction of a critically endangered, long-lived species. Oikos 2023, e09801. https://doi.org/10.1111/oik.09801

Raverty, S., Duignan, P., Greig, D., Huggins, J.L., Huntington, K.B., Garner, M., Calambokidis, J., Cottrell, P., Danil, K., D’Alessandro, D., Duffield, D., Flannery, M., Gulland, F.M., Halaska, B., Lambourn, D.M., Lehnhart, T., Urbán R., J., Rowles, T., Rice, J., Savage, K., Wilkinson, K., Greenman, J., Viezbicke, J., Cottrell, B., Goley, P.D., Martinez, M., Fauquier, D., 2024. Gray whale (Eschrichtius robustus) post-mortem findings from December 2018 through 2021 during the Unusual Mortality Event in the Eastern North Pacific. PLoS One 19, e0295861. https://doi.org/10.1371/journal.pone.0295861

Stimmelmayr, R., Gulland, F.M.D., 2020. Gray Whale (Eschrichtius robustus) Health and Disease: Review and Future Directions. Front. Mar. Sci. 7. https://doi.org/10.3389/fmars.2020.588820

Takeda, M., Ogino, M., n.d. Record of a Whale Louse, Cyamus scammoni Dall (Crustacea: Amphipoda: Cyamidae), from the Gray Whale Strayed into Tokyo Bay, the Pacific Coast of Japan.

Von Duyke, A.L., Stimmelmayr, R., Sheffield, G., Sformo, T., Suydam, R., Givens, G.H., George, J.C., 2016. Prevalence and Abundance of Cyamid “Whale Lice” (Cyamus ceti) on Subsistence Harvested Bowhead Whales (Balaena mysticetus). Arctic 69, 331–340.

Würsig, B., Thewissen, J.G.M., Kovacs, K.M., 2017. Encyclopedia of Marine Mammals. Elsevier Science & Technology, Chantilly, UNITED STATES.

The whale’s scale: Emphasizing the scale of process, not the scale of observation

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

Baleen whales must navigate a seemingly featureless world to locate the resources they need to survive. The task of finding prey to feed on in the vast seascapes relies on the use of several sensory modalities that operate at different scales (Torres 2017; Figure 1). For example, baleen whale vision is believed to be rather limited, with the ability to see objects about 10-100 meters away. Yet, baleen whale somatosensory perception of oceanographic stimuli is thought to be on the order of 100-1000s kilometers. This diversity in sensory ability has led scientists to believe that whales, in fact all animals, perceive cues and make decisions at several scales. As ecologists, we endeavor to understand why and when animals are found (or not found) in certain locations as this knowledge allows us to better manage and conserve animal populations. With this information we can aim to minimize potential anthropogenic disturbance and protect important resource areas, such as foraging or nursing grounds. In order to accomplish this goal, we ourselves must conduct studies and test hypotheses at several scales (Levin 1992; Hobbs 2003). As someone who tackles spatial foraging ecology questions, I am particularly interested in understanding whale behavior and movement in the context of feeding. Since accurately measuring predator and prey distribution at the same scales can be challenging, we often resort to environmental variables to serve as proxies for prey, whereby we look for correlations between environmental variables and whales to understand and predict the distribution of our population. 

Figure 1. Schematic of hypothetical interchange of sensory modalities used by baleen whales to locate prey at variable scales. X-axis represents log distance to prey from micro (left) to macro (right). Y-axis represents the relative use of each sensory modality between 0 (no contribution) to 10 (highest contribution). Each line and color represent a different sensory modality. Figure taken and caption adapted from Torres 2017.

What do I mean when I use the word ‘scale’? The term scale is typically explained by two components: grain and extent (Wiens 1989). The grain is the finest resolution measured; in other words, how detailed we are measuring. The extent is the overall coverage of what we are measuring. These components can be applied to both spatial scale and temporal scale. For example, spatially, if we were using a 1×1 meter sampling quadrat to count the number of crabs on a rocky shore, then our grain would be the 1 m2 quadrat and the extent would be the entire exposed rocky intertidal area that we are surveying (Figure 2). Temporally, if we placed a temperature logger at the mouth of Yaquina Bay that took a temperature recording every minute for two years, then our grain would be one minute and the extent would be two years. So, when designing a study, it is imperative for us to decide on the spatiotemporal scales of the ecological questions we are asking and the hypotheses we are testing, as it will inform what data we need to collect. When making this decision, it is important to think about the scale at which the ecological process happens, as opposed to the scale at which we can observe the process (Levin 1992). In other words, we need to think from the perspective of our study species, as opposed to from our own human perspective. Making informed and ecologically reasonable decisions regarding the choice of scale relies on having prior knowledge of an animal’s biology, such as knowing that baleen whales might see a prey patch that is 50 meters away, but it may also somatosensorily perceive an oceanic front where zooplankton prey aggregate from 500 kilometers away.

Figure 2. Schematic of spatial scale where the extent (depicted by dashed orange box) is the entire exposed rocky intertidal area being surveyed and the grain (solid yellow box) is the 1×1 m quadrat being used to count crabs.

There is a wealth of studies that have explored space use patterns of wildlife relative to environmental variables to better understand foraging behavior. I want to share a couple from the marine mammal realm with you that I find particularly fascinating. In their 2018 study, González García and colleagues used opportunistic sightings of blue whales around the Azorean islands of Portugal and modeled their distribution patterns relative to physiographic and oceanographic variables summarized at different spatial (fine [1-10 km] and meso [10-100 km]) and temporal (daily, weekly, monthly) scales. The two variables that were most correlated with blue whale occurrence was distance from the coast and eddy kinetic energy (a measure of mesoscale variability of ocean dynamics). Both of these variables were interestingly found to be scale invariant, meaning that no matter which spatial and temporal scale was investigated, the relationship between blue whales and these two variables stayed the same; blue whale occurrence increased with increasing distance from the coast and was maximal at an eddy kinetic energy value of 0.007 cm2/s2 (Figure 3).

Figure 3. Functional response curves between presence of Azorean blue whales and distance to the coast (panel 1 on left) and eddy kinetic energy (panel 2 on right). The top row of each panel represents the low spatial scale and the bottom row represents the high spatial scale. Each column represents a different temporal scale (from left to right: daily, weekly, monthly). Note that the general shape of the relationship remains similar across all spatiotemporal scales and that the peak of the curves tend to occur at the same values for distance to coast and eddy kinetic energy across all scales. Figures taken from González García et al. 2018.

However, not all studies find scale invariant relationships. For example, Cotté and co-authors (2009) found that habitat use of Mediterranean fin whales was very much scale dependent. At a large scale (700-1,000 km and annual), fin whales were more densely aggregated during the summer in the Western Mediterranean where there was consistently colder water than in the winter. However, at a meso scale (20-100 km and weekly-monthly), fin whale densities were highest in areas where there were steep changes in temperature, as opposed to consistently cold temperatures. The authors explain that these differences in fin whale density and temperature at different scales are likely due to whale movement being driven by annually persistent prey abundance at the large scale, but at the meso scale, where prey aggregations are less predictable, the fin whales’ distribution becomes more driven by areas of physical ocean mixing.

As I investigate the environmental drivers of individual gray whale space use using our 8-year GRANITE (Gray whale Response to Ambient Noise Informed by Technology and Ecology) dataset, these studies (and many more) are at the top of my mind to interpret the patterns we are detecting. Our goal is to quantify and describe what environmental conditions (1) lead to a higher probability of a gray whale being seen in our central Oregon coast study area (~70 km) at a daily scale, and (2) influence space use patterns (activity range, residency, activity center) of different individual whales at annual scales. Our results show both consistency and variation in the environmental drivers of gray whales across these scales, leading me to deeply consider how gray whales make decisions at different points in their lives, based on information gained through various senses, to maximize their chances of capturing food. Previous work from the GEMM Lab on the relationships between gray whales and prey, at both fine (read more here) and large (read more here) scales have guided my work by providing specific hypotheses regarding environmental variables and lag times for me to test. Investigating the environmental drivers of animal space use and behavior is exciting work as it reveals that no single environmental variable determines animal distribution, but rather that multiple processes are happening concomitantly that animals respond to at different scales continually. It is only by studying animal space use patterns across spatiotemporal scales that we can begin to understand their complex decision-making patterns.

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References

Cotté, C., Guinet, C., Taupier-Letage, I., Mate, B., & Petiau, E. (2009). Scale-dependent habitat use by a large free-ranging predator, the Mediterranean fin whale. Deep Sea Research Part I: Oceanographic Research Papers, 56(5), 801-811.

González García, L., Pierce, G. J., Autret, E., & Torres-Palenzuela, J. M. (2018). Multi-scale habitat preference analyses for Azorean blue whales. PLoS One, 13(9), e0201786.

Hobbs, N. T. (2003). Challenges and opportunities in integrating ecological knowledge across scales. Forest Ecology and Management, 181(1-2), 223-238.

Levin, S. A. (1992). The problem of pattern and scale in ecology: the Robert H. MacArthur award lecture. Ecology, 73(6), 1943-1967.

Torres, L. G. (2017). A sense of scale: Foraging cetaceans’ use of scale‐dependent multimodal sensory systems. Marine Mammal Science, 33(4), 1170-1193.

Wiens, J. A. (1989). Spatial scaling in ecology. Functional ecology, 3(4), 385-397.

Are You Seeing Scars Too?: Examining Gray Whale Scars and Skin Conditions

By Serina Lane, GEMM Lab NSF REU Intern, Georgia Gwinnett College

Hello, everyone! My name is Serina and I’m a Research Experience for Undergraduates (REU) Intern at the Hatfield Marine Science Center (HMSC) this summer. I’ve had a love for the ocean for as long as I can remember. Honestly, it started off with just dolphins, but I soon started to realize that the ocean is full of fascinating creatures!

How I ended up here…well, I’ve never been to Oregon, I’m escaping the hot weather of Georgia, but I’m also getting to interact with like-minded marine biologists and experienced individuals at an amazing marine laboratory. At the age of 29, I’m also an older undergraduate student, and I will be graduating soon! I took a very long break from academics and coming back was hard, especially switching from business to biology. I have participated in surveys that asked how I felt about the statement “I am a scientist,” along with the degrees of agree and disagree. For most of my undergraduate career, I picked “slightly disagree”. I was getting great grades, but I did not feel like I was ever going to be able to accomplish the type of work scientific papers are written about. I really felt the need to gain more experience in the career path I intended to follow. All of these are the whirlwind ingredients that went into applying for the HMSC REU Internship at OSU! I’m being mentored by the lovely Natalie Chazal and Leigh Torres, and I am grateful for the opportunity and very excited to experience everything Hatfield has to offer. A little over a week of being here, I already feel my answer sliding from “neutral” to even “slightly agree”. There is still so much to learn!

The project I’m helping with is analyzing the scarring and skin conditions of Eastern North Pacific gray whales alongside the GRANITE team. My job will be analyzing over 100,000 pictures from the past eight years to detect various scars and potential skin conditions (yes, the comma is in the correct spot and no, there are no extra 0’s). Scars can come from a variety of sources such as boat propellers, fishing gear, and killer whales! A study conducted by Corsi et al. consisted of documenting killer whale rake marks (bites, essentially) on different types of whales in the eastern North Pacific. Their results showed that gray whales had the highest percentage of observed rake marks in sighted individuals, and provided insight into why body sections of observed marks are important. Most baleen whales had rake marks predominantly on their flukes, because they are often used for defense and if fleeing, are the closest area to bite. Fascinatingly, Corsi et al. consider that the higher occurrences of gray whale rake marks are due to killer whales adopting species-specific hunting approaches. Gray whales have predictable migratory routes, and we already know how intelligent killer whales can be. If I knew a truck had a specific delivery route and I could wait to intercept a fresh delivery of Krispy Kreme donuts, why wouldn’t I? 

Donuts aside, I’ll also be categorizing where the scars/skin conditions are located – for example, certain regions on the tail (like above) or on their left or right back (often due to boat collisions). Then I’ll define what I believe to be the source of scarring and rate my confidence in that decision based on the photo. Now, not all of the photos are clear enough for me to make informed decisions, so realistically I could end up with only a few hundred usable photos. At the end of the summer, we’ll gather the results and compare the different rates of scarring sources and the body parts where they occurred, and analyze any patterns in skin conditions, such as whether a skin condition has worsened or improved on an individual we have sighted multiple times over the years.

 Figure 1. A little look into a table I made to give examples of what scarring from different sources look like.

Surprisingly, cetaceans can heal deep wounds on their own without medical intervention. Scientists have discovered that compounds in their blubber layer, such as organohalogens and isovaleric acid, may naturally fight off infections and help wounds heal faster. Unlike humans and other terrestrial animals that form scabs when injured, cetaceans develop a different protective layer over their wounds. This layer consists of degenerative cells mixed with tiny bubbles and covers the injured area. This unique adaptation might help protect the wound from seawater and other environmental factors. While there have been studies on how surface wounds heal in captive dolphins and whales, there’s still much to learn about how these animals heal large, deep wounds. Understanding how wounds heal can help us to more accurately assess the frequency at which whales are wounded, whether it be from fishing gear or boats, to cookie cutter sharks or killer whales.

It seems like a lot, and it is, but our ultimate goal is to assess the effects that scarring and skin conditions can have in the ecology of marine megafauna. Assessing the individual gray whales in the photos can provide a bigger picture of the health of a whole population. We can also look for any patterns of skin conditions between mother and calf, individuals that are around each other often, adults and juveniles, or males and females. Scars may also play a role in a population’s health. If a gray whale had an open wound previously, did it develop into a skin condition? Did a skin condition worsen? Did it leave them more vulnerable to predators? These are the questions we would like to elaborate on with this research. A great read on this topic was conducted by Dawn R. Barlow, Acacia L. Pepper and Leigh G. Torres, which will be in the references below (Barlow et al., 2019). A better understanding of potential patterns is a better assessment of our current marine management practices. Is it enough, or do we need to change and do more?

Okay, lastly, let’s talk about artificial intelligence (AI). Would using AI methods for this project make our lives easier? Yes. If we could train AI to accurately identify specific scars and skin conditions, our 100,000 photos could be done within minutes. For my job security, woo no AI! But on a serious note, this approach could free up time that could be spent on other efforts, or speed up the process of assessing marine management. However, we gain so much by reviewing the photos ourselves which is still important to do when training AI on what specifics to search for. Over the summer, I’m going to get to know different whales and see how they may change over 8 years, just by their pictures. My excitement grew as soon as I looked at my first 3 gray whales and learned their names. It’s forever important to remember that we can always learn from sharing connections with the organisms we study and interact with. We share the same planet and we have to work together to preserve it. I thank you all for taking a trip through our summer research with me and I hope to meet some of you around Hatfield!

References

Barlow, D. R., Pepper, A. L., & Torres, L. G. (2019a). Skin deep: An assessment of New Zealand blue whale skin condition. Frontiers in Marine Science, 6. https://doi.org/10.3389/fmars.2019.00757 

Bradford, A. L., Weller, D. W., Ivashchenko, Y. V., Burdin, A. M., & Brownell, Jr, R. L. (2009). Anthropogenic scarring of Western Gray Whales (Eschrichtius robustus). Marine Mammal Science, 25(1), 161–175. https://doi.org/10.1111/j.1748-7692.2008.00253.x 

Corsi, E., Calambokidis, J., Flynn, K. R., & Steiger, G. H. (2021). Killer whale predatory scarring on Mysticetes: A comparison of rake marks among blue, humpback, and gray whales in the eastern North Pacific. Marine Mammal Science, 38(1), 223–234. https://doi.org/10.1111/mms.12863 

NOAA. (2020, April 4). Fisheries of the United States. https://www.fisheries.noaa.gov/national/sustainable-fisheries/fisheries-united-states

Hamilton, P. K., & Marx, M. K. (2005). Skin lesions on North Atlantic right whales: Categories, prevalence and change in occurrence in the 1990s. Diseases of Aquatic Organisms, 68, 71–82. https://doi.org/10.3354/dao068071 

Pettis, H. M., Rolland, R. M., Hamilton, P. K., Brault, S., Knowlton, A. R., & Kraus, S. D. (2004). Visual health assessment of north atlantic right whales (Eubalaena glacialis) using photographs. Canadian Journal of Zoology, 82(1), 8–19. https://doi.org/10.1139/z03-207 

Silber, G. K., Weller, D. W., Reeves, R. R., Adams, J. D., & Moore, T. J. (2021). Co-occurrence of gray whales and vessel traffic in the North Pacific Ocean. Endangered Species Research, 44, 177–201. https://doi.org/10.3354/esr01093 Sun, L., Engle, C., Kumar, G., & van Senten, J. (2022). Retail market trends for Seafood in the United States. Journal of the World Aquaculture Society, 54(3), 603–624. https://doi.org/10.1111/jwas.12919

Expand your rolodex and meet some more IndividuWhales!

In case you aren’t already aware, I want to remind you of a website called IndividuWhale we created about Pacific Coast Feeding Group (PCFG) gray whales we study as part of our GRANITE project. IndividuWhale features stories of some of the Oregon coast’s most iconic gray whales, as well as information about how we study them, stressors they experience in our waters, and even a game to test your gray whale identification skills. We also provide details about where to best spot gray whales along our coast and the different behaviors you might see gray whales displaying at different times of the year. Since launching the website in late 2021, we have made small tweaks and updates along the way, but now, after about 2.5 years, the time has come for a major content update as we are introducing you to three new individuals and their stories! Head over to IndividuWhale.com to check out the updates or continue reading for a preview of the content…

Lunita

Even though “Lunita” is only two years old (as of 2024), they (sex currently unknown!) have quickly become a star of our dataset and hearts. We documented Lunita as a calf with their mother “Luna” (hence the name Lunita, which means little Luna/moon) in 2022. We observed the mom-calf pair in our study area for almost two weeks during which it seemed like Lunita was a very attentive calf, always staying close to Luna and appearing to benthic feed alongside their mom. As is often the case when we document mom–calf pairs, we wonder whether we will see the calf again and how it will fair in an environment increasingly impacted by human activities. Much to our delight, we were reunited with Lunita later in the same summer when we saw them feeding independently, indicating that they had successfully weaned. We were even more delighted when we were reunited with Lunita again many times during the summer of 2023 as Lunita spent almost the entire feeding season along the central Oregon coast. This is yet another example, much like “Cheetah” and “Pacman,” of successful internal recruitment of calves born to PCFG females into the PCFG sub-population.

Lunita’s high site fidelity to our study area in 2023 meant that she was an excellent candidate for the suction-cup tagging we have been conducting in the last few years. During suction-cup tagging, we attach a device (or tag) via suction cups to a whale’s back. The tag contains a number of different sensors, including an accelerometer (to measure speed), a gyroscope (to measure direction), and a magnetometer (to measure magnetic field), as well as a high-definition video camera and hydrophone (or underwater microphone). These tags typically stay on for a maximum of 24 hours before they pop off the whale leaving no harm to the whale. Upon retrieval, we can recreate the whale’s dive path and see the environment and conditions that the whale experienced over several hours. We sometimes refer to tagging as giving the gray whales some temporary jewelry because the tags are a very flashy, bright orange color. From the video from Lunita’s tag shows how they soared through kelp forests feeding on mysids for many, many hours. Check out their profile here: https://www.individuwhale.com/whales/lunita/

Burned

There are many ways to assess the health of a whale. In our lab, we calculate body condition from drone images to determine how fat or skinny a whale is, examine different hormones from their poop, and assess growth rates via length measurements from drone images. Another health assessment metric that we explore in the lab is the skin and scarring on the individuals that we see in our central Oregon study area. By conducting a skin and scarring analysis, we can identify scarring patterns and lesions that may indicate interactions with human activities and track the progression of skin diseases that will help us understand the prevalence and impacts of pathogens on whales. One skin condition that we are particularly interested in tracking appears as a thick white or gray layer that can mask a gray whale’s natural pigmentation. An example of a whale that has experienced this skin condition is “Burned.”

Burned is a female who is at least 9 years old (as of 2024), as she was first documented in the PCFG range in 2015. We saw Burned for the first time in 2016. At the time, we noticed small, isolated, gray patches of the skin condition on both sides of Burned’s body. Throughout the years as we have continued to resight Burned, we noticed the skin condition spreading progressively across her body. We saw the skin condition at its maximum extent in 2022 when, at first glance, Burned was hardly recognizable. Luckily, we can identify gray whales using more than just their pigmentation patterns (learn more on our whale identification page). Interestingly, when we saw Burned in June 2024, it appeared that the skin condition completely disappeared! Burned is just one example of whales with this skin condition, leaving us with many questions about its origin and impact on the whales: What causes the skin condition (viral, fungal, bacterial?); How it is transmitted (via air or contact?); Is it harmful to the whale (weakened immune system?). Our research is aimed at addressing these questions to make this skin condition a little less mysterious. Check out her profile here: https://www.individuwhale.com/whales/burned/

Heart

“Heart,” who is also known as “Ginger,” is a very well known and popular whale in the Depoe Bay region. Heart is a female who is particularly famous for being a “tall fluker,” meaning that when she dives, she arches her tail fluke high in the air before it glides elegantly into the water. Heart was first documented as a calf in 2010, which means that she is 14 years old (as of 2024). At 14 years of age, we would expect for Heart to have had at least one, if not more, calves by now, as it is believed that gray whales reach sexual maturity at age 8 or 9. However, Heart has never been documented with a calf. Why?

While we cannot know for sure, we have a theory that it might be linked to her body length. Recent work in our lab has explored how growth of PCFG whales has changed over time. Using measurements of whales from our drone data, we  investigated how the asymptotic length (i.e. the final length reached once an individual stops growing) for the PCFG whales has changed since the 1980s. Shockingly, we found that starting in the year 2000 the asymptotic length of PCFG whales has declined at an average rate of 0.05–0.12 meters per year. Over time, this means that a whale born in 2020 is expected to reach an adult body length that is 13% shorter than a gray whale born prior to 2000. In Heart’s case specifically, when we last measured her length at 13 years old, she was 10.65 meters long. If she had been born prior to 2000, then she would be 12.04 meters long by now at the age of 13. That’s a whole 1.5 meters (or almost 5 feet) shorter!

You might be wondering how Heart’s length links back to her ability to have a calf. It takes a lot of energy to be pregnant and support the fetus, so by being smaller, Heart may not be able to store and allocate enough energy towards reproduction. Many of the whales we commonly see are shorter than expected based on their age (including “Zorro”), so we are monitoring the number and frequency of calves in the PCFG to see how this decline in length may impact the population. Check our her profile here: https://www.individuwhale.com/whales/heart/

Be sure to head over to IndividuWhale.com to explore all of the whale profiles and lots of other information that we have provided there about PCFG gray whales and how we study them here in Oregon waters!

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Blubber and Barnacles: An Introduction to Cetacean Skin Disease

By Natalie Chazal, PhD student, OSU Department of Fisheries, Wildlife, & Conservation Sciences, Geospatial Ecology of Marine Megafauna Lab

Ever noticed how our skin gets pruny and overly soft after just ten minutes in the water? That’s because human skin is adapted for life on dry land, where retaining moisture is a primary concern. In contrast, cetaceans have evolved remarkable adaptations to thrive in the cold, salty ocean water for their entire lives. Understanding cetacean skin is crucial for conservation efforts, as it allows us to monitor and assess the overall health of these marine populations. By analyzing skin conditions, we can identify scarring patterns and lesions that may indicate interactions with human activities, such as entanglements or boat strikes, which can inform more effective risk assessment and mitigation strategies. Additionally, tracking the progression of skin diseases provides vital information on the prevalence and impact of pathogens, in order to guide more targeted management strategies to improve whale health and population resilience in their changing environments. To fully appreciate why monitoring skin diseases in cetaceans matters, let’s first explore the anatomy and physiology of cetacean skin and understand how scarring and diseases occur.

Whale skin has similar layers to our own, but modified over millions of years of evolution. Thicker than terrestrial mammals, the epidermis (the outermost layer) in marine mammals is designed to help maintain hydration in a hyperosmotic (very salty) environment where water is trying to flow into the cells of the whale. This top layer sloughs off at the surface as new cells are continuously renewed. The hypodermis, or blubber layer, is composed of primarily vascularized fat cells which insulate, store energy, and regulate buoyancy (Figure 1). 

Figure 1. Major layers of whale skin with the pop up showing a detailed figure of the epidermal/hypodermal junction (Mouton et al. 2011). 

Some other interesting skin adaptations that allow whales to maximize their efficiency underwater include near hairlessness, no sweat glands, and high levels of melanin. First, cetacean hairlessness helps them reduce drag in the water, but they don’t quite lack all hair. Most species of whales have hair around their mouths when they’re developing in the womb and then lose their hair either before birth or shortly after. Some species, like the humpback, have tubercles that are modified hair follicles to help them sense their surroundings, similar to whiskers on a dog. Second, because sweating is not effective for thermoregulation in the aquatic environment, whales have lost the sweat gland structure in their skin, making it slightly less permeable than terrestrial mammals. Their lack of glands also means that whales don’t secrete their own oils to maintain the moisture of the skin. So, if they’re exposed to dry air, their skin will dry out faster than the skin of terrestrial mammals. Lastly, melanin pigments vary from species to species. You can easily see this when we compare lateral surface photos of different species (Figure 2).

Figure 2. Comparison of surfacing photos between blue whales (upper left), Cuvier’s beaked whale (upper right), gray whale (lower left), and beluga whale (lower right) coloration. Blue and gray whale photos from GEMM Lab, beaked whale photo from Cascadia Research Collective (https://cascadiaresearch.org/files/Discriminating-between-Cuviers-and-Blainvilles-beaked-whales.pdf), and beluga whale photo from NOAA (https://www.fisheries.noaa.gov/event/2022-belugas-count)

This difference in coloration can be used by animals for camouflage either to avoid predators or to help ambush prey, and helps us to identify the species while they are at the surface. Coloration can also change as an animal ages and can help signal to us or other conspecifics the age or reproductive status of the individual (Caro et al. 2011). The melanin that creates these different colorations can protect whales against the harmful effects of UV radiation by absorbing and dissipating UV radiation, which decreases how far it penetrates into the skin, reducing cell damage (Morales-Guerrero et al. 2017). 

Thus, whale skin is very well adapted to the aquatic environment, from thick blubber layers to no sweat glands. However, despite these adaptations, cetaceans remain vulnerable to a range of pathogens. The major skin diseases documented in whales can fall into 4 categories: viral, bacterial, fungal, and parasitic. Viral infections in cetaceans involve the invasion of host cells, where viruses replicate and cause cell death or dysfunction, leading directly to skin lesions or nodules. Viruses can also manipulate the host immune response, suppressing immunity and exacerbating inflammation, which further contributes to skin damage. In contrast, fungal infections typically involve fungal growth and colonization on the skin surface or within tissues, with some fungi producing toxins that directly damage cells or provoke inflammatory responses (Espregueira et al. 2023). Bacterial infections in cetaceans often result from bacterial invasion and multiplication within skin tissues, accompanied by toxin production that damages cells and triggers a robust inflammatory response (Bressem et al. 2009). Parasitic infections, such as barnacle and whale lice infestations, can cause irritation, abrasions, and compromise the skin’s protective function, leading to localized inflammation and potential secondary infections. 

Understanding the specific causes of skin conditions in cetaceans is crucial because different pathogens spread through populations in distinct ways, impacting both individuals and population level health. Viral infections, for instance, can spread rapidly within populations through direct contact or respiratory droplets, potentially leading to widespread outbreaks and systemic effects. Fungal infections may persist in environmental reservoirs (spores of fungus can exist in seawater, sediment, organic marine debris, and the air) and can affect multiple individuals over time, particularly in conditions favoring fungal growth. Bacterial infections often spread through direct contact or contaminated environments, posing risks of localized outbreaks and secondary complications. Parasitic infestations, such as barnacles and whale lice, can transmit between individuals through close contact or shared habitat spaces (Romero et al 2012). By accurately identifying the causative agents of skin diseases, we can assess their transmission dynamics, anticipate population-level impacts, and implement targeted management strategies to mitigate disease spread and preserve whale health.

There are complex factors that contribute to skin disease prevalence in cetaceans. Environmental degradation, chemical pollution, climate change, and other anthropogenic stressors are known to lower immune systems, and degrade prey quality and quantity (Bressem et al. 2009). To understand the interactions between disease and the environment, we have to begin by establishing baseline health metrics. This summer, we will characterize an emerging skin disease in gray whales (see Zorro’s progression in Figure 3) using the photographs taken from the last 9 years of GRANITE fieldwork. Gray whales are particularly vulnerable to environmental threats because of their reliance on nearshore habitats. Unlike some other cetacean species that venture into deeper waters, gray whales are primarily coastal dwellers, feeding on benthic and epi-benthic organisms found in shallow, nutrient-rich waters. This dependence on nearshore environments exposes them to numerous risks. Pollution from runoff, oil spills, and plastic debris accumulates in these coastal waters, disrupting their immune systems leaving them more susceptible to disease. Climate change can induce shifts in the environment that alter the availability and quality of these habitats, potentially forcing them into proximity of other animals or places that harbor more disease. Habitat degradation due to coastal development and human activities like overfishing and increased vessel traffic further restricts their access to critical feeding areas (Bressem et al. 2009).

Figure 3. Comparisons of Zorro (a PCFG gray whale) between a year with no skin condition, 2020 (left panels) and this year where he came back covered in an unknown skin condition, 2024 (right panels). The upper panels capture his left side and the lower panels capture his right side.

These cumulative impacts increase the susceptibility of gray whales to diseases and stressors, highlighting the urgent need for baseline health assessments and identifying early signs of environmental stress (Stimmelmayr 2020). By documenting and analyzing skin conditions of gray whales through photographs, we can track changes over time and correlate them with environmental factors like pollution levels or habitat alterations. This non-invasive approach not only provides valuable insights into the prevalence and severity of skin diseases but also helps to understand broader ecological health trends in gray whale populations. 

P.S. Check out IndividuWhale to explore some great examples of how the skin condition of some of the local Oregon PCFG gray whales compare to each other and how we use their specific markings to help identify them in the field. 

References

Barlow, D.R., Pepper, A.L., Torres, L.G., 2019. Skin Deep: An Assessment of New Zealand Blue Whale Skin Condition. Frontiers in Marine Science 6.

Bressem, M.-F.V., Raga, J.A., Guardo, G.D., Jepson, P.D., Duignan, P.J., Siebert, U., Barrett, T., Santos, M.C. de O., Moreno, I.B., Siciliano, S., Aguilar, A., Waerebeek, K.V., 2009. Emerging infectious diseases in cetaceans worldwide and the possible role of environmental stressors. Diseases of Aquatic Organisms 86, 143–157. https://doi.org/10.3354/dao02101

Callewaert, C., Ravard Helffer, K., Lebaron, P., 2020. Skin Microbiome and its Interplay with the Environment. Am J Clin Dermatol 21, 4–11. https://doi.org/10.1007/s40257-020-00551-x

Caro, T., Beeman, K., Stankowich, T., Whitehead, H., 2011. The functional significance of colouration in cetaceans. Evol Ecol 25, 1231–1245. https://doi.org/10.1007/s10682-011-9479-5

Espregueira Themudo, G., Alves, L.Q., Machado, A.M., Lopes-Marques, M., da Fonseca, R.R., Fonseca, M., Ruivo, R., Castro, L.F.C., 2020. Losing Genes: The Evolutionary Remodeling of Cetacea Skin. Front. Mar. Sci. 7. https://doi.org/10.3389/fmars.2020.592375

Menon, G.K., Elias, P.M., Wakefield, J.S., Crumrine, D., 2022. CETACEAN EPIDERMAL SPECIALIZATION: A REVIEW. Anat Histol Embryol 51, 563–575. https://doi.org/10.1111/ahe.12829

Morales-Guerrero, B., Barragán-Vargas, C., Silva-Rosales, G.R., Ortega-Ortiz, C.D., Gendron, D., Martinez-Levasseur, L.M., Acevedo-Whitehouse, K., 2017. Melanin granules melanophages and a fully-melanized epidermis are common traits of odontocete and mysticete cetaceans. Veterinary Dermatology 28, 213-e50. https://doi.org/10.1111/vde.12392

Mouton, M., Botha, A., Mouton, M., Botha, A., 2012. Cutaneous Lesions in Cetaceans: An Indicator of Ecosystem Status?, in: New Approaches to the Study of Marine Mammals. IntechOpen. https://doi.org/10.5772/54432

Pitman, R.L., Durban, J.W., Joyce, T., Fearnbach, H., Panigada, S., Lauriano, G., 2020. Skin in the game: Epidermal molt as a driver of long-distance migration in whales. Marine Mammal Science 36, 565–594. https://doi.org/10.1111/mms.12661

Romero, A., Keith, E.O., 2012. New Approaches to the Study of Marine Mammals. BoD – Books on Demand.

Stimmelmayr, R., Gulland, F.M.D., 2020. Gray Whale (Eschrichtius robustus) Health and Disease: Review and Future Directions. Frontiers in Marine Science 7.

Su, C.-Y., Hughes, M.W., Liu, T.-Y., Chuong, C.-M., Wang, H.-V., Yang, W.-C., 2022. Defining Wound Healing Progression in Cetacean Skin: Characteristics of Full-Thickness Wound Healing in Fraser’s Dolphins (Lagenodelphis hosei). Animals (Basel) 12, 537. https://doi.org/10.3390/ani12050537

Van Bressem, M.-F., Van Waerebeek, K., Duignan, P.J., 2022. Tattoo Skin Disease in Cetacea: A Review, with New Cases for the Northeast Pacific. Animals 12, 3581. https://doi.org/10.3390/ani12243581