Month: December 2022

GEMM Lab 2022: A Year in the Life

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

Another year has come and gone, and with the final days of 2022 upon us, it is my honor and pleasure to present to you, dear reader, this summary of achievements by the GEMM Lab this year. It has been another big year for us, so snuggle up with your favorite holiday drink and enjoy our recap of 2022!

Leigh working hard during GRANITE field work

2022 was a huge year of milestones for each lab member. The biggest happened just a few weeks ago when, on December 1st, our primary investigator (PI) and the captain at the GEMM Lab helm, Leigh Torres, started her sabbatical!!! Leigh, who received tenure and became an Associate Professor in 2020, was eligible for a sabbatical this year and took the opportunity to take a very well-deserved three months in New Zealand with her family. Leigh established the GEMM Lab in 2014, and it has since grown into a 13-person strong team that aims to advance marine science and conservation through innovative and engaged research across 11 active projects. I know I speak for all my lab mates when I say that we are incredibly grateful and thankful for Leigh, who always prioritizes us, even when she is busy with other things. Leigh, enjoy New Zealand and your time off! Your crew will man the GEMM Lab ship while you are away, under the leadership of the four postdocs, your first mates. Speaking of which…

Dawn Barlow defended her PhD dissertation “Ecology and Distribution of Blue Whales in New Zealand Across Spatial and Temporal Scales” in April and became the latest Dr. of the GEMM Lab! Dawn’s achievements were recognized by OSU’s College of Agricultural Sciences as she was awarded the prestigious Savery Outstanding Doctoral Student Award in the spring. Finishing her PhD also marked the culmination of a decade of blue whale research in New Zealand, which began with Leigh’s hypothesis of a resident blue whale population in the region. Thankfully, we have not had to say goodbye to Dawn as she is now a GEMM Lab postdoctoral scholar (more below). The milestones kept coming after Dawn’s defense as PhD student Clara Bird became PhD candidate Clara Bird in April after passing her qualifying exams. Four of us – MS students Allison Dawn and Imogen (also called Miranda) Lucciano, and PhD students Rachel Kaplan and myself – successfully defended our research proposals to our committees and had fruitful discussions about how to best accomplish our ambitious proposed research. Morgan O’Rourke-Liggett rejoined the GEMM Lab after being the undergraduate intern in the 2017 TOPAZ/JASPER (Theodolites Overlooking Predators and Prey / Journey for Aspiring Students Pursuing Ecological Research) field season, and they completed their graduate certificate in Geographic Information Systems in the Fall. For their capstone project, Morgan is now working on accounting for GRANITE (Gray whale Response to Ambient Noise Informed by Technology and Ecology) survey effort in order for us to then understand whether and how distribution patterns of gray whales have changed. Finally, Imogen completed her Graduate Certificate of Wildlife Management and moved into an M.Sc. program. Hip-hip-hurrah for all of these degree milestones!

Clockwise: New Dr. Dawn Barlow with her committee after successfully defending her PhD dissertation; Lisa (me) celebrating after a successful PhD research review; Dawn and Leigh during a successful OPAL field day; the R/V Bell M. Shimada science team on the September cruise (Rachel is second from left in the back row); the 2022 TOPAZ/JASPER field team hard at work

This year, it felt like someone in the GEMM Lab was always either preparing for fieldwork, in the field, or completing the post-fieldwork tasks of gear maintenance and data download. This reality is not surprising given that we have five active projects that involve fieldwork, which keep us busy on the ocean. Another two successful gray whale field seasons are on the books! Our project GRANITE wrapped its 7th consecutive year of field work in Newport on October 15th, while the integrated projects TOPAZ/JASPER completed an 8th consecutive field season in Port Orford at the end of August. The GRANITE field team grew with the addition of Master’s student Kate Colson, who is co-advised by Leigh and Dr. Andrew Trites at University of British Columbia. Down south in Port Orford, Allison successfully led her first solo field season after taking over the project from me last year. But the nearshore is not the only place that captured the GEMM Lab’s attention. HALO (Holistic Assessment of Living marine resources off Oregon) completed three survey cruises in January, June, and July, which included the successful recovery and replacement of three hydrophones, providing Imogen and Cornell PhD student Marissa Garcia with their long-awaited acoustic data. Imogen oversees cruise coordination for this GEMM Lab effort, and several lab members have gone to sea for HALO, including Imogen, Rachel, Dawn and Leigh. We also continued our participation in the Northern California Current (NCC) cruises, where we collect marine mammal and krill data for the OPAL (Overlap Predictions About Large whales) project. Dawn, Rachel and Clara all headed out together on NOAA’s R/V Bell M. Shimada in May, while Rachel was the sole GEMM Lab representative on the September cruise. Offshore biopsy efforts and U.S. Coast Guard helicopter flights also contributed data to OPAL through the year. Finally, Leigh and Dawn also participated in the MMI-wide MOSAIC (Marine Offshore Species Assessment to Inform Clean energy) cruises in August and October. Despite spending so many hours on the water, we were productive onshore too…

Gray whale suction cup tagging
HALO hydrophones back!
GRANITE field team
Dawn during OPAL field work
Rachel, Dawn & Clara on the NCC cruise

Our faraway postdoc Solène, who has been working remotely from New Caledonia, has made steady progress on the OPAL project. Her biggest achievement this year was finishing the first, NOAA section 6-funded component, and helping to acquire funding for the second phase of the project, which Rachel started work on for her PhD. We were lucky to have Solène visit the lab in January, where she met the new and reunited with the old faces of the GEMM Lab. While her time in Oregon was only 6 weeks or so, we managed to rope her into her first and second gray whale paper (stay tuned for that sometime in 2023). And to top off our quest of making Solène an Oregonian, we are so thrilled to announce that she and her husband Micah have finally acquired their visas to move here in just a few weeks, landing in January 2023!!

Solène & Micah after receiving their visa to come to the USA in January 2023

We have been, and continue to be, busy processing and analyzing all of the rich datasets that we collect during our intense field efforts. While I do not have time to mention all of the work that occurs in the lab and on our computers, I want to highlight some of them. Our postdoctoral scholar Alejandro A. Fernández Ajó is currently back at his graduate institute, Northern Arizona University, conducting lab work to analyze the 63 fecal samples collected from 26 individual gray whales during our 2022 GRANITE field season. Rachel and her amazing team of krill interns have been doing lots of bomb calorimetry all year to better understand the caloric value of different krill species and cohorts. Imogen spent a month at Cornell University in Ithaca, New York, to hone her skills for baleen whale recognition in acoustics data and to become well acquainted with OSU affiliates Dr. Holger Klinck, PhD student Marissa Garcia, and other researchers at the K. Lisa Yang Center of Conservation Bioacoustics. 

Rachel sorting krill
Imogen w/daughter Mavis, & Marissa & Holger

Even with all these projects underway, it seems that we cannot go a full year in the GEMM Lab without launching new endeavors. 2022 saw the creation of two more projects. For her postdoctoral research, Dawn is leading the newly-launched EMERALD (Examining Marine mammal Ecology through Region-wide Assessment of Long-term Data), which investigates spatiotemporal distribution patterns in harbor porpoise and gray whales in the nearshore NCC waters. Secondly, postdoctoral scholar KC Bierlich and Leigh have received funding to kickstart MMI’s Center of Drone Excellence (CODEX), which will launch in 2023. CODEX will focus on developing open-source tools and software to help analyze drone imagery, with the aim of offering online tutorials and hosting workshops. Both EMERALD and CODEX are funded by sales and renewals of the special Oregon gray whale license plate, which benefits MMI. We gratefully thank all the gray whale license plate holders, who made this research possible, and encourage any Oregonians that don’t have a whale on their tail yet, to do so in 2023!

Describing a year in the life of the GEMM Lab would not be complete without mentioning our outreach and education efforts as well. Allison, Clara, and I put on our teaching hats and gave guest lectures and labs for Dr. Renee Albertson and Dr. Kate Stafford’s marine mammal classes here at OSU as well as host an Introduction to R/RStudio workshop for undergraduates in our roles as coordinators for the Fisheries & Wildlife Mentorship Program. Alejandro gave a virtual talk to graduate students at the University of Pretoria South Africa about conservation physiology, highlighting his research with southern right whales. KC was invited to talk about using drones and computer science to study whales at Newport High School’s Computer Science Course and Oregon Sea Grant’s Whale Ecology Homeschool Program. He also gave the keynote presentation at the 25th Annual Salmon Bowl, part of the National Oceanic Sciences Bowl, which was hosted by OSU in February. Clara and myself were both invited speakers for Cape Perpetua’s monthly speaker series, where we presented our PhD research. Furthermore, GEMM Lab members also presented our work at numerous scientific conferences including the Society of Marine Mammal conference, Ocean Sciences, PICES annual meeting, and TWS Oregon Chapter, to name a few. The dissemination of our work to the scientific community and the public is a central focus of our lab, and we also prioritize providing hands-on opportunities and experiences to students eager to participate in ecological research. We mentored a total of 12 students in 2022, from high school to graduate level, who were involved in all aspects of our research including kayaking in Port Orford to collect prey samples, meticulously measuring drone images of whales, and spending hours hunched over microscopes identifying tiny crustaceans. 

Clockwise: 2022 TOPAZ/JASPER team (Charlie, Luke, Allison, Nicola, Zoe); REU student Braden Virgil discussing his poster; krill interns Abby and Henley; REU student Celest with mentors Clara and Leigh

We have once again been prolific writers, contributing 19 total peer-reviewed publications to 15 different scientific journals. If you are in the mood for some holiday reading, you will find the full list of publications at the end of this post. All authors in bold are (or were) GEMM Lab members when the work occurred.

And YOU, our awesome, supportive readers, have once again been busy, with a whopping 25,368 views of our blog this year!!! Thank you for joining us on our 2022 journey! We hope you have enjoyed the tales that we have told and the knowledge we have (hopefully) conveyed. On one final note, if you are still looking for that perfect holiday gift for the whale-lover in your life, and if you want to support our research, consider adopting a whale from our IndividuWhale website. As a small incentive, if you adopt a whale before the end of the year, you will be entered into our Oregon South Coast Whale Watch Experience giveaway! We will reveal the giveaway winner in January 2023. We wish you all restful, happy, and most importantly, healthy holidays, and hope you will join us again in 2023!

The GEMM Lab with their white elephant gifts during our annual holiday party

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Publications

Barlow, D.R., Klinck, H., Ponirakis, D., Holt Colberg, M., Torres, L.G. (In Press). Temporal occurrence of three blue whale populations in New Zealand waters from passive acoustic monitoring. Journal of Mammalogy.

Barlow, D.R., Estrada Jorge, M., Klinck, H., Torres, L.G. (2022). Shaken, not stirred: blue whales show no acoustic response to earthquake events. Royal Society Open Science. 9:220242.

Bierlich, K.C., Hewitt, J.,  Schick R.S., Pallin, L., Dale, J., Friedlaender, A.S., Christiansen, F., Sprogis K.R., Dawn, A.H., Bird, C.N.,  Larsen, G., Nichols, R., Shero, M., Goldbogen, J.A., Read, A., Johnston, D.W. (2022). Seasonal gain in body condition of foraging humpback whales along the Western Antarctic Peninsula. Frontiers in Marine Science. 9, 1–16. https://www.frontiersin.org/articles/10.3389/fmars.2022.1036860/full   

Cade, D.E., Kahane-Rapport, S.R., Gough, W.T., Bierlich, K.C., Linksy, J.M.J., Johnston, D.W., Goldbogen, J.A., Friedlaender, A.S. (in press). Ultra-high feeding rates of Antarctic minke whales imply a lower limit for body size in engulfment filtration feeders. Nature Ecology and Evolution.

D’Agostino, V.C., Fernández Ajó, A., Degrati, M. et al. Potential endocrine correlation with exposure to domoic acid in Southern Right Whale (Eubalaena australis) at the Península Valdés breeding ground. Oecologia 198, 21–34 (2022). https://doi.org/10.1007/s00442-021-05078-4

Derville, S., Barlow, D.R., Hayslip, C., Torres, L.G. (2022). Seasonal, annual, and decadal shifts of three baleen whale species relative to dynamic ocean conditions off Oregon, USA. Frontiers in Marine Science 9:868566.

Goetz, K.T., Stephenson, F., Hoskins, A., Bindoff, A.D., Orben, R.A., Sagar, P.M., Torres, L.G., et al. (2022). Data quality influences the predicted distribution and habitat of four southern-hemisphere Albatross species. Frontiers in Marine Science 9:782923. https://doi:10.3389/fmars.2022.782923  

Gough, W.T., Cade, D.E., Czapanskiy, M.F., Potvin, J., Fish, F.E, Kahane-Rapport, S.R., Savoca, M.S., Bierlich, K.C., Johnston, D.W., Friedlaender, A.S., Szabo, A., Bejder, L., Goldbogen, J.A., (2022). Fast and Furious: Energetic tradeoffs and scaling of high-speed foraging in rorqual whales. Integrative Organismal Biology, 4(1) obac038,  https://doi.org/10.1093/iob/obac038

Green, C-P., Ratcliffe, N., Mattern, T., …, Torres, L.G., Hindell, M.A. (2022). The role of allochrony in influencing interspecific differences in foraging distribution during the non-breeding season between two congeneric crested penguin species. PLoS ONE https://doi.org/10.1371/journal.pone.0262901

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. Marine Ecology Progress Series 695:189-201. https://doi.org/10.3354/meps14115   

Hunt, K.E., Buck, C.L., Ferguson, S.H., Fernández Ajó, A., Heide-Jørgensen, M.P., Matthews, C.J.D. (2002). Male Bowhead Whale Reproductive Histories Inferred from Baleen Testosterone and Stable Isotopes, Integrative Organismal Biology, 4: obac014, https://doi.org/10.1093/iob/obac014

Lemos, L.S., Haxel, J.H., Olsen, A., Burnett, J.D., Smith, A., Chandler, T.E., Nieukirk, S.L., Larson, S.E., Hunt, K.E., Torres, L.G. (2022). Effects of vessel traffic and ocean noise on gray whale stress hormones. Scientific Reports 12:18580.

Mouton, T.L., Stephenson, F., Torres, L.G., Rayment, W., Brough, T., McLean, M., Tonkin, J.D., Albouy, C., Leprieur, F. (2022). Spatial mismatch in diversity facets reveals contrasting protection for New Zealand’s cetacean biodiversity. Biological Conservation 267:109484. https://doi.org/10.1016/j.biocon.2022.109484

Nazario, E.C., Cade, D.E., Bierlich, K.C., Czapanskiy, M.F., Goldbogen, J.A., Kahane-Rapport, S.R., van der Hoop, J.M., San Luis, M.T., Friedlaender, A.S. (2022). Baleen whale inhalation variability revealed using animal-borne video tags. PeerJ 10:e13724 https://doi.org/10.7717/peerj.13724

Pallin, L., Bierlich, K.C., Durban, J. Fearnbach, H., Savenko, O., C.S. Baker, E. Bell, Double, M.C., de la Mare, W., Goldbogen, J., Johnston, D.,  Kellar, N., Nichols, R., Nowacek, D., Read, A.J., Steel, D., Friedlaender, A. (2022) Demography of an ice-obligate mysticete in a region of rapid environmental change. Royal Society of Open Science. 9(11).  https://doi.org/10.1098/rsos.220724

Reisinger, R.R., Brooks, C.M., Raymond, B., …, Torres, L.G., et al. (2022). Predator-derived bioregions in the Southern Ocean: Characteristics, drivers and representation in marine protected areas. Biological Conservation 272:109630. https://doi.org/10.1016/j.biocon.2022.109630

Rivers, J.W., Guerrero J.B., Brodeur, R.D., …, Torres. L.G., Barth, J.A. (2022). Critical research needs for forage fish within inner shelf marine ecosystems. Fisheries 47(5):213-221. https://doi.org/10.1002/fsh.10725

Segre P.S., Gough, W.T., Roualdes, E.A., Cade, D.E., Czapanskiy, M.F., Fahlbush, J., Kahane-Rapport, S.R., Oestreich, W.K., Bejder, L., Bierlich, K.C., Burrows, J.A., …Goldbogen, JA. (2022). Scaling of maneuvering performance in baleen whales: larger whales outperform expectations. Journal of Experimental Biology. 225 (5): jeb243224. https://doi.org/10.1242/jeb.243224  

Torres, L. G., Bird, C. N., Rodríguez-González, F., Christiansen, F., Bejder, L., Lemos, L., Urban R, J., Swartz, S., Willoughby, A., Hewitt, J., & Bierlich, KC. (2022). Range-Wide Comparison of Gray Whale Body Condition Reveals Contrasting Sub-Population Health Characteristics and Vulnerability to Environmental Change. Frontiers in Marine Science, 9. https://www.frontiersin.org/article/10.3389/fmars.2022.867258

How fat do baleen whales get? Recent publication shows how humpback whales increase their body condition over the foraging season. 

Dr. KC Bierlich, Postdoctoral Scholar, OSU Department of Fisheries, Wildlife, & Conservation Sciences, Geospatial Ecology of Marine Megafauna (GEMM) Lab

Traveling across oceans takes a lot of energy. Most baleen whales use stored energy acquired on their summer foraging grounds to support the costs of migration to and reproduction on their winter breeding grounds. Since little, if any, feeding takes place during the migration and winter season, it is essential that baleen whales obtain enough food to increase their fat reserves to support reproduction. As such, baleen whales are voracious feeders, and they typically depart the foraging grounds much fatter than when they had arrived. 

So, how fat do baleen whales typically get by the end of the foraging season, and how does this differ across reproductive classes, such as a juvenile female vs. a pregnant female? Understanding these questions is key for identifying what a typical “healthy” whale looks like, information which can then help scientists and managers monitor potential impacts from environmental and anthropogenic stressors. In this blog, I will discuss a recent publication in Frontiers in Marine Science (https://doi.org/10.3389/fmars.2022.1036860) that is from my PhD dissertation with the Duke University Marine Robotics and Remote Sensing (MaRRS) Lab, and also includes GEMM lab members Allison Dawn and Clara Bird. In this study, we analyzed how humpback whales (Megaptera novaeangliae) along the Western Antarctic Peninsula (WAP) increase their fat reserves throughout the austral summer foraging season (Bierlich et al., 2022). This work also helps provide insight to the GEMM Lab’s GRANITE project (Gray whale Response to Ambient Noise Informed by Technology and Ecology), where we are interested in how Pacific Coast Feeding Group (PCFG) gray whales increase their energy reserves in response to environmental variability and increasing human activities. 

Eastern South Pacific humpback whales, identified as Stock G by the International Whaling Commission, travel over 16,000 km between summer foraging grounds along the WAP and winter breeding grounds between Ecuador and Costa Rica (Fig. 1). Like most baleen whales, Stock G humpback whales were heavily exploited by 20th century commercial whaling. Recent evidence suggests that this population is recovering, with an estimated increase in population size of ~7,000 individuals in 2000 to ~19,107 in 2020 (Johannessen et al., 2022). 

However, there are long-term concerns for this population. The WAP is one of the fastest warming regions on the planet, and regional populations of krill, an important food source for humpback whales, have declined steeply over the past half-century. Additionally, the WAP has seen a rapid expansion of human activities, such as tourism and krill fishing. Specifically, the WAP has experienced an increase in tourism from a total of 6,700 visitors from 59 voyages in 1990 to 73,000 visitors from 408 voyages in 2020, which may be causing increased stress levels amongst Stock G (Pallin et al., 2022). Furthermore, the krill fishery has increased harvest activities in key foraging areas for humpback whales (Reisinger et al., 2022). Understanding how humpback whales increase their energy reserves over the course of the foraging season can help researchers establish a baseline to monitor future impacts from climate change and human activities. This work also provides an opportunity for comparisons to other baleen whale populations that are also exposed to multiple stressors, such as the PCFG gray whales off the Newport Coast who are constantly exposed to vessel traffic and at risk of entanglement from fishing gear. 

Figure 1. The migration route of the Stock G humpback whale population. Figure adapted from Whales of the Antarctic Peninsula Report, WWF 2018.

To understand how humpback whales increase their energy reserves throughout the foraging season, we collected drone imagery of whales along the WAP between November and June, 2017-2019 (Fig. 2). We used these images to measure the length and width of the whale to estimate body condition, which represents an animal’s relative energy reserve and can reflect foraging success (see previous blog). We collected drone imagery from a combination of research stations (Palmer Station), research vessels (Laurence M. Gould), and tour ships (One Ocean Expeditions). We used several different drones types and accounted for measurement uncertainty associated with the camera, focal length lens, altitude, and altimeter (barometer/LiDAR) from each drone (see previous blog and Bierlich et al., 2021a, 2021b). We also took biopsy samples to identify the sex of each individual and to determine if females were pregnant or not. 

Figure 2. Two humpbacks gracefully swimming in the chilly water along the Western Antarctic Peninsula. Photo taken by KC Bierlich & the Duke University Marine Robotics and Remote Sensing (MaRRS) Lab.

Our final dataset included body condition measurements for 228 total individuals. We found that body condition increased linearly between November and June for each reproductive class, which included calves, juvenile females, juvenile whales of unknown sex, lactating females, mature whales of unknown sex, and non-pregnant females (Fig. 3). This was an interesting finding because a recent publication analyzing tagged whales from the same population found that humpback whales have high foraging rates in early season that then significantly decrease by February and March (Nichols et al., 2022). So, despite these reduced foraging rates throughout the season, humpback whales continue to gain substantial mass into the late season. This continued increase in body condition implies a change in krill abundance and/or quality into the late season, which may compensate for the lower feeding rates. For example, krill density and biomass increases by over an order of magnitude across the season (Reiss et al., 2017) and their lipid content increases by ~4x (Hagen et al., 1996). Thus, humpback whales likely compensate for their lower feeding rates by feeding on denser and higher quality krill, ultimately increasing their efficiency in energy deposition. 

Figure 3. Body condition, here measured as Body Area Index (BAI), increases linearly for each reproductive class across the austral summer foraging season (Nov – June) for humpback whales along the Western Antarctic Peninsula. The shading represents the uncertainty around the estimated relationship. The colors represent the month of data collection.

We found that body condition increase varied amongst reproductive classes. For example, lactating females had the poorest measures of body condition across the season, reflecting the high energetic demands of nursing their calves (Fig. 3). Conversely, non-pregnant females had the highest body condition at the start of the season compared to all the other classes, likely reflecting the energy saved and recovered by skipping breeding that year.  Calves, juvenile whales, and mature whales all reached similar levels of body condition by the end of the season, though mature whales will likely invest most of their energy stores toward reproduction, whereas calves and juveniles likely invest toward growth. We also found a positive relationship between the total length of lactating females and their calves, suggesting that bigger moms have bigger calves (Fig. 4). A similar trend has also been observed in other baleen whale species including southern and North Atlantic right whales (Christiansen et al., 2018; Stewart et al., 2022).

Figure 4. Big mothers have big calves. Total length (TL) measurement between mother-calf pairs. The bars around each point represents the uncertainty (95% highest posterior density intervals). The colors represent the month of data collection. The blue line represents the best fit from a Deming regression, which incorporate measurement uncertainty in both the independent (mother’s TL) and dependent variable (calf’s TL).

The results from the humpback study provide insight for my current work exploring how PCFG gray whales increase their energy reserves in relation to environmental variability and increasing human activities. Over the past seven years, the GEMM Lab has been collecting drone images of PCFG gray whales off the coast of Oregon to measure their body condition (see this GRANITE Project blog). Many of the individuals we encounter are seen across years and throughout the foraging season, providing an opportunity to evaluate how an individual’s body condition is influenced by environmental variation, stress levels, maturity, and reproduction. For example, we had nine total body condition measurements of a female PCFG whale named “Sole”, who had a curvilinear increase in body condition throughout the summer foraging season – a rapid increase in early season that slowed as the season progressed (Fig. 5). This raises many questions for us: is this how most PCFG whales typically increase their body condition during the summer? Is this increase different for pregnant or lactating females? How is this increase impacted by environmental variability or anthropogenic stressors? Repeated measurements of individuals, in addition to Sole, in different reproductive classes across different years will help us determine what body condition is considered a healthy range for gray whales. This is particularly important for monitoring any potential health consequences from anthropogenic stressors, such as vessel noise and traffic (see recent blog by GEMM Lab alum Leila Lemos). We are currently analyzing body condition measurements between 2016 – 2022, so stay tuned for upcoming results!

Figure 6. Body condition, here measured as Body Area Index (BAI), increases curvilinearly for “Sole”, a mature female Pacific Coat Feeding Group gray whale, imaged nine times along the Oregon coast in 2021. The colors represent the month of data collection. 

References

Bierlich, K. C., Hewitt, J., Bird, C. N., Schick, R. S., Friedlaender, A., Torres, L. G., et al. (2021a). Comparing Uncertainty Associated With 1-, 2-, and 3D Aerial Photogrammetry-Based Body Condition Measurements of Baleen Whales. Front. Mar. Sci. 8, 1–16. doi:10.3389/fmars.2021.749943.

Bierlich, K. C., Hewitt, J., Schick, R. S., Pallin, L., Dale, J., Friedlaender, A. S., et al. (2022). Seasonal gain in body condition of foraging humpback whales along the Western Antarctic Peninsula. Front. Mar. Sci. 9, 1–16. doi:10.3389/fmars.2022.1036860.

Bierlich, K., Schick, R., Hewitt, J., Dale, J., Goldbogen, J., Friedlaender, A., et al. (2021b). Bayesian approach for predicting photogrammetric uncertainty in morphometric measurements derived from drones. Mar. Ecol. Prog. Ser. 673, 193–210. doi:10.3354/meps13814.

Christiansen, F., Vivier, F., Charlton, C., Ward, R., Amerson, A., Burnell, S., et al. (2018). Maternal body size and condition determine calf growth rates in southern right whales. Mar. Ecol. Prog. Ser. 592, 267–281.

Hagen, W., Van Vleet, E. S., and Kattner, G. (1996). Seasonal lipid storage as overwintering strategy of Antarctic krill. Mar. Ecol. Prog. Ser. 134, 85–89. doi:10.3354/meps134085.

Johannessen, J. E. D., Biuw, M., Lindstrøm, U., Ollus, V. M. S., Martín López, L. M., Gkikopoulou, K. C., et al. (2022). Intra-season variations in distribution and abundance of humpback whales in the West Antarctic Peninsula using cruise vessels as opportunistic platforms. Ecol. Evol. 12, 1–13. doi:10.1002/ece3.8571.

Nichols, R., Cade, D. E., Kahane-Rapport, S., Goldbogen, J., Simpert, A., Nowacek, D., et al. (2022). Intra-seasonal variation in feeding rates and diel foraging behavior in a seasonally fasting mammal, the humpback whale. Open Sci. 9, 211674.

Pallin, L. J., Botero-Acosta, N., Steel, D., Baker, C. S., Casey, C., Costa, D. P., et al. (2022). Variation in blubber cortisol levels in a recovering humpback whale population inhabiting a rapidly changing environment. Sci. Rep. 12, 1–13. doi:10.1038/s41598-022-24704-6.

Reisinger, R., Trathan, P. N., Johnson, C. M., Joyce, T. W., Durban, J. W., Pitman, R. L., et al. (2022). Spatiotemporal overlap of baleen whales and krill fisheries in the Antarctic Peninsula region. Front. Mar. Sci. doi:doi: 10.3389/fmars.2022.914726.

Reiss, C. S., Cossio, A., Santora, J. A., Dietrich, K. S., Murray, A., Greg Mitchell, B., et al. (2017). Overwinter habitat selection by Antarctic krill under varying sea-ice conditions: Implications for top predators and fishery management. Mar. Ecol. Prog. Ser. 568, 1–16. doi:10.3354/meps12099.

Stewart, J. D., Durban, J. W., Europe, H., Fearnbach, H., Hamilton, P. K., Knowlton, A. R., et al. (2022). Larger females have more calves : influence of maternal body length on fecundity in North Atlantic right whales. Mar. Ecol. Prog. Ser. 689, 179–189. doi:10.3354/meps14040.