Expanding MMRP’s efforts across the Pacific - Studying gray whales in Mexico

Written by Cameron Nemeth

I was fortunate to spend the last couple of weeks in a remote lagoon on the western shore of Baja California Sur alongside Dr. Will Gough, where we worked in collaboration with the Gray Whale Research in Mexico organization to deploy non-invasive suction cup tags on gray whales.

The team all together for one last time at the lab before Will and I started the long journey back home following a successful week of deploying suction cup tags on gray whales. Pictured left to right: Sergio Martínez, Regina Lobo, myself (Cameron Nemeth), Francesca Diaz Cabal, Aitana Romero, Fabián Rodríguez, Ernesto Partido, Will Gough.

This field expedition marks the resumption of collaborative efforts between MMRP and Gray Whale Research in Mexico. Back in 2018, there was a short, preliminary field season where Professor Lars Bejder and Dr. Aude Pacini from the MMRP joined the team in Mexico to deploy DTags on gray whales. Despite the success of that initial field season, it hasn’t been until this year that we have been able to make it back out, but this comes at a very exciting time for us at the MMRP. We have spent the last 7-8 years deploying Customized Animal Tracking Solutions (CATS) tags on the humpback whales in Hawaiʻi and in Alaska, and developing an analytical framework linking drone and tag data to quantify the bioenergetics of marine mammals in greater detail than ever before. 

The gray whales seen in Baja California make one of the longest migrations of any mammal, traveling up to 20,000 km from their summer feeding grounds in northern Russia and Alaska to their winter breeding grounds, passing through the Southern California Bight all the way down to Baja California Sur. 

An image displaying the long migration made by gray whales annually from northern Alaska to the lagoons of Baja California, Mexico. Credit: NOAA Fisheries.

These breeding grounds offer a refuge from predators, cold waters, and other challenges of their northern feeding grounds, providing a safer environment for gray whales to give birth, nurse their calves, and mate. While these low-latitude breeding grounds offer a safe haven, they lack sufficient food, driving the gray whales' long-distance migrations. However, problems arise when gray whales lack adequate nutritional resources on their feeding grounds to support the prolonged periods of fasting during migration and on their breeding grounds, which may last nearly six months. This is precisely what we are now witnessing as a result of human-induced climate change, extreme weather events, and overfishing. Between 1999 and 2020, gray whales experienced two distinct unusual mortality events (UMEs), marked by mass strandings, population declines, poor body condition, and reduced calving rates (Christiansen et al., 2021). Our goal was to join up with the Gray Whale Research in Mexico organization at their home base in the San Ignacio Lagoon, and deploy these suction cup tags on gray whales to better understand the energetics of their reproductive behavior on their breeding grounds. 

Led by Dr. Steven Swartz and Dr. Jorge Urbán, the team from the Gray Whale Research in Mexico has been regularly working out of the San Ignacio lagoon for over 20 years now, and they’re expertise in the area definitely shows. The team has nearly 50 years of photo identification images of individual whales that visit the lagoon, and within the past eight years they have made a dedicated effort to incorporate drones into their research to evaluate the body condition of these animals. The day to day field operations are led by Dr. Sergio Martínez, alongside a great group of ~five students that spend the entirety of the three month field season at their camp in the lagoon. Given the extremely remote location, the team lives in tents near the coast, with a small field laboratory just steps away. 

The unique desert landscape of the field camp at the San Ignacio Lagoon. The building pictured foremost is the field laboratory, and behind the lab to the left are the tents that everyone sleeps in. The ocean is a short 1-2 minute walk from our tents. Also, notice the very cool gray whale skull on the wall of the lab!

On a regular day the team will wake up early, grab a quick breakfast, and head to the water for the majority of the day where they will spend most of their time collecting photos of individuals to later be identified. Their drone pilot, Fabián Rodríguez, will launch the drone from the shore and spend the day collecting aerial imagery. 

Drone imagery of a calf with one of our CATS tags attached, exhibiting playful behavior as it rolls around its mother, also equipped with one of our CATS tags.

Every five days the team will conduct a census, where they follow a predetermined track at a set speed and count the whales seen. This census has been a regular part of the team's efforts in the lagoon since 1977 and is critical to evaluating trends in population abundance. Everyday wraps up with dinner, and some data processing back at the lab, just in time to give everyone a chance to rest and get back out the following day to do it again. 

The strong foundation built by the research team in Mexico through long-term monitoring efforts makes this new collaboration especially exciting. By integrating novel tag data with their extensive dataset on individual whales and health metrics, we have the opportunity to conduct powerful analyses and gain deeper insights into the fine-scale energetics of these animals. The San Ignacio Lagoon hosts a remarkable abundance of gray whales, drawing thousands of tourists each year. To support conservation efforts, Gray Whale Research in Mexico collaborates closely with local management agencies, providing scientific data to inform policies that protect both the whales and their habitat. Through this collaboration, we aim to provide robust data and informed recommendations for policymakers, helping to ensure that both the whales and the lagoon have the best chance to thrive in the future.

As this season was preliminary, the goals of our fieldwork were to familiarize ourselves with the lagoon, the whales, and the team here, and to deploy 10 tags on gray whales. Over the past week, Will and I were able to deploy 11 tags on gray whales, including two mothers, one calf, and eight single whales. The tag deployment on the calf was the longest in duration, lasting nearly 12 hours! This is very exciting because we are hoping to capture suckling behavior and draw comparisons to some of the work that MMRP PhD candidate Gussie Hollers is doing with the humpback whale calves in Hawaiʻi. 

The gray whale calves were extremely tactile, always remaining in close contact with mom. This inevitably led to the CATS tag getting knocked around a lot!

While we did surpass our goal of tag deployments, the season had its fair share of challenges. We set out with the intent of primarily tagging mother and calf pairs to compare with the data we have collected in Hawaiʻi, but the team in Mexico has only observed four mother-calf pairs across the entire season. This is surprisingly low considering the numbers of mother-calf pairs observed in 2022 (41), 2023 (84), and 2024 (22).

One of the mother-calf pairs, both with CATS tags attached and interacting with a bottlenose dolphin. Drone imagery by Fabián Rodríguez.

The other big challenge was the strength of the currents. When the tide is going out of the lagoon, our tags can travel very quickly towards the outside of the lagoon, leading to some interesting recoveries. One of the single whales we had tagged decided that it did not want to be in the lagoon anymore and quickly left, forcing us to navigate one of the small boats (pangas) over 5 km through the surf and outside of the lagoon to recover the tag.

The location of the lagoon along the western Baja California Sur coastline (left), and a closer look at the recovery location of the tag that floated outside of the lagoon (right).

We tagged the calf a day or so after this and we definitely did not want to lose that important data. Unfortunately, the tag popped off around 9 pm, so immediately Will and I thought we would have to cross our fingers and hope the tag was still in the lagoon (or not far) in the morning. However, when we told the Gray Whale Research in Mexico team, they quickly mobilized and within 20 minutes we were on the water attempting a night recovery of the tag - something we’ve never done before. We loaded up the panga with all kinds of flashlights and Fabián flew the drone overhead with a spotlight, and we had the tag back within the hour!

Will pulling the CATS tag out of the water at 9:54 pm with the help of the team illuminating the water from all angles. This was critical in ensuring the strong currents did not carry the tag out of the lagoon overnight and that this important data from the 9 hour deployment on a calf would make it back to the lab.

We can’t thank the team from the Gray Whale Research in Mexico program enough for their incredible hospitality, willingness to help out whenever possible, and passion for good science. They have an extremely passionate group of hard-working people that bring amazing energy to every day. From coordinating travel plans to following tagged whales around in the pangas, they played a key role in the success of this field season. Myself, Will, Lars, and everyone else at the MMRP look forward to many more successful field seasons in the pursuit of new discoveries and the conservation of the gray whale.