(tranquil music) - [narrator] They are one of the oceans' long-distance travelers.

undertaking some of the longest seasonal migrations in the animal kingdom.

- [adam] Humpback whales are found in all the major oceans on the planet.

- [lars] There are 14 different distinct population segments of humpback whales in the world.

(camera shudder clicking) - [adam] The focus of our work is on the Hawai i distinct population segment.

- [stephanie] They breed in the Hawaiian Islands, and they feed in Alaska, British Columbia.

- [adam] They are migrating some 2,500, 3,000 miles up to their feeding grounds and then back down to their breeding grounds.

- [lars] The humpback whales get to Alaska usually around early April, and then they stay up there until about late November while they're feeding all the time up there.

And then they turn around again and usually start coming back in Hawaiian waters even in December, and peak in February.

And then by end of March, it's slim pickings down here in Hawai i.

- [jens] It's called a trickle migration because we don't have the entire population coming down at once.

- [stephanie] And while they're in the breeding grounds, they are not eating at all.

They're just surviving off of their blubber.

So it's very energetically costly to undergo that migration each year.

- [narrator] Now scientists in Hawai i and Alaska have teamed up to better understand how this prolonged period of fasting is impacting the whales' body condition and overall health.

- [andy] We now have these very nuanced tools that we can look not just at the health of the population, but of individuals.

It's allowing us to see things we never did before.

- [lars] One of the main questions that we're trying to address is pretty simple.

What does it cost to be a humpback whale?

How much energy do these animals spend migrating, breeding, and those are the costs which then they need to replenish while they're up in Alaska.

- [martin] Unfortunately, we still don't really understand what a healthy humpback whale looks like.

So for us to be able to figure out when a population is impacted, we need to know what the baseline is.

- [stephanie] Which is quite important because this whale population is particularly vulnerable right now.

In the last few years we've seen changes happening to the sighting rates here in Hawai i and our colleagues in Southeast Alaska reported the same thing.

- [kristi] They are certainly sentinels of ocean health.

- [shannon] They can be good bellwethers for change.

- [adam] Scientists have studied humpback whales, since the 1970s, behaviorally.

And so over the past almost 50 years now, we've learned a ton, but these types of questions that we are now trying to ask are showing us how much more we have to go.

- [lars] This is a really exciting time to do research.

- [narrator] How do scientists measure the whales' natural fluctuations in body size and overall health?

And what might that tell us about their ability to cope with future environmental stressors?

(dramatic music) - [announcer] Major funding for this program was provided by the Batchelor Foundation, encouraging people to preserve and protect America's underwater resources.

Additional funding was provided by the Parrot Family Endowment for Environmental Education.

(majestic music) - [narrator] Southeast Alaska.

Remote islands covered in dense temperate rainforest give way to scenic glacier-cut fjords, that are bountiful feeding grounds for One group studying humpback whales in this rugged wilderness is the Alaska Whale Foundation.

Its remote field station is located in the small community of - Most of our work has focused on humpback whale populations here in Alaska by studying both the actual animals themselves and the underlying prey.

- [narrator] From April through October, a small but dedicated team of scientists and interns use the field station as their base to conduct research in the surrounding waters.

- [andy] Our study area is a large portion of Northern Southeast Alaska; Frederick Sound, Chatham Strait, Icy Strait, and the nearest towns would be Petersburg, Sitka, and Juneau.

We probably cover about 50% of that area at this point, and we're still expanding.

We have colleagues who are working in various other spots.

- And this is one of the key areas that the humpback whales come up to feed throughout the summer and fall months.

It's a very productive area.

- [andy] The diet of these animals is about 80% krill.

- [martin] They're also feeding on different forage fish that are quite important to the area.

Things like Pacific herring.

- Juvenile salmon, increasingly at least in recent years, capelin, sand lance, all things that are small and schooling or swarming that occur in abundance.

- It does vary a little bit throughout the season.

- [narrator] Over the course of the summer whale season, the team conducts four to five multi-week surveys as part of the organization's comprehensive whale health and abundance program.

- We're using these point count surveys to systematically sample.

This means sitting on different designated points for 15 minutes, looking for whales, counting every animal we see.

How far away is it, what bearing is it?

And from that, we can calculate, A, how many animals, but B, where they're situated as well.

Once these point counts are finished, we can then head over to the whales, and we try and get a photo ID image of their flukes.

This will then tell us who the animal is.

Is it a new animal to the catalog that we have, or do we know who it is already?

This tells us who is around at what periods of time.

- [narrator] Scientists can identify individual whales by looking at their tail flukes.

Each fluke has a distinct trailing edge as well as a unique pattern of black and white pigmentation on its underside that, like a human fingerprint, is unique to that animal.

- We also want to get some environmental information on the ecosystem around them.

- [narrator] During their surveys, the scientists are collecting water samples so they can analyze the nutrients that are fueling the bottom of this very productive food chain.

They also deploy devices known as CTDs.

- Which allow us to profile the temperature and salinity of the water column.

So we're tracking some of the sort of physical and chemical properties of the underlying ocean.

- [narrator] Knowing the physical properties of the water column enables biologists to understand the base of the food chain, which can switch to less nutritious plankton as water temperatures rise.

In recent years, a severe marine heatwave in the north Pacific had devastating impacts on animals up and down the food chain, including the humpback whales.

Now the scientists' goal is to link what they see in the underlying ecosystem to the humpback's health.

- [martin] Takeoff.

- [narrator] As part of a partnership between the Alaska Whale Foundation and the University of Hawai i at Manoa, Ph.D. student Martin van Aswegen collects body condition measurements of the humpbacks from the air.

- We try and sample any and every whale that we come across up here.

So we're using these drones to noninvasively get over the top of the whales as they're surfacing.

And as they surface, we can get a video, a high-resolution image of their body contours.

So we can see how long the whale is, but also how wide the animal is.

- [narrator] The drones are equipped with flat lenses and very precise height estimators, which make it possible to translate the pixels in an image into exact measurements.

- And using some software that we have, we can measure the total length of the animal, as well as the width, across 20 different points on the body.

We can do this again and again and again, with the same animals and different animals.

And this allows us to see how quickly these whales are gaining mass throughout the summertime while they're up here feeding.

Their job up here is essentially just to gain as much mass and weight as they can.

It tells us a little bit about how productive the system is for one.

And this is important because we can look at the variation on this across different years, but also looking at different environmental variables that may result in this variation.

And that can be an indicator of how the population is fairing both within a season, but also across multiple years.

Beautiful.

- And so, by incorporating all this physical, chemical, and biological oceanographic data and simultaneously looking at how the population are responding in month to month, year to year, we're hoping we will be able to make those links between whale health and ocean health.

- [narrator] As the whales migrate south in the winter months, so does the research.

- [martin] 3-2-1 takeoff.

- [narrator] Hawai i's warm, shallow waters make for an ideal place to breed and give birth to vulnerable calves.

(majestic music) While in Hawai i, Martin teams up with collaborators with the Pacific Whale Foundation and the Marine Mammal Research Laboratory at the University of Hawai i at Hilo.

- Pacific Whale Foundation was founded in the 1980s with the focus of learning more about the humpback whales that come to Hawai i each year.

- [narrator] Each January, February and March, the scientists conduct regular whale surveys in the leeward waters off Maui, where most of the whales tend to congregate during the breeding season.

- The females are coming to give birth.

The males are coming to compete and breed with those females.

The project is focusing specifically on mother calf pods as well as competition pods.

And so the first thing we always wanna try and get are those fluke identifications.

Once we know who the individual is, we can link that back to archives and begin to understand a bit more about that individual.

Is it a male, is it a female?

How reproductive was that female throughout its life history?

- We might know it's age or it's minimum age.

If we have seen a whale as a calf, for example, and then watched it grow.

- When it comes to photo identification in Hawai i, there's two really long-term robust catalogs.

There's the one that Adam Pack curates, and there's the one that Pacific Whale Foundation curates.

And if you put those two together, we have a really good understanding of the individuals that come here to Hawai i.

And then Alaska Whale Foundation of course has its own Alaska humpback whale catalog.

- [narrator] To further supplement the sighting history of the whales, the team uploads the fluke shots to a unique online database called Happy Whale, which logs sightings worldwide.

- Happy Whale is a website that has an automated fluke matching algorithm built into it.

So when you upload your photograph to Happy Whale, it compares against every other photograph on the Happy Whale system and returns results for you.

- A lot of people are now starting to use which now allows us to track animals across these large areas.

- [narrator] Once photo ID images of all the animals in the pod have been collected... - [martin] 3-2-1 takeoff.

- [narrator] Martin launches his drone to take videos of all the animals from the air.

- And our focus with mother and calf groups is looking at that energy exchange between mothers and calves.

And so we know that mom is providing the energy for that calf solely.

- These mothers are under extreme, energetic stress.

- So we expect mother's body condition to decrease and the calf's body condition to increase.

What we're trying to answer with the drone work is how fast that energy exchange happens and how much of it happens while they're here in Hawai i and then how much is still going on when they're up in Alaska.

And so if we're able to determine exactly how energetically costly that is and how much time they need here to do that, we can begin to model or predict impacts of climate change, for example, on humpback whales' ability to complete important life history cycles, such as birthing and calving.

- [narrator] The scientists also study what are known as competitive groups.

- These are, you know, my favorite groups to encounter.

You have a lot more whales in close proximity and you have a female that is ready to mate.

And so you have males fighting or competing for the position next to the female.

And so you have a male that's called the principal escort, meaning he has the primary position next to a female, that's defending that position against secondary escorts that are coming in to try and take that primary position away from the current animal that holds it.

- The competition pods are very dynamic and the composition is always changing where whales will come and join the group, whales will leave the group.

- That was a calf, fluke up dive.

- [narrator] Also part of the team is Dr. Adam Pack, a longtime whale researcher from the University of Hawai i at Hilo.

- Since 1976, when my mentor, Lou Herman, pioneered the scientific study of humpback whales in Hawaiian waters, he and his students, which include myself, have studied the Humpbacks and the behavioral ecology both in Hawaiian waters and in Southeast Alaska.

- [narrator] Once the team has gathered the photo ID and drone data, Adam collects a small skin and blubber biopsy of each whale in the group.

- We do this using a technique which is well established, a cross bow, which fires an arrow with a little stainless-steel tip, that's sterile on the end of it.

Let her commit.

We will start paralleling each whale and waiting patiently for that whale to come up in a high arch dive.

We want to have the biggest profile we can of the whale's body.

And my goal is I want to go about a foot below the dorsal fin, plus or minus.

It basically bounces off the whale and extracts a small sample of skin and blubber.

In most cases, the whale just continues with its dive.

Occasionally a whale might do it a little tail flick, in those situations, it might be like a little mosquito bite.

- [narrator] To date, Adam has collected nearly 500 biopsy samples as part of this project, which are sent to Dr. Shannon Atkinson's lab at the University of Alaska Fairbanks for analysis.

- One of the big areas that we tend to focus on is the endocrine system, and what that really is, is hormones.

Hormones are what drives behavior.

And so these hormones, we extract from the blubber and then we run them through tests in our lab.

They're really in two different categories.

Some of them, we call them the sex steroids and they're related to sexual activity, sexual reproduction, everything that has to do with sex.

We can start to look at things like pregnancy rates and whether the pregnancy rate of animals is going up or going down, or is very stable.

- We look at testosterone in males, how does that naturally fluctuate over the course of the reproductive season, but also in conjunction with the various behavioral and social roles these animals take.

- And so is there a relationship in the testosterone level of the males that are at the principal escort position and those that are further back that are just hanging out, is there a relationship with the amount of aggression we see?

- [narrator] Shannon's lab also analyzes the whales' metabolic hormones.

- They tend to have more to do with the body condition of the animal, the health of the animal, in terms of its wellbeing or its state of stress.

- As they are using up these energy reserves, including mothers that are not only metabolizing their fat for their own needs, but also for the needs of their newborn calf, how is that being translated into stress?

We really don't have a baseline of understanding the physical health characteristics and the reproductive health characteristics of humpback whales, so that we have something to compare chronic stress to.

Once we establish that baseline, then we're better equipped to understand what happens when these animals experience non-natural stressors, or natural stressors that have to do with climate, like a warming ocean that may negatively impact food resources.

- [shannon] 1-9-6 - [narrator] A sub-sample of the biopsies goes to Dr. Kristi West and her team at the University of Hawai i Health and Stranding Lab.

- We're specifically looking at stable isotopes in effort to better understand the foraging of each individual.

- [narrator] Stable isotope analysis lets scientists trace elements as they move up the food chain.

- [kristi] And we focus on nitrogen as well as carbon.

And ultimately this is a signal in the whales' tissue.

So in the skin samples that are collected from these live whales, and we can match that signal to prey sources that these whales may have foraged upon prior to the collection of the sample.

And we think that this gives us the timeframe of a month or more.

- [narrator] Knowing what the whales have preyed upon gives scientists an idea about the health of the food chain.

- So it certainly has the power to help us tease apart what changes have happened, in terms of looking at their foraging.

And then of course, that next question is what drove that foraging change in the first place that may be negatively impacting the health of the whales.

- [narrator] Kristi's team is also developing a new method of analyzing the fat cells in a whale's blubber to correlate their size with the animal's body measurements from the drone.

- This is an analytical tool to try and really quantify how much fat storage does each individual have on them.

We're looking for those fat cells so that we can identify them and measure their size.

And then we ultimately are measuring maybe 100 of those in any individual slide to get a really strong average of that fat cell size.

And then we are also using software to calculate for us the degree of connective tissue in any given image, as opposed to those fat cells.

So that we have an idea of how much of that area that we are examining is represented by which is probably only gonna have really small fat cells, versus a large number of nice, robust fat cells and just a little bit of connective tissue serving the purpose of holding that tissue altogether.

- [narrator] Data from stranded humpbacks has shown that emaciated whales tend to have much smaller fat cells than animals that have a robust body size.

- So really exciting to have a chance to put the whole story together, through working with such a large and collaborative team across the ocean basin.

- We certainly rely on each other to be able to provide different datasets to fill in gaps where we can, in order to just keep working on this puzzle piece by piece.

We're starting to get a diverse, but long data set that encompasses And the idea is to keep this going so we can have a multi-decadal dataset over time, which is going to be a lot more powerful.

- [narrator] Between 2018 and the end of the 2022 breeding season... - Two more coming up.

- [narrator] Martin captured approximately 6,300 drone measurements of over 5,000 humpbacks in Hawai i and Alaska.

This includes repeat sightings of more than 120 individual animals, in both locations, within six months of each other.

- Some of the measurements that we're getting are quite surprising, things like adults losing up to 28 inches of their body width while on the breeding grounds, for example, and that's without a calf, that's just a regular mature adult.

But also the calves have been really interesting, because we can sample calves in Hawai i throughout the season.

They're typically there for 60 days.

To be able to do it a few months later, once they get back to Alaska, that's incredibly rare and difficult to do so those data points are really valuable.

So for example, some of the calves that we sampled in Hawai i initially were 11 to 13 feet in length.

And about four months later, they were about 28 feet in length.

And some of them were about 900% heavier in terms of the body volume, which is incredible.

The amount of stress that must put on the female who at that point is 35% lighter than she was a few months earlier.

- Some of Martin's results are showing that on average, when a female is here in Hawai i and lactating, she loses about 100 kilograms per day.

So I weigh 80 kilograms, so it's more than my weight every single day.

- [martin] Mothers are the rock stars of this population.

- [narrator] Martin's drone measurements also reveal that humpback mothers with nursing calves don't regain all their lost weight once they return to the feeding grounds, but instead they are plateauing at best.

- In other words, all that food she's been eating, she's offloaded it to that calf as it's becoming a yearling.

Now, when we look preliminarily at the steroid hormone analysis, what we see is mothers of yearlings have significantly greater cortisol stress hormone concentrations than mothers of newborn calves.

That's exciting because that piece of the puzzle is marrying very well with what we're finding with the body condition and what we see behaviorally from these whales.

- [narrator] The scientists say understanding the natural changes in the humpbacks' body condition and stress levels is critical in the face of future climate change and shifting prey availability.

- We're a lot more well equipped to identify when whales are under stress in the future.

- These long-term monitoring programs and science projects are really, really important, particularly when it comes to management.

- If we're able to monitor the health of individuals, we're very quickly able to say if the population is healthy and our oceans are healthy, or if humpback whales are unhealthy, the oceans are unhealthy, and we need to look at what we can do to reduce any potential impacts that we're seeing.

- We know that the ocean is going to warm.

And so we are positioning ourselves to be able to respond more quickly.

- And in that way, I think our work can really make a difference.

(majestic music) (tranquil music) - [announcer] Major funding for this program was provided by the Batchelor Foundation, encouraging people to preserve and protect America's underwater resources.

Additional funding was provided by the Parrot Family Endowment for Environmental Education.