Stellar progress on Steller Watch!

A Steller Watch project update


January 18, 2018
Katie Sweeney



Steller Watch has been live for over 270 days since we launched on March 15, 2017 and I must say, it has been an absolute pleasure working with all of you! We are so thankful for each and every one of you who have joined us online to classify images. Your contributions are what make this project such a success and a vital step for figuring out why the endangered Steller sea lion continues to decline in the Aleutian Islands, Alaska.

We have seen a lot during this time! Citizen Scientists have reported seeing killer whales, sperm whale vertebrae washed up on shore, sea lion pups laying on their mother (what I like to call “pup pancakes“), a rogue puffin going for an epic selfie, and of course many many marked sea lions! I hope you have been enjoying the journey and finding these gems sprinkled among the images.

The power of citizen scientists has blown us away! You all have saved us almost 300 hours by eliminating images that don’t have sea lions with readable markings. You have identified the 7% of images that are the highest priority among hundreds and thousands.

Since this project began, we have had almost 8,000 volunteers join us from 70 different countries around the world that completed over 3 MILLION classifications! That is a total of 340,000 images retired, so far. Absolutely amazing!

I have compiled all of the classifications you have completed over the first 170 days of this project to find out just how much you’re help is benefiting Steller sea lions. What we know is your classifications in the Presence or Absence workflow have helped us eliminate 44% of the images that had no sea lions present.

The images from the Presence or Absence workflow that you all classified as “Yes!”, (sea lions were present in the image) were then used in the Presence of Marked Animals workflow. This workflow is very important because your classifications indicate to us which images are most important for us to review to record sightings of marked sea lions. Most importantly, we are looking for the sea lions with readable markings. You can read this blog post to understand what we can learn from these sightings and how they can help us discover why this part of the population continues to decline.


As you all know, finding marked sea lions and reading the markings can be quite tricky! Well, based on how many well you all have been identifying these images, maybe it’s not that tricky, after all—with your help, we know that 61% of these images had no marked sea lions present. That. is. HUGE. Since images with sea lions take more time to examine for readable markings, you have saved us an incredible amount of time. We categorized the remaining 39% of images into three different levels of priority:

  • 1 – Highest priority: there are marked sea lions that are readable
  • 2 – Medium priority: there are marked sea lions that are likely readable
  • 3 – Lowest priority: there are marked sea lions that are not readable


Ultimately, we think that it will only be necessary for us to look through images in priority category 1 and 2, which is about 13% of the images with sea lions present.

The power of citizen scientists has blown us away! You all have saved us almost 300 hours by eliminating images that don’t have sea lions with readable markings. You have identified the 7% of images that are the highest priority among hundreds and thousands.

And this is just the beginning. This is a long-term study and we are committed to following these marked sea lions over their lifetime (up to 30 years!). We will continue to need your help along the way. Currently, we just have 50,351 images to go through in the Presence of Marked Animals workflow and I know, with your help, we can get through these in no time!

current progress.PNG

It’s amazing to see citizen scientists like you, from all over the world, come together to help us on Steller Watch and for me, one of the greatest parts of this project is the Talk forum. I have been able to observe and participate in so many thoughtful conversations and discussions. I have had the pleasure of chatting with many of you answering questions personally and have seen citizen scientists working together to answer each others’ questions. One of my favorite parts of my day are when I get to log-on and communicate with you all. We have some of the greatest citizen scientists on our Steller Watch team! And, if you’re just joining us, don’t be shy! We warmly welcome you to join in on the conversation and ask questions.

From the Steller Watch team, we thank you all for you dedication and contributions in helping us find out why the endangered Steller sea lion continues to decline in the westernmost Aleutian Islands, Alaska. 


I have been a biologist in NOAA Fisheries Alaska Fisheries Science Center studying Steller sea lion population abundance and life history for over 10 years. I am an FAA certified remote pilot and have been flying marine mammal surveys with our hexacopter since 2014. I earned my B.S. in Aquatic and Fishery Sciences at the University of Washington and my Master in Coastal Environmental Management at Duke University. 


Why do we permanently mark Steller sea lions?


December 12, 2017
Lowell Fritz


We permanently mark Steller sea lions to estimate vital rates of the population, which are:

  • Survival (from year to year)
  • Reproduction (how often females give birth to a pup)
  • Dispersal (where marked sea lions are observed at each age)

Why is estimating vital rates important?

By seeing marked animals through time, we can determine which vital rate is most likely responsible for this decline.

For a population that’s declining, like Steller sea lions in the Aleutian Islands, estimating survival, reproduction and dispersal can help us determine what factors might be affecting the population. For instance, we know Steller sea lions in the western Aleutian Islands are declining at an alarming rate of about 7% per year. If they continue to decline at this rate, they could be go extinct in this region within the next 50 years. Which is why we need your help to classify images on Steller Watch.

Because the number of Steller sea lions (or abundance) is going down in the western Aleutian Islands we know that either they are dying faster than new pups are being born or they are abandoning this area and settling elsewhere.

Biologists look for marked Steller sea lions.

By seeing marked animals through time, we can determine which vital rate is most likely responsible for this decline. For example, suppose we discover that survival during the first 2 years in the western Aleutians is similar to areas where the species is currently increasing. This would suggest that factors that directly kill young sea lions, such as entanglement in fishing nets or predation by killer whales, are likely not affecting the western Aleutian population any more than in parts of the range where the population is increasing.  If we knew this, then we could focus our research and management attention on other pieces of the puzzle, such as factors that would affect reproduction (e.g., disease, nutritional stress) and adult survival (e.g., illegal shooting). In addition, because we know a lot about each of the pups that were marked, we can determine whether males and females are affected differently, or whether the weight of the pup (which is an indication of the health and age of its mother) was a factor.

A Steller sea lion pup that has been marked and a hair sample collected is being monitored in the pup recovery area.

We began marking Steller sea lion pups in the western Aleutian Islands in 2011, so as of December 2017, the oldest marked animals from this region are only about 6½ years old. Given that female Steller sea lions can live to be about 30 years old and don’t start having pups until they are 4-6 years old, this means we don’t yet have enough years of sightings to estimate reproduction or adult survival.  However, we are closer to being able to estimate juvenile survival.

I’m going to provide a short introduction into how we estimate survival, in this case, of juveniles. This will get a little messy and into the muddy math so skip ahead to the last two paragraphs if you want to skip this part. To set the stage, let’s look at a table of a simplified version of our experiment with ‘pretend’ data:


Imagine we marked 100 pups in 2011 and set them free. In each of the following years, there are really only 2 options for us as researchers: we either see them alive that year or we don’t. Let’s say in the 2nd year (in 2012) we observed only 50 of these 100 marked individuals. In the 3rd year (2013), we only saw 30. We want to try to estimate the percent of animals that survived to the 2nd and 3rd years (and beyond) which we call survival. In the most simplistic terms, survival is 50% to year 2 and 30% to year 3.

20150626_ULAK REMOTE CAMS_2.JPGBut it’s not that simple! What complicates this is sighting probability, or the chance that we will actually observe a live marked animal. While we have remote cameras at several locations and visit the Aleutian Islands at least once a year, we know that we do not see every single marked sea lion that is alive in the population. This means we have to account for the probability of observing a live marked animal, and how that might change over time, for instance, as the animals age or with different levels of sighting effort.  Another reason we might not see a marked animal is that it completely left our study area never to be seen by us again. We collaborate with researchers in Russia and look for marked animals in other parts of Alaska, but we still try to account for this possibility, however slim. For these reasons, we use the term “apparent” survival to describe what we are actually estimating since we can’t distinguish death from permanent emigration. But for this blog, we’ll just call it survival.

So, how do we account for sighting probability and how it might vary between years so we can estimate survival? This is where some math comes into play and why collecting data over many years is so valuable.

Capture history of marked sea lion sightings up to Year 2.

The table to the right is what we call a capture history of how many marked sea lions were seen (Y) or not seen (N) in Year 2. Of course, all of the 100 sea lions marked in 2011 were “seen” in the first year, which is why they have a “Y” listed for the first year. Then in year 2 (2012) there were 50 marked sea lions seen so their capture history is “YY”, and the other 50 were not seen which means their capture history is “YN”.

Pretty simple for year 2, right?  They were either seen or not seen.

Let’s add sightings collected during Year 3 (2013), and you can see that this is when it starts to get complicated. In the first table, you can see we saw only 30 marked animals in Year 3. Of those 30 marked animals seen, 10 were seen all three years so they have a capture history of YYY. The other 20 were not observed in year 2, so their capture history is: YNY.

Capture history of marked sea lions to year 3.

Seventy of the original 100 marked sea lions were not observed in year 3 but 10 of these were seen in year 2 so they have a capture history of YYN. That leaves the remaining 60 who were not seen in year 2 and 3, and these have a capture history of YNN.

How is this sighting data by year used to estimate sighting probability (P) and survival (S) in years 2 and 3? We use a mathematical model that finds the values of P and S that best fit the following equations. Let’s start from the top by examining the number of sea lions that had each type of capture history in year 3 and equations that express the probabilities for each one.

In our data, 10% of the original marked group of 100 pups has a capture history of “YYY” in year 3. This can also be expressed as:

Pr[YYY] = 0.1 = [P2 * S2] * [P3 * S3]

Our data indicate that the probabilities of both being seen (P2) and surviving (S2) to year 2 multiplied by the probabilities of both being seen (P3) and surviving (S3) to year 3 is equal to 0.1 or 10%.


That tells us a little bit but not too much about the individual values of each of the 4 parameters. Some more information will come from examining the equations associated with the other capture histories.

We not only have sighting probability and survival in our model, but we also have their opposites: the probability of NOT surviving (or dying) and of NOT being seen. Let’s say that we estimated that S = 0.6 for a particular year. The opposite of that, or the probability that an animal did NOT survive that year, would be (1 – S) = 0.4. In other words, if an animal had a 60% chance of surviving, it also had a 40% chance of dying. Similarly, if a marked animal had a 70% chance of being observed (P = 0.7), it also had a (1 – P) = 0.3, or 30% chance of NOT being observed. So for the capture history of “YNY” we would use the equation below:

Pr[YNY] = 0.2 = [(1-P2) * S2] * [P3 * S3]

For these 20 animals, we know they survived through year 2 because they were observed alive in year 3. Therefore, during year 2, the probability of being NOT seen (1-P2) is multiplied by the probability of surviving (S2), while for year 3, the terms are exactly the same as for the animals with capture histories of “YYY” since they were seen alive in year 3.

Pr[YYN] = 0.1 = [P2 * S2] * [(1-S3) + (S3 * (1-P3))]

OK, now it’s starting to look ugly, right?  Let’s just break it down term by term.  Since these 10 animals were all seen alive in Year 2, the equation has the same terms for year 2 as the “YYY”s. But year 3 is where it really starts to change, and this is because we don’t know if they didn’t survive to year 3 or they were alive but just not observed that year.  Data obtained in year 4 and beyond will help us untangle this, but at this point in the analysis of these example data, we do not know. Therefore, the year 3 term takes into account both possibilities: the probability that these 10 animals did NOT survive to year 3 (1-S3) and the probability that they survived to year 3 (S3) but were NOT observed (1-P3).

And now the messiest of all is the equation for the probability of having a capture history of “YNN”.

Pr[Y N N] = 0.6 = [(1-S2) + (S2 * (1-P2))] * [(1-S3) + (S3 * (1-P3))]

These 60 animals were marked in year 1 and never seen again, but we don’t know if they survived to year 3 (S2 and S3) but were just not observed either year [(1 – P2) and (1 – P3)]; if they didn’t survive to year 2 (1 – S2) and were not available to be seen in year 3; or if they survived to year 2 (S2) and were not observed (1 – P2) and then died in year 3 (1 – S3).

Without going into the gory detail, finding the values of sighting probability (P) and survival (S) for each year that best fit the data is quite a process, and luckily there’s a program called MARK that performs this task (and many more!) with remarkable speed.

For this example, survival to year 2 (S2) is estimated to be 0.82.  In other words, we estimate that 82% of the marked sea lion pups survived to celebrate their first birthday. Sighting probability during year 2 (P2) was estimated to be pretty low, only 0.19.  In other words, there was a 19% chance of seeing a marked animal during year 2.  You can see how adding sighting probability significantly changed our perception of survival, given that our first ‘guess’ for survival during year 2 was 50% when we only considered how many we actually saw alive in year 2. At this point in the data collection, P3 and S3 are not estimable with much precision because it is the last year of data in the analysis and we don’t have enough information to know whether a marked animal that was not seen in year 3 was alive or not. For each additional year of sightings, the number of years for which survival can be estimated usually increases, and the number of unique capture histories doubles. So you can see that the equations expressing the probabilities get very complicated very quickly! Add some other variables (also called co-variates) to the mix, such as sex, cohort (different island rookeries, different birth years), and weight at the time of marking, and you’ve got yourself quite a sophisticated model.

And that’s Survival 101!

I have been studying Steller sea lions since 1990 with NOAA Fisheries Alaska Fisheries Science Center in Seattle.  My primary research interests are sea lion population dynamics, demographics, and interactions with commercial fisheries.  I’ve also worked on fish during my career with NOAA, particularly species eaten by sea lions, like Atka mackerel, walleye pollock (you may know them as fish sticks and imitation “krab”), and Pacific cod.   I graduated from Bucknell University (B.A. Biology, 1976) and College of William and Mary (M.S. Marine Science, 1982), and started my science career in 1982 at Rutgers University as a Research Associate.  At Rutgers, I worked at the Haskin Shellfish Research Laboratory in Bivalve, NJ (down the road from Shellpile… you can’t make this up) studying the shells of mollusks living in habitats ranging from freshwater lakes and streams to deep-sea hydrothermal vents. I even had the opportunity to go down in the Alvin submersible!

To stay or go?

Different strokes for different sea lions?


October 24, 2017
Michelle Lander



If you recall our blog back on May 9th, we directed you to some preliminary findings for a subset of 13 adult female Steller sea lions that were captured and tagged between 2011 and 2015 (marked =24 through =36) in the Aleutian Islands. To follow-up, here’s an update on some of the final findings for those animals.

So, what influences a sea lion’s decision to stay close to home or hit the highway, so to speak? Is it size, age, offspring dependency, geographic region, prey availability, or just individual preference? Actually, it’s hard to say because we couldn’t find many patterns in the data.

Overall, we found that 7 of 13 animals remained exclusively on the continental shelf and close to shore (and in most cases their capture locations). The remaining 6 animals used both shelf and offshore habitats, traveling as far as 420 km (261 miles) into the open ocean, often referred to as ‘pelagic waters’. In some cases, sea lions traveled south of the Aleutian Island chain into the North Pacific Ocean, either near or beyond the Aleutian Trench, whereas two sea lions visited off-shelf areas in the western Bering Sea.

Map of tracklines from the 13 adult female sea lions satellite tagged in the Aleutian Islands during the fall female capture trips.

So, what influences a sea lion’s decision to stay close to home or hit the highway, so to speak? Is it size, age, offspring dependency, geographic region, prey availability, or just individual preference? Actually, it’s hard to say because we couldn’t find many patterns in the data. For example, there did not appear to be a relationship between distance traveled from haul-out site and sea lion body weight. In fact, both the smallest and largest individuals we captured displayed similar movement behaviors. Remember, =34 was the largest sea lion we captured and =35 was the smallest sea lion we captured, yet both of them stayed close to shore (though =34 wasn’t strictly a homebody; see map below). We’re also uncertain if age influenced the movements of those animals because they weren’t permanently marked previously, nor did we use methods to age them with certainty. As a whole, however, the adult females did tend to venture into offshore areas more frequently than the juveniles we’ve tagged in the past.

Map of tracklines from adult female sea lions satellite tagged. This is zoomed into =34 (gray dots that stay close to Amchitka Island) and =35 (blue dots stayed close to shore near Ulak Island).

Perhaps the age of the females’ offspring influenced their behaviors. For this study, we specifically targeted females that appeared to have a dependent pup and/or juvenile. For the most part, we were able to determine that most of the tagged females were lactating when they were captured and three females may have had a yearling (=32, =33, and =34). Again, there did not appear to be an obvious pattern in the data suggesting that adult females with offspring of different ages behave differently, but additional samples are needed to explore this idea. Similarly, our sample size was too small to detect any inter-annual or regional patterns in the data. However, it’s probably worth noting that some sea lions tagged at the same site during the same year even displayed different behaviors.


More than likely, females that traveled offshore were targeting oceanographic features known to concentrate prey items like meso-scale eddies, fronts, or currents, whereas females that remained close to shore may have been targeting prey items associated with benthic features. Although these habitat associations weren’t readily apparent for all individuals, the dive data tended to support this theory.

Overall, we found females primarily foraged at night. They used a combination of benthic (to the sea floor) and epipelagic (surface waters or top zone of the ocean where light still penetrates) foraging strategies. The satellite tags of 10 females were programmed such that dives were tallied into depth bins, which were received as histogram messages for six hour periods throughout the day. Together, these data indicated that average dive depths were shallow during night and deeper during day when they were in pelagic waters (open ocean), whereas the opposite occurred when they were in waters on the continental shelf, or nearshore. This pattern suggests the females were possibly feeding on vertically migrating prey species (e.g. Salmonidae, Myctophidae, and Gonatidae) while off-shelf, whereas when foraging closer to shore, they may have been feeding on Atka mackerel. Atka mackerel display surface directed vertical excursions during daylight hours and little to no vertical migration during night.

Interestingly, the remaining three sea lions (=33, =34, and =36) had tags that provided dive depths with a time stamp. This allowed us to interpolate their dives to their location data along with some bathymetry data. Those data indicated most of the dives for =34 and =36, which primarily remained on the shelf, were benthic dives (most of which occurred at night). In contrast, the majority of dives for =33, which used both shelf and non-shelf habitat, were epipelagic (or shallow surface) dives throughout the day. To that end, maybe the old adage “different strokes for different sea lions” goes without saying.

I am a wildlife biologist with MML’s Alaska Ecosystem Program, where I am responsible for designing, implementing, and reporting field research related to the foraging ecology and health of Alaskan Steller sea lions and northern fur seals. I received a B.S. in biology from SUNY Albany, a M.S. in marine science at Moss Landing Marine Laboratories, and earned my Ph.D. from the School of Aquatic and Fisheries Sciences at the University of Washington. Prior to my employment at MML in July of 2004, I held positions with North Pacific Wildlife Consultants and The Marine Mammal Center.

Seals and sea lions: What’s the difference?

There are a few tricks to tell the difference between these two animal groups


September 13, 2017
Katie Sweeney



Now that we have started seeing reports of northern fur seal sightings from citizen scientists in our remote camera images on Steller Watch, I thought this would be the perfect time to discuss the differences between seals and sea lions! Northern fur seals add a bit confusion as they have “seal” in their name but, are they true seals? The short answer is, “no!”

Pinnipeds can be found in waters all over the world, even some lakes!

Here’s the long answer…

Pinnipeds (or suborder pinnipedia, which means “feather-” or “flipper-footed”) include three different groups of animals: walrus (the Odobenidae family), seals (Phocidae family), and sea lions (Otariidae family). The walrus is the only species alive in the Odobenidae family and can be found throughout the arctic (North Pacific and North Atlantic Oceans). They are one of the largest pinnipeds and actually have air sacks in their chest that they can inflate to help them float, much like a life jacket (reference: Marine Mammal Center)!

Generally accepted classification of the carnivora order. These sorts of classifications can change over time as new fossil and DNA evidence becomes available.

Seals, or ‘phocids’ (sounds like “faux-sids”), are often referred to as true seals or earless seals. They do in fact have ears though no external ear flaps, just small holes on either side of their head. Phocids also have small front flippers and while on land, galumph, or “inchworm”, to move around. At-sea, they use their hind flippers to propel themselves.

This is a great infographic showing different phocid species. Created by Peppermint Narwhal (via Facebook).

Sea lions, or ‘otariids’ (sounds like “oat-a-ry-ids”), are often referred to as eared seals include both sea lions and fur seals. Otariids have external ear flaps and large front flippers that they can rotate around and down in order to stand upright and “walk” on land. At-sea, they mostly use their large front flippers to propel themselves through the water. Fur seals do differ a bit from their fellow sea lion otarrids in that they have longer flippers and thicker fur. So, both northern fur seals and Steller sea lions are otariids and not phocids, or “seals”! Check out the images below of a northern fur seal pup and Steller sea lion pups showing those external ear flaps and upright posture and rotated flippers.

Pinnipeds can be found in waters all over the world, even some lakes! You may notice that there aren’t many species that inhabit warm tropical areas around the equator, though there are a few.

National Geographic infographic of pinniped species worldwide distribution (1987).

We will be sharing more about these northern fur seals in Alaska that many of you may start to see at Cape St. Stephens (Kiska Island) in remote camera images. There is an interesting project happening right now that I will share more about in our next blog post!

I have been a biologist in NOAA Fisheries Alaska Fisheries Science Center studying Steller sea lion population abundance and life history for over 10 years. I am an FAA certified remote pilot and have been flying marine mammal surveys with our hexacopter since 2014. I earned my B.S. in Aquatic and Fishery Sciences at the University of Washington and my Master in Coastal Environmental Management at Duke University. 

The fastest aerial survey of them all!

Check out the blog written by our aerial survey team

Josh Cutler                 Lowell Fritz                   Katie Luxa

Here is the blog from AFSC’s Dispatches from the Field written by this year’s aerial survey team—and featured Steller Watch bloggers—during the 2017 Steller sea lion aerial survey they conducted from June 27th to July 6th.

How Many Steller sea lions are there?

June 21, 2017—It is impossible to know exactly how many Steller sea lions are in the ocean. Luckily, the sea lions converge every summer on shore to give birth, mate, and rear newborn pups. For us researchers, this is a fantastic opportunity to count how many are on shore every year.

However, we must conduct our survey within a three week window. The timing has to be just right to ensure females have given birth. Wait too long and the animals (including newborn pups) will begin to disperse.

On top of the time constraint, we have 2,500 miles of coast to survey, from southeast Alaska through the Aleutian Island chain.


Collecting Information from the air

With the help of NOAA’s Aircraft Operations Center, we fly over the Steller sea lion rookery (where most of the pups are born) and haul-out sites in a Twin Otter plane.

This year we are going to fly over southeast Alaska, Prince William Sound, the Kenai Peninsula, and Kodiak Island. We will start our survey in Sika on June 26 and end near Kodiak on July 10.


Cameras mounted to the belly of the plane take high-resolution images of the sites below. Because it would take more than three weeks to survey all of the beaches, islands, and offshore rocks of Alaska, we alternate between the eastern (southeast Alaska through Kodiak) and western (the western Gulf of Alaska and Aleutian Islands) halves each year.

Technology helps us cover more ground

Our group also uses unmanned aircraft to survey Steller sea lions, primarily in hard-to-reach sites of the Aleutian Islands. This survey is done off the U.S. Fish and Wildlife research vessel M/V Tiĝlâx when we are surveying from the Twin Otter. See this link for more information.

Analyzing collected data

At the end of the survey, two scientists will independently count every sea lion in the 1000’s of high-resolution images that we took.


Counts of Steller sea lions during the breeding season are a consistent proportion of the total population (since some are at-sea when our images are taken). However, when compared across years, these counts allow us to track population trends.

A lot of ground covered in under two weeks

July 14, 2017—The 2017 Steller sea lion aerial survey went by so fast that we did not have a chance to send out an update until it was over! We had nearly perfect weather for flying and aerial photography: low winds, little precipitation, and high clouds. In 2015, this survey took 17 days to complete. We completed the 2017 survey in 10 days. There were only 3 “down days” – days we could not fly due to weather – during the survey period. Over the course of the 7 days in the air, we surveyed 196 sites , took 22,184 photographs, and traveled almost 6000 miles in approximately 40 hours of flight time. This includes 23 bonus sites in the Shumagin Islands, an area we did not plan to survey until the 2018 Aleutian Islands survey. The weather in the Shumagins is often poor and dangerous, so we took advantage of our extra time and unusually good weather to survey the islands this year.


What we saw

We saw sites with 1 or 2 lonely males, and sites with thousands of sea lions packed on a beach. We will know how many sea lions were actually at those sites in the next couple of months after two scientists independently count every sea lion in the images we took.

We even saw some of our marked sea lions from our survey altitude of 750 feet. You can read about the valuable information we learn from marked sea lions, and you can even help us find marks in the western Aleutian Islands at Steller Watch.

Not so black and white

Understanding the role of killer whales in the Aleutian Islands

Processed with MOLDIV

August 22, 2017
Kristin Campbell



As I peer through the binoculars, a jet-black, triangular dorsal fin slowly arcs over the ocean’s glassy horizon. There is no mistaking it… we found killer whales!

NOAA Fisheries. Permit No. 20465

For centuries killer whales have captured the human imagination. Although arguably one of the most recognizable species, there is a lot we still do not know about them… but we are learning! NOAA Fisheries’ Cetacean Assessment and Ecology Program has been studying killer whales in the Aleutian Islands of Alaska since 2001. As researchers, our goal is to better understand the abundance (how many whales there are), distribution (where the whales are), social structure, and feeding behavior of killer whales in the Central and Western Aleutian Islands. The information we learn about these populations can help us understand the role of killer whales within this fragile ecosystem. We are particularly interested in how, or if, Bigg’s (“mammal-eating”) killer whale predation or resident (“fish-eating”) prey competition may be impacting Steller sea lion recovery in the Western Aleutian Islands.

Transient killer whale predation on marine mammals in the Aleutian Islands has rarely been observed. However, on this year’s cruise we happened upon a predation event in-progress at Hasgox Point on Ulak Island.

During this year’s Steller sea lion cruise, killer whale biologist, Dr. Paul Wade, and I conducted cetacean (whale, dolphin, and porpoise) surveys from the highest point of our research vessel, the flying bridge. We spent hours scanning the horizon with our binoculars as our ship traveled from one Steller sea lion site to the next. When we sighted whales or porpoises we noted the species, group size, and their GPS location. This year we saw many cetacean species on our voyage including sperm whales, fin whales, humpback whales, Dall’s porpoise, beaked whales, and others. Surveys give us information about whale population abundance and distribution within the Aleutian Islands.

dorsal fin

When we encountered killer whales, we suspended our survey in order to collect photographs of the killer whale’s dorsal fins and adjacent saddle patch pigmentation. We are able to make an initial determination of ecotype (“fish-eating” resident or “mammal-eating” Bigg’s) in the field based on physical characteristics of the dorsal fin and saddle patch, group size, and behavior. However, photographs allow us to later confirm the ecotype designation and even identify individual killer whales from their natural markings. If conditions permitted, we launched a small vessel for closer approaches to collect tissue biopsies or deploy satellite tags.


Transient killer whale predation on marine mammals in the Aleutian Islands has rarely been observed. However, on this year’s cruise we happened upon a predation event in-progress at Hasgox Point on Ulak Island. We observed two transient killer whales methodically “working” the sea lion rookery. The killer whales closely approached sea lion groups on the shore and in the water.


These killer whales may seem menacing, but Steller sea lions are not defenseless! Steller sea lions are large, agile in the water, and have big teeth that could harm killer whales. Even though many sea lions were in the water, the killer whales were not successful in making a kill and eventually moved on. The next morning we observed another group of four Bigg’s killer whales at Ulak Island. This group was more active, they hunted further away from the rookery, and displayed exciting behaviors like tail slaps, spy hops, and even porpoising.

Image credit: NOAA Fisheries. Permit# 20465 MML/AFSC/NMFS/NOAA

This year we successfully deployed two satellite tags on Bigg’s killer whales. Satellite tags give us information about where the whales travel and how deep they dive, unlocking the mysteries of their daily activities. Previous satellite data from Bigg’s killer whales in the Western Aleutians has revealed distinct foraging patterns. The tagged Bigg’s killer whales made shallow dives around Steller sea lion rookeries in the early mornings and repetitive deep dives (to almost 400m!) in the evenings. This data has revealed that Bigg’s killer whales in the Central and Western Aleutians forage on both marine mammals and squid!

NOAA Fisheries. Permit No. 20465

We look forward to analyzing the data we have collected this field season (including photographs, remote camera images, satellite tag data, and survey data) and discovering more about whales in the Aleutian Islands of Alaska.

I am a volunteer researcher for NOAA’s Marine Mammal Lab studying killer whales and for the Burke Museum of Natural History and Culture studying sea otter morphology and foraging behavior. I earned my B.S. from the University of Washington in Biology. I plan to attend graduate school in marine mammal science.

Getting away from it all . . .

Returning from two months away at a remote field camp


August 15, 2017
Molly McCormley



I was one of the seven researchers who lived on a remote Alaskan island to study Steller sea lions during the 2017 summer breeding season. These field camps are important for studying behavior and vital rates (like survival and birth rates) of Steller sea lions across their range – much like what you’re doing on Steller Watch! People always ask me what it’s like to spend two months on a remote island in the Aleutians. I can honestly say that it’s some of the best months of my year!

I have just returned from my fifth summer at a Steller sea lion field camp and was stationed on Marmot Island for the first time! Picture a cabin in the middle of moss-covered woods, situated a couple hundred feet back from the beach, next to a fresh water lagoon. Can’t get more picturesque than that! Now imagine you get to wake up to birds chirping every morning and while you sip your coffee on the deck, fox kits (baby foxes) wrestle a few yards away and deer graze a little way off. Doesn’t sound too bad, huh? Those days make up for the times when the weather refuses to cooperate (heavy rain or strong wind) and fog obscures even the lagoon from view.


I was stationed at this cabin with one other field camper. Each day, we completed a four-hour shift at a Steller sea lion rookery (breeding site). A two-mile uphill hike is required to get to this site which, depending on the day, can be amazing. However, care must be taken to avoid devils club, a spiky monstrosity, and cow parsnip (also known as pushki), which contains a photosensitive chemical – it reacts with the sun and can cause blistering or skin discoloration. Machetes are sometimes required, especially in the beginning of the season, to clear the path and we take extra precautions to avoid coming into contact with pushki “juice”.

Image credit: Koa Matsuoka, NOAA Fisheries

Once at the site, we sit about 500 feet above the sea lions, with harnesses and climbing ropes clipped into an anchor system to ensure our safety. Our location allows us to observe the sea lions without disturbing them. Using binoculars and spotting scopes, we observe and record behavior of marked sea lions, as well as any other marine mammals in the area (e.g., killer whales), disturbance events (e.g., caused by rock slides), or sightings of Steller sea lions entangled in fishing gear and other marine debris.

Most days, these shifts fly by since watching Steller sea lion behavior never gets old to me. There’s always cute pups suckling or playing together; juveniles bouncing around the rookery, sometimes sneaking milk from females who are unaware; females giving birth; and males fighting to keep their territories. Having done this project for many years, I get to see the same animals every day and sometimes across multiple years. This allows me to get to know these individuals and makes collecting data exciting. What always amazes me about these animals is their hardiness and their ability to survive in harsh sub-arctic conditions!


One unique thing that I observed this summer was a female nursing two juveniles! It’s rare for sea lions to have two dependents, though having a juvenile and a new pup is more common on Marmot Island than Ugamak Island. However, I have never seen a female nursing two juveniles. That’s a lot of milk that she has to supply each of them. That means that this female must be very healthy, which is a great sign!

IMG_3891.jpgAt the end of the day, if it’s cold or raining, we light a fire in the wood stove to dry our field clothes and gear and get cozy inside our cabin. Our evening entertainment consists of watching the fox kits play or suckle mom, observing eagles or kingfishers perched around the lagoon, or maybe even just curling up with a good book by the fire. It’s nice to get away from the rush of normal life for a while. I count myself lucky that I get to study Steller sea lions from such an amazing location and I hope to continue this work for many years in the future!

Want to see how field camps operate in the Northwest Hawaiian Islands? Check out this blog by fellow biologists from the Pacific Island Fisheries Science Center about monk seal research in this other remote Pacific Island chain.

I am currently working towards my M.S. at the University of the Pacific studying elephant seals and their hormonal reactions to stress. I earned my B.S. from the University of California, Santa Cruz (UCSC). After undergraduate school I worked at the Ocean Institute and at UCSC’s Cognition and Sensory Systems Lab. I have worked at the Marine Mammal Laboratory’s summer field camps for the last five seasons to study Steller sea lion behavior and life history.