What’s that on the rookery?

Illuminating an interesting Steller Watch find…

ksweeney

February 13, 2017
Katie Sweeney

Biologist

 

From our Steller Watch survey, I learned a lot about many of you—thank you to everyone who filled out the survey, so far! One thing I saw was that you all are interested in hearing about other marine mammals and related research. This ties in nicely with today’s blog post. On the Steller Watch talk forum, I’ve seen many reports of an odd sighting on one of the rookeries: there is a uniform row of white squares that has been spotted on the beach at Cape St. Stephens (Kiska Island; see image below). Many of you guessed it was a part of a whale and you were right! This is the vertebrae (and other parts) of a sperm whale that washed up onshore.

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Remote camera image of the unique sighting spotted at Cape St. Stephens rookery on Kiska Island.

I’m no whale biologist but I have some information I can share with you about this discovery and sperm whales in the North Pacific Ocean.

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Tom Gelatt holding a sperm whale vertebrae.

We first discovered this whale when we visited in the summer of 2014. We were fortunate to have whale biologists with us during the research cruise who identified it as a sperm whale. We found many teeth in the tidal pools surrounding the large skull. Other parts of the whale had drifted down the beach (blubber and vertebrae), into the view of the cameras. I think those vertebrae may stick around for awhile, or at least until the next big storm. Check out this picture to see just how big one of those vertebrae really are!

Sperm whales are one of the most widely distributed whale species and are found all over the globe. They typically live near deep water and are able to dive as deep as 3,000 (915 meters) to over 6,500 feet (2,000 meters). Their heads are huge, almost 40% of their body length, and they have the largest brain of any creature that has ever lived (that we know of). Males can grow to about 60 feet (18.3 meters) while females are up to 43 feet (12.1 meters) long. Unlike many other whales, sperm whales have one blow hole (instead of two) that is located in the left of the forehead, which is why their blows are always angled to the left.

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Sperm whales use echolocation in the form of clicks or a series of clicks for communication and/or to locate their prey. According to Peppermint Narwhal, sperm whales are the loudest animal on earth and can produce sounds louder than a thunder clap! The spermaceti organ, which is located in their head, at the front of their skull, helps propagate and amplify their calls. Echolocation is especially important for sperm whales as they have relatively small eyes and are believed to have poor eye sight.

Because of the large amount of oil in the spermaceti organ and other body parts, sperm whales (among other whale species) were the target of intensive whaling in the North Pacific Ocean, which reduced their population by 68%. Commercial harvesting ended in the late 20th century though there were illegal killings recorded until the 1960s. Not a lot is known about sperm whales. Prior to whaling, it is believed that the sperm whale population in the north pacific was over 1.2 million individuals. Currently, this population is estimated to be just over 100,000 individuals.

Credit: Tim Cole, NOAA Fisheries

Sperm whales primarily eat medium to large squid, which tend to live in deeper waters. This is why we typically see sperm whales in waters near or above deep trenches along the Aleutian Islands (like the Delarof Islands). Sperm whales also feed on large quantities of sharks, skates, and fishes. In fact, some sperm whales have even figured out how to steal their lunch from fisher’s longlines. These types of interactions are becoming more common in the Gulf of Alaska and can cause quite a nuisance to fisheries. Also, did you know sperm whales sleep vertically deep in the ocean?

Keep your eye out for any other interesting finds and I’ll share what I can about them.

Sources: NOAA Fisheries and NOAA Stock Assessment Report

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. 

Stellar progress on Steller Watch!

A Steller Watch project update

ksweeney

January 18, 2018
Katie Sweeney

Biologist

 

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.

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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

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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!

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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. 

SURVIVAL 101

Why do we permanently mark Steller sea lions?

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December 12, 2017
Lowell Fritz
Biologist

 

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.

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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.

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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:

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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.

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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.

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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%.

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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?

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October 24, 2017
Michelle Lander

Biologist

 

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.

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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.

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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.

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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.

Studying northern fur seals

Understanding northern fur seal relationship with prey key to conservation

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October 11, 2017
Carey Kuhn

Biologist

 

This blog was featured on the Alaska Fisheries Science Center’s Dispatches from the Field. Since we have seen a sighting of a northern fur seal on Steller Watch we thought it would be great to share this incredible project with you all. Katie Sweeney of the Steller Watch team recently returned from the trip effort in September!

What’s Happening?

July 7, 2016—The northern fur seal population on the Pribilof Islands, Alaska has been experiencing an unexplained decline since the mid-1970s. This despite it being one of the most studied marine mammals.

Critical information is still lacking about the relationship between fur seals and their prey, which is mostly fish. That’s why this summer scientists will begin researching where the prey is located, how abundant it is and how that affects fur seals’ behavior and population trends.

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Pribilof Islands (St. Paul and St. George Islands) in Alaska, USA

In mid-July, we start tracking adult female northern fur seals in the Bering Sea near the Pribilof Islands using temporary tags glued onto the animals. The tags are removed after the animals make a few trips to sea.

At the same time, researchers will also be measuring the availability of fish that are the seal’s main food source. This part of the study is made possible by using two Saildrones. The Saildrones are unmanned, solar and wind powered boats that are collecting data across the Bering Sea this summer. Follow their movements here.

This project is an important step forward in our understanding of northern fur seal ecology and behavior. It’s vital for developing effective management and conservation strategies as the northern fur seal population continues to decline.

Check out the blog posted during the first year of this project conducted during the summer of 2016.

Tagging females at strategic breeding site on the northeast point of St. Paul Island

July 20, 2016—We’re half way through our field work capturing and tagging fur seals breeding on St. Paul Island, Alaska. We arrived on St. Paul on July 13 and after gathering our gear and doing basic upkeep to our equipment, we headed out to a northern fur seal rookery, or breeding site, last Thursday. We’re working at the northeast point of St. Paul Island, at the Vostochni rookery.

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Vostochni rookery on St. Paul Island, Pribilof Islands, Alaska, USA

This site was chosen for a number of reasons. One consideration was the ability to maneuver around the terrain and groups of animals, which are called harems, with our capture gear.

The terrain also provides great cover to easily recapture the animals later in the season. The instruments we use to track the fur seals record and store all of the data so it’s necessary to recapture these animals to get a complete picture of their behavior over the summer breeding season.

But the most important reason we chose Vostochni rookery is that we have good historical data on the fur seals that breed here. Based on previous studies we know that fur seals from northeast point generally feed north and northwest of the island on the Bering Shelf. This information helps us know where to direct the unmanned Saildrones that will gather information about fur seals’ prey.

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Dr. Kuhn and Dr. Sterling look for adult females with pups to capture and tag

For this part of the study, there are three of us on the field team: Jeremy Sterling a colleague from the Marine Mammal Lab, John Skinner a volunteer who works for the Alaska Department of Fish and Game and me.

So far, we’ve captured and instrumented 17 females and we are aiming for 30. Each fur seal is equipped with a satellite-linked dive recorder that will measure dive behavior and provide at-sea location information. These data will be linked with the fish abundance data measured by the Saildrones to help us understand how prey availability influences fur seal behavior.

Met our tagging goal and already obtaining important at-sea data about northern fur seals

July 25, 2016—Today the team is heading home to Seattle after a very successful field session. But I’ll be coming back in September to complete the study. For this first leg, we reached our goal and captured 30 fur seal mother-pup pairs and deployed 30 satellite tracking instruments on the adult females. We were pretty excited about that 30th fur seal. As of today, all but four of the fur seals are out to sea on their first summer foraging trip of the year. The remaining four will likely leave in the next day or two.

We use what we call the “box” or “tank” to move into the rookery, between harems, and work on an animal. I can’t help but think of the Flintstone’s car as we pick up our box and drive it into the rookery each day.

I mentioned in the last post that I’d tell you how we catch the fur seals. It’s not easy during the early breeding season (July) since male fur seals are aggressive about holding territories and keeping females within their harem, or group of females.

We use what we call the “box” or “tank” to move into the rookery, between harems, and work on an animal. I can’t help but think of the Flintstone’s car as we pick up our box and drive it into the rookery each day. Often, we can position the box right next to a harem with minimal disturbance. Check out this blog to learn more about the box-capture technique.

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The box is used on the rookery to keep biologists safe as they move through the rookery during the peak of the breeding season

We then select a female and pull her into our box leaving her head out, facing the harem. This year we also collected each female’s pup to get its weight measurement. This will help us track the pup’s growth over the season which is linked to mom’s success finding food. The more fish a female fur seal can find, the more milk she can give her pup.

Now that most of the females are out at sea, the tags are collecting detailed diving data which are stored on the device until I can recover them. The tags also send location information through satellites so we know where the fur seals are and we can watch the fur seals’ movements in relation to the two Saildrones that are measuring fish densities.

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Saildrone in St. Paul, AK

Currently, each Saildrone is following a grid pattern that we had established before tagging the females. But as the season progresses, we can adjust the pattern to make sure the Saildrones are sampling the feeding areas that our tagged fur seals are using.

As I said, I head back to St. Paul Island in September but I’ll be with a different team of researchers. We’ll recover all of the satellite tracking instruments and see how much the pups have grown.

In the coming weeks, I’ll share the latest information we’re getting from the fur seals, the Saildrones (click to follow the Saildrones’ movements), and any new discoveries we come across. This is crucial information that will help us in our efforts to conserve northern fur seals.

Early results from Saildrone research mission, one fur seal traveled 165 miles for food

August 22, 2016—We’re quickly approaching the final days of the northern fur seal portion of the Saildrone 2016 mission. The two Saildrones have already surveyed more than 1700 miles within the fur seal foraging area. Devices attached to the unmanned boats are measuring and locating walleye pollock, northern fur seals’ main food source.

As for the fur seals, I’ve been closely monitoring limited real-time data coming in from the tags glued onto the animals. All tracking instruments continue to send useful information about the fur seals’ movements and dive behavior. Each fur seal has made between three and five foraging trips, alternating time at sea with time on land nursing their growing pup and resting too.

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Adult female rests with her pup after a foraging trip

I’m really looking forward to September when I head back to St. Paul Island to weigh the pups, measure their growth and recover the tracking instruments, obtaining a wealth of information stored directly on the tags.

Meanwhile, there is still that smaller group of fur seals not feeding within the grid pattern the Saildrones have been following. We want to learn more about what they are feeding on too. That’s why in the next couple of days we’ll have the Saildrones move farther north and east, where the other animals are traveling.

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Saildrone path (straight line transect grid in yellow-orange) over adult female fur seal satellite tag tracklines in the Bering Sea near St. Paul Island in the Pribilof Islands, AK

After that, one Saildrone will make a quick trip east to listen for critically endangered North Pacific Right whales. There are just an estimated 30 left. Then both boats head back to Dutch Harbor, Alaska to end the mission.

The next step will be starting the process of analyzing all the data from the fur seal tags and the devices on the Saildrone. It will take a couple of months for my colleague, fisheries biologist Alex De Robertis and me to process all the information. We are excited to get a better idea of the prey available to the fur seals during these summer months which may help us unravel why this population continues to decline.

Recovering instruments and collecting blood samples to gain a wealth of new information

September 29, 2016—I’m back on St. Paul Island and fur seal recaptures are well underway. We started the work on Thursday and have already recovered 22 instruments! It’s been an intense couple of days but we are happy to be ahead of schedule.

Catching fur seals this time of year is much different than catching them in July. The box has been put back into storage. Now we are spending much of our time on the ground, crawling among the fur seals. Read how seasons affect fur seal capturing techniques.

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Biologists look for tagged adult females to recapture and carefully remove satellite tags.

Once an animal is caught, her tracking instruments are removed by cutting the top layer of hair just under the instrument. This layer is called the guard hair and it will regrow after the fur seal goes through her annual molt in October. We also collect external or morphometric measurements, including the animals’ weight and length, and take a blood sample. The blood will be used in a variety of studies, including: an assessment of general health, a study investigating mercury levels, and research measuring stable isotopes as a method for identifying foraging locations.

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Dr. Kuhn carefully removing a satellite tag that was glued on an adult female northern fur seal

While mother fur seals are out at sea feeding, their pups are spending time sleeping, playing, and roaming the rookery in little pup packs. This makes the pups a little harder to catch. And since pups are not marked in any way, it’s also difficult to match mothers with their rightful pups. An instrumented mom and her pup are often surrounded by a number of other pups awaiting their moms’ return. But despite this challenge, we have been quite successful and captured 12 mother-pup pairs so far.

The ten other recaptured females were not with their pups when we caught them. So, as we wait for the remaining instrumented females to return to the island, we will try to catch as many of those pups as we can. Pups are an important part of the study because we can use their weight gain over the summer to determine how successful their mothers were during foraging trips. The largest pup to date was 34 pounds, more than double what he weighed in July.

Since the majority of the instruments have been recovered, we expect the remaining animals to trickle in over the next few days. Check back next week for more instrument recovery updates. Will we meet our goal? I’ll also share a glimpse of the data that we collected this year!

New data from satellite instruments shows stark differences in fur seal feeding behavior

October 13, 2016— After a very busy couple of weeks, I am happy to report that I am back in Seattle and ready to start the next leg of our 2016 Saildrone mission: data analysis!

We were able to recapture 29 of the 30 instrumented females and remove their tags, resulting in one of our highest instrument recovery rates in years. Eighteen of those females were caught with their pups, giving us the ability to link the females’ foraging behavior and their reproductive success.

I wanted to share with you what our fur seal dive records look like. Below are two females’ dive patterns. They’re good examples of how different dive behavior can be between individuals. The graphs show dive behavior over the same 12 hours window – but on different days. The top plot is for July 28. The second plot is from July 30. Notice how both the number of dives and dive depths differ between these two fur seals.

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Dive profiles of two adult female northern fur seals

The first female (top graph in image above) was regularly diving more than 70 meters which is about 200 feet. The second female (bottom graph) never went past about 65 meters and only went to that depth twice. Yet, the foraging grounds used by these two females were relatively close, just northeast of St. Paul Island. We don’t know why there are such differences but we hope to find out.

The data collected from the Saildrone will be able to tell us more about the fish at these fur seals’ foraging sites. Perhaps we’ll find that where the first seal was feeding the pollock were larger in deeper water.

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A satellite tagged adult female lies on a log with her pup

The data analysis stage will take several months and the process is a collaborative effort. I’ll be analyzing all of the fur seal data and will work with my colleague Alex De Robertis who is examining the fish abundance data. That information was collected from acoustic devices attached to the Saildrone. We’ll merge the data sets to get a clearer picture of fur seals and their pollock prey in the Pribilof Islands.

This field season was incredibly successful overall and it wouldn’t have been possible without the hard work of my field teams in both July and September. Their enthusiasm and commitment, even in some awful weather conditions, made it possible to recover a wealth of data that will be vital for helping us understand fur seal declines.


Carey Kuhn is an ecologist at the Alaska Fisheries Science Center’s Marine Mammal Laboratory. Carey joined the Lab’s Alaska Ecosystems program in 2007 after completing her Ph.D. at the University of California Santa Cruz. Her research focuses on the at-sea behavior of northern fur seals.

*Notes: Research conducted and photos collected under the authority of MMPA Permit No. 14327. All data presented here are preliminary analyses and subject to change.

Seals and sea lions: What’s the difference?

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

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September 13, 2017
Katie Sweeney

Biologist

 

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)!

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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.

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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.

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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. 

Not so black and white

Understanding the role of killer whales in the Aleutian Islands

Processed with MOLDIV

August 22, 2017
Kristin Campbell

Biologist

 

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.

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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.

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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.

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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.