Biologists return to the office!

We’ve completed our 2019 field season!

ksweeney

October 1, 2019
Katie Sweeney

Biologist

 

Somehow it feels as though we just left for our summer field season and yet, it’s nice to be back with gigabytes of data! We had another successful field season in Alaska studying Steller sea lions and northern fur seals. Our Steller sea lion research included our annual aerial survey and our annual vessel survey to the far west Aleutian Islands. Unfortunately, this year we did not get around to conducting a vessel survey to look for marked animals in the eastern Aleutian Islands and Gulf of Alaska. Fortunately, our partners in the Alaska Department of Fish and Game were able to look for marked animals in parts of the Gulf of Alaska.

Expected 2019 field work conducted by the Alaska Fisheries Science Center. NOAA Fisheries.
Expected 2019 field work conducted by the Alaska Fisheries Science Center. Full-resolution version can be downloaded from the NOAA Fisheries website found here!

Northern fur seal research was conducted during a vessel survey to Bogoslof Island, in the eastern Aleutian Islands, as well as some land-based trips to look for tagged animals on the Pribilof Islands, where the largest aggregation of fur seals can be found. Many of our team just returned from the Pribilof Islands from a pup and adult female tagging trip, as well. And, as with previous years, we’ve had more camera tags deployed on adult female fur seals to collect rare footage of foraging at sea.

All in all, another jam packed field season and I can’t wait to share more stories with you, soon.


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. 

Off we go!

It’s time for the 2019 field season!

ksweeney

June 1, 2019
Katie Sweeney

Biologist

 

It’s that time again! We are about to set out for another summer field season to collect data on Steller sea lions and northern fur seals in Alaska! We’ll be conducting several trips to the field on ships, land, and aerial surveys to collect aerial images for counting individuals, ship- and skiff-based counts, sightings of branded sea lions and tagged fur seals, collect remote camera images, brand more sea lion pups out west, and deploy and reterieve more camera tag videos on fur seals. A busy summer indeed! Check out the map below (and check out the link in the caption to download the full version!) to see all the field work the Alaska Fisheries Science Center will be doing this summer.

Expected 2019 field work conducted by the Alaska Fisheries Science Center. NOAA Fisheries.
Expected 2019 field work conducted by the Alaska Fisheries Science Center. Full-resolution version can be downloaded from the NOAA Fisheries website found here!

We will miss you and while we’re away our trusty moderator will be present when he can on the Talk Forum. Thank you all for your efforts throughout the year! We’ll see you when we return in September!


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. 

Part II: Is that a healthy pup?

With a few measures we can check on the health of pup and find out about mom too

profilepic

April 24, 2018
Brian Fadely
Biologist

 

In my last post, I shared how we use pup weights and lengths to calculate a condition index to better understand the health of the pups. When we handle Steller sea lion pups that will be marked, we also collect blood, tissue, and fur samples. Collecting blood and other tissue samples allows us to evaluate health status in another way involving work in a lab. We look at blood chemistry and hematology parameters, to test for signs of disease, contaminant exposure, or other systemic concerns.

Some degree of clinical issues or disease is normal to find in any wild population; we’re interested in determining whether there is evidence of clusters of disease, contaminant exposure, or other concerns at a rookery or greater area. This can provide insight into local conditions that may help explain population declines or lack of recovery. Samples are collected while the pup is gently but firmly restrained by hand.

DCIM101GOPRO
Collecting a blood sample from a restrained pup. The restraint board helps prevent wriggling so the procedure is safe for the pup and handlers.

The board that we place the pup on helps prevent wriggling so the procedure is safe for the pup and handlers. We looked at blood chemistry and hematology profiles of 1,231 pups sampled during 1998-2011 throughout Alaska. We found no indications that pup condition was compromised during their first month after being born, including pups within the declining parts of the Aleutian Islands (Lander et al. 2013).

Exposure to heavy metal contaminants (like mercury) is a concern since Steller sea lions are apex predators, or predators that feed at highest trophic level. In other words, Steller sea lions eat prey that are high up in the food web. That means, if there are contaminants in an environment, the contaminants can bioaccumulate and biomagnify through the food chain. Exposure to high levels of mercury can cause neurological disruption that may impact health and consequently survival and reproduction. Pups accumulate mercury during gestation in utero (while they are a fetus in their mothers), and again once they are born and suckling milk from their mothers. In a project led by collaborators at the University of Alaska Fairbanks and Alaska Department of Fish and Game, we’re investigating the mercury burden of pups throughout their range in Alaska and Russia. We shave off a small patch of hair from the pups when we handle them and are then able to measure the mercury content. Specifically, we can figure out the mercury concentration the pup was exposed to from its mother over a period of several months during gestation.

hairpatchpup
The patch where hair was removed for a sample to measure mercury content is evident on this pup chilling with mom at Agattu/Gillon Point. 

We found that pups in some areas of the endangered western population had a higher mercury exposure than pups from Southeast Alaska (Castellini et al. 2012). The greatest exposure is shown by pups from the Gillon Point rookery on Agattu Island, with three pups showing exposure levels known to cause neurological effects in other fish-eating wildlife (Rea et al. 2013). If you look at the figure below, you can see the difference in mercury exposure (median values are shown by colored lines and average values by black lines) between pups from Agattu Island and other rookeries can be seen in this boxplot that was published in Rea et al. (2017).

hgfig

We do not have direct evidence that this exposure to mercury during gestation leads to health consequences for the pups and their subsequent survival, nor that it impacts adult reproduction. But, these levels of mercury exposure do indicate that further research is necessary to better understand the role of contaminants in the ecology and biology of Steller sea lions.


I am a research wildlife biologist with NOAA Fisheries Alaska Fisheries Science Center in Seattle, in the Alaska Ecosystems Program where I’ve studied Steller sea lions and northern fur seals since 2000. My primary research interest is vertebrate physiological ecology, which at NOAA Fisheries translates into studying sea lion foraging behavior, health status, and body condition to help address conservation questions and wildlife management issues.

Part I: Is that a healthy pup?

Part 1: Studying the condition of sea lion pups

profilepic

April 10, 2018
Brian Fadely
Biologist

 

When we handle Steller sea lion pups that will be marked, we also check their condition and health status, similar to when you take your pets to the veterinarian for a check-up.  Collecting health data can give an indication of local environmental conditions, and allows testing of some hypotheses for the population decline.

DCIM101GOPRO
Pups are weighed by holding them in a small hoop net and measuring with a digital scale suspended from a tripod. Photo by Kristen Campbell.

While we are handling the pups, we weigh them and measure their length and girth as indicators of condition. We look at these measurements relative to the weighing date (since we don’t know a pups birth date), as well as, their weight relative to their length. Both are used as indices of body condition and help us explore trends among pup measured across regions or over years.

Weighing and measuring pups is straightforward, as simple as suspending them from digital scale while nestled in a hoop net. Length is measured from the tip of nose to the tip of their tail, and girth is measured around the body just behind the front flippers.

OLYMPUS DIGITAL CAMERA
A pup that fell asleep in the net while being weighed

Pups are born between late May and early July but half of the pups are born by June 10th. For consistency, we try to sample pups between June 20th and July 7th, which means we’re sampling them when they are 12-25 days old, but possibly 5-37 days old. At this young age, the size and health of the pup largely reflects the mother’s condition while she was carrying the pup, since about April. Pup condition can vary with many factors including age and size of the mother and the local foraging conditions she encounters, which we typically don’t have any way to directly assess.

Looking at pup measurements collected throughout the Aleutian Islands from 1990 to 2017, the weight of female pups (a total of 1,958 measured) has ranged between 33 and 97 Ibs (15 to 44 kg), or an average of 62 Ibs (28 kg). The weight of male pups (a total of 2,234 measured) ranged between 29 and 115 Ibs (13 to 52 kg), with an average of 75 Ibs (34 kg). Male pups tend to weigh about 11 Ibs (5 kg) more than females. Generally, pups grow just under a pound (over a third of a kg) per day.

Just as with human infants, we can compare the size of any pup against all others to determine whether they are relatively large, small, or about average. In the figure below, the sizes of pups from Hasgox Point on Ulak Island (white squares) and Gillon Point on Agattu Island (black circles) are compared to all other Aleutian Island pups (light gray circles) for females (F, left figure) and males (M, right figure). It’s evident that while some individuals are small or large compared to others, the size ranges of pups from these islands are similar to all others.

MLpupsfig
In these plots, each dot represents the weight of a single pup. The left plot shows females and the right, males. The two sites you may be familiar with are Hasgox Point on Ulak Island (white squares) and Gillon Point on Agattu Island (black circles). The light gray circles are all other pups in the Aleutian Islands.

Since we don’t weigh the pups on the same day and they put on weight each day as they grow, to compare pup condition over years or between rookeries, we create a condition index. The condition index compares the weight we collect to the weight we would expect to see on the weighing date, or to the weight expected for their length. This condition index is a ratio of the measured weight to the expected weight which is calculated from doing a regression of all pup masses by weighing date.

In the figure below is called a box plot (also called a box and whisker plot). This is a great way to visualize data. The condition index ratio we described above is plotted in the following two figures. Median values (black lines) are shown within the 25th and 75th data percentiles (boxes), and outlier values (black dots) are plotted outside of the whiskers (1.5 times the percentile range, showing data dispersion). This box plot above shows the data collected from female pups measured from 1994 to 2017 at rookery sites within the area we have remote cameras deployed in the Aleutian Islands. Essentially, if the observed and expected weights are the same, then the condition index ratio is 1.0 (the horizontal dashed line).

CIfems

Values above that are interpreted as ‘better’ condition (they weigh more than expected for their length), and ratios less than 1 are ‘poorer’. Pups from Agattu Island rookeries tended to weigh less for a given length than did pups at Kiska or Ulak Islands, though overall there is not a great difference among these sites.

ci-ulak

Alternatively, we can look at differences in pup condition over the years at specific sites or region. The box plot above shows the condition indices for female pups at Hasgox Point (Ulak Island) collected from 1994 to 2017. This data suggest that the pup cohort of 1994 was in apparently relatively poorer condition compared to later years, while cohorts since 2013 have been in relatively better condition.

All of this information are valuable pieces in the puzzle towards figuring out why Steller sea lions have not recovered in the Aleutian Islands. In the next blog, I will be sharing what we can learn from the different samples that we collect from pups along with weight and length measurements. Be sure to sign up for blog notifications by filling in your email and clicking the “Follow” button!


I am a research wildlife biologist with NOAA Fisheries Alaska Fisheries Science Center in Seattle, in the Alaska Ecosystems Program where I’ve studied Steller sea lions and northern fur seals since 2000. My primary research interest is vertebrate physiological ecology, which at NOAA Fisheries translates into studying sea lion foraging behavior, health status, and body condition to help address conservation questions and wildlife management issues.

To stay or go?

Different strokes for different sea lions?

Lander.jpg

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.

telem_all.jpg
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.

=34and35_2.jpg
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.

=32_3.JPG

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

Kuhn.jpg

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.

FurSeals_PribilofMap350W
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.

FurSeals_2016_1_Vostotchni
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.

furseals_2016_1careyjeremy-e1507739978837.jpg
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.

FurSeals_2_Boxwork
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.

FurSeals_2_SaildroneStPaulHarbor
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.

FurSeals_3_Mompup
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.

FurSeals_3_trackmap
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.

FurSeals_5_searching
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.

FurSeal_4_removinginstrument
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.

FurSeals_5_smallgraph
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.

FurSeals_5_tag
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.

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.

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.

Campbell_photographs.jpg

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.

Blog-2

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.