May 1st: ~16

Sea Lion of the Month

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Here you can see ~16 suckling from his mother in October 2012 when he was just over a year old.

The Sea Lion of the Month for May is one that was nominated by one of our Steller Watch team. This months sea lion is a male who we marked as ~16 at Gillon Point (Agattu Island) on June 23, 2011—this is when the first group of sea lions was marked in the western Aleutian Islands! When he was marked he weighed about 84 pounds (38 kg) and was almost 4 feet (113 cm) long and over 2.5 feet (79 cm) around his torso, just below his flippers. That is one big pup and ~16 will be 7 years old this summer!

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This sea lion is quite the adventurer judging by all of our sightings at six different locations! In fact, we have seen him at least once per year since he was marked. Mostly, it seems as though he was hanging around Agattu Island (both at Gillon Point, his birthplace and Cape Sabak). Then in 2013 he seemed to have spread his wings to nearby Alaid and Attu Islands. When he was in 2014 he began to range farther and we saw him at Buldir and Ulak Island in between visits back to Agattu and Alaid.

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~16 from an aerial perspective with the drone during the summer of 2016.

I expect that during the summer breeding season, now that he’s getting a bit older, we’ll see him around Gillon Point since he’ll be hoping to someday be big enough to defend a breeding territory. Kind of like in 2016 when we saw him with our drone!

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Fall of 2016, ~16 was spotted at Hasgox Point at Ulak Island.

Curious about other pinnipeds (seals and sea lions)? Check out our neighbors in the Pacific Islands to the south, the monk seals of the Northwest Hawaiian Islands. The Pacific Island Fisheries Science Center features their own Monk Seal of the Month!


We will share the story of one marked sea lion each month. Be sure to check our Sea Lion of the Month page on the 1st of every month to learn about our featured Steller sear lion. You may nominate a sea lion by submitting their full mark on the Sea Lion of the Month nomination forum. Thank you all for your nominations! 

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

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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.

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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.

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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).

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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

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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.

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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.

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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.

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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).

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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.

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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.

April 1st: ~91

Sea Lion of the Month

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Happy April Fool’s day! The Sea Lion of the Month for April is no joke. This male sea lion was marked at Gillon Point (Agattu Island) on June 24, 2013. That means he will be 5 years old this summer! When he was marked he weighed about 51 pounds (23.2 kg) and was just over 3 feet (98 cm) long and 2 feet (64 cm) around his torso, just below his flippers.

According to our sighting records, the only time we see ~91 is from remote camera images captured at Alaid Island in the summer of 2014!

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We have never seen him during our summer research cruises. This is a case that definitely shows how vital these remote cameras and your efforts to classify images is to finding these marked animals! If we didn’t find animals like this that we miss during our summer cruise, we would not be able to accurately estimate important population rates that will help us figure out why this part of the population continues to decline.

Luck for us, you diligent and skilled Steller Watch citizen scientists have your eyes peeled and discovered ~91 on Gillong Point in the images posted to our current workflow. Keep up the great work!

 

Curious about other pinnipeds (seals and sea lions)? Check out our neighbors in the Pacific Islands to the south, the monk seals of the Northwest Hawaiian Islands. The Pacific Island Fisheries Science Center features their own Monk Seal of the Month!


We will share the story of one marked sea lion each month. Be sure to check our Sea Lion of the Month page on the 1st of every month to learn about our featured Steller sear lion. You may nominate a sea lion by submitting their full mark on the Sea Lion of the Month nomination forum. Thank you all for your nominations! 

March 1st: ~35

Sea Lion of the Month

The Sea Lion of the Month for March is ~35. This sea lion was in the first group of sea lions that was marked on Gillon Point (Agattu Island) back in 2011 and has had a pretty adventurous life so far! When this female was marked on June 23, she weighed about 53 pounds (24.2 kg) and was almost 3.5 feet (105 cm) long.

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~35 after she was marked on Gillon Point (Agattu Island) on June 23, 2011.

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In our records, we only saw ~35 once more on June 23, 2014 and then we never saw her again… Where could she have gone? Well, it turns out, she showed up again in 2016 all the way on Medny Island in the Commander Islands in Russia! This Island group is the next group just west of the Near Islands which is the westernmost part of the United States.

The great news was that when they spotted her at the Medny field camps, she had just birthed a pup! This means she was 5 years old when she had her first pup. She also gave birth to her second pup this past summer of 2017.

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~35 spotted in 2016 with her first pup in Russia. You can also see M750, an adult female marked on Medny Island.

This sea lion isn’t the only one to show up in Russia, they also spotted ~141 last summer for about five days on the Medny Island rookery among hundreds of fur seals! Can you see how much smaller fur seals are compared to Steller sea lions?

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~141 from Gillon Point (Agattu Island, U.S.) spotted among northern fur seals on Medny Island from July 30 to August 8 in 2017.

Curious about other pinnipeds (seals and sea lions)? Check out our neighbors in the Pacific Islands to the south, the monk seals of the Northwest Hawaiian Islands. The Pacific Island Fisheries Science Center features their own Monk Seal of the Month!


We will share the story of one marked sea lion each month. Be sure to check our Sea Lion of the Month page on the 1st of every month to learn about our featured Steller sear lion. You may nominate a sea lion by submitting their full mark on the Sea Lion of the Month nomination forum. Thank you all for your nominations! 

What’s that on the rookery?

Illuminating an interesting Steller Watch find…

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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. 

February 1st: A1

Sea Lion of the Month

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I thought for this month’s featured sea lion, it would be interesting to share the story of a male sea lion that we have observed over his entire life-span. The February Sea Lion of the Month is A1. When we would see him in the field, we would fondly call him, “steak sauce,” after the well known A.1. Steak Sauce. Did you know, according to Wikipedia, in 1824, the English King George IV tried the sauce and called it “A.1.”, the highest category to classify ships for insurance purposes (meaning high quality)? And so was the name coined…

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Anyway, the sea lion, A1, was the first to be marked on Ugamak Island in 2001 on June 27th. At the time, he was just under 3.5 feet (99 cm) long and weighed just over 50 pounds (24 kg). Typical of male juvenile sea lions, he was not seen much after 2001 until 2004 at Billings Head on Akun Island. Shortly thereafter in June, he returned to his birth place, Ugamak Island. The next sighting was all the way up at St. George Island (of the Pribilof Islands, in the Bering Sea), almost 300 miles north, in January. He then went back to Billings Head in May before being spotted again on Ugamak during the summer breeding season.

From then on, it seems A1‘s general trend was to spend some time on St. George in the winter, and always returning to his birth place on Ugamak during the summer breeding season. In fact, amazingly, he held a breeding territory with females (also called a “harem”) for 5 summers in a row from 2008 (when he was 7) to 2013 (when he was 12 years old. That’s quite impressive considering that means he was onshore fasting while holding those territories. This also means he was involved in many territorial fights with other males, which is very obvious in this picture where you can see several superficial wounds.

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Our last sighting of A1 was on July 5, 2013, on the haulout part of the rookery, where males without breeding territories hang out with other males. He had arrived on Ugamak on May 29 of this year and held a territory however, he did not have any females until June 28th and only until July 4th. It’s hard work maintaining a territory and it seems this was his final year to do so. Since it’s been almost 5 years since we have seen him, and he would be almost 16 years old by now (which is fairly old for a male sea lion), it’s likely steak sauce has died. But, I still hold out hope that we will catch a glimpse of him one last time living the good life on St. George…

Curious about other pinnipeds (seals and sea lions)? Check out our neighbors in the Pacific Islands to the south, the monk seals of the Northwest Hawaiian Islands. The Pacific Island Fisheries Science Center features their own Monk Seal of the Month!


We will share the story of one marked sea lion each month. Be sure to check our Sea Lion of the Month page on the 1st of every month to learn about our featured Steller sear lion. You may nominate a sea lion by submitting their full mark on the Sea Lion of the Month nomination forum. Thank you all for your nominations!