Gearing up for the field season

We heading off to Alaska and we will be back in August!

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June 6, 2017
Katie Sweeney
Biologist

 

The office has been humming with energy lately. It’s that time of year, the field season is just around the corner. Spring and summer are busy times at the Alaska Fisheries Science Center. This is the time of year when the Center conducts the majority of its field work. Weather in Alaska over the winter isn’t conducive to getting work done, though summer weather offers no guarantees, either!

While we’re away, we will be putting the Steller watch project on hold starting June 20th. Since we won’t have internet while we are in Alaska we can’t respond on the Talk Forum but don’t worry! We’ll be back in August with many more images and stories to share with you all.

Some of the Center’s research trips this year include bottom trawl and hydro-acoustic groundfish surveys, marine mammal aerial surveys in the Arctic, harbor seal vessel surveys, Cook Inlet beluga aerial surveys, and vessel surveys to deploy passive acoustic recorders to record marine mammal sounds. Along with Steller sea lion surveys, our program will also conduct several studies on northern fur seals.

We have four Steller sea lion trips planned, similar to our efforts in 2016. And like all the field work at the Center, these trips require a lot of preparation. It is a coordinated effort to ensure we have everything we need since we will be isolated in very remote places and can’t just run to the store if we forgot something. Here’s a little background about each of our Steller sea lion trips:

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One of our featured bloggers, Katie Luxa, has been working with other biologists to accomplish the large task of packing and preparing gear to be shipped up to Alaska to our remote field camps. They have also been preparing the week-long training class for the seven biological observers who will be living on two uninhabited islands (Ugamak and Marmot Islands) for almost two months. The field campers will live in rudimentary shelters with limited electricity, no internet or cell phones, and no running water. They will be perching above sea lions, going unnoticed to collect data on marked animals and sea lion behavior.

Research cruise

One of the trips I will be participating in will be our annual research cruise on board the U. S. Fish and Wildlife Service (USFWS) Research Vessel (R/V) Tiĝlax̑ (pronounced TEKH-lah; Aleut for eagle). For two weeks, 13 people from the Alaska Fisheries Science Center will call this 120 foot vessel home. Every summer, six skilled USFWS crew members operate this vessel, a vital platform, for nearshore research along the Alaska Maritime National Wildlife Refuge.

During our trip, the primary goal is to study sea lions to collect population counts, service our 20 remote cameras and download images (more images to come for our citizen scientists team members!), look for marked individuals, and mark individuals for on our ongoing research project. Along with sea lion biologists, there are two fish biologists who will dropping an underwater camera near sea lion sites to get a better idea of the available prey. There will also be two killer whale biologists on board looking for killer whales and other species of whales.

hexacopterTo prepare for this trip, I’ve been working with our other remote pilots to test out our new camera mount, called a gimbal, mounted to our hexacopter (or drone). The gimbal mount ensures that the camera will always point directly down and over the sea lions no matter how much the wind causes the hexacopter to tilt. I’m excited to see these mounts in action! We also have a new person on our team who you heard form in our last post about the NOAA Corps. LTJG Blair Delean will be heading up to Alaska with us for the first time to help with hexacopter surveys.

Aerial survey

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Biologists (and featured bloggers) Lowell Fritz, Josh Cutler, and Katie Luxa will be heading out on the annual aerial survey. The team will meet up with NOAA Aircraft Operation Center flight team and Twin Otter aircraft in southeast Alaska. They will survey along the coastline, capturing images of sea lions hauled out on land at known sites.

The aerial survey team assembled and tested our camera mount that holds three cameras; it will be installed on the NOAA Twin Otter. Now we know it’s working fine, I’m packing up all the gear to ship to Alaska.

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After the aerial survey and research cruise, Katie Luxa and I will meet up in Dutch Harbor (Unalaska Island) for our final survey. We will be on board a small boat for six days, checking out nearby sea lion sites for marked animals.

While we’re away, we will be putting the Steller watch project on hold starting June 20th. Since we won’t have internet while we are in Alaska we can’t respond on the Talk Forum but don’t worry! We’ll be back in August with many more images and stories to share with you all. Thank you all for your contributions classifying so many images before we head out. It’s been a joy to share our research with such dedicated people and we are so happy to have you as apart of our team!

Wish us calm seas, clear skies, low winds, and many sea lions!


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. 

Service Meets Science

The life of a NOAA Corps officer

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May 24, 2017
LTJG Blair Delean
NOAA Corps Officer

Unmanned Aerial Systems (UAS) have recently become a major tool for studying wildlife. UAS allow scientist to capture aerial imagery of marine life in remote locations with more flight flexibility, and at lower cost than most manned aircraft missions. As a Lieutenant (Junior Grade; LTJG) in the NOAA’s Commissioned Officer Corps (called “NOAA Corps”) and recently designated UAS Pilot in Command at the Alaska Fisheries Science Center, I will be traveling to the Aleutian Islands this summer to study Steller sea lions using UAS. This is the same research cruise that members of the Steller Watch Project research team will be a part of to collect remote camera images.

The NOAA Corps today consists of a team of professionals trained in various scientific disciplines who operate NOAA’s ships, aircraft (like the annual Steller sea lion aerial survey), conduct diving operations, manage research projects, and serve in staff positions throughout NOAA offices.

The NOAA Corps is one of the Nation’s seven uniformed services comprised of 321 officers who serve throughout NOAA’s line and staff offices to support virtually all of the agency’s programs and missions. TheNOAA Corps traces its roots to the former U.S. Coast and Geodetic Survey, which originated in 1807 under President Thomas Jefferson.

The NOAA Corps today consists of a team of professionals trained in various scientific disciplines who operate NOAA’s ships, aircraft (like the annual Steller sea lion aerial survey), conduct diving operations, manage research projects, and serve in staff positions throughout NOAA offices. NOAA Corps Officers are primarily stationed in the continental United States; however, there are some positions located as remotely as Antarctica, Hawaii, and the Samoan Islands in the South Pacific.

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NOAA Aircraft Operations Center in Florida

Currently, officers operate 16 research vessels which are strategically stationed at various locations around the country. These places include Norfolk, San Diego, Gulf of Mexico, Pacific Northwest, and Honolulu which is where I was last stationed before my assignment to the Alaska Fisheries Science Center in Seattle. The ships are crewed by both NOAA Corps Officers and civilian wage mariners to serve NOAA’s fisheries, hydrographic, or oceanographic missions. The aviation component is comprised of both manned and unmanned aircraft systems operated by Corps officers stationed at the Aircraft Operations Center in Florida.

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My BOTC class on graduation day.

My path to becoming a UAS pilot for NOAA began following my graduation from the Basic Officer Training Class (BOTC) at the United States Coast Guard Academy in the spring of 2014. I was then assigned to the NOAA Ship Oscar Elton Sette in Pearl Harbor, Hawaii. While on the Sette my primary duty was to drive the ship, manage scientific operations, and to serve as the Navigation Officer. Some of my other responsibilities included being the environmental compliance, dive, and property officer. We sailed the main Hawaiian Islands and beyond through the remote Northwest Hawaiian Islands which extend 1,200 miles from Kauai.

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The NOAA Ship Oscar Elton Sette off the coast of Laysan Island in the Papahanaumokuakea Marine National Monument (Northwest Hawaiian Islands).

In the fall of 2016, following my tour on the Sette, I was assigned to the Marine Mammal Laboratory at the Alaska Fisheries Science Center in Seattle, WA. This is when I became involved in UAS operations. I completed the Federal Aviation Administration’s remote pilot exam, followed by the UAS manufacturer training, and then received my UAS Pilot in Command designation from NOAA. Since obtaining my PIC designation I have completed a few practice flights with the scientist UAS team here in Seattle in preparation for the upcoming Steller sea lion field research cruise in the Aleutian Islands this summer. I’m looking forward to my first trip to Alaska—it will be a big change from Hawaii.


I graduated from the University of Maryland, College Park with a degree in Environmental Science and Policy, Marine and Coastal Management (2010). While in college I also played baseball for the Terps, and completed an internship at the Cooperative Oxford Laboratory in Oxford, Maryland. Following graduation (prior to the NOAA Corps) I worked as a contracted Special Investigator for the Office of Personnel Management, and as in intern at the White House Council for Environmental Quality in Washington, D.C.

Discovering the secret lives of Steller sea lions

Where do sea lions go when they’re not onshore?

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May 9, 2017
Brian Fadely
Biologist

 

Our remote camera images give us insights about sea lion behavior onshore, but where do they go when they’re at sea? To better understand why their numbers are declining in parts of the Aleutian Islands, we need to know where Steller sea lions forage (or hunt) for their prey that consists of fish and squid. Due to our concern with declining pup births, we are focusing on monitoring adult females’ hunting patterns while they are pregnant, and may also be nursing a pup.

The best way to track an individual sea lion’s movements and dive behavior is by using satellite-linked transmitters, also known as satellite tags. The tags are slightly larger than a deck of cards and allow us to see where sea lions go, how deep they dive, and when they come to shore. This information is saved to the tag, then up-linked to satellites (via the Argos satellite location and data collection system) so we can download the data later when we’re back at the office.

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Looking out the back (aft) window of the ship towards Attu Island on a day we wish wasn’t so typical. Photo credit: Aaron Christ

The best time to attach tags on females is complicated by their biology and the weather in the Aleutians. Sea lions shed their fur from August through November. That means if we attach a tag before she has molted, the tag will fall off with her shed fur. Unfortunately, large storms and typhoons tend to kick up after September, and the high seas and strong winds can keep us from being able to work. By November the storms intensify through winter. So, we schedule our trips during October when many of the females have already molted and storm activity is just beginning.

Attaching the tags onto the animals is a coordinated effort to minimize any impacts on the sea lions and any risks to the researchers who must get close to adult females that weighs more than 800 pounds.

Attaching the tags onto the animals is a coordinated effort to minimize any impacts on the sea lions and any risks to the researchers who must get close to adult females that weigh more than 800 pounds. We work with colleagues from Alaska Department of Fish and Game, University of Alaska Fairbanks, and the Vancouver Aquarium to safely capture and handle the adult female sea lions. It can take up to 12 scientists to have the expertise necessary to safely capture, sample, and attach a satellite tag.

Similar to our summer research cruises to look for marked animals, we visit known sea lion sites and take the inflatable skiff to shore to drop off the team and heavy gear. The problem with finding animals during October is that they are a lot harder to locate than they are during the summer breeding season when they gather on land in larger numbers. But your work classifying remote camera images on Steller Watch, helps us pinpoint the most popular sites.

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Gear schlepping processional across Amchitka Island. Photo credit: Kimberlee Beckmen

Once we arrive near a site with a good number of females, we find a safe place to land, which can sometimes be up to a mile away. The whole team hikes and climbs to a staging location and the scouting begins. A few people, including a skilled darter, will sneak up to get a closer look, searching to maximize our chances for a successful capture. When all the conditions are just right, sedatives are loaded into a dart that will be delivered from C02-powered rifle.

It takes a lot of stealth and patience to slowly sneak in for the perfect line-up. Steller sea lions have great sensory capabilities. That means if they smell, see, or hear you, they will head into the ocean. Once in position and a female is in a good location, the skilled darter will take the shot and the dart—essentially a flying syringe—launches and hits, the sedative is delivered immediately and the dart falls out.

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A puff of C02 launches a dart filled with sedatives on Kiska Island. Photo credit: Martin Haulena

The rest of the team hears the good news on the radio call and waits about 10-minutes for the sedative to kick in. The veterinarian and a few others are the first to approach the adult female. The veterinarian administers gas anesthesia and as soon as she is assured that the animal is doing well, she gives the OK. Suddenly the team erupts into hurried and quiet movements and a lot happens very quickly and efficiently to ensure safety of the sea lion and keep the handling time as short as possible.

I immediately get to work on attaching the satellite tag on top of her head—the best body location to maximize satellite up-links. First, I clean and brush the fur to remove dirt and loose fur, then I align the tag for good fit, and finally I use quick-setting epoxy to glue the tag to the fur. In the meantime other biologists are taking measurements and samples for laboratory analysis that will allow us to assess her physical condition, health, and whether she has any diseases or contaminants. She is marked for future identification, just the like the animals you see in the remote camera images. When everyone is done, we clear away and the veterinarian administers the reversal agents to counteract the sedatives, and removes the gas anesthesia device. The female starts to wake and rather quickly is up and on her way, usually to the water, as we all watch, hidden from her view.

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Here I am positioning a satellite tag amidst a flurry of measuring and sampling activity. Photo credit: Michael Rehberg

Between 2011 and 2015, 13 adult females have been captured and tracked in the Aleutian Islands; you’ll see them in the remote camera images marked with an equal sign (“=”) and numbers, from 25 to 36. We’ve had great success with the satellite tag data—we even tracked one female up to 254 days! This information offers insights into their behavior leading up to when they give birth in the following summer breeding season. Adult female Steller sea lions in the Aleutian Islands have shown a diversity of foraging behaviors, from remaining exclusively nearshore on short trips, to trips of over 260 miles (420 km) offshore and lasting six days.


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.

Sea Lion Summer Camp

Living and working at remote field sites in Alaska

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April 22, 2017
Katie Luxa
Biologist

 

Have you ever wanted to get away from it all? No phone, no internet, no car, no electricity. Just you and a little cabin in the wilderness…and a few thousand noisy neighbors.

Each summer, NOAA’s Alaska Fisheries Science Center sends observers to field camps on two remote islands in Alaska: Marmot Island, near Kodiak Island in the Gulf of Alaska, and Ugamak Island, near Dutch Harbor in the eastern Aleutian Islands. Observers spend about 10 weeks on the islands where we are responsible for monitoring Steller sea lions hauled out on beaches. Every day, we scan the beaches for marked animals, count the sea lions on land, and record behavioral observations. These data provide a fine-scale look at two Steller sea lion populations and, in conjunction with other field studies and the remote images you’re helping to examine, contribute to our understanding of this species across its range.

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So how do we get to a Steller sea lion field camp on an uninhabited island in Alaska? By helicopter, of course! But our journey really begins in Seattle. Field camp observers go through a week-long training in Seattle where we learn about Steller sea lion biology, data collection, and the responsibilities involved with living in a remote shelter on a small island with only 1 or 2 other people, away from it all. In many cases, this is also our first opportunity to get to know one another – communication and cooperation are vitally important when working with a team in remote location for over two months.

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After training, we spend 3 days in the town nearest our assigned field camp (Kodiak or Dutch Harbor) to organize equipment which includes our rain gear, datasheets, cameras, etc. We also complete one of our most daunting tasks: buying 2 months’ worth of groceries. On deployment day, the helicopter transports us – along with all of our food and gear – to our temporary island homes. I also like to hum the Jurassic Park theme to myself as we land. Once we have unloaded, we get straight to work and by the end of the day, we will have set up our composting toilet hut (no indoor plumbing here!), solar panels, water filter, propane cook stove, cabin heater, and put away all of our food. It’s still light outside, but the clock reads 10:00 pm. Welcome to the land of the midnight sun!

The next day is dedicated to setting up our observation sites so we can start collecting data. Depending on the camp, the site may be just a few minutes’ walk away over wind-blown tundra dotted by wildflowers or at the end of a 2-mile hike through dewy meadows and moss-covered Sitka spruce. These are some of my favorite places on Earth. No matter how close the observation site is, though, we always make sure we’re prepared: datasheets and extra pencils, a camera with charged batteries, binoculars, a satellite phone, a VHF radio, a Personal Locator Beacon for emergencies, extra layers of clothes, bear spray (for those on Marmot Island), and plenty of water and snacks.

We use the same observation sites from year to year; these spots were selected because they allow us to safely observe sea lions without disturbing them. Our goal is to go the entire 10 weeks without the sea lions realizing we’re there. The sites range from about 350-1,000 feet above the beaches, so we use anchor systems and wear climbing harnesses each time we approach the cliff edge.observation-site As soon as we’re clipped into the anchor system, we’re ready to get comfortable and watch the hundreds of sea lions on the beach below.

Within a few days, we settle into an easy rhythm of data collection and camp life. We get to know the daily patterns of the marked animals. We witness fierce battles over territories. We watch sea lion pups learn to swim. And we live happily ever after. That is, until it’s time to decide who gets to empty the composting toilet.

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


I’m a research scientist with the University of Washington’s Joint Institute for the Study of the Atmosphere and Ocean. I study food habits of Steller sea lions and northern fur seals, as well as Steller sea lion population abundance and survival, at the Alaska Fisheries Science Center. I’ve worked at the Center for just over six years. I received my undergraduate degree in Marine Science from the Southampton College of Long Island University and my Master’s degree from Western Washington University.

Low, slow, and good to go!

Taking flight to count Steller sea lions means covering 2,500 miles on a deadline

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April 11, 2017
Josh Cutler
Biologist + Information Systems Specialist

 

For most of the year, Steller sea lions in Alaska spend their time alone or in small groups spread across the expansive waters and shores surrounding the state. But every summer sea lions converge on land in large groups to give birth, mate, and rear newborn pups. For researchers this period is a fantastic opportunity to count every sea lion on shore and estimate the population.

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The opportunity comes with high stakes. We must conduct the counts within a three week window. The timing has to be just right to ensure females have given birth, but, wait too long and the the animals will disperse again for the year, making counts impossible.

We must conduct the counts within a three week window.

On top of the time constraint, Steller sea lions are spread across 2,500 miles of Alaska’s southern coast, through the Aleutian Island chain. That is a lot of ground to cover in a short time frame. So, in addition to our ship-based survey, we also take to the sky. With help from NOAA’s Aircraft Operations Center team, a few scientists fly over Steller sea lion sites, allowing us to conduct the survey efficiently. The airplane we use is a Twin Otter and we mount a large camera in the belly of the plane so we can capture images as we fly over sea lions. The motto of this Twin Otter aircraft? Low, slow, and good to go! Which means we can fly low and slow and capture high resolution images.

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Me at the camera mount controller with two scientific observers at the front bubble windows.

Flying in the Twin Otter is nothing like flying in a commercial plane. The fuselage is just big enough to fit six people and our equipment; the ceiling is too low to stand. We wear flame-retardant flight suits for our safety. And we get to fly low and slow through some of the most beautiful places I have ever seen.

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Biologist Katie Luxa at the bubble window.

The team consists of two pilots, one field mechanic, and three scientists. One scientist operates the mounted cameras from a computer station near the back of the plane. The other scientists look for sea lions through bubble windows on each side of the plane and help the pilots navigate to make sure our cameras capture all the animals. My favorite position is at the bubble window — I often see whales, walruses, active volcanoes, and glaciers, and I occasionally find new Steller sea lion sites.

Most days start with scientists and pilots meeting to discuss the weather forecasts and if it’s looking good to safely travel through the terrain. Alaska’s foggy, rainy and cloudy summer days often ground us due to low visibility. When the weather is good, we can fly all day. We spend nights in towns along our survey track: Sitka, Homer, Kodiak, Dutch Harbor or Adak.

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Perfect conical volcanoes peaking through the ceiling of low fog.

At the end of the survey, two scientists independently count every sea lion in each aerial and ground photo. Counting the animals allows us to make estimates about the total population. Using yearly figures we can also track population trends. Despite the challenges, we do the work because it is vital to monitoring Steller sea lions’ overall health.


I am a research scientist with the University of Washington’s Joint Institute for the Study of Atmosphere and Ocean (JISAO) and have worked at the Alaska Fisheries Science Center for six years. I develop data systems, conduct manned and unmanned aerial surveys, and often conduct field work for various Steller sea lion and northern fur seal studies. I received my undergraduate degree from the University of Massachusetts and my Master’s degree from Sonoma State University.

We’d also like to know what you’d like to hear about. Head to our Talk forum to post a Question for Biologists and your question could be selected for a future blog post!

The conundrum of counting Steller sea lions

Searching for innovative solutions to count Steller sea lions

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March 23, 2017
Katie Sweeney
Biologist

 

The images you’re viewing on Steller Watch are from the remote cameras we placed at the westernmost reaches of the U.S., where Steller sea lions have declined dramatically. The remote cameras along with marking the animals are two research projects that are part of our mission to pinpoint why Steller sea lions in the western half of the Aleutian Islands are not rebounding like they are to the east.

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The NOAA Twin Otter flying over Yunaska Island to capture image of Steller sea lions.

In addition to Steller Watch, we just launched an effort to develop a program to automate the yearly Steller sea lion population count, our biggest and perhaps most important research project of the year. We partnered with Kaggle to accomplish this. Kaggle connects people to coders who compete to find a solution to big data challenges, saving organizations time and money. The project called NOAA Fisheries Steller Sea Lion Population Count is now live and runs through the end of June. This story was shared by the Alaska Fisheries Science Center if you’d like to read more.

Counting the Steller sea lion population is vital to monitoring the species and staying on top of abundance trends. Each summer, we head to Alaska and gear up for weeks at sea on a research vessel. Summer is best because it’s when Steller sea lions go on land, which biologists call hauling out. During the rest of the year, sea lions spend a lot of time in the open ocean.

So, how do we count? We use a handful of methods depending on the situation.

The summer months are a busy time for Steller sea lions – females give birth, begin rearing their pups and adults breed. Aggressive males stay on land and fast for months to defend their breeding territories. Even non-breeding juveniles and sub-adult males (males that are not yet sexually or socially mature) haul-out with greater consistency during the breeding season. There’s a flurry of activity at sea lion sites and scientists from the Alaska Fisheries Science Center are closely monitoring as much as possible while we count the population.

hexacopterSo, how do we count? We use a handful of methods depending on the situation. At smaller sites with fewer sea lions, we can count on land or by boat, either on the research vessel itself or by launching small skiffs to get a closer look. At large sites, we take aerial images from a plane or an unoccupied aircraft system, or hexacopter drone. During our 2016 survey, we collected over 20,000 aerial images that we counted 29,427 sea lions from, back at the office.

It takes two biologists up to four months to look through those aerial photos. And in those pictures, there are tens of thousands of individual sea lions, and we count and identify the age and sex of each one we count. We hope computer scientists will connect with us on Kaggle to create an innovative algorithm that can recognize sea lions in aerial photos. Automation, or partial automation, would make counting more efficient and give us biologists more time to focus on other important Steller sea lion research studies.

In our next blog, one of our biologists will share what it’s like to conduct aerial surveys in the traditional way, using a small plane.


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.

We’d also like to know what you’d like to hear about. Head to our Talk forum to post a Question for Biologists and your question could be selected for a future blog post!

You are what you eat

The not-so-glamorous way we investigate Steller sea lion diets

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March 15, 2017
Lowell Fritz
Biologist

 

You are what you eat. That’s the basic philosophy behind monitoring the diets of wild animals. In the case of Steller sea lions, we can’t see what they are eating since they feed at-sea, so we have to investigate their diet in other ways. The most common way to find out what Steller sea lions are eating is to — wait for it — collect and analyze their feces. That’s right, we go onshore to sea lions sites, where they have hauled out and pick up after them. Here’s a picture of a group of us ready to collect scat.

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Check out that male sea lion on the right! He’s has not quite grown to start competing with larger males for a breeding territory.

Collecting scat is just like cleaning up after your dog, if your dog weighed over 2,000 pounds! We use gallon size bags for samples. A good collection of many scat samples from one site might weigh 60 lbs.

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Welcome to the not-so-glamorous world of being a field biologist!

What can we learn about their diet from analyzing their scat? Well, quite a bit. Sea lions can swallow many fish, squid and octopus whole. Fish bones and squid and octopus beaks from their mouth parts, gradually make their way through the sea lion’s digestive tract. We can isolate these hard parts in the scat to identify individual prey species from just a few bones.

In the lab, the scats are washed in sieves and the hard debris left behind is cleaned and studied further under a microscope. Each solid bit is compared to other parts kept in our reference collection of known sea lion prey species.  As you can imagine, it takes a lot of skill and time to make identifications from small fragments.

Aside from cataloging hard parts, we can also analyze prey DNA found in the soft parts of the scat. This technique is especially good at detecting prey that don’t have very many hard parts (invertebrates like squid and octopus), fish that are very large and may not always be consumed whole (like Pacific cod), and fish that have small and fragile bones (like smooth lumpsucker) that may not make it through the digestive track undamaged. But DNA studies are expensive, so, we use this technique to supplement the traditional studies of hard parts, such as a recent description of the late winter diet of sea lions in the Aleutians.

Collecting scat is just like cleaning up after your dog, if your dog weighed over 2,000 pounds!

Steller sea lions target fish that aggregate near the bottom of the ocean or in the middle the water column. While sea lions can dive a lot deeper than humans, they aren’t considered deep divers compared to other marine mammal species. Most of the prey they target live on the continental shelf in waters less than 650 feet deep — that’s still a little deeper than the Space Needle in Seattle is tall.

Steller sea lions in the Aleutian Islands have a diverse diet. In the Aleutians, there are almost 300 species of fish alone, plus dozens of species of squid and octopus. Steller sea lions consume about 50 different species, usually whatever is the most abundant fish in the area.

Here are some of the most common prey items we see in the Aleutian Islands:

Atka mackerel: 

atkamackereAtka mackerel is one of the most abundant yearlong resident fish in the Aleutians Islands, and it also sustains the largest commercial fishery in the region. During the summer, Steller sea lions feed on enough Atka mackerel to make up more than half of their diet.  In winter, the fish make up about a quarter of their diet.

Pacific cod: cod

Like Atka mackerel, Pacific cod are year round residents and since they grow up to 43 inches long and weigh up to 37 pounds they are probably the biggest fish that sea lions eat in the Aleutian Islands. Pacific cod are consumed more often in winter than summer. In winter, Pacific cod make up about one quarter of the sea lion diet.

redirishlordSculpins: 

Sculpins are bottom-dwelling (demersal) fish that are widely distributed on the continental shelf. Steller sea lions eat mostly red Irish lords based on our DNA analyses. They eat sculpins mostly in winter, when they make up about 15 percent of their diet.

Salmon: salmon

Salmon aren’t considered year round residents of the Aleutian Islands. Steller sea lions eat mostly pink and sockeye salmon based on our DNA analyses, and they eat salmon mostly in summer.

Smooth lumpsuckers: 

smoothlumpsuckerThese funny little guys are an enigma. Not much is known about their abundance and distribution, but Steller sea lions eat them far more often in winter (10 percent of their diet), when lumpsuckers aggregate to spawn, than in summer. Lumpsuckers are named for their pelvic fins that have evolved to form an adhesive disk that enables them to latch onto rocks in areas with a lot of current, like the Aleutian Islands.

Squid and octupuses:octopus

Cephalopods are a group of invertebrates that includes both squid and octopus. Based on DNA evidence in scat, we know Steller sea lions more commonly prey on giant Pacific octopus. Cephalopods make up about 10 percent of the sea lion diet in winter.


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!

*Images of Aleutian Island sea lion prey were borrowed from other NOAA Fisheries programs.