Discovering the secret lives of Steller sea lions

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

profilepic

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.

Figure1-0-P1010016-AC
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.

OLYMPUS DIGITAL CAMERA
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.

Figure5-Capture
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.

Figure6b-IMG_0013
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

Katie.jpg

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.

helo-with-gear

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.

food-shopping

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.