Hovering UAVs over sea otters

Otters impact their environment in ways that can benefit people / Photo by Randy Davis
Otters impact their environment in ways that can benefit people / Photo by Randy Davis

“Do you want lots of kelp forests? Than you want sea otters in your system.”

“A kelp forest is a forest; it’s like you’re flying through a redwood forest.” Brenda Konar, professor in marine biology at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences, both dives and teaches divers to handle cold Alaskan waters. She told Frontier Scientists that a spot off Alaska’s Aleutian islands is the best diving around. She favors the dynamic nature of Alaska’s kelp, which grows 33 feet [10 meters] in a month. In warm waters over coral Konar said she’s seen “Lots of pretty-colored fish but you can’t swim through it and feel like you’re flying. I like cold because you get a lot more structure.”

Talk to scientists in Alaska, and you’ll hear over and over again that they fell in love with Alaska.

Dan Monson, research wildlife biologist with the U.S. Geological Survey’s Alaska Science Center in Anchorage, Alaska, described accepting a job to work on sea otters in Alaska: “He said get here as soon as you can. I basically got in my truck and drove to Alaska, and never left– I loved it.” Monson has been studying sea otters since 1987.

Some of Monson’s research has focused on sea otter distribution and abundance. He’s participated in otter populations surveys requiring a small single engine plane to fly slow speeds at low level over ocean, circling for hours as the scientists spot and record otters resting or surfacing from dives. “There’s risk involved. It’s what we call the dull dangerous and dirty work; you’d rather not put people in the air if you can help it,” Monson described. One of the reason for new tests involving Unmanned Aerial Vehicles.

Keystone climate defenders

So why do scientists accept the risks? Otters are a keystone species; they have a strong impact on their ecosystem. “They have a big effect on especially their preferred prey, things like clams and crabs and sea urchins,” Monson said, a direct effect– they eat them. That’s important because sea urchins are what Monson terms “Voracious herbivores.”

“When you don’t have sea otters in the system– which happened after historic harvests of Russian and American fur trade–” otters weren’t keeping the sea urchin populations in check, Monson noted, “The urchins took over and developed what they call urchin barrens.” In urchin barrens “Kelp has almost no chance to establish themselves because they are grazed back so quickly by the urchins.” Monson said it wasn’t until sea otter populations “Recovered in a lot of places then they would limit the urchin population and enable the canopy forming kelp in particular to re-establish.”

Urchin barrens limit production, while healthy kelp forests provide a habitat for fish and other creatures. Kelp forests also sequester carbon as effectively as tropical rainforests; they draw in CO2 and cause it to be stored on the ocean floor with fallen kelp remains. That means that in protecting growing kelp forests, sea otters act as climate defenders.

“They have this big effect on their ecosystem,” Monson said. “They can basically change it from a fairly one dimensional place when they are not there to this very three dimensional, with structure, kelp forest community.”

Konar underscored: “Sea otters are huge as far as impacting these coastal systems.” She said “A great example is out in the Aleutians Islands: there used to be a lot of otters out there, there used to be huge kelp beds out there. Recently– the last 10 years or so– the otters have disappeared.” While otter populations are stable in much of the Gulf of Alaska, offshore from Alaska’s Aleutians Islands Konar said there’s next to none left. “We get excited if we actually see an otter out there now. And there used to be thousands and thousands of otters out there.” The scientists aren’t 100% certain what happened, but the common idea is that killer whales ate the Aleutian otters in their search for prey when the whales’ preferred prey became less available. “We are looking at how much, across the Aleutian Chain, how much the sea otter loss has cost the ecosystem,” Konar said. “The urchins have eaten all the kelp,” and “So we are looking at the loss of primary productivity because there is basically no more kelp, there’s nothing out there photosynthesizing that much and producing materials for animals to graze on. And then we are also looking at the loss to biodiversity.”

“Sea otters are a really big driver of what these coastal communities look like just because they eat a lot,” Konar stated. “They eat a lot of the things people like to eat: sea urchins as an example or sea cucumbers, fish, crab, clams, a lot of octopus, a lot of things that a lot of people like to eat. If you have a lot of sea otters, then a lot of things are going to disappear. But you’ll have very healthy kelp forests.”

Hovering UAVs spot sea otters ecosystem keystone science / Photo by Randy Davis
UAVs are being used to spot otters’ dinner / Photo by Randy Davis

UAV research potential

New trials test the effectiveness of Unmanned Aerial Vehicles in aiding sea otter research. Monson and Konar collaborated to test the use of UAVs in foraging observation. They watched sea otters feed using video cameras affixed to remote-controlled rotary wing UAVs.

Usually to learn what sea otters are eating, scientists use visual observation through high powered telescopes. They set up the scopes on shore; sighting through one from a boat isn’t feasible due to bumpy wave action. Once they spot an otter holding food it’s a quick race to see and record what species is for lunch and how large it is. With UAVs, the hope is to improve foraging observation potential. A UAV can be launched from shore or from a boat. It can spy on otters feeding far from shore, where they might be bagging different meals (and probably are because diving deep expends more energy, and it wouldn’t make sense to do it unless there’s payoff). Capturing a video of what otters are eating gives scientists more time to identify the species and size of the prey… image analysis software could garner more accurate size readings. (Konar said the scope method is usually to compare prey size to the sea otter’s paw– half a paw, two paws.) Perhaps more importantly– and therefore the focus of early tests– UAVs have the potential to get this coveted information without disturbing the otters.

For the flight tests the scientists set up across Kachemak Bay from Homer in the Kasitsna Bay Laboratory area to test the UAVs’ stare-and-hover capabilities. Sea otters are a marine species protected by very specific laws, and Monson cautioned not to harass them. “People should not be taking their own systems and flying them out over these animals. But under our research permit we were able to do that and we wanted to sure we could do it without disturbing them.” The team flew in UAVs 40 meters above a foraging otter then dropped the aircraft altitude while the animal was underwater looking for food by 5 meter increments. Konar described “If you just come in slowly, they don’t notice the difference in noise as it was coming closer and they just acclimate to it. So I think there is a lot of promise.” Otters didn’t react too strongly to the presence of the UAVs. “Nobody completely freaked out and dove or took off from the area. And some of them didn’t even look at the UAV,” Konar said.

Monson: I wanted to drop it to the point when we disturbed them a bit. I wanted to know kind of where our threshold was. Basically at 5 meters everybody noticed it. That’s not all that high. But at 10-15 often the animals didn’t seem to notice the UAS, especially if there was any tiny bit of breeze, or if they were busy.” [Here Monson is using the acronym UAS: Unmanned Aerial System.]

More uses for UAVs

What about using Unmanned Aerial Vehicles for other sea otter research? UAVs might be used to conduct population surveys like Monson took part in via small single engine airplanes. “You can be up there and fly that same type of a survey without the risk to humans. And in addition, the UAS is potentially quite a bit cheaper,” Monson said. While airplanes require gas and a not-too-distant airport to fuel up, a UAV can be launched from a boat and be recharged there too. That opens survey access to truly remote areas of Alaska. The technology pushes the limits of what’s possible now. Tight controls make for easier handling in terms of making tight circles while spotting sea otters during detailed aerial surveys. Video recordings provide advantages over visual counts. Infrared sensors could be equipped to spot heat signatures. And networking capabilities can let UAVs download information from tags deployed on sea otters that record GPS location, depth measurements (how deep did the otter dive while foraging), and even reproductive information. Currently to retrieve the information, scientists have to re-capture the tagged otters. Monson said “I can imagine a UAS being essentially a receiver of data.” He explained “If you need to transmit that information for any long distance, like to a satellite for example, you need a huge amount of battery power. We don’t have that battery power, so we are really limited in the distance that you can transmit the information,” since the tags equipped on otters need to be tiny. UAVs open new possibilities.

Laura Nielsen 2016

Hovering UAVs spot sea otters ecosystem keystone science

Mother otter with pup / Photo by Randy Davis
Mother otter with pup / Photo by Randy Davis

“I came up to Alaska during the oil spill, the Exon Valdez oil spill, back in the day… and fell in love with Alaska. So when it was time to do my PhD research I wanted to work in colder waters. … I did it in the Aleutians. I spent 2.5 years living on Shimia Island which is a little tiny island at the end of the chain. Fell in love with it and have been going back to the Aleutians ever since. It’s just the best diving around. It’s beautiful out there.” ~ Brenda Konar

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