No light reaches the deepest part of Lake Superior, known as Superior Maximus, but that doesn’t mean there’s no life more than 1,300 feet under the surface.
This past weekend, researchers and documentarians sent a remotely-operated vehicle down to the bottom of the lake to explore the depths.
Shawn Sitar is a fisheries biologist with the state Department of Natural Resources who was a part of the dive.
"You have to think of it as an extreme environment, kind of like think of it as like Mount Everest, and we're actually working at the summit of that area," Sitar said.
During the dive, researchers spotted fish, like sculpin, which scuttle along the bottom of the lakebed, as well as anemone-like hydra, which stick themselves to the rocks. There was also a more unexpected find: a Busch beer can.
"We also saw the beer can, of course, which shows that humans do have an impact on our environment, even at such an extreme extent."
Sitar was keeping an eye out for deep water siscowet, a type of lake trout. Over the past few decades, researchers have noticed these fish looking emaciated and thin, giving what Sitar calls a zombie-like appearance. They believe there's a natural reason for their alarming appearance, but they're still figuring out the cause.
"Our default hypothesis, or what we think is a natural, like starvation event, so it got to the extreme where we think it's a famine event occurring," he explained.
When it comes to other threats to the natural ecosystem, Sitar says invasive species, like sea lamprey, are a problem in Lake Superior, but not as much as in other Great Lakes.
"The siscowet that we sample down there do have sea lamprey wounding," he said. "I think [Lake Superior has] been buffered from a lot of impacts because of its distance from the ocean. It's more remote. It's less populated, but also that large depth, and it's always very cold."
Sitar says it's important to keep diving down deep because of how interconnected ecosystems within just Lake Superior can be. He compares the lake to an engine that needs all of its parts to work, and because the deep water areas are so delicate and extreme, they can be an indicator of bigger issues.
"Like the canary in the coal mine. So, if there's any unhealthy things happening, you know these are areas that can give you clues early on of some problem that may occur."
Interview Highlights
On what he calls "zombie" fish that are found in the depths
We've been monitoring siscowet populations out there since about 2006 and we've noticed a slight decline, which is natural ecologically, but in recent years, we've noticed a high prevalence of these highly emaciated fish, and our default hypothesis, or what we think is a natural, like starvation event, so it got to the extreme where we think it's a famine event occurring. So, we are keeping an eye on that.
On livestreaming the dive for a public audience
I think one of the missions of science is to disseminate it, not only to ourselves but also to the public and resource managers. So, it was really great to have a live feed because humans have this innate curiosity about the unknown in nature, sometimes where we fear it, but deep down I think we're always wanting to learn. So, it was exciting to actually see the bottom that I've been studying for 20 years, and I thought the amount of life we saw there was remarkable, and it was great to share with others, you know, with the way technology has advanced.
On why monitoring Superior Maximus is important
Ecosystems are connected, you know, we do our priority studies on a species and areas that we maybe have more direct impact, but ecosystems are highly interconnected. Think of a like an engine, there's other areas of the engine that work fine, we think so, you know, it appears that nothing goes wrong with them, but you have to maintain and monitor all components in the ecosystem, like an engine. And so, I look at the deep water areas as very delicate, extreme systems, but you can look at them since they're so delicate, that, like the canary in the coal mine. So, if there's any unhealthy things happening, you know these are areas that can give you clues early on of some problem that may occur.
Interview Transcript
Sophia Saliby: No light reaches the deepest part of Lake Superior, known as Superior Maximus, but that doesn’t mean there’s no life more than 1,300 feet under the surface.
This past weekend, researchers sent a remotely operated vehicle down to the bottom of the lake to explore the depths.
Shawn Sitar is a fisheries biologist with the state Department of Natural Resources who was a part of the dive, and he joins us now from Lake Superior. Thank you for being here.
Shawn Sitar: Thanks for having me.
Saliby: What do we know about this deepest point, Superior Maximus, and what actually lives down there?
Sitar: So, in 2006 our team went out there for the first time to sample for fish, and we discovered the siscowet lake trout inhabit that, and that's the deepest form of lake trout in Lake Superior. They're actually four sub-species in the system.
Saliby: And you are primarily interested in what you're calling these "zombie" fish. They are emaciated, that look like they're unhealthy, but you found there's a more natural reason for their kind of scary appearance. Tell us more about that.
Sitar: We do long-term monitoring of fish populations. In fact, we have a large vessel fleet on all of the Great Lakes, and so we just happen to have the largest of the lakes on #arth. Actually, we have about 50% area of responsibility to Lake Superior, so we monitor near-shore populations, the ones that humans harvest, we also work offshore, because the ecosystems are interconnected, even the deepest parts.
So, we've been monitoring siscowet populations out there since about 2006 and we've noticed a slight decline, which is natural ecologically, but in recent years, we've noticed a high prevalence of these highly emaciated fish, and our default hypothesis, or what we think is a natural, like starvation event, so it got to the extreme where we think it's a famine event occurring. So, we are keeping an eye on that.
Saliby: And what did you find during this specific dive on Sunday?
Sitar: Superior Maximus is the deepest in the Great Lakes, so you have to think of it as an extreme environment, kind of like think of it as like Mount Everest, and we're actually working at the summit of that area, so it's an extreme place, and when we dove the ROV down, we actually saw quite a bit of life.
And a lot of those sculpins that were scurrying on the bottom really indicates that the ecosystem seems to be healthy out there with a food source out there. We also saw the beer can, of course, which shows that humans do have an impact on our environment, even at such an extreme extent.
Saliby: You know, I think there's a lot of concern, specifically in Lakes Michigan and Huron, about invasive species. Lake Superior, is that happening there? You know, if it's happening I feel like in the deepest parts, it must be happening in other parts of the lake. So, what are you seeing that kind of relates to these kind of external threats?
Sitar: That's a really good point in that the invasive species typically come with human impact, and even at the deepest extent, we saw the beer can, but also the siscowet that we sample down there do have sea lamprey wounding. So, sea lampreys are invasive parasites that invaded the Great Lakes, but for Lake Superior, we're pretty fortunate that the system is mostly natural.
I think it's been buffered from a lot of impacts because of its distance from the ocean. It's more remote. It's less populated, but also that large depth, and it's always very cold, has limited the impacts of invasives. As you mentioned, Lake Huron and Lake Michigan have a lot of invasives. It's been catastrophic to the ecosystem. You know, zebra mussels are an invasive mussel that really filters the water column and makes it less productive.
Lake Superior is buffered from that because of the geology, in that we don't have a lot of calcium-based rock formation. So, fortunately, the system is in pretty good shape.
Saliby: What I thought was interesting about this dive is that you livestreamed part of it. I think a lot of times people think research happens, and then researchers publish their studies, and then it kind of stays within the scientific community.
Can you talk about kind of making this dive open to the public in a way where people could ask questions as you were working?
Sitar: I think one of the missions of science is to disseminate it, not only to ourselves but also to the public and resource managers. So, it was really great to have a live feed because humans have this innate curiosity about the unknown in nature, sometimes where we fear it, but deep down I think we're always wanting to learn.
So, it was exciting to actually see the bottom that I've been studying for 20 years, and I thought the amount of life we saw there was remarkable, and it was great to share with others, you know, with the way technology has advanced. So, these are the positive sides of technology to allow people to visualize and experience things that otherwise they may not have been able to.
Saliby: And why is it important to explore this part of the Great Lakes?
Sitar: Ecosystems are connected, you know, we do our priority studies on a species and areas that we maybe have more direct impact, but ecosystems are highly interconnected. Think of a like an engine, there's other areas of the engine that work fine, we think so, you know, it appears that nothing goes wrong with them, but you have to maintain and monitor all components in the ecosystem, like an engine.
And so, I look at the deep water areas as very delicate, extreme systems, but you can look at them since they're so delicate, that, like the canary in the coal mine. So, if there's any unhealthy things happening, you know these are areas that can give you clues early on of some problem that may occur.
Saliby: Shawn Sitar is a fisheries biologist with the Michigan DNR. Thank you for joining us.
Sitar: Thanks for having me.
This conversation has been edited for clarity and conciseness.
