 They've been known to live for 75 or 100 years. These fish can reach upwards of 20, 30, 40 pounds in some very, very productive areas. Really impressive fish. And also fish we like to eat. They're like salmon, so they're very tasty, a little bit oily for some people's taste. So they've been commercially fished for a couple hundred years in the Great Lakes and they're sport fish almost everywhere in their range project. A lake trout disappeared from Lake Champlain around 1900. Maybe in part due to overfishing, other effects we don't know. The state of Vermont has been stocking lake trout since 1972 and all of the fish you see out in Lake Champlain right now are stocked fish. The goal is to restore a self-sustaining population. Why pay for something that could be naturally produced? So my research for the past 12 years basically is trying to find out why lake trout aren't self-sustaining. Given that we're stocking them, they're surviving well into adulthood. I think we might have enough room to set up the air. Really? I think you're bound on, yeah. It's a branch. There's something there. There's something on the left then. What is that fish doing? Just looking miserable. Huh. I'm starting to think about John's comment about famine deficiency. Are these ones that are just hanging there? You know, are they the ones that are going, ooh. Now, do you need anything else from up here? That's a bad one either. About 10 years ago, we looked for spawning areas. We found a number of places where they're spawning. Then we looked to see whether they're spawning successfully there, they are. Then we looked to see whether those eggs that are deposited in November hatched successfully in April and the fry emerge out of the substrate. Yes, we're good there. Are the numbers high enough? Yes, we've got very high numbers. And now we're continuing to push that research forward to understand what happens to those fry as they progress through life. Because at the moment we see no sustained, successful survival of naturally-reproduced fry past about four weeks of age. All the fish in the lake are stocked. An ROV is a remotely-operated vehicle, or you could think of it as a remotely-operated video built for underwater use. So what this is is a little remote-controlled robot, if you will, that allows us to go underwater. And from our perspective, what we want to do is just do filming. The densities of lake Trout out there are astounding. It's sort of surreal after a while. And we have to wonder how much of is it an artificial density because they're attracted to the hatchery effluent? We don't know. They have an important ecological role as a predator. So in Lake Champlain, for example, there are really only about three, four top predators that will eat, smelt, and the rest of the forage base. It's the most important thing It's the major offshore, deep water, cold water predator. So they help the balance of the lake by consuming part of the forage base that is smelt. There's three things that could affect them. Disease, predation, starvation. Disease, we're fairly confident. There aren't any diseases we don't know about in the lake. There's no weird syndromes showing up that we don't know about. Starvation is a possibility. And the fry themselves, the newly hatched ones, are feeding very early, very successfully. So they're not starving, but it is possible that once they leave the reef, there's some imbalance in the food supply. We have to find them to know whether they're starving and at the moment we can't find them after they leave the reef. So it's difficult to study. Predation is another possibility. The community of the lake has changed a lot with the addition of exotic species. We've stocked things like brown trout and rainbow trout and we've got ale wife in the lake. We've got white perch in the lake. They could be competing for food. They could also be directly consuming lake trout fry. It's hard to find that sort of smoking gun. We have to find fry in the stomachs of those predators after they've left the reef. So we can look at them on the reef and there's lots of predation and they are being eaten by a lot of fish. Probably not enough to engulf every last fry, but we have to extend that outwards now off the reef and see who's eating them. At about four weeks old, they leave the spawning reef and they should be going off into deeper water. It gets very hard to follow them at that point. We never see them again and that's our obstacle right now, our black hole. Yeah, we might as well, because we've got a good 10 minutes we'll just get it down to that spot. Yep, yep. Yeah, I see, I say we do one more video dive. Nobody told him about bananas. Oh, if the footage doesn't come out, it's going to be your fault. You don't bring bananas on boats.