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MICHAEL DUNNE: I'm Michael Dunne. One of my favorite things about doing this show is that I get to learn new things almost every day. In talking to today's guest, I learned something that I never knew, that the vast majority of our natural lakes in the Cascades originally had hardly any fish at all, but in fact, fish are an almost completely introduced species in our high mountain lakes. Today, on the show, you'll hear from a state biologist who's forgotten more about fish than I’ll ever know, and he discusses how he and his team go about stocking our lakes with fish. It's an aerial high wire act, and it's also a balancing act between protecting our wild forests and also providing fish for our throngs of recreationalists who hit the cascade lakes every year. Jeff Ziller, the Upper Willamette District fish biologist for the Oregon Department of Fish and Wildlife. Thanks so much for coming on and talking to us.
JEFF ZILLER: Oh, this is great, yeah. I like to get the word out.
MICHAEL DUNNE: Well, let's start with this. What does a fish biologist do?
JEFF ZILLER: We do a lot of balancing, is what we do, and we tend to work at a lot of conservation tasks trying to maintain endangered species, fish populations, you know, just doing that basic management of the habitat and populations so that we can sustain these populations over a long period of time. That's, you know, part of our job. And then the other part of our job is providing recreation, and that part of it is looking at what we can do for creating fisheries in the area, including, you know, stocking fish, building regulations to maintain a good, I guess, spreading out of the natural resources to the general public. When you know you could have some regulations out there that say you can harvest 100 100 trout, you know, well, that that's great for the one person that does 100 trout. But most of our regulations are designed to kind of smooth out the harvest and get it to as many people, citizens of Oregon as we can.
MICHAEL DUNNE: Generally speaking, especially in the district that you manage, what is the overall health of our fish population?
JEFF ZILLER: That's kind of a hit or miss question. We have some species, obviously, that are on the endangered species list that are not doing as well as some others. On the negative side, our spring Chinook salmon populations in the upper Willamette here, especially the wild populations, are at a pretty low level right now, somewhere between 1200 and maybe two or 3000 per year up here. If you want to look back in history, you know we're probably more like 50 to 75,000 maybe more in the upper Willamette in historic times. Okay, so it's, they're not doing all that great. This year. In particular, we've seen a pretty low number of spring Chinook coming back. On the other hand, there's, we have an endangered species, the Willamette bull trout, and that population went down to very, very low numbers, you know, probably less than 100 adults in the upper Willamette, when back in the 1980s early 1990s and we have that population back up to a level where we pretty we're pretty confident that we're up above 500 adults in the upper Willamette now. So that's a pretty neat success story. And people are catching bull trout, having a good time seeing them, letting them go again.
MICHAEL DUNNE: It begs the question: how do you count fish?
JEFF ZILLER: Counting fish is really easy when you have a dam like at Leeburg Dam, we have two fish ladders on the dam, and we have cameras. And as the fish go through, we count them okay with their on motion activated recording device, and so it's pretty easy to count fish there on a stream where you don't have where fish aren't moving around a lake, such as a bass population or whatever, you have to actively go out there and either observe them. And depending on how much of the area you can see clear water helps, or you can capture them, tag them, go back in at a later time and recapture, you know, capture fish again. Look at the percentage of tagged fish that you have in there, and from that ratio, you can tell within limits, how many fish you actually have in the water body.
MICHAEL DUNNE: Talk about this back country fish stocking program. How does it work? And I guess maybe part of that is, how do you determine what lakes you're going to stock?
JEFF ZILLER: Yeah, that's a great question. We have a lot of years of working in the Cascades, trying to get our handle on the best species to put in these lakes, the best stocking density. And then, you know, looking at how much harvest there is on those, how often they are put in them. So, for the most part. I mean, this goes back into the 1800s when people were putting fish into lakes in the Cascades, hoping to come back and harvest them at a later time and have you known, something to eat up there. But starting in the 1900s early 1900s there was a much more dedicated effort to getting fish into the mountain lakes. People took a basic idea on how many fish per acre to put up there, and then released various sized fish, mostly just unfed fry, very small fish right out of the egg, and released them into the lakes up there. Well after a number of years of pluses and minuses on success up there. During the 1950s we started looking at these lakes much more systematically and measuring the depth, the actual productivity that might be in the lake, based on vegetation in the lakes, how shallow they were, how deep they were, what the temperatures were, what kind of inflow and outflow they had for potential spawning fish. And we then came up with, over a series of years, actually decades, a formula for how many fish to put in the lakes. And it was done by horseback. It was done by backpack. And then after World War Two is done from the air. So, it was quite a process, and we, we kind of stick to that now, except for one little detail that has changed, and that is we have certain lakes that we leave for other wildlife, including amphibians and other invertebrates up there, so that we still have lakes that have a natural Fauci in them. Okay, I say that because most of these lakes were fishless prior to European people getting here.
MICHAEL DUNNE: Oh, interesting. So, literally, a lot of the lakes that are in the Cascades now, prior to settlement by Europeans, they didn't have, they didn't have fish. They had other things like, like frogs and whatnot and not fish, correct?
JEFF ZILLER: Yeah, there were very few lakes that had natural reproduction of native fish. Most of those were cutthroat lakes. And in my area up here, I can count the number of lakes. That had natural cutthroat populations in them, in the high cascades on two hands.
MICHAEL DUNNE: Wow, wow. I didn't realize that. So, okay, dropping fish from the air. How do you do it? Because I imagine that's got to be something to see. But also, you know, I imagine there's a lot of steps in that process. Talk about it.
JEFF ZILLER: There are, it's a, it's a really interesting process we have. I can go into the history of it from, you know, like I said, backpacking horses, packing fixed wing airplanes, and then to helicopters. We've actually graduated from having silly or, you know, containers of water and fish inside the helicopter to a device that's hung outside the helicopter on a long tether, and it has 30 compartments in it. Each of those compartments holds about four gallons of water and then up to about four pounds of fish. So, we put the fish in at a very small size. It's anywhere from 150 to the pound to sometimes as small as three or 400 to the pound. Wow. And so, in one little container, you know, you can, if you're on average, you have maybe 1200 fish in one container. These, these, this device can has a there's a control panel that is up in the helicopter, and we have who's called a bombardier up there, and the pilot will fly over the lake and we'll count down to a time when the actual release is made, and he'll say, you know, release. And the person hits the button for that particular container, and it's, there's an activation plunger that gets pulled up off of the bottom of the container, and all the water and fish just drop right out of the out of the helicopter, out of the what's called the aerial stocking device, and then it's like, raining fish.
MICHAEL DUNNE: Um, raining fish! I think I read something that is actually because I know people listening, going, Oh my goodness. I imagine a lot of fish died during this. But as I was reading, given their small size, that's the real advantage, isn't it?
JEFF ZILLER: Yeah, if you know, if we were putting catchable size fish in there, you know, 810, inch fish, and we dropped them from, you know, 50 feet in the air, there'd be a lot of mortality from that, that event. But because these fish are so small, they just kind of flutter down through the air and hit the water, the mortality rate on them is actually very, very low.
MICHAEL DUNNE: I imagine, too, that you are raising these fry, these fish in fisheries and whatnot, and then you release them into these lakes. Maybe this is a dumb question, but, I mean, how do you account for the changes in the environment? I imagine perhaps the water temperature may be different. Plus, I mean, I don't know much about young fish. Do they just sort of know what to do once they get in the lake? Or, I mean, do some of them just not cope with that big change in the environment?
JEFF ZILLER: Yeah, that's, that's a really good question, because we, one of the things that we do try to target is that period of time before the water temperatures in the lakes get too warm during the summertime. So, we're usually air stocking these cascade lakes right after the fourth of July. We may be moving that up a little bit as we see that the climate is changing and these lakes are getting a little bit warmer earlier in the season. So, I suspect that we're going to start looking at maybe doing it in late June, but that we try and make sure that the water temperature in the container that we drop into the lake, and the water temperature of the lakes themselves are not more than about 10 degrees different. Some years you can, you can hit it right on the nose, you know, other years when it warms up early, we have problems with that. And so, we have noticed in some years where we had unusual heat waves early in the season, that our survival has not been as good. So, it's a, it's a, it's a fair question. We don't, we don't always get it right, but we're, we're trying to move toward a time frame that looks or that is in the best interest of the fish surviving.
MICHAEL DUNNE: You mentioned that a lot of these lakes under non-human invasive situations do not have fish. So, what happens in a lake when you're stocking fish? What happens to the rest of the environment? Because obviously, I imagine now that there's a lot more fish in a lake that's going to impact insects and other things. How does that sort of all balance out changing that particular environment through fish stocking?
JEFF ZILLER: Yeah, there's no question that it does change the other fauna in the lake and especially invertebrates are eaten. Salamanders are eaten, frog larvae are sometimes eaten. So, one thing about fish is they are very opportunistic, and whatever is swimming in front of them, they're probably going to try and bite at it. And so it is a it is something that we plan for, if we know that we're going to have a big impact on a population of other things that are in the lakes when we put fish in there are, again, like I was talking about at the very beginning, we have a job that is quite a balancing act between conserving the natural Fauci that we have in the in the state, and providing recreation. And so what I'm trying to do in the upper Willamette, we used to stock somewhere around 220 to 240 lakes in the in this area of the of the Cascades, we're down to 100 now, and a lot of that is because we wanted to strike a balance between those lakes that we don't Stock and those state lakes that we do stock and make sure that those populations of amphibians and invertebrates and such can have some places where they aren't going to be eaten.
MICHAEL DUNNE: I also imagine, though, on the sort of the other side of that equation is mammals and whatnot, that that would, that would prey on fish that suddenly becomes a pretty, big increase in a food source for them. Wouldn't that be the case?
JEFF ZILLER: It does. Anytime you we have a lake in the Cascades that has a decent population of fish in it, and some sort of waterway going to that lake, there's always the opportunity to see otters up there during the wintertime and the summertime, for that matter, osprey and bald eagles take up residence near these lakes that have fish in them. Mink are good fish catchers also. So, there's a lot of different animals that actually benefit from having the fish up there in you know. And our target audience, of course, is the animal that happens to have a fishing rod on their hand and wants to have a meal in the high lakes.
MICHAEL DUNNE: My last question for you, Jeff, is this, obviously, we've been disrupting the rhythm of our ecosystem. I'm speaking about climate change. Maybe, if you could just briefly, you know, what are the impacts of a warming planet, of climate change that you're seeing specifically around the fish, not even necessarily the endangered one, but the overall population.
JEFF ZILLER: If we focus on the Cascades, we are seeing some lakes that were kind of on the edge of being fish producers. These are usually fish that are lakes that have depths of somewhere between eight and 12, maybe 14 feet. Those lakes are getting warmer. The water in the Cascades is going out earlier in the season because the snow melts earlier, and those lakes are not producing quite as well. They'll end up at a very low point at the end of the summer, it starts to freeze over. There's not much depth there. If you do have some fish in there, the snow comes covers up the sunlight that is coming into the lake, and therefore there's no photosynthesis, which will create oxygen under the ice, and just the breakdown of the plants that are there during the wintertime because they're dying, they don't have any sunlight. That bacterial action takes all of the oxygen out of the water, and the fish all die. Yeah. Hmm, so that is a definite consequence of some of the changes that we've seen in the temperatures and water flow in the Cascades. Other things that we see more down the slope are streams becoming drier earlier, not quite so much production for fish like cutthroat that run up quite high in the system, try and spawn high in the system, and then those juveniles don't get out of there in time, because the water is going down a lot quicker than it used to. The water temperatures in the main stem are going up the McKenzie, the Middle Fork, Willamette, even though they're very cold, kind of refugia type streams that some of our key species, like bull trout and Chinook salmon, can count on, they're getting warmer, and as they get warmer, they are not quite as productive, or diseases become more virulent in in those systems, and we end up with lower populations. So those are, those are things that are very real, very apparent as time is marching on here, and yeah, you know, we'll, we'll, maybe we'll be a state of introduced warm water fish here in another never, bunch of decades.
MICHAEL DUNNE: Let's hope not. Fascinating stuff. Jeff Ziller, the upper Willamette district Fish Biologist for Oregon Department of Fish and Wildlife, really appreciate you taking time to talk about this fascinating subject.
JEFF ZILLER: Great anytime.
MICHAEL DUNNE: That's the show for today, all episodes of Oregon On The Record are available as a podcast at KLCC.org. Tomorrow, on the show, you'll hear from a scientist at Oregon State University who led a study which determined that the reintroduction of wolves in Yellowstone Park is already improving the lives of many other species. I'm Michael Dunne, and this has been Oregon On The Record from KLCC. Thanks for listening.
