Take me to the River
Join social ecologist and river restoration expert Dr. Siwan Lovett in conversations about the ideas, issues and opportunities that relate to our connections with nature and each other. This podcast offers open, honest and practical insights for us to reflect on in our daily lives.
Take me to the River
Stocky Needs Our Help: Saving native freshwater fish from extinction with Dr. Mark Lintermans
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Stocky Galaxias, or 'Stocky', is one of Australia's most critically endangered species — a tiny fish hidden away in the pristine alpine waters of Kosciuszko National Park.
Can the survival of this elusive, critically endangered species illuminate the future of Australia’s rivers? In this conversation we discuss efforts to save Stocky from the devastating 2019/2020 Black Summer bushfires and the subsequent rallying of agencies and community groups to protect, conserve, and re-home this special little fish to ensure its survival for future generations. Dr. Siwan Lovett and long-time freshwater fish conservationist and researcher Dr. Mark Lintemans invite you on a journey through the challenges and breakthroughs in conserving this remarkable species. From the thrill of discovering a previously unknown new population, to the innovative strategies that blend natural and artificial solutions for habitat protection, this episode is packed with insights into the delicate balance of river ecosystems, invasive fish, community collaboration and conservation strategies.
We take a deep dive into the ongoing efforts to safeguard species like the Galaxiids and Macquarie perch while respecting the interests of recreational fishing. You'll hear how barriers, riparian vegetation, and even shifts in attitudes among trout enthusiasts are contributing to a new paradigm in fisheries management. These changes are essential to maintaining the health of aquatic ecosystems and ensuring that both native and introduced species can coexist.
Finally, we discuss the urgent issue of genetic diversity, a key factor in the resilience of fish populations against climate change. Discover how genetic research is transforming conservation strategies, with new approaches like cross-breeding and relocation aimed at boosting the genetic health of species under threat. Our conversation extends to the broader picture of Australia’s freshwater fish crisis, highlighting the pressing need for comprehensive conservation efforts.
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Speaker 2:My job is to protect threatened fish, and it can be a paid job, it can be an unpaid job. That's my passion, right, and I've had immense pleasure out of interacting, dealing with monitoring, handling, fondling fish over the years, and so I want my grandkids to have that same opportunity and I feel that it's sort of my responsibility to look after fish, and I think the community would be really interested in these things if they knew what was going on. Freshwaters around the world are in real trouble, and Australian freshwater fish are in real trouble, and Australian freshwater fish are in real trouble. I think we just need to up our game a bit, not just worry about the furry ones or the gaudy feathered ones. We need to think about the things that are underwater out of sight, and so if you look after stocky Galaxias, you will also be looking after the little spiny crayfish that are in the streams, or the weird little stoneflies or other little greeblies that don't really float in my boat, but there's plenty of people out there that are stonefly huggins.
Speaker 1:Hello and welcome to Take Me to the River, sharing stories and inspiring hope with extraordinary people who care for our rivers. I'm your host, dr Shu-Anne Lovett. Today I'm talking to Dr Mark Lintemans. Mark is a long-time friend of the show and of the Australian River Restoration Centre. In fact, mark was a guest on our very first interview episode of this show. It's a pleasure to have him back to reflect on what's changed, what's next in fish, ecology, climate, threatened species and more.
Speaker 1:Just before the 2019-20 Black Summer, bushfires swept through some of Australia's most unique and vulnerable ecosystems in Kosciuszko National Park. Australia's most unique and vulnerable ecosystems in Kosciuszko National Park. Mark and a team of dedicated conservationists journeyed to the mountains on January the 14th 2020 to try to relocate as many endangered little species known as the stocky galaxiad. Let me do that again. Mark and a team of dedicated conservationists journeyed to the mountains on January 14, 2020, to try and relocate as many stocky galaxies, a small endangered species, in something of a Hail Mary.
Speaker 1:The crew managed to capture 142 of these little beauties, which would have been affected more by the violent storms forecast for the area than the bushfire themselves. Heavy rain would wash ash and burnt vegetation into the stream, smothering waterways, destroying habitat and potentially depleting it of oxygen. Fast forward nearly five years and that initial population has been successfully bred in captivity due to the efforts of researchers at Charles Sturt University and folks at the Gaydon Hatchery. So successfully, in fact, that a small population was released into the wild at a speciallydon Hatchery. So successfully, in fact, that a small population was released into the wild at a specially prepared site in 2023. We're going to chat with Mark about what it was like to save some of those remaining fish and what comes next for this critically endangered and beloved small-bodied fish.
Speaker 2:Thank goodness it's not live. I can do some interpretive dance, if you like there you go, leave that one so mark welcome to the show and for all of those listening.
Speaker 1:Mark is a very good friend of mine. We co-own a property together and we have been working together for a long time now. He has a wicked sense of humor, but I just wanted to share a bit of an insight into some of the names that people have called Mark because he does, at this time of year, look a bit like Santa Claus. But when I told my team I was coming to interview him this morning, he was described as the Gandalf of fishes, and so he has got a magnificent white beard and that tends to spark lots of interest from everywhere he goes. So, as a poster child for Santa, can you tell us a bit more about what you've been doing over the last five years with the stocky galaxid?
Speaker 2:Yeah, great pleasure to be here again, joanne Good. So we've been doing a lot of work on stocky galaxius in the last five years. The most exciting thing, I think, is that we found a new population of the species in a totally different catchment. It's only about 30 kilometers as the crow flies from the original one, but it's 350 kilometers as the fish swim, so it's a long way. So that's at the top of the Goodredigby catchment, and the original and what was previously the only population is at the top of the Upper Murrumbidgee, above Tantangara Dam, in a place called Tantangara Creek. So, yes, we found a new population and we've been doing lots of work on that, and so we've done a population estimate there for stockies, and so we now have just over 9,000, we think fish in this tiny little stream. It's even smaller than Tantangarra Creek. It'd be 80 centimetres wide, maybe 20 centimetres deep and about 2.8 kilometres long and about 2.8 kilometres long. The thing that it shares with the original population is they are both above huge waterfalls, and it's huge waterfalls that keep trout out, because stockies and trout can't coexist.
Speaker 2:One of the other things that we've done over the last few years is the original population was infested with feral horses. And so when feral horses cross streams, they degrade bank vegetation, they break down the banks, they put a whole lot of sediment and stuff into the stream, and so, while they're not the primary cause or major threat to stockies, when you've only got one or two populations left, you try and do everything in your power to remove those threats. And so, with the great assistance of New South Wales National Parks and Wildlife Service, they built two exclosures around the population at Tantangarra Creek, and so they went up. They were due to go up just as the bushfires roared through, and so there was a bit of a due to go up just as the bushfires roared through, and so there was a bit of a delay and they ended up getting finished in about April that year after the bushfires were out. And so we've been back to monitor the horse crossings across the stream, and it's really gratifying to say that if I didn't have a GPS with me, I could not find the horse crossings anymore, because the vegetation has just come back, like you wouldn't believe. That's incredible. The stream banks and the in-stream habitat is still a bit trash because it's still full of sand and gravel and the banks are degraded or whatever. So that will take decades or more to recover, but we now have the vegetation recovering, and the vegetation is so important for little Galaxids because it can provide 30% of the food of Galaxids. So the grasshoppers, the ants, the whatevers fall onto the surface of the stream and these little fish will eat them. So that's one of the things we've been doing.
Speaker 2:We've also had a PhD student who's just submitted his thesis, working up there since 2016.
Speaker 2:And so he's had a look at or described the breeding ecology of the species, when they breed and how many eggs they have, and all that sort of stuff. He's described the home range of the species. Most individuals move less than five metres in their lifetime, so they're pretty stay-at-home little guys. And even more excitingly is he has pioneered a new system for finding waterfalls, and so, because waterfalls are so important for the persistence of stocky Galaxies or the existence of stocky Galaxies, we can now use LIDAR remote sensing to find out where there's a change in elevation, and if there's a metre drop between pixels or whatever, then we can say well, there's a waterfall there, so we can go out and survey for it. So we have a chance of finding more populations of stocky Galaxies, and we have a good chance of finding more streams that don't have trout in them, so then they can be reintroduction sites. So that's just some of the things we've been doing. There are other things, but we'll move on to, oh, captive breeding. We can't forget the captive breeding.
Speaker 1:Yeah, but hang on a minute Just before we go to captive breeding that just raised so many questions going through my head, so the first one I wanted to ask was the new population. How did you know to look there? How did you find that there was this new population of stockies? Because last time we spoke it was all looking pretty dire for stock eagle accidents.
Speaker 2:Well, it's still looking dire, and if I tell you the true story story, it's going to make me look like a bit of a fool. So, anyway, here we go. So I was actually out there looking for spiny crayfish because I did a survey for the commonwealth as part of a larger project to look at the bushfire impacts on these spiny crayfish that live in highland streams and, as a by-product, whenever I caught any galaxids in my traps or electrofishing, I just just took a fin clip, threw it in a jar, threw it in the backpack, didn't think about it, came back to Canberra, threw some samples to my friendly geneticist and he then rings me up and says oh, I found something interesting in your galaxia's fin clips. And I said, oh, yeah. And he said what do you reckon it is? And I said I've got no idea. And he said you've got another population of stocky Galaxias and I just about fell off the chair. I said you're kidding me. And so there you go.
Speaker 2:So it always pays just to take little bits of thin clips or whatever, because, for the people that don't know, stocky Galaxias was only described in 2014. And prior to that, it was a part of a thing called the Mountain Galaxius Complex and a friend of mine, tama Raddick, did the taxonomy on them as part of his PhD and he described 15 galactic species from one, and Stocci Galaxius was part of it. And sort of the funny thing is that 40 years ago another colleague, well before my time actually he was a later colleague he had rolled, I think, eight or nine species of Galaxus into mountain Galaxus. So there's this splitting and lumping that's been going on over the last 50 years. Anyway, with the advent of modern genetics you can find different species and then you go back and look at the morphology, the appearance of the fish, and you go oh yeah, they are different, this one's got this and this one's got that, you know. So anyway, there you go. I didn't even know I'd found it and I had.
Speaker 1:That's fantastic. How brilliant. I mean. That must have been well a cause for rejoicing, given that we're just trying to protect this other one by putting fences up to keep horses out. Like to have one in the wild is awesome actually.
Speaker 2:It was amazing, and so what it does is it gives you great hope that there are other populations out there, and so one of the things that is going to happen in early 2025 is that, as part of the Snowy 2.0 approval conditions, there will be a broad catchment survey, commence using the new technique developed with LIDAR and whatever, and so Hugh Allen, my PhD student, will be out there assisting with that, and it will run over a couple of years and they'll be looking at a large number of sites A to see whether they can find new populations of stocky Galaxies, and B to try and find those troutless streams which may then be translocation sites to establish new populations.
Speaker 1:So let's talk a bit more about why trout and stockies can't live in the same stream.
Speaker 2:Well, as your listeners will be aware, trout are a really popular recreational fish, and they are popular because they're a predator. They chase lures, they eat things, okay, and so basically nearly all of the Galaxids are at about the entree or hors d'oeuvre size for trout, and so they just eat them. And you know, like a good-sized trout, a 350-millimetre trout can eat a fish that might be 180 millimetres long, and most Galaxias are less than 100. So they just hoover them up, and so they literally cannot coexist together except under some really special circumstances.
Speaker 2:And so galaxids were the top predator in the stream. They were the only fish that were up there in these tiny streams, right? So if they saw a trout, they'd just swim up to it with their fin out to shake fins and say how you going, mate. And of course trout would have a different idea. So they have to be separated, and the usual way of separating them is a waterfall, and a waterfall of a certain height, so it can't be less than a metre, because trout jump. Australian native fish don't jump very much, trout do. That's how they migrate to their upstream spawning locations and things like that. So if you find waterfalls, you find natural barriers in the landscape and that's where you go looking for weird little Galaxids.
Speaker 1:So if you had an unlimited budget, would you be building waterfalls up in the snowies to separate Galaxids and trout, Because we know that trout are now here, they're not going anywhere? But surely there are opportunities there to say, okay, well, trout can be found here, but not here, because this is where we want our native fish to be able to live successfully and thrive.
Speaker 2:So one of the things you can do is you can build artificial barriers, and there are lots of them out there. There are little stream gauging weirs that have been built in the 70s that are now no longer used, and trout may have died out upstream of the weir in a drought or been eliminated by a bushfire, and so then you could go and you augment those weirs, you make them a bit higher and then you've got a place to reintroduce stockies. There are lots of natural barriers in streams, cascades or little waterfalls, and again in the millennium drought in the Cotter River catchment in the ACT, brown trout disappeared from an awful lot of habitats, and so that was an opportunity to go and augment barriers or whatever. Government tends to move pretty slowly and so unfortunately, the drought broke before we could do things like that. So you wouldn't go out to build waterfalls, you wouldn't go out necessarily to put barriers in sort of virgin habitat, but you find areas where there's a barrier that is probably pretty effective but not totally effective, and you make it totally effective.
Speaker 2:So there's a habitat immediately adjacent to Tantangara Creek, a little place called Kyandra Creek, and so I've done some trout surveys out there and we flogged ourselves along this stream and we got about half a dozen trout in about a kilometre of a stream. And so you think, we know, there's a sort of a barrier downstream so it keeps most of the trout out but not all of the trout. So one of the options is to augment that barrier and then you have to remove the trout out but not all of the trout. So you know, one of the options is to augment that barrier and then you have to remove the trout from the stream and that becomes controversial because you know, anglers think that there's a conspiracy theory to eradicate trout from Australia. We couldn't do that if we wanted to and we don't want to. But yes, you can go and build barriers.
Speaker 1:Yeah, and it sounds like there's enough opportunities. These are really small streams, quite far-flung places as well, to be able to do that whilst not really disturbing the opportunities for wrecked fishes and trout.
Speaker 2:That's right, and so you know. This stocky Galaxius occurs in tiny streams, you know, a metre wide, 10 to 20 centimetres deep. Really, you don't have good trout fishing opportunities there. There's not that much food there. The fish will be small. If you lose that as a trout fishery or something, you could not lose very much at all and you compensate by stocking trout somewhere else where the damage has already been done or where there's no damage to be done. So the Snowy Mountains lakes you can be in Jindabyne are stocked well with trout. There's great trout fishing there. There's plenty of other streams with good trout fishing. So it's about trying to alleviate the fears that there's some surreptitious movement to try and kill trout fishing in Australia, because that's not the case. You've just got to be able to set aside some little streams for native fish that are highly endangered and then you can continue with your trout fishing in other areas.
Speaker 1:Yeah, so when we look at other species, then how do fish like the Macquarie perch cope with trout?
Speaker 2:So Macquarie perch and trout usually coexist because Macquarie perch they used to occur in the Murray River and Edward Warkool and places like that and there's now just too much silt, sediment and water regulation in those streams that Macquarie perch don't persist there. So mackers, as I call them, exist mainly in upland streams with good riparian vegetation. They're well shaded, they're rocky, whatever, and that's also good trout habitat. And so while they do coexist, that doesn't mean there isn't an interaction between the two. You have very few populations of Macquarie perch left in the country. Maybe there's a dozen or 15.
Speaker 2:And so again it's like the horse exclusion. You want to do all that you can to protect these populations, to allow them to prosper as much as they can. You would not ever attempt to eradicate trout from those streams because you can't. But you may stop stocking those streams with extra trout because the science quite clearly shows that if there is a self-sustaining trout population in a stream and you throw more trout in, it doesn't add to the fishery. Okay, the stream is at its capacity. You end up with either more small trout that you can't really fish for very well, or you just don't end up with any more trout at all. The ones that you've stocked die out or don't persist very much.
Speaker 1:So more isn't necessarily better.
Speaker 2:No, no, not at all. You want to promote a better fishery and so fisheries regulations do that. So some streams are catch and release. So you catch your trout, you take your photo, you release it again, so that trout is there to grow bigger and fatter over the years and so you have those trophy streams and you can have the bread and butter like streams or impoundments or even put and take fisheries. So in some of the places in the Alps and around the world where you don't have good spawning habitat for trout but you might have good rearing habitat like a lake, you put the trout in, they grow, the anglers catch them out, it's all good, you take them home, you show your family you've had a good time and they stock them again next year. So it's about separating the areas that you want to conserve and those that you want to promote for recreational fisheries.
Speaker 1:Why do you think people get so afraid of this idea that somehow all the trout are going to become extinct? Because I can never recall that being a message that has ever been shared.
Speaker 2:No, and it's people don't like change. Ok, and so you know my granddad used to fish for trout here and we've always, you know, put trout in the waters here and it was a mammoth effort to spread trout across the highland areas of Australia. You know they went in milk cans on horseback and all that sort of stuff. And so there's that, that history, that sort of cultural element that still persists. Fisheries don't want to get rid of trout at all. Fisheries sell a lot of trout licenses.
Speaker 2:They make you know, revenue out of that, which then goes back into threatened fish conservation or improvements to trout fisheries. It's just how it is. Nobody trusts the government. It's like they're not looking after us, they're just trying to make money or do something like that. And so really it's about trying to educate people and find some common ground, and I've dealt with many people who are in the trout fraternity and we can have a good chat and all the rest. On some issues we just cannot see eye to eye, and that's the way it is. It's not animosity.
Speaker 2:I don't hide my bent, which is for conserving freshwater fishes, and that's fine, but it's just about reaching that middle ground where you can say, well, some of these tiny little streams, they're rubbish trout fisheries anyway, how about we turn them over to conservation? And so that's what you try and do and that message is getting across. You know the old guard is changing. The new guard is coming in. I'm part of the old guard. That's fine. Trout clubs are now assisting with planting riparian trees or doing things like that, and that's great. So you look after streams, everyone benefits.
Speaker 1:Yeah, for sure. So one of the things you also mentioned before I had to go back and ask more questions from your introduction was genetics. Tell me a bit more about the genetics and the stockies.
Speaker 2:Genetics has come ahead in leaps and bounds in the last 20 years, 10 years, five years. We're making new genetic discoveries all the time.
Speaker 1:Why is that Mark? Is it a new piece of technology or have we just got smarter?
Speaker 2:Well, people have got smarter, but the technology and the cost of doing genetics has dropped quite dramatically and the pace that you can do it at has increased dramatically. And so now you can take a little fin clip maybe two millimetres by three millimetres from a fish and you can tell. If you've got enough fin clips, you can tell who the brothers and sisters are, who the parents are, whether they come from the same family at a site or from a family downstream, whether the families mix. All of that sort of stuff, as well as the big science questions about when did the species diverge from each other, and things like that. So genetics is really becoming part of the bread and butter of fisheries management. It's shedding insight into things that we never knew, we had problems with. For instance, we can have another discussion at another time about Macquarie perch, because there's some really exciting genetic stuff that's just come out of that.
Speaker 1:Oh well, I think we'll keep talking. So I'm too fascinated by that. So just with the stockies, the Goodredigby population, do they have the same genetics as the Tantangra Creek population?
Speaker 2:So at the broad scale they do. They're definitely the same species. So all of the samples cluster together, so you can see they're the same species and they cluster separately to the other Galaxid species. When you get down to the finer scale, you can look at genetic diversity of populations, and so genetic diversity is really important because of future threats like climate change. So if you have a diverse genetic makeup, it means you have the capacity to adapt to new challenges. So you might have a gene that allows you to thrive under warmer water conditions or things like that. Or breed a little later in the year or earlier in the year or things like that. You might have better disease resistance genes.
Speaker 2:So everyone loses genetic diversity, just by chance. It's just the way it happens. It's genetic drift, and so if you have isolated populations that are not connected, that genetic drift means that you tend to lose your genetic diversity because there's no one coming from downstream to put the gene back into your population. So you slowly become a little more inbred, basically, and that's not a recipe that we want to follow under climate change scenarios.
Speaker 1:So are we in terms of our work on genetics. With the stock eagle accident, are we at the point where we're actually breeding or cross-breeding those two populations?
Speaker 2:So we haven't got there yet. We have only bred the Tantangarra Creek population at the moment. We've just done some genetic work on them and have shown that they are genetically distinct. I think the Sally's Flat Creek population has slightly higher genetic diversity, but nothing to really write home about. In Tantangarra Creek the Stokke Galaxies population is subdivided by a sort of a steep gradient area, so there's two what I call flats. You know level pieces of ground. So there's one at the bottom and one at the top, and funnily enough they're called bottom flat and top flat.
Speaker 2:We're very imaginative in the fish world, and so what we know is that bottom flat has slightly higher genetic diversity than top flat, and that's because top flat is losing diversity just by chance and the bottom flat can't quite get up there to replenish it.
Speaker 2:So we will probably do some mixing there. And then what we found with other species is that all of these isolated populations of whatever it is Macquarie perch they were all kept separate for the last 50 years because people were worried about diluting the special adaptations that these animals had to their own habitat. And so now we realise that by keeping them separate we're just losing genetic diversity. They're getting closer and closer to winking out, and so now we want to breed super maccas or super sooty grunters in the Northern Territory, whatever it is, and so we're now mixing our genetic stocks, and so that will improve our genetic diversity. We had some concerns where closely related species mired into breeds, so Macquarie perch actually has three species in it, one in the coastal rivers, one in the Murray-Darling Basin and then one in Kangaroo River, which we think is now extinct. So anyway, so genetics is really a fantastic tool, and we now have a totally different management paradigm where we mix our stocks to improve the genetics rather than keeping them separate.
Speaker 1:So it really is about that word that we hear so much nowadays, particularly with climate change resilience, isn't it? It's building resilience into the species.
Speaker 2:Absolutely yeah, Because you're never sure what individual sites are going to do. Some might be spring fed, some might be more prone to wildfire, some might be more prone to alien fish invasion. So you're never sure what the threat is going to be. But the higher the genetic diversity that you have, the better chance you have of surviving those sort of things.
Speaker 1:So you know we've talked about threatened species and I know that you love talking about fish. Other people like talking about koalas or platypus and you always, always do an eye roll lol, because fish are just so much cooler. Why should anyone care about the stocky galaxid?
Speaker 2:Well, as I said earlier, stocky galaxias they're the top predator in their stream. Right, they were the top dogs. You need predators and prey in streams to have balanced ecosystems. If you have no predators, then the cats take over, whereas the dingoes will keep them down a little bit, and so they were a very important part of that ecosystem. Why should people care about them?
Speaker 2:Well, my job is to protect threatened fish, and it can be a paid job, it can be an unpaid job.
Speaker 2:That's my passion, right, and I've had immense pleasure out of interacting, dealing with monitoring, handling, fondling fish over the years, and so I want my grandkids to have that same opportunity, and I feel that it's sort of my responsibility to look after fish, and I think the community would be really interested in these things if they knew what was going on. And so freshwaters around the world are in real trouble, and australian freshwater fish are in real trouble, and so, you know, I think we just need to up our game a bit, not just worry about the furry ones or the gaudy feathered ones. We need to think about the things that are underwater, out of sight, you know. And so if you look after stocky galax, you will also be looking after the little spiny crayfish that are in the streams or the weird little stoneflies or other little greeblies that don't really float my boat, but there's plenty of people out there that are stonefly huggers. I've seen people with stonefly T-shirts. You know, I think that's going a little too far, but that's all right. We all have our little peccadillo.
Speaker 1:This is from the man who wears a t-shirt that says Fish Fondler Pty Ltd.
Speaker 2:Well, that's right. You know, you've got to have some fun in life as well. So that's what I've described myself as for the last 40 years I'm a fish fondler. You know I handle a lot of fish. Anyway, we digress. So, yes, stockies were at the top of the ecosystem. They're lovely little fish. It's nice to know that there are still some relatively pristine streams out there that can support aquatic fauna, and by promoting their existence to the general public and everyone else, then hopefully we look after our streams a bit better.
Speaker 1:Yeah, I think that's one of the reasons I love working in rivers so much creeks, wetlands, billabongs, whatever you'd like to look wherever there's a waterway because you protect one thing and it protects a whole other ecosystem around that one thing, and part of the magic is that it's underwater and you don't necessarily see it. So when I talk to scientists like you and I get my eyes open to this whole other world. It really is quite exciting. And I know up in the Snowy Mountains we've got a number of really special species like the stocky, like the crayfish you mentioned. There's also a dragonfly that's endangered, that we're also trying to raise awareness about. So letting people know that these special species are up there, what are we asking them to then do? Because we don't necessarily want them to go and find them, because there's so few of them, so we kind of have to love them from a distance.
Speaker 2:Yeah, you just need to A know that they're there and B know that they're in trouble and C know what the things are that are making them in trouble. You know, I meet people all the time who don't know that trout are not a native species. I meet people all the time who don't know that trout are not a native species. I meet people all the time that don't know that carp are not a native species. And so by educating people about what the true situation is, then once you know, then you're empowered and you tell your kids and you might tell someone else you've been on holidays and you went up there and you saw these lovely little sausages swimming in the stream. What are they? You know, and so people get an appreciation for those sort of things.
Speaker 2:I don't expect people to go out and try and do on-ground management, but, for instance, there's a subset of the community that are landholders, broad acre landholders, and so when you know what the threats are or know where the special places are because not all of these fish exist in national parks you know some of them are on private land. So then you can think, oh well, I won't plow to the river edge or, gee, I'll plant some trees to put some shade on the stream, or gee that erosion cut in a gully up there. Maybe I need to do something to try and prevent that sedimentation going into the stream. And you can't do that all on your own and there are government programs and subsidies to do that sort of work. There's land care, there's all sorts of things that you can get involved in. But just to know what's out there, what the threats are, and to tell other people, that's one of the great things that anyone can do.
Speaker 1:Absolutely agree. Yeah, that's a terrific answer. Thank you for making that so clear for everybody listening. So, yes, as Mark says, we're not expecting you to go out on ground and do stuff, but just knowing more broadly what's happening. That's really important so that we know how we can look after these. In this case, we're talking endangered fish. So I wanted to now just expand to national level, australian level, because I know that you've mentioned a couple of times that freshwater systems in Australia and indeed the world are in trouble, and I know you've recently done some work with the Biodiversity Council looking at fish across Australia. Can you tell us a bit about the main findings for that?
Speaker 2:So many people would be aware that there's an international conservation listing process run by the IUCN, and it's called the Red List, and it uses exactly the same criteria for assessing whether a species is threatened as the Australian government does. So we 53 scientists, over a period of about the last three or four years, have done an assessment of all of Australia's freshwater fish, and so that's really important to do them all at once so that you can actually compare apples and apples, whereas previously people nominate one species and then 10 years later, another one gets nominated and they both end up with the same categorisation you think. Are they really the same now, or has the one that was done 10 years ago? Is that better or worse, etc. So doing a strategic assessment of all of Australian freshwater fish is what we did. So we looked at over 240 species and the frightening, the unwelcome conclusion is that 37% of Australia's freshwater fish are now threatened, and that figure is only going to go up. Okay, because what people may not realise is that we still have a third of Australia's freshwater fish that don't have names, haven't been described yet. So people are still finding new species of fish all the time, and so generally, it's those new species that have been overlooked before, that turn out to be really threatened. And so in that mountain galaxius complex where I said 15 had been described from one, so the one was not considered threatened at all. Of the 15, nine are now listed as threatened. So that's sort of what happens. So, yes, we've found that 37% of Australian freshwater fish are threatened. 35% of the species that we assessed are not on the EPBC list yet. So that's the National Conservation Listing. So we really need to get our act together to get those fish formally assessed under the national legislation. So then funds, resources, awareness raising activities can flow towards those species. So that's the first thing is we've got to get all these things listed.
Speaker 2:There was some good news in the assessment. So Murray Codd, which is currently listed as vulnerable, we think, has now recovered to the stage where it no longer merits listing as a threatened species. Now that doesn't mean it's fully recovered and it's back to where it no longer merits listing as a threatened species. Now, that doesn't mean it's fully recovered and it's back to where it was in 1750 or whatever, but it means that it has now expanded its range or abundance so that it is no longer considered a threatened species and then there was a couple of other species which we think can be downlisted.
Speaker 2:So a close relative of Murray Cod is Trout Cod. It's currently listed as endangered. There's been 30 years of concerted, more than 30 years of concerted action to recover that species and we think we can now get that down to vulnerable from endangered, which is only one step away from being delisted. And so there's a few good news stories like that. I guess one of the major findings was that the major threat to freshwater fish in Australia is alien and invasive species and that is the area where we are putting the least resources, and we're putting the least resources there because it's a really gnarly problem.
Speaker 1:And so many people will have heard of the carp virus and you know we get contacted all the time at the River Restoration Centre by people saying when are you going to release the virus? And we sort of go back to them and say well, look, opinion is divided about whether this is a tool that we can use what's your take on the virus? And whether it's the sort of approach that we would need to take for invasive species.
Speaker 2:So I've always been wary of silver bullets, and the virus is a silver bullet. So, yes, overseas, where they've had outbreaks of the virus, it has decimated carp populations, which is a good thing, and most of those have been in relatively small water bodies. Where people have been, the anglers have been able to go out in their little tinnies and they pick up dead carp that are floating on the surface and all that sort of stuff. The concern that I have in Australia is that what happens if you have an outbreak of the virus in the Darling River, where there's very little population density? It's a lot of river and there's no one to go out and pull these dead bodies out, and so that's one of the concerns I have. So if all these fish get rolled at once, then what happens to the aquatic environment when all those carp are rotting there? There's still some modelling and work to be done on that.
Speaker 2:As I understand it, the proposal for the virus is back with the states. I think certainly the agriculture ministers are pretty in favour of probably releasing the virus. I'm not sure how the environment ministers would feel about that. I don't think there's any concern about the virus jumping from carp to another species. I think the science on that is pretty clear, and so that's not an issue. It's really about the environmental impacts that will occur when a whole lot of fish die.
Speaker 2:The other concern is that when silver bullets are promoted, everyone takes their foot off the gas on everything else. We don't need to worry about restoring fish passage or mitigating thermal pollution or replanting riverbanks. We're just going to knock all these carp on the head with this virus job done, and so that's usually not a good idea, because evolution is a wonderful thing and it will be working seven days a week to try and develop a resistant car, or the virus itself mutates and becomes less lethal, and so then you get resistance building up, and so all of these you know viral things, myxomatosis it gave us a 30 or-year window where we could then do other things to mop up the remainder of the rabbits that weren't infected. These days, people still look for silver bullets.
Speaker 2:Yeah, and think in political terms, you know, as in terms of government four years, yeah, yeah, no, yeah, we'll have this job done, you know sort of thing. And all of these things are going to take decades and decades. It took 50, 100 years for some of these species to decline. You're not going to bring them back just by snapping your fingers and releasing a virus.
Speaker 1:No, I think you're right. I think one of the big things we do like because we're so now used to instant gratification is we want that similarly for things in our environment, and I had the pleasure of facilitating workshop with the Tanarang people down in Victoria. They were releasing a new management plan. It had a 100 year time frame and I thought, well, you know what? That's pretty accurate. It also means that we don't, as the individual involved, feel as much overwhelm because we're part of something bigger that's going to last beyond us, and I actually think that's really important. How do you keep doing this work when you do come across things like 37% of freshwater fish you know are in trouble? How do you retain your mojo really to keep doing what you're doing?
Speaker 2:Yeah, I'm a slightly cantankerous, stubborn man who refuses to give in and that's not the best way to get success. But certainly you know I'm not going to give up. So I think you know you've got to get the community on side and the community will come on side, you know, once they realise how dire things are. And so you know koalas. If you love them or don't love them so much and I worked on koalas the early part of my career I do not dislike koalas at all.
Speaker 1:Just getting that on the record.
Speaker 2:I'm just getting that on the record, all right. I do not want any correspondence from the koala huggers saying this Linnaman's guy, you know, he's off the planet. So the thing that annoys me is that people have this and or attitude. You know it's got to be one thing or another. And so if you go to a meeting and discuss threatened species and someone says koalas, it just sucks all the oxygen and all the funding out of the room, and so then there's no room for anything else.
Speaker 2:Okay, the people who are interested in bugs or reptiles or whatever would be the same Plants. God, not a lot of love for plants other than the iconic ones Willamette Pine, things like that. And so we've got to get better at multitasking. We've got to get better at devoting funding and resources to things that maybe aren't that sexy. You've just got to keep plugging away and eventually you'll have a breakthrough, and they happen few and far between, and so at the moment I'm in a position where two pots of money have fallen from the sky. I've been waiting over 40 years for that, so I don't think I'm going to be around when the next pot falls, or if it falls, it'll probably hit me on the head and squash me, so I won't be around to benefit from it anyway.
Speaker 2:But you've just got to keep putting it out there and eventually someone sees the value in the argument you know, and you get someone on side, a large group who you've, you know, haven't had great traction with before, suddenly comes on side and it's fantastic. You know, land care was one of those things, you know. I mean, can you imagine sort of farmers involved in land care 50 years ago? No, mate, no. And so it was a generational change, you know. And so those sorts of things will happen and if you can enthuse, you know, the next generation, the current generation, about conservation, then job's done, you know then job's done, you know.
Speaker 1:So, as we bring our discussion to an end, I just wanted to touch on the positive aspects that you were talking about, because we've heard about the stockies. We've found a new population, which is fabulous, and there's ongoing work there now to protect them and to look into the genetics. I know a species that's already had some work done on the genetics is the Macquarie perch, and we love the maca. There it is, on your arm, and we have a population of Macquarie perch in the river, on the property that Mark and I own together. So can you just give us an update on where we're at with the good old maccas?
Speaker 2:So I've worked on maccas for more than 40 years as well, and so I've mainly done my work in the cotter catchment in the ACT, which is Canberra's water supply catchment. So it's intact, the vegetation is good, it has three Soggan Big Dams on it, but that's a minor thing, and so I've done a lot of work on those over the years. But I've also been working sort of at a low level on New South Wales' biggest Macquarie perch population. Sorry, I'll recast that Biggest natural Macquarie perch population because there were some that were introduced into coastal impoundments over 100 years ago. So the population I'm talking about is in the upper Murrumbidgee River, sort of from about Cooma for 90 odd kilometres upstream, and so I've been monitoring some sites in that population for nearly 30 years now, and so I go out with my little friendly soft nets and I set them overnight and I can catch 60, 80 young of the year. So these are the new babies, right. So I go out and sample in March and these fish were born in November and so they're about 50 mil long when I catch them and I count them and kiss them and let them go and I think, wow, I've got a big swag, a little baby fish here the population's doing pretty good.
Speaker 2:Over the last five or six years I've been doing some more intensive monitoring of a whole range of sites out there and taking the little thin clips. Every time I do it Didn't know what I was going to do with them, just put them in the freezer which is why there's not much room in my freezer for ice cream or anything else, but that's all right and keeping them. And then the opportunity came to do the genetics on those and to give people a bit of background. This upper Murrumbidgee population it's in steep sort of rocky, gorgey, well-forested you know eucalypt country mainly private landholders on either side, so it's not like it's overrun by people recreating in it or fishing in it or whatever.
Speaker 2:But it is downstream of a dam, tantangarra Dam that was built in the 1960s and Tantangarra Dam takes about 90% of the flow out of the river. So I've been out there monitoring fish and in the last five years I've collected all these fin clips. Well, we've done the analysis on the fin clips and the results are eye-opening, to say the least. So one of the sites where I catch all of these little baby fish every year. From the genetics you can estimate how many breeders were involved in breeding events each year to produce those fish, and science theory says that you need a minimum of 100 to prevent sort of severe inbreeding impacts and you need 500 to 1,000 breeders to ensure that evolutionary adaptive capacity. So you want to have a guess how many fish or how many breeders there were at my best site at the top of the river.
Speaker 1:That's the site you've been going back to. That's the site I've been going to for 25 years Lots of babies. Really happy with it. Really happy with it. Yep, let's go 400. Okay.
Speaker 2:So the genetics came back and we did it over three separate years where we had enough samples and the number of breeders was three. The next year three, the next year, 12.
Speaker 2:Okay, whoa very closely related up there instead of sitting back and cracking another beer and patting myself on the back for what a wonderful job I've done in monitoring this population, you realise that I've been monitoring the wrong thing, and so that's a real call to arms, because there's still people that go up there and fish and they catch a mackerel by mistake and they don't know what it is and they eat it. So the number of breeders is not the total number of fish there. The number of breeders is about 10% of the number of fish. So if there's three breeders, there's 30 fish in that pool. Okay, that could breed and you sort of go wow.
Speaker 2:What we also found was that all I did about eight sites along this 90 odd kilometers of stream, and we found that, apart from the bottom three sites, which sort of mixed a little bit so fish from downstream could swim to the next upstream site and vice versa, in the middle and upstream sites there was no exchange of fish between adjacent sites. Now these sites are 5 10k apart. Macquarie perch can do that in an evening if they feel like it, and so what it shows is that the lack of flow in the river means that there's lots of little barriers in between these sites, that there's lots of little barriers in between these sites that we didn't really know about, which are preventing mixing, and so you know we need to mix these fish up a bit. So the ones at the downstream site, the number of breeders down there was around 120, 130. That's all right.
Speaker 2:It's not great, but it's all right. But if you look at the top, where you've got three or a dozen or 15 fish, they're all related, they're all in the same families and they're not mixing at all Then that just shows well, their genetic diversity was low. That shows what I was talking about earlier, where they're just slowly losing genes over time and so we need to mix it up. So one of the things that I'm going to be doing next week with one of the pots of money that's fallen from the sky, oh, I love these pots.
Speaker 1:I wish I could find some.
Speaker 2:Some of them are small pots, some of them are big pots. You know you don't want to have so much money that you don't know what to do with it. I don't think I've ever been in that situation. I've ever been in that situation, Neither have I. I don't think I'm at risk of ever being in that situation.
Speaker 1:No, I don't think so. I'm not either.
Speaker 2:Anyway. So I'm going to start a little Uber service right where I'm going to catch fish from the bottom, throw them in the back of my ute in tubs, take them up to the top and let some go, and so that's going to provide some more genetically diverse fish to these upstream sites which aren't mixing. And so, anyway, that's my current cunning plan, and we'll take fin clips of everything we move and fin clips of everything we catch over the next few years during monitoring and we'll see whether it makes a difference. The other exciting thing that has happened up there is a colleague in New South Wales DPI has also been running a separate project on genetic rescue. One of these big populations in a coastal reservoir which is not really meant to be there, but it was translocated there a hundred years ago for recreational fishing purposes, is they're the long lost Murrumbidgee cousins, right? They haven't had a family reunion for over a hundred years. Okay, you look through the family album. Uncle George from Cooma is not there.
Speaker 2:And so we have been doing this what's called genetic rescue, where we introduce genetically more divergent fish into populations, and so New South Wales DPI has been doing this for the last three or four years. We did it in the ACT for a while. They've done it in Victoria for a while, and we found that some of these fish that we released there are breeding with the locals okay, which is great. And we found that some of these fish that we released there are breeding with the locals okay, which is great. And so the offspring of those fish because again you can tell which fish they came from, which individual bred, you know to do this are about twice as genetically diverse as the locals, and so that's great. So we're going to be doing that again as well, and so that's the sort of things that genetics has allowed us to do, because otherwise you would have been doing what another great terrestrial ecologist described as counting the books while the library burns.
Speaker 1:Yes, yeah, I can definitely see that. That is just fascinating, mark, and I know that we're going to have a lot more people going off to uni to become a fish scientist, having heard you speak about the amazing things that we're doing. So you're a fish fondler. You're also a bit of a Tinder service, but you don't actually scream beforehand. You're an Uber driver and you're Santa. I don't know how you have time for everything that you do.
Speaker 2:You've got to have fun in life, you've got to have fun.
Speaker 1:I totally agree. So there's three questions that we ask at the end of every episode. The first one is do you have a favourite river, waterway or body of water?
Speaker 2:Well, I started off as a snorkeller in Melbourne, in Victoria, right. So I grew up on the beach and I was a marine snorkeler. But for the last 40 years I have worked on the bidgie in Canberra basically, and that's my favourite river, waterway or body of water and some of the trips. So the cotter. I did my master's on the cotter. I've done a lot of work on the cotter as well, so that sort of upper bidgie catchment is what floats my boat.
Speaker 1:Yeah, I have to agree, it's mine too. Where do you feel most connected to country and to nature? You've got some beautiful art around your house that I can see here.
Speaker 2:Yeah, so I like getting out in the bush, whether there's water there or not. Really I love the desert country. I haven't been out there very much, but when I get out there it's just mind-blowing. I was asked recently about what I liked about water and I can just. I mean, I have a pretty crappy little creek at my back fence here, but every day I go down I look at the ducks, I look for water, rats and things like that, and so just being out in the environment anywhere, the natural environment, it's just all the woes of the world fall away and you think, wow, you know, that's pretty special. So the desert country is great, but I love the high country. You know, I just like being out in the bush really.
Speaker 1:Yeah, I know that feeling too. Whenever we go out to the desert country. I think that's where I feel awe the most and apparently that's very important for humans to actually go wow. I really am small and that's really really big, yeah, and that's okay.
Speaker 2:You go to summit. Like you know, I spend a bit of time in Kakadu and the Kimberley and whatever. And so there's one side out in the upper Murrumbidgee which I've been to virtually every year for the last 26 years or whatever, and it has this red sandstone-y cliff, you know, and I just think, oh, I'm in the Kimberley here, you know, and so it's great. It just it's that sense of awe and you never quite know what's going to happen or what you're going to catch or what you're going to see, and that's fantastic, and I think we've covered this a bit.
Speaker 1:Really, what drives you to do?
Speaker 2:what you do? Yeah well, as I said earlier, you know, freshwater fish are in trouble. Freshwater environments in the world are in trouble. 75% of freshwater fish in Australia are found nowhere else. We have a very unique fauna. It's the equivalent of our marsupials, really. We did some work a little while ago and we documented that 22 freshwater fish in Australia are likely to go extinct in the next 20 years, and so my job is to make sure that doesn't happen, and I refuse to lose species under my watch and, as I said, I want my grandkids to be able to enjoy them as much as I do.
Speaker 1:Well, hear, hear to that, and I will stand shoulder to shoulder while we do that, because it's the sort of thing that really drives me to do what I do too. So thank you so much for giving up your time again. I know you probably got to own Moonlight at the local shopping centre now as a Santa to make sure more pots of money fall from the sky. But in all seriousness, thank you for all that you do. We really do appreciate it. And, listeners, we'll put some links so that you can find out more. Mark has a wonderful book, fishes of the Murray-Darling Basin, which can give you a blow-by-blow account of all those Galaxids. There's also a fact sheet about the recent work he's done on the national populations and a few links there as well, and he is indeed known as the Fish Fondler Proprietary Limited. So that is a company to watch out for. Until next time, bye.
Speaker 1:For now you can subscribe to Take Me to the River. Wherever you get your podcasts. Visit arrcau forward slash podcast to learn more. That's arrcau forward slash podcast. We acknowledge and respect Aboriginal and Torres Strait Islander peoples as the traditional and continuing custodians of the country and the rivers on which we live. Learn, love and play. We respect and learn from elders past, present and emerging, valuing their knowledge, insights, cultures and connections to the waterways we all love and care for.