A whopping 35 freshwater fish are being recommended for national listings as being at risk of extinction after an Australia-wide survey. The study which was the largest of its kind found more than a third of freshwater species are at risk of extinction.
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00:00Yeah, so that's the Kangaroo River Perch. That would be the first confirmed freshwater
00:07fish extinction in Australia. It hasn't been seen in the wild since the late 1990s, and
00:14the last one died in captivity in about 2010.
00:19I'm surprised you say this would be the first time there's been freshwater species go extinct
00:25in Australia.
00:27Yeah, we've been pretty lucky so far, you know, compared to mammals or other groups
00:31of animals. But we've got a whole lot of species that are in trouble, and we think this is
00:37the first one that we know has gone. There's probably other species that we've lost over
00:42time, but we didn't even know they were separate species.
00:45And so, yeah, how do you feel about this, and seeing that image of the fish there as
00:49well?
00:51Oh, well, it's always terrible to lose a species. It's a salutary tale for everyone, really,
00:57that fish are usually ignored. They're underwater, they're out of sight, people don't pay them
01:03much attention, they're not very charismatic. But this study is a wake-up call that we really
01:09need to do something about freshwater fish.
01:11Yeah, so this must have been a huge undertaking for you, the first comprehensive review of
01:16the nation's freshwater fish. How much work went into this?
01:21Well, we started in 2018, and it was sort of 2020 when we'd sort of wrapped up most
01:28of it. And then we sort of stopped and got our breath back for a bit, and then finally
01:33wrote the paper, which has just been published. So it was about a two-year process from woe
01:37to go.
01:38And so you concluded that there are around 35 species at risk of extinction. Mention
01:45a few of those for us.
01:48Yeah, there's 35 additional species that aren't on the national freshwater fish threatened
01:55list yet. So some of them are small, some of them are big, most of them are small species.
02:02I think the first one I wanted to talk about was trout cod, I think. Oh, sorry, kangaroo
02:08river perch, we've just mentioned that. Trout cod, which is a large species, closely related
02:13to Murray cod. And this is actually a good news story in that this is one that we can
02:20downlist. So the picture on your screen shows what it looks like. This is a species that
02:26has had about 30 years of dedicated recovery action to it. And we now think that it can
02:33be downlisted from endangered to vulnerable. So that's a good news story.
02:38And where is its habitat?
02:41It's a Murray-Darling Basin fish. It only occurs naturally in two places now, one in
02:48a small tributary in Victoria and one in the Murray River near Yarrawonga. It was previously
02:53much more widespread, but has largely disappeared from those areas. But restocking has established
02:59populations in a number of areas. And the trajectory for this fish is looking pretty
03:05positive.
03:06Yeah, and I think we can go to a couple of more fish now.
03:10And so the next one will be Stocky Galaxius. And so this is a very small fish with a very
03:17small distribution. It's probably only as long as your finger. And it occurs in Kosciuszko
03:24National Park. And the major threat to this and most of the other galaxids is introduced
03:30species like trout, which have driven them to the very edge of their range. And so now
03:37they're only in, you know, this one's only in two streams, about five kilometres long.
03:44And it's protected there by a waterfall that excludes trout. And that's a really common
03:48story with galaxids.
03:52And you've got another, I think.
03:54And the last one is the Uchi Rainbow fish. And so the Rainbow fish as a group are quite
04:01unique in that they have a threat from introduced species that is different to what normally
04:07occurs. And so these are threatened and other Rainbow fish by aquarium releases of related
04:14Rainbow fish, which are then hybridising with them and basically taking a lot of them out
04:18of existence.
04:19So we end up with a pack of mongrels rather than individual species. And so that's a real
04:25threat to Rainbow fish across Australia. An aquarium fish is where most of our new introduced
04:33fish species are coming from. And so while we're tackling that pretty well, we're not
04:37dealing with the other introduced fish in Australia like trout or redfin perch or carp
04:44very well at all.
04:45And what can you tell us about the spots where those Rainbow fish, like where were they once
04:48found and where are they restricted to now?
04:52So the Rainbow fish occurs, that Uchi Rainbow fish occurs just south of Cairns. It's now
04:58restricted to agricultural land where they're growing tea and bananas and sugar cane and
05:04things like that. And so the habitat conditions are slowly degrading as you get fertilisers
05:10and pesticides going into stream and sediment. And also the fringing vegetation alongside
05:17streams has been cleared. So the streams are getting hot and the insects that used to fall
05:22onto the water surface, which are their food source, are disappearing as well.
05:25Yeah, but the positive news out of this and that you pointed out with the second fish
05:29that you mentioned, the trout, is that with an effort, the fish can be helped to fight
05:36back and improve their numbers.
05:38That's right. So that trout cod has recovered with multi-state coordinated activity. So
05:45Victoria, ACT, New South Wales have all worked pretty hard on that for a number of years.
05:50And another good news stories is about Murray cod. So it can now be delisted because
05:55there's been three decades or more of stocking that has established a number of
06:00populations. But it's the focus on those big charismatic species like the cod that
06:06tend to distract from the fate of the really small bodied species that people don't
06:11think about. You know, they just think of them as guppies or minnows and don't really
06:16give them much value or concern.
06:18Yeah, well, you're bringing this to people's attention now. So, for example, with the
06:24rainbow fish, what could be done over the coming years to ensure its numbers bounce
06:29back?
06:31So one of the things that we try to do for these small species is try and establish new
06:36populations elsewhere in better habitats where the threats that are currently driving
06:42them down aren't active.
06:44So for some of the other rainbow fish, we've established populations above barriers to
06:49alien fish. And so then they're thriving in those habitats where they're not being
06:54hybridised out of existence, for instance.
06:57Yeah. So, yeah. So there is work that can be done.
07:01There is work that can be done. It just needs resources and the willpower to do it.