Our official processes for threatened species are failing to save the Running River rainbowfish, which is rapidly mating itself into oblivion.
In August last year, fish biologists Peter Unmack and Michael Hammer were dragging seine nets through the shallow waters of Running River, which winds down from the Paluma State Forest, about 80km northwest of Townsville, Queensland, to the larger Burdekin River. Their target was the Running River rainbowfish, a tiny, vibrantly coloured species that lives exclusively in a 13km stretch of the river.
Despite their limited range, the fish themselves were easy to find. “Rainbowfish are typically supremely abundant,” says Unmack, a freshwater ecologist at the University of Canberra. “So if you took a hundred metres of river you’d probably have several thousand fish in a typical stretch.”
While inspecting their catch, the pair got their first hint that something was wrong. Tangled alongside the Running River rainbowfish was the odd fish that looked different — more like the eastern rainbowfish, which usually lives further downriver. This was unusual, but they didn’t think too much of it at first.
The researchers moved upstream to the top section of Running River, where rainbowfish had never been reported, and stopped to sample some purple spotted gudgeons. Instead, within seconds, Unmack plucked another eastern rainbowfish from the water. He immediately realised what was happening.
“It really wasn’t until we went upstream, to where there were supposed to be no rainbowfish, that the penny dropped that this was a catastrophe about to happen.”
Even among rainbowfish, the Running River species is particularly striking. Its body, about 60mm long, is coloured yellow to green, with red fins and several bold black lines that zig-zag across its flank. The species was discovered in 1982, but never formally described because its taxonomy was uncertain; it was considered either a variety of the eastern rainbowfish or a distinct species. Recent evidence suggests it is indeed genetically distinct.
For centuries, the Running River rainbowfish lived alone in its short stretch of river, isolated between two gorges. The lower gorge formed an impenetrable natural barrier that prevented a neighbouring population of eastern rainbowfish from moving upstream. However, recently — around 2013 — eastern rainbowfish were introduced, either deliberately or accidentally, to the upper reaches of Running River. These introduced fish are now moving downstream, interbreeding with the Running River rainbowfish as they go. By all accounts, these invaders are quite irresistible.
"The rainbowfish that is invading up there is a larger species, and so is a bit more attractive, we think, for mating opportunities,” says Mark Lintermans, a freshwater ecologist at the University of Canberra. “And so there's quite a deal of pressure for those introduced rainbowfish to spread throughout the threatened populations."
In other words, the Running River rainbowfish is very rapidly mating itself to extinction, diluting its only wild population with interspecies hybrids.
Hybridisation remains one of the most unappreciated pathways to extinction. Although gene flow between populations, even between species, is a natural process that can inject useful variation into the gene pool, human activities often bring together species that otherwise would never have met. In the rapidly-warming Arctic, for instance, previously separate species such as polar and grizzly bears are more frequently crossing paths and mating with each other.
Hybrid individuals created through interspecies mating are not necessarily sterile, and will sometimes re-mate with one or both parent populations. This can have one of several outcomes for the species involved. Genetic swamping occurs when all of the ‘pure’ individuals from one species are replaced with hybrids. Less commonly, in what is known as demographic swamping, the genetic material from one species is lost entirely.
A certain amount of hybridisation has always occurred between Australia’s many rainbowfish species. Over the millennia, as natural dispersal barriers arose and broke down, different populations have naturally mixed their genes together, and this is observable in their genetic makeup. But the Running River rainbowfish has been isolated for long enough that it is both phenotypically and genetically distinct from neighbouring species. Its unique colours and patterns, which have made it a favourite among fish hobbyists, could disappear forever as a result of hybridisation.
The researchers have caught the species at a crucial moment. “It felt like we were there pretty much at the invasion front,” says Michael Hammer, Curator of Fishes at the Museum and Art Gallery of the Northern Territory, who took part in the August 2015 expedition. “So in the wild population, we did see some fish that looked suspiciously like hybrids, and the odd eastern rainbowfish in amongst them, so it was just starting to occur.”
Mark Lintermans convenes the Australian Society for Fish Biology's Threatened Species Committee, who since 1985 have maintained a list of Australia's most threatened fish. In September, at a meeting in Hobart, Tasmania, the committee members voted to list the Running River rainbowfish as critically endangered — at very high risk of extinction in the near future — due to the threat of hybridisation.
"The Running River rainbowfish could go extinct within the next two to three years, it's that quick,” says Lintermans. “So it's important for us to list them now, even before they have their formal names, to try and raise awareness about their conservation plight.”
Without any formal conservation funding, the researchers have had to look elsewhere to finance their work. In collaboration with the Australia New Guinea Fishes Association, they mounted an emergency crowdfunding campaign, which, as of September this year, has raised over $10,000. More than half of that funding came from amateur aquarium clubs, mostly in North America but also Europe and Australia. One private donor, a rainbowfish enthusiast from Switzerland, gave $1000 to support the project.
This funding has been used to collect genetically pure Running River rainbowfish from the wild and breed them in captivity at the University of Canberra. In August last year, immediately after discovering the invasion, Unmack and Hammer captured 52 fish and brought them back to the university to be kept in 50-litre aquaria. It can be difficult to distinguish pure Running River rainbowfish from first-generation hybrids — females look essentially identical, and male hybrids are identified by the flecking on their fins — so genetic testing was used to identify the purest individuals for breeding. Males and females were paired up to avoid inbreeding and maximise overall genetic diversity. The goal was to breed an insurance population, should the wild population become irreversibly compromised.
Here, once again, the input of amateur breeders proved invaluable. Rainbowfish hobbyists have been keeping the species for decades, so there was already a wealth of available knowledge on how to maintain healthy aquarium stocks. Captive fish from amateur breeding populations, some collected as early as 1997, also provided a genetic baseline for what pre-invasion Running River rainbowfish should look like.
As it happens, Running River rainbowfish take very well to captivity: In just over a year, the university’s breeding population has burgeoned to about 3000 fish. Many of these are now being held at James Cook University in Townsville, with a plan to introduce them back into the wild. For the moment, returning the fish to Running River is not an option, since they would only hybridise with their invaders. Instead, the researchers have had to find alternative release sites. Two nearby tributaries, Deception Creek and Puzzle Creek, fit the bill perfectly: both have permanent water, no existing rainbowfish populations, and run through land managed by the Australian Wildlife Conservancy.
Even if these introductions are successful, the researchers acknowledge that they are only a band-aid solution. At a minimum, more insurance populations will need to be established in other creek systems. But the true challenge — and the ultimate goal of conservation — is to preserve the Running River rainbowfish in its natural range. Even at this early stage, reversing the eastern rainbowfish invasion would be difficult and expensive, requiring considerable funding and coordination at all levels of government. The Running River rainbowfish simply doesn’t have this degree of support: Conservation funding in Australia is limited, and the official processes in place to support threatened species are slow, particularly for undescribed species.
"It highlights a bit of a gap between some of our national threatened species approaches,” says Lintermans, “because until you have a formal listing under the EPBC [Environment Protection and Biodiversity Conservation] Act, then generally it can't get a priority for action. But it will take quite possibly a year to get listed under that Act, and the fish may be gone before then."
It’s still too early to know exactly how the eastern rainbowfish invasion will pan out. In the last 14 months, the proportion of hybrid rainbowfish in Running River has steadily increased. “I would presume, in another year or two we’ll have a really good idea as to whether everything’s mixed up, or whether they’ve managed to maintain some pure fish amongst the hybrid mess,” says Unmack. “But I suspect they won’t — in other cases where this has happened, it’s been a complete whitewash.”
Here, Unmack has in mind another undescribed rainbowfish from northern Queensland, the Malanda rainbowfish. This species exists as three populations, but two are “on the verge of being wiped out” following an eastern rainbowfish invasion. “Whether that’s one year, two years, six months — it’s really hard to know,” says Unmack. To stave off extinction, he and his colleagues have instigated yet another eleventh-hour project.
“Yeah, we’ve started,” says Unmack, a little wearily. “We’re going to try to do some translocations into farm dams. There’s very little left in two of these creek systems out of the three; we’re just gonna try to do some emergency stuff, to move a few and hopefully they take in those dams. And then, I don’t know what we do after that.”
It seems unfair that the fate of not one but two Australian rainbowfish should fall to only a handful of researchers, with such little government support. Of Australia’s 14 recognised species, only the Lake Eacham rainbowfish is currently listed as threatened under Australia’s EPBC Act, and hence has a reasonable chance of securing government funding. But many more rainbowfish need conservation action.
Across the species' range, habitat modification for agriculture has created aquatic environments that favour generalist species over more specialised ones. Species translocation is also a major problem, particularly in northern Queensland. Property owners often introduce rainbowfish to their farm dams, not realising that a single flood event can spread invasive species into nearby waterways, where they out-compete or hybridise with local fish.
“There are specific areas, particularly in the Atherton Tablelands — and the Burdekin River falls into that general area — that are a centre for biodiversity,” says Hammer. “There’s a lot to lose, and the threats are building up in the area. So overall we’re not going to lose rainbowfish from Australia, but we’re going to start to incrementally lose some of the more interesting members of the group.”
It's not all grim news, of course. Unmack and his colleagues are humbled by the generosity of rainbowfish enthusiasts worldwide, whose support has given the Running River rainbowfish a glimmer of hope that it didn’t possess a year ago. “It’s a bit shameful, though,” he says, “when it’s a bunch of amateurs from around the world doing this stuff, and yet Federal and State Governments have got nothing.”
Members of Queensland Fisheries have been very supportive of the project, providing the necessary permits and permissions at short notice. But, in general, our official processes for threatened species have failed to cope with such a conservation emergency, and the lack of government funding has severely limited what could be achieved. Unmack is frustrated that we are neglecting our own fish species, especially those in such dire need.
“One of the real challenges of this type of stuff is when shit hits the fan, where do you get money to do any of this stuff, right? There’s nothing. Absolutely nothing. Everything I’ve done, I’ve had to go do it and sacrifice all the other things I’m supposed to be doing at the same time.
“But, you know, the Queensland Government has zero money, the Federal Government is basically useless. We submitted a proposal to the Threatened Species Commissioner, and heard nothing back. If it wasn’t for support from the aquarium side of things, then it never would’ve happened.
“The key issue that comes out of this is how do we conserve fish that are about to go extinct when a clear emergency happens? And who pays for it? And at the moment, basically they just go extinct. There is no one to pay for it.”'
Last week, Karl Moy, a master's student at the University of Canberra, carefully carried bucketloads of Running River rainbowfish to Deception Creek, where the researchers hope to build the first of several insurance populations. He released 250 captive-bred fish into small aquatic enclosures to allow them to acclimatise to the water conditions.
The following day, the enclosures were opened and the fish swam off into the creek. Moy has since been monitoring the population through snorkelling and baited remote underwater video, and says that so far they look to be doing well. But it will be several more months before we know if they can survive and reproduce in their new location.
These rainbowfish, released without ceremony into an otherwise nondescript creek, currently hold the hopes of their entire species. It's a strange and surreal feeling, says Moy, to watch the fish swimming around in the wild, knowing that they wouldn't be there without him.
To help support conservation research on the Running River rainbowfish, visit here.
Edited by Ellie Michaelides