Saving the Running River Rainbowfish

What is Running River Rainbowfish?

When we discovered that Running River Rainbowfish were in trouble (Unmack & Hammer 2015), we had no concrete information on their taxonomic status. The recent review on rainbowfishes in the Burdekin system (Martin & Barclay 2016) really helped to clarify the occurrence and distribution of different forms in this system. Essentially there are populations of rainbowfish in the Burdekin that are Eastern Rainbowfish, but there are also a group of populations called Burdekin Rainbowfish that have a collection of traits that make them stand out as being different to Eastern Rainbowfish; but how different has remained an unanswered question, until now. Preliminary examination of high resolution nuclear genetic data suggests Running River Rainbowfish is distinct relative to other rainbowfishes in the Burdekin system. Initial examination of morphology by Gerry Allen and Michael Hammer also found some traits that differ. Further work is continuing which should lead to the species being described and named in the near future.

Captive genetic results

We examined captive fish from six people who had existing stock of Running River Rainbowfish. We examined 8–10 fish from most stocks and 35 fish from one source. Some fish were from old collections: 1997 (one remaining live fish) and 1998. Some were more recent collections: one from 2010, two from 2012, and one where the date and origin of the fish was unknown. Two of those populations (the one fish from 1997 and the unknown date) were not pure Running River Rainbowfish. All un-pure fish were removed from any breeding. One breeder’s fish had strong deviations from wild fish probably as a result of inbreeding (new individuals have since been incorporated into their breeding population to bring genetic diversity back up); other populations were consistent with wild fish.

Hybridisation in the wild

It is clear that the number of hybrids in the wild, while still low, is increasing. There are also biases in what fish we have tested; most have been larger adult fish for our breeding program which are less likely to be hybrids due to the short time that Eastern Rainbowfish have been present (first detected in August 2015 by Unmack & Hammer). Upper portions of the river closer to where the introduced Eastern Rainbowfish are present should have more Running River Rainbowfish hybrids – as they are closest to the invasion front – than populations at the far end of the reach. Identifying hybrid fish in the wild is difficult, especially females (Figure 5), although we expect that with sufficient closer examination of larger numbers of fish that hybrids will become easier to identify. We genetically tested 11 fish that I collected and preserved in 1997 as our “control” sample to compare to new collections. We tested 52 live fish plus six preserved samples collected in August 2015 (we did however observe a number of Eastern Rainbowfish living along side them which we specifically avoided), all were pure Running River Rainbowfish based on genetic comparisons to rainbowfishes from across and beyond the Burdekin River system. Of the seven live male fish collected in November 2015, one was an F1 hybrid. We examined additional fish collected in February 2016, from the upstream and downstream extent of their known distribution within the the Running River and noticed many fish from the upper site looked odd. We then sequenced five “odd” fish and five “pure” fish, plus 10 small (~1.5 cm) fish. Of those, two “odd” fish proved to be F1 hybrids and two were backcrosses between F1 hybrids and Running River Rainbowfish. One of the “small” fish was an F1 hybrid. Thirty-two larger live fish from the lower site on Running River (Figure 5) were genotyped for captive breeding, two of those were female F1 hybrids (Figure 6), however it is clear that of the additional ~170 untested live fish that some are almost certainly hybrids. Additional preserved samples were collected in August 2016 but have not been genetically tested. Again, upper sections of the river seemed to have more “odd” looking fish, while those from the lower section mostly looked good (keeping in mind that our ability to pick hybrid fish in the wild may not be highly accurate especially as backcrossing progresses). It is important to note that we have only sequenced a small number of the fish we have preserved, thus if future funding becomes available we will be able to clarify hybridisation patterns with less bias (note that we have only used the crowd funding money to address immediate questions relating to Running River Rainbowfish conservation – not broader research questions).

Fish breeding

As a result of the genetic sequencing, we now have evidence consistent with Running River Rainbowfish being a distinct species; a species under threat from hybridisation, and found only in a single habitat with a very restricted distribution. We initiated a breeding program (Figure 7) using the wild genotyped fish to breed fish for release into nearby tributaries of Running River; namely Deception and Puzzle creeks. By doing so we aim to establish wild populations that are safe from invasion by other rainbowfish (and hence hybridisation), and provide the species with a new home where it’s genetics will remain pure. We plan to start releasing fish in October/November of 2016. All translocation efforts are being closely coordinated with Queensland Fisheries.

Once we knew that our initial 26 pairs of wild fish collected in August 2015 were pure we paired them all up with the help of Luciano Beheregaray’s lab at Flinders University. Luciano’s lab group ran a series of analyses to allow us to pair up individual fish to maximise the genetic diversity between them and to reduce any chances of full or half sibling matings to minimise inbreeding. The other key point about breeding fish for conservation is to get an even number of offspring from each pair to ensure the genetic diversity from each individual fish is well represented in the translocated populations. This meant collecting mops from 26 pairs all in individual 50 litre aquariums and then transferring spawning mops for a week worth of breeding to 26, 20 litre aquariums, and raising those fish until they were large enough to be moved to larger aquariums. Each week of spawning required an additional 26 aquariums to house the new fry in! We raised approximately 110 fish from each pair of fish for a total of about 2800 fish. We have subsequently added 24 new breeding fish from our February 2016 collection and switched to breeding fish in groups of four fish (two pairs) per aquarium due to space limitations and because the fish settle in better when four are present vs. two. We are hoping to raise another 2000 or so fish for release.

Fortunately we have had terrific help from Jason Schaffer and Damien Burrows in TropWATER at James Cook University, Townsville. They have been providing all of the on-growing facilities and personnel to take care of fish. Once fry at the University of Canberra are large enough we have been shipping them up to Townsville as they have much warmer conditions to on-grow the fish prior to their release (Figure 8).

Finding new homes for Running River Rainbowfish

Peter Unmack, Steve Hume, Jason Schaffer and Mark Lintermans visited the Running River region on Febuary 27–28, 2016 (Figure 2). The primary goal was to try and determine whether some tributary creeks might hold Running River Rainbowfish and/or be suitable as translocation sites for Running River Rainbowfish to ensure they can persist in the wild. With the terrific help of Eridani Mulder from the Australian Wildlife Conservancy we sampled parts of Puzzle and Deception creeks as well as collecting more rainbowfish from Running River. We determined that both creeks would be suitable translocation sites based upon the presence of substantial waterfall barriers, areas of permanent water and the lack of existing rainbowfish populations.

Deception Creek is a major tributary that enters Running River below the lower gorge (Figure 2). The lower section of Deception Creek flows through a rugged gorge, before entering the lower plains and meeting Running River. We sampled three sites in the mid reaches, from the uppermost permanent water (Figure 9), a site at the upper end of the gorge section with a waterfall (Figure 10) and one site in between. Only one fish species, Spangled Perch (Leiopotherapon unicolor) was found at all sites examined. Several Saw Shell Turtle (Myuchelys latisternum) were observed along with a Cherax crayfish and Paratya shrimp, all of which suggests that water is fairly permanent in this system.

Puzzle Creek is a major tributary that enters Running River in the middle of the upper gorge (Figure 2). Most of the lower half of Puzzle Creek flows through rugged gorges with several major waterfalls of up to ~20 m, before dropping over one last waterfall and meeting Running River a few hundred metres downstream (Figure 3). We sampled the lower reaches of Puzzle Creek (Figure 11) to just above the lowermost waterfall and the uppermost permanent water. Only Spangled Perch were found in the lower reaches. Despite introduced Eastern Rainbowfish being present at the mouth of the creek, none were found further up Puzzle Creek as it has a steep gradient just upstream of where it drops into the upper Running River gorge. No other fish were observed, however, Purple Spotted Gudgeon (Mogurnda adspersa) were probably present in the lower reaches as well. We also sampled the uppermost permanent waterhole on Puzzle Creek at night and captured abundant Purple Spotted Gudgeon and Macrobrachium australiense shrimp. Spangled Perch were not captured, but are known to be present.