Spawning of Threatened Barred , (Teleostei: )

DANIEL J. STOESSEL , TARMO A. RAADIK AND RENAE M. AYRES

Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, 123 Brown Street, Heidelberg, Victoria, 3084

Published on 27 April 2015 at http://escholarship.library.usyd.edu.au/journals/index.php/LIN

Stoessel, D.J., Raadik, T.A. and Ayres, R.M. (2015). Spawning of threatened barred galaxias, Galaxias fuscus (Teleostei: Galaxiidae). Proceedings of the Linnean Society of New South Wales 137, 1-6.

Barred galaxias Galaxias fuscus is an endangered freshwater fi sh endemic to south-eastern Australia. Little is known of the ’ ecology. We investigated spawning biology of G. fuscus in three headwater streams and found spawning to occur mid-August to late September when photoperiod was 10 h 39 min – 12 h 25 min. Spawning sites were in fresh (range 35.3 – 56.6 EC, mean 44.7 EC), slightly acidic (range 5.7 – 7.1 pH, mean 5.9 pH), moderate to fast fl owing (range 0.4 – 2.0 m/s, mean 1.0 m/s), shallow (range 70 – 310 mm, mean 174 mm), well oxygenated (range 10.8 – 12.4 mg/l, mean 11.3mg/l), clear (range 1.2 – 6.3 NTU, mean 3.8 NTU), cool waters (range 8.4 – 10 °C, mean 9.1°C) immediately upstream of pools. Multi-layered clusters of up to 218 eggs were generally adhered close to the stream bed on the downstream side of cobbles greater than 180 mm diameter.

Manuscript received 14 September 2014, accepted for publication 22 April 2015.

Keywords: Freshwater, life history, nest site, reproduction

INTRODUCTION and as Critically Endangered Internationally (Wager 1996). The barred galaxias, Galaxias fuscus is a small Knowledge of G. fuscus biology is limited. (maximum 160 mm TL, 40 g), endemic, scaleless, Preliminary observations suggest that spawning non-migratory fi sh (Raadik et al. 1996). Remnant occurs in late winter-early spring, and is likely to populations are restricted to 12 geographically isolated be triggered by increasing day length and water headwater streams above 400 m in elevation in the temperature (Raadik 1993, Shirley and Raadik 1997). Goulburn River system in south-eastern Australia Fecundity is low (~500 ova), and eggs are adhesive and (Raadik et al. 1996; Koehn and Raadik 1995; large (~2.2 mm; Raadik 1993). Limited observations Allen et al. 2003). This range is likely to represent of two nest sites, suggest multi-layered clusters of fragmentation of a much wider and continuous eggs are laid underneath and on the downstream side historic distribution within headwater streams within of large rocks in fast-fl owing, shallow, cold (1 – 5 the catchment (Raadik et al. 2010). Predation by alien °C) water (Raadik et al. 2010), and incubation time of rainbow trout (Oncorhynchus mykiss) and brown eggs is approximately 30 days in water at 7 °C in an trout (Salmo trutta) (Salmonidae) is the primary aquaria (Raadik, T. unpublished data). cause of the decline (Raadik et al. 1996; Raadik et al. This paper further investigates the spawning of 2010). Changed water regimes, genetic isolation and G. fuscus, and includes data on habitat, spawning deleterious stochastic events including wildfi re and season and site, egg description, incubation period, drought also represent signifi cant long-term threats to and description of larvae. The biological information G. fuscus (Raadik et al. 2010). The species is listed as obtained is vital for the preparation of management Endangered under the Commonwealth Environment strategies to maintain, enhance or restore processes Protection and Biodiversity Conservation Act 1999 fundamental to survival, reproduction and viability of (EPBC Act) and the Australian and New Zealand remnant populations. Environment Conservation Council (ANZECC), SPAWNING OF BARRED GALAXIAS

MATERIALS AND METHOD clear, well-oxygenated, cool, narrow (1 – 4 m wide), had moderate to fast fl ow and alternating sequences Study area and sites of pools and riffl es. The substrate was typically The study was conducted in three geographically composed of boulder, pebble, gravel and sand (Raadik closely associated headwater streams (S Creek, et al. 1996). Kalatha Creek and Luke Creek) of the Goulburn Within each reach, a 100 m long monitoring site River in south-eastern Australia (37º 28´ S, 145º was established and surveyed repeatedly during the 28´E) (Fig. 1). Considerable bushfi res in the region in study to assess for the presence of reproductively ripe February 2009, had resulted in varying loss of riparian females. A second site, 200 m in length, and located cover. At the S Creek reach riparian vegetation and immediately upstream was later searched for newly tree canopy cover was non-existent, while at Luke laid eggs. Creek approximately 50 % of tree canopy cover remained, and at Kalatha Creek the area remained Monitoring of fi sh spawning condition unburnt. Coarse sand within the stream channel was G. fuscus were surveyed weekly from July to most prevalent in the S Creek study reach and least September 2010 (mid austral winter to early austral noticeable at Kalatha Creek. spring) at the monitoring site in each study reach, using G. fuscus was the only fi sh species present in a Smith Root® model LR20B portable electrofi shing the study reaches (Raadik et al. 2010), which were at backpack unit operated at settings of 70 Hz and 500 elevations above 400 m (Australian Height Datum) to 1000 V. caudal fork lengths (mm) and weights and located 1 – 2 km upstream of large natural (g) were recorded. Females were determined as ripe, instream barriers which had prevented the headwater when ovaries fi lled >90 % of the body cavity, eggs colonisation by other native fi sh and, importantly, were large, body cavity clearly distended, and eggs by alien salmonids. The freshwater streams were could be extruded by gentle pressure on the body wall. Spawning vent in males and females in addition was enlarged and extended (see Pollard 1972). All fi sh collected were released once processed.

Spawning habitat search Once ripe females were no longer observed at all monitoring sites, searches to locate eggs were conducted. All instream structures, including timber debris, undercut banks, and closely associated riparian habitat, were examined for the presence of eggs. Where eggs were found, they were left instream and their location marked with fl agging tape so the site could be avoided during kick sampling (see below). A drift net (500 mm mouth opening, 150 μm mesh) was deployed downstream of each site within each stream during the search period to capture drifting eggs or newly hatched larvae. The contents of the drift net were sorted at the completion of the search period. In addition, substrate kick sampling was undertaken over multiple, randomly chosen stream sections (1 x 1 m) at each site to search for eggs potentially deposited on sand or gravel beds. This involved gently disturbing an area of stream bed immediately upstream of a dip- net (250 x 300 x 20 mm with a 400 mm long Figure 1. Location of barred galaxias study sites in Ka- x 1 mm multifi lament mesh bag attached) for laltha, Luke and S creeks in south-eastern Australia. approximately 10 seconds.

2 Proc. Linn. Soc. N.S.W., 137, 2015 D.J. STOESSEL, T.A. RAADIK AND R.M. AYRES

Where eggs were located, water depth, fl ow multi-layered (up to three layers), and coated with (Hydrological Services Current Meter Counter Model sand and fi ne gravel particles. Eggs were not found CMC-20), the type and dimensions of the spawning attached to timber debris, aquatic plants, or moss. structure, and the characteristics of the placement No eggs or larvae were collected in kick samples or of eggs on the structure, were recorded. In addition, larval drift nets. water electrical conductivity (EC standardized to Water-hardened, fertilised eggs were spherical, 25ºC μS.cm-1), pH, dissolved oxygen (mg/L and % approximately 3 – 4 mm in diameter, adhesive, saturation), turbidity (NTU) and temperature (ºC) were demersal, and transparent to relatively opaque. measured in situ at a maximum depth of 0.2 m below Embryos in approximately half of the egg clusters the water surface during each spawning condition from Kalatha Creek, and the majority from Luke monitoring event, and immediately adjacent to egg Creek, were suffi ciently developed to clearly nest sites using a TPS 90FL-T Field Lab Analyser. distinguish their eyes when visually inspected in the fi eld. Embryos in the egg cluster from S Creek were Egg Incubation fully developed and hatched within 30 minutes of On completion of recording habitat attributes being located and removed from the creek 29 Sept at nest sites, eggs were transferred to aquarium 2010. facilities and placed into indoor 20 l aquaria. Each Eggs from Luke Creek placed into the aquarium aquarium contained a Perspex holder housing eight facility hatched 6 Oct 2010 –11 Nov 2010, those from egg hatching baskets (see Bacher and O’Brien 1989), Kalatha Creek 1 – 17 Nov 2010, and those from S into each of which was placed a single batch of eggs. Creek 29 Sept 2010 – 5 Oct 2010. Ninety percent of Aquarium water was aerated, recirculated and kept eggs hatched within 44 days of being brought into chilled to between 9.5 – 10.5 °C. Hatching baskets captivity, with the last eggs hatching by day 48. were removed each day from aquaria, placed under a Newly hatched larvae were transparent, 8.4 – 9.7 microscope and eggs inspected for fungus. Any found mm in length (mean 9.0 mm, n = 10) and were active to be infected or killed by fungus were removed swimmers which utilised the entire water column using sterilised tweezers. The presence and degree of excluding times when they were seen to periodically embryo development was visually inspected and the lay motionless on the bottom of aquaria in the days time and date of any hatching recorded. Following immediately after hatching. Yolk sac (1.5 – 2.0 mm in inspection all hatching baskets (along with eggs) diameter) absorption was generally complete within were placed into a salt solution (10 g/l) for 20 min to 3 days of hatching, and feeding commenced within minimise the possibility of fungus infection, before 24 – 48 hours of hatching. Larvae appeared to use the being returned to the aquarium. entire water column for feeding, were only limited by gape size as to what they were feeding, and readily switched from one feed to another. RESULTS

Spent female G. fuscus were present at all sites DISCUSSION in surveys conducted 21 Sept 2010. Subsequent egg searches undertaken 28 – 30 Sept 2010, located This study confi rms that G. fuscus are a demersal 13 egg clusters: four in Kalatha Creek (the least egg layer, preferring to use nest sites on cobble sediment and fi re affected site); eight in Luke Creek substrates located in moderate to fast fl owing water. (the moderately sediment and fi re affected site); and Eggs are relatively large and generally laid in a one in S Creek (the most severely sediment and fi re tight multi-layered cluster, spawning occurs during affected site). Individual clusters were adhered to the late austral winter to early spring, and the time of downstream side of cobbles (115 – 280 mm, mean 180 larval development is relatively long. As the only mm) close to the stream bed, in riffl es immediately other nest sites located (n=2) prior to this study were upstream of pools, in moderately to fast fl owing (0.4 found attached to boulders (Raadik, T. unpublished; – 1.9 m/s, mean 1.0 m/s), shallow (20 – 310 mm, Raadik 1993; Raadik et al. 1996; Raadik et al. 2010), mean 174 mm), cool (8.4 – 10.0 ºC, mean 9.1 ºC), a substrate size that was lacking in our study streams, fresh (35.3 – 56.6 EC, mean 44.7 EC), slightly acidic the combined fi ndings suggest that G. fuscus prefer (5.7 – 7.1 pH, mean 5.9 pH), well oxygenated clear to lay eggs on larger in stream rock substrates, and to water (10.8 – 12.4 mg/l, mean 11.3 mg/l). Clusters avoid pebbles and gravels. were composed of up to 218 (mean = 78) eggs, were Despite the average fecundity of mature females suggested as being ~500 (Raadik et al. 1996),

Proc. Linn. Soc. N.S.W., 137, 2015 3 SPAWNING OF BARRED GALAXIAS individual nest sites found in this study had an average and over-storey canopy cover at S Creek, and to a of ~80 eggs present. This suggests that females may lesser extent at Luke Creek, it is possible that such spawn at multiple sites, laying many, small clusters differences may be attributed to increases in light of eggs, thereby reducing the risk of potential loss intensity, and resident fi sh perception of photoperiod of all eggs deposited if laid in a single cluster. This at these sites. Similar changes in the time of spawning strategy is uncommon in the Galaxiidae, having as a consequence of photoperiod alterations, often only been documented in the fl at-headed galaxias independent of temperature, have also been shown in (Galaxias rostratus) (Llewellyn 1971), which is other fi sh species (see Björrnsson et al. 1998; Davies comparatively highly fecund, and lays batches of eggs and Bromage 2002; Elliot et al. 2003; Howell et al. over an extended spawning period of up to a month 2003). (Llewellyn 1971). The spawning period of G. fuscus Nest-site characteristics of G. fuscus are is alternatively likely to be relatively short, as we similar to that described for the ornate mountain found the proportion of mature/ripe females declined galaxias (G. ornatus; see Raadik 2014). Both lay rapidly once spawning began at individual reaches. a small number of relatively large, adhesive eggs Therefore if G. fuscus undertake spawning at multiple in a protected site, usually on rock (O’Connor and nest-sites, it is likely that this occurs over a period of Koehn 1991). In addition, both barred and ornate days, rather than weeks. mountain galaxias lay their eggs predominantly in Eggs collected from the wild took a maximum of riffl es, where the surrounding water is relatively fast- 48 days to hatch in captivity. Assuming eggs which fl owing and well-oxygenated (O’Connor and Koehn hatched last were spawned just prior to collection, 1991). Adhering eggs to large stone substrates can this fi nding extends the suggested incubation period be advantageous as the substrate is relatively stable by at least 18 days (Raadik 1993; Raadik et al. 1996; and thus eggs remain within the area chosen by the Raadik et al. 2010). However, a strong relationship parent. However, demersal egg-laying may result in between development of larvae and ambient water eggs being susceptible to environmental disturbances temperature exists for many fi sh species (Pauly and to streambeds, such as siltation (Growns 2004). In Pullin 1988; Pepin 1991; Pepin et al. 1997), and addition, reduced water levels during the breeding therefore annual differences in stream temperatures season may expose spawning habitat or eggs at nest would likely alter the incubation period of eggs of sites, thereby limiting spawning habitat availability the species. Back-calculating by the egg incubation and reducing egg survival and overall spawning period of 30 – 48 days suggests a spawning period for success (Moore et al. 1999). Similarly, post-fi re G. fuscus lasting from about mid-August to the end of sedimentation can reduce the availability of spawning September (late austral winter to early spring). habitat thus limiting spawning potential, or smother Differences in the stage of maturation, and in eggs at nest sites causing egg mortality and decline in the subsequent date of hatching, of eggs between spawning success (O’Connor and Koehn 1991). the three study streams indicates spawning was not The study reconfi rms the importance of larger synchronous across the populations within a small loose rock substrates for G. fuscus reproduction geographic area (~10 km2). The S Creek population (spawning), and highlights that the loss of such habitat probably spawned several weeks prior to the Luke could result in the decline of remnant populations of Creek population, which in turn spawned one to the species. Similar loss of habitat has been implicated two weeks earlier than the population in Kalatha in the decline of a number of fi sh species worldwide Creek. Similar variation in the time of breeding in (see Scott and Helfman 2001; Pillar et al. 2004; Wyatt other galaxiid species has been attributed to water et al. 2010). Much of this habitat has been lost due temperature (O’Connor and Koehn 1991; Allibone and to anthropogenic degradation of riverine habitats, Townsend 1997) and changes in stream levels (Moore primarily through siltation. Rehabilitation of streams is et al. 1999). However, environmental cues that initiate today common, however, the strategy is often tailored spawning were not obvious in this study and could towards improving habitat of larger, auspicious, not be directly associated with changes in water fl ow recreational fi sh species. To date, little augmentation or water temperature, although spawning did occur of suitable substrates for smaller bodied, demersal egg at a time when water temperature was increasing. laying freshwater fi sh has occurred. The introduction Photoperiod may also be infl uential (Shirley and of rock substrates to streams affected by siltation may Raadik 1997). However, the lack of synchronicity be of particularly value where threatened demersal across the populations in the current study suggests egg laying fi sh exist, and where remediation works additional stimuli could be responsible. As fi re had (such as fencing and replanting of the riparian zone) recently removed much of the riparian vegetation has occurred.

4 Proc. Linn. Soc. N.S.W., 137, 2015 D.J. STOESSEL, T.A. RAADIK AND R.M. AYRES

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