A general survey of the freshwater fish fauna of the Bomaderry Creek catchment in southern coastal New South Wales.
A field survey of the freshwater fishes of the Bomaderry Creek catchment in 1994-1995 recorded nine native species and one introduced species. One of the species recorded, Climbing Galaxias Galaxias brevipinnis, is of conservation concern in New South Wales. A report of an additional four native species was obtained from secondary sources. A concrete weir on Bomaderry Creek was found to represent a discontinuity in the distribution of some fish species. Four out of the six diadromous species recorded in the field survey were found only below the weir, while the two potamodromous species recorded were both found above and below the weir. The subsequent decommissioning of this weir in 1998 may substantially increase the potential habitat available for diadromous fish species in the Bomaderry Creek catchment. (The Victorian Naturalist 134 (4), 2017, 108-114)
Keywords: survey, New South Wales South Coast, Sydney Basin bioregion, freshwater fish, diadromous, potamodromous, weir barrier
The freshwater fish fauna of Australia has relatively low species diversity by global standards but is significant because of a high level of endemism (Allen et al. 2002; Leveque et al. 2008). River regulation and agricultural and urban development of catchments in south-eastern Australia have had a major impact on freshwater habitats and fish communities (Koehn and O'Connor 1990; Faragher and Harris 1994). Stream barriers such as dams and weirs can have a significantly adverse impact on freshwater fish populations, obstructing spawning and seasonal migrations and altering habitat conditions (Mallen-Cooper 1993; Morris et al. 2001; Gehrke et al. 2002; Rolls 2011). Government agencies and community groups have made a considerable effort in recent years to reverse some of the damage and to restore catchment connectivity and aquatic habitat values. Actions taken have included decommissioning of obsolete dams and weirs, construction of fishways specifically designed for Australian native fish, allocation of water for environmental river flows and restoration of riparian vegetation (Arthington and Pusey 2003; Bond and Lake 2003; Gilligan et al. 2003).
Bomaderry Creek, on the lower Shoalhaven River near Nowra on the south coast of New South Wales (NSW), is one of many coastal streams in south-eastern Australia modified by construction of a weir for local water resource development. This paper documents the results of a general survey of the freshwater fish fauna of the system prior to the decommissioning of this weir. Freshwater fishes are categorised in this paper as including estuarine species that often venture into freshwater, consistent with general references such as Allen (1989), McDowall (1996) and Allen et al. (2002).
Bomaderry Creek (34[degrees] 50.7' S, 150[degrees] 35.4' E) (Fig. 1 and see front cover) is located 125 km SSW of Sydney, in Dharawal Aboriginal Country in the Illawarra subregion of the Sydney Basin bioregion. The Bomaderry Creek catchment is about 36 [km.sup.2] in area, with an elevation range of 10-620 m (Australian Height Datum), and is a mix of farmland, forest and urban areas. The Bomaderry Creek system includes the upper tributaries Tapitallee Creek, Browns Creek and Good Dog Creek. The lowest part of the creek is estuarine (Fig. 2). In 1938, a concrete weir (Fig. 3) was constructed on Bomaderry Creek about 5.3 km above its confluence with the Shoal-haven River to provide a reliable water supply for the township of Bomaderry (NSW Office of Environment and Heritage 2016). Approximately 21 km of stream occurs above the weir.
[FIGURE 1 OMITTED]
The primary survey method involved wading along streams at night with a spotlight and a hand-held fine mesh dip-net. Larger fish were identified by sight while smaller species were captured for identification and then released. Species were identified by reference to Allen (1989). Surveys were done on nine nights between April 1994 and August 1995 (Appendix 1). The majority of surveying was done along the section of creek within about 1 km upstream and downstream of the weir (sites 4 to 7) (Appendix 2). This part of the creek is within the Bomaderry Creek Bushland, an urban bushland area situated between North Nowra and Bomaderry (Barratt 1994; NSW Office of Environment and Heritage 2016). Additional sites were sampled lower (sites 1 to 3) and higher (sites 8 to 12) in the catchment (Fig. 1 and Appendix 2). The author also accompanied NSW Fisheries officers surveying the lower 6 km of the creek on one afternoon and night in August 1995. The methods employed comprised electrofishing (sites 4, 5 and 7) and use of minnow traps and gill nets (sites 1, 5 and 6). Of particular interest was site 1 on the estuarine section of the creek, where the stream was too deep to sample effectively by wading. Assessment of the local status of species in the Bomaderry Creek system was based on the number of sites where species were recorded and the relative abundance of species at a site. Categories used were rare, uncommon and common.
Seven species of freshwater fish (six native and one introduced) were recorded in the Bomaderry Creek catchment by the spotlight/dip-net wading survey method (Table 1). Two species (Australian Bass Macquaria novemaculeata and Striped Gudgeon Gobiomorphus australis) were found only downstream of the weir, and one species (Climbing Galaxias Galaxias brevipinnis) was found only in the headwaters of the catchment (at an elevation of about 200 m AHD). One additional native freshwater species (Bullrout Notesthes robusta) was recorded by NSW Fisheries officers in the deeper estuarine section of Bomaderry Creek. It was captured in gill nets together with several estuarine species, of which two (Striped Mullet Mugil cephalus and Flat-tail Mullet Liza argentea) are also listed here as they can often be found in the lower freshwater reaches of coastal rivers. Overall, the field survey recorded nine freshwater fish species below the weir and five above the weir (Table 1 and Appendix 3).
[FIGURE 2 OMITTED]
Bomaderry Creek has a relatively diverse native freshwater fish community considering its small size, and the apparent absence of additional introduced species such as Carp Cyprinus carpio and Goldfish Carassius auratus at the time of the survey is also noteworthy. The nine native species reported here comprise about 43% of the native freshwater fish species known from the Shoalhaven River downstream of Tallowa Dam (Bishop and Bell 1978; Gehrke et al. 2002; Murphy unpublished data) and about 29% of the species known from the south coast of NSW (Faragher and Harris 1994). Further survey effort in Bomaderry Creek, particularly in the estuarine section, would be likely to identify additional species. Barratt (2015) reported an additional four species from the lower (Bomaderry Creek Bushland and estuary) sections of the creek: Estuary Perch Macquaria colonorum, Freshwater Mullet Myxus petardi, Yellow-eyed Mullet Aldrichetta forsteri and Flat-headed Gudgeon Philypnodon grandiceps. Southern Blue-eye Pseudomugil signifer has been recorded in the Shoalhaven River 15 km upriver from Bomaderry Creek at the mouth of Bengalee Creek (Murphy pers. obs. Feb 1995). Other possible species include Short-headed Lamprey Mordacia mordax, Short-finned Eel Anguilla australis, Common Jollytail Galaxias maculatus and Empire Gudgeon Hypseleotris compressa.
Climbing Galaxias has been identified as a species of conservation concern in NSW (Morris et al. 2001), although it has not been formally listed as a threatened species under the NSW Fisheries Management Act 1994 (current to June 2017). The distribution of this species is considered likely to have been fragmented as a result of forest clearing and predation by introduced trout (McDowall and Fulton 1996). The forest-shaded headwater stream where it was recorded in the present study is typical of the species' habitat (O'Connor and Koehn 1998). An ecologist residing in the local area has noted that Climbing Galaxias has not been seen at this site or in the local area since about 2000 and may now be locally extinct (G Daly pers. comm. October 2016).
The results of this survey suggest that the weir represented a discontinuity in the distribution of some fish species in the Bomaderry Creek system. Variation between species distributions was in part a reflection of differences in life-history habits. The two potamodromous (migrating wholly within freshwater) species recorded in the field survey, Australian Smelt Retropinna semoni and Cox's Gudgeon Gobiomorphus coxii, were evidently able to maintain populations above the weir. In contrast, only two of the six diadromous (migrating between freshwater and the sea) species recorded were found above the weir (Table 1). A diadromous life history includes catadromous species (species that migrate from freshwater to the sea as adults to spawn, e.g. Long-finned Eel Anguilla reinhardtii and Australian Bass) and amphidromous species (species that live and spawn in freshwater with the hatchlings being swept downstream to the sea before returning to freshwater, e.g. Climbing Galaxias), as well as anadromous species (species that migrate from the sea to freshwater as adults to spawn--nil recorded in this study). Dams and weirs have been found to affect populations of diadromous fish species more than potamodromous species (Gehrke et al. 2002; Rolls 2011). Three of the four native species recorded above the Bomaderry Creek weir are known for their ability to climb vertical obstacles such as waterfalls and the damp walls of dams and weirs: the potamodromous Cox's Gudgeon (Bishop and Bell 1978; Larson and Hoese 1996) and the diadromous Long-finned Eel (Bishop and Bell 1978) and Climbing Galaxias (McDowall and Fulton 1996; O'Connor and Koehn 1998).
[FIGURE 3 OMITTED]
The Bomaderry weir was occasionally overtopped during extremely high stream flows (Murphy pers. obs.) but was usually a barrier to fish movement. The weir was obsolete by the early 1970s and in 1998 (three years after this survey) a section was removed to restore natural stream flows (NSW Office of Environment and Heritage 2016) (Fig. 4). The decommissioning of the weir has provided opportunity for additional diadromous fish species such as Bullrout, Australian Bass and Striped Gudgeon to recolonise Bomaderry Creek above the weir. The information documented here provides a useful benchmark of the composition and distribution of the freshwater fish community of Bomaderry Creek in the mid-1990s when the weir was still in place, and will be of value in any future assessment of the catchment area's freshwater fish community.
[FIGURE 4 OMITTED]
This research was done under a scientific research permit issued by NSW Fisheries. Thanks to Sam Murphy for company in the field in 1994-1995 and 2016, Alan Lugg for inviting the author to accompany the Fisheries survey and allowing the results to be included in this paper, Terry Barratt for information from his plan of management, Garry Daly for access to his property at the headwaters of Tapitallee Creek and for information on the local status of Climbing Galaxias, Jess Murphy for help preparing Fig. 1 and an anonymous reviewer whose suggestions improved the paper.
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Barratt T (2015) Fish species in Bomaderry Creek Bushland. Available online at: www.friendsofbomaderrycreek.com.au/uploads/9/8/0/6/9806783/bomcrkpomapp6fish.pdf
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Received 1 December 2016; accepted 8 June 2017
Appendix 1. Survey dates for 1994-1995 Bomaderry Creek fish survey. 14 April1994 Sites 2, 3 08 September1994 Sites 5, 6 10 September1994 Sites 3, 5, 6, 7 14 September 994 Site 12 15 September1994 Sites 1, 4, 5, 6 03 June1995 Sites 8, 9, 10 11 June1995 Sites 5, 6, 7, 11 15 July 1995 Site 8 31 August1995 Sites 1, 4, 5, 6, 7 Appendix 2. Location of 1994-1995 survey sites. Sites are numbered by increasing distance from Shoalhaven River (see Fig. 1). 1 ZLions Park boat ramp, Bolong Rd, Bomaderry 2 ZSporting field, Bolong Rd, Bomaderry Z(shallowly inundated at time) 3 ZFrog Hollow wetland, Bolong Rd Bomaderry 4 ZMossy Gully, Bomaderry Creek Bushland 5 ZPool below weir, Bomaderry Creek Bushland 6 ZPool above weir, Bomaderry Creek Bushland 7 ZEnd of West Cambewarra Rd, ZBomaderry Creek Bushland 8 ZHockeys Lane crossing, Tapitallee Creek 9 ZMain Rd crossing, Good Dog Creek 10 Tapitallee Rd crossing, Tapitallee Creek 11 Browns Mountain Rd crossing, Tapitallee Creek 12 Private property on Flannery Rd, Tapitallee Creek 1 34[degrees] 51.42' S, 150[degrees] 36.46' E 2 34[degrees] 51.42' S, 150[degrees] 36.37' E 3 34[degrees] 51.55' S, 150[degrees] 36.08' E 4 34[degrees] 50.84' S, 150[degrees] 35.45' E 5 34[degrees] 50.70' S, 150[degrees] 35.38' E 6 34[degrees] 50.68' S, 150[degrees] 35.39' E 7 34[degrees] 50.49' S, 150[degrees] 35.24' E 8 34[degrees] 50.24' S, 150[degrees] 33.69' E 9 34[degrees] 49.40' S, 150[degrees] 33.71' E 10 34[degrees] 49.50' S, 150[degrees] 32.48' E 11 34[degrees] 49.39' S, 150[degrees] 31.34' E 12 34[degrees] 49.07' S, 150[degrees] 30.44' E Appendix 3. Freshwater species recorded at each of 12 sites in Bomaderry Creek catchment 1994-1995. Sites 1-5 were below the weir and sites 6-12 above the weir. Species Site number 1 2 3 4 5 6 7 8 9 10 11 12 Long-finned Eel x x x x x x Climbing Galaxias x Australian Smelt x x x x x x Eastern Gambusia x x x Bullrout x Australian Bass x Striped Mullet x Flat-tail Mullet x Cox's Gudgeon x x x x x x Striped Gudgeon x Total 3 1 1 2 4 3 4 4 1 2 1 1
Ninety Years Ago
EXCURSION TO FISH HATCHERIES
About 30 members and friends attended the excursion to the Fish Hatcheries--at Studley, Park, under the leadership of Mr. F. Lewis, Chief Inspector of Fisheries and Game, on the afternoon of Saturday, September 10th. After giving a short explanation of the methods of hatching the eggs of Rainbow and Brown Trout, Mr. Lewis conducted the party through one of the hatcheries, where the eggs of these fishes were in process of being hatched. The ova were in various stages of development. The leader showed us through another hatchery, where the most modern apparatus for the propagation of fish has been installed, with the object of hatching native fishes, such as Murray Cod, Perch, and Blackfish. Success, it is confidently expected, will be ultimately achieved. The ponds in which many of the more mature fishes are kept were inspected. A vote of thanks was tendered to Mr. Lewis.--L. L. HODGSON.
From The Victorian Naturalist XLIV p 169, October 5, 1927
Michael J Murphy
'Blackbird Grange', 2 Rundle Street, Coonabarabran, NSW 2357
Table 1. Freshwater fishes of the Bomaderry Creek catchment 1994-1995. (*) Introduced species. # Estuarine species extending into freshwater. Family Scientific name Common name Anguillidae Anguilla reinhardtii Long-finned Eel Galaxiidae Galaxias brevipinnis Climbing Galaxias Retropinnidae Retropinna semoni Australian Smelt Poeciliidae Gambusia holbrooki (*) Eastern Gambusia Scorpaenidae Notesthes robusta Bullrout Percichthyidae Macquaria Australian Bass novemaculeata Mugilidae Mugil cephalus # Striped Mullet Liza argentea # Flat-tail Mullet Eleotridae Gobiomorphus coxii Cox's Gudgeon Gobiomorphus Striped Gudgeon australis Family Local status Life history Anguillidae Common above and Diadromous uncommon below weir (Catadromous) Galaxiidae Rare above weir Diadromous (headwaters) (Amphidromous) Retropinnidae Common above and Potamodromous below weir Poeciliidae Uncommon above and Unspecified below weir Scorpaenidae Rare below weir (estuary) Diadromous (Catadromous) Percichthyidae Uncommon below weir Diadromous (Catadromous) Mugilidae Rare below weir (estuary) Diadromous (Catadromous) Rare below weir (estuary) Unspecified Eleotridae Common above and Potamodromous below weir Rare below weir Diadromous (Amphidromous)
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|Publication:||The Victorian Naturalist|
|Date:||Aug 1, 2017|
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