Snowy River priority native fish assessment D. Stoessel June 2014 Arthur Rylah Institute for Environmental Research Unpublished Client Report for East Gippsland Catchment Management Authority
Snowy River priority native fish assessment Daniel Stoessel Arthur Rylah Institute for Environmental Research 123 Brown Street, Heidelberg, Victoria 3084 June 2014 In partnership with: Arthur Rylah Institute for Environmental Research Department of Environment and Primary Industries Heidelberg, Victoria
Report produced by: Arthur Rylah Institute for Environmental Research Department of Environment and Primary Industries PO Box 137 Heidelberg, Victoria 3084 Phone (03) 9450 8600 Website: www.depi.vic.gov.au/ari State of Victoria, Department of Environment and Primary Industries 2014 This publication is copyright. Apart from fair dealing for the purposes of private study, research, criticism or review as permitted under the Copyright Act 1968, no part may be reproduced, copied, transmitted in any form or by any means (electronic, mechanical or graphic) without the prior written permission of the State of Victoria, Department of Environment and Primary Industries. All requests and enquiries should be directed to the Customer Service Centre, 136 186 or email customer.service@depi.vic.gov.au Citation: Stoessel, D. (2014) Snowy River priority native fish assessment. Arthur Rylah Institute for Environmental Research Unpublished Client Report for East Gippsland Catchment Management Authority, Department of Environment and Primary Industries, Heidelberg, Victoria Disclaimer: This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
Contents Acknowledgements... ii Summary... iii 1 Introduction... 1 2 Methods and materials... 3 2.1 Study area... 3 2.2 Fish surveys... 4 2.3 Processing... 5 2.4. Water parameters... 6 2.5 Data analysis... 6 3 Results... 6 3.1. Fish surveys... 6 3.2. Water parameters... 9 4 Discussion... 10 4.1. General... 10 4.2. Australian Grayling... 10 4.3. Australian bass... 10 5 Conclusion... 12 6 References... 13 7 Personal communication... 15 Appendix 1... 16 Appendix 2... 17 i
Acknowledgements I would like to thank the East Gippsland Catchment Management Authority (EGCMA) for funding the assessment. In addition, I would like to thank Graeme Dear, Bec Hemming and Ken Judd (all EGCMA) for supporting the programs implementation, Jarod Lyon and Tarmo Raadik for project guidance, Jason Lieschke for field assistance, Michael Nicol for field and mapping assistance, Peter Fairbrother for data entry and equipment management, and Joanne Kearns (all Arthur Rylah Institute) for reviewing the document. Surveys were conducted under Fisheries Victoria Permit No. RP827 and NP135, and Flora and Fauna Guarantee Permit No. 10006542. ii
Summary The 2006 Snowy River Native Fish Recovery Plan outlines the serious decline of fish populations of the Snowy River. In an attempt to halt the decline of the health of the catchment, plans to increase environmental flows back to the Snowy River were implemented in the early 2000s. In addition, considerable instream and riparian rehabilitation works have been conducted along the entire length of the Snowy River since 2002. Recovery of the Snowy River is therefore ongoing. Promisingly, the river continues to support a diverse range of native freshwater and estuarine fish species, some of which are listed as threatened at a national or state level, while others have considerable recreational importance. Two species in particular, the nationally threatened Australian grayling (Prototroctes maraena) and the iconic Australian bass (Macquaria novemaculeata) have been identified as important in the management of the Snowy River freshwater and estuarine reaches due to these species suspected of being impacted by modifications to flow. This project aimed to improve knowledge of the status of priority freshwater fish (Australian bass and grayling) in the Snowy River system. Outcomes, and data collected as part of the assessment, will add to that of a closely associated investigation as to effects of environmental flows on priority species. The survey reconfirmed that the Snowy River catchment supports a large and diverse range of native fish. A single Australian grayling was recorded in the survey. As such it appears likely, that resources and/or processes required for the completion of the life history of this species is currently limited. We suggest that recruitment may be improved if the mouth of the Snowy River is open for at least a portion of late spring to summer (a time when juvenile Australian grayling are recruiting). As little is known of the Snowy River Australian grayling population, the exact cause of the decline is difficult to discern. Current survey data suggests that multiple Australian bass cohorts may be present within the Snowy River system. It is unknown, however, as to what proportion of the bass population is the consequence of natural spawning or from recent stocking. Future work will aim to determine the proportion of stocked versus naturally recruited individuals within the population. If a proportion of individuals are from natural recruitment, the age of these fish will be used to determine under what historic flow conditions spawning and recruitment occurred. Genetic clips and otoliths collected as part of this project will be important for informing future research, and the provision of management advice regarding environmental flows delivered to the system for the benefit of priority species. iii
iv
1 Introduction The Snowy River Native Fish Recovery Plan outlines the serious decline of fish populations in the Snowy River (Lugg et al. 2006). This deterioration is attributed to the severe reduction in flows, and the contribution of other factors such as sedimentation from catchment erosion, the impact of competition and predation from alien species, disease and willow invasion (Lugg et al. 2006). In an attempt to halt the decline of the health of the catchment, plans to increase environmental flows to the Snowy River were implemented in the early 2000s (Musgrave 2008, Morton et al. 2010, DEPI 2013). It is only since 2011, however, that sufficient water allocations have been available (largely due to drought) to make large releases and hence initiate significant change in the condition of the Snowy River (EGCMA 2013). Nevertheless, considerable instream and riparian rehabilitation works have been conducted since 2002 along the entire length of the Snowy River, in NSW by the Southern Rivers Catchment Management Authority (SRCMA), and within Victoria by the East Gippsland Catchment Management Authority (EGCMA) in partnership with the Department of Environment and Primary Industries (DEPI) Victoria (Green 2009, DEPI 2013). Recovery of the Snowy River is therefore ongoing. Promisingly, the river continues to supports a diverse range of native freshwater and estuarine fish species (Fulton and Hall 2011, McCarraher 1986, Raadik 1992, Raadik 1995, Raadik and O Connor 1997, Raadik et al. 2001). Some of these species are listed as threatened at a national or state level, while others have considerable recreational importance (Backhouse et al. 2008, Brown 2009, Douglas 2011). Two species in particular, the nationally threatened Australian grayling (Prototroctes maraena) and the iconic Australian bass (Macquaria novemaculeata) have been identified as important by the EGCMA in the management of the Snowy River freshwater and estuarine reaches due to these species being suspected of being impacted by modifications to flows in the system. Intactness and connectivity of widely diverse habitats is of critical importance to the Australian grayling (Figure 1). The species breeds in the lower freshwater reaches of rivers (Amtstaetter et al. 2012, O'Connor et al. 2012, Koster et al. 2013). Once spawned, eggs sink and settle in the interstices of the substrate and hatch after 10 20 days (Backhouse et al. 2008). The larvae are swept to the sea (Berra 1982, Crook et al. 2006), where they remain for 6 10 months before returning to freshwater (Bishop and Bell 1978, Berra 1982). There are few recent records of the capture of Australian grayling within the Snowy River (see Stoessel et al. 2014). The status (population abundance and distribution) of the Snowy River Australian grayling populations therefore remains unknown. Australian bass life history is similarly complex. It is suggested in studies of a population in the Hawkesbury River in NSW, that the species breeds in the upper part of estuaries on sandbars and/or submerged aquatic plants, and larvae hatch 1 4 days later (Llewellyn and MacDonald 1980, van der Wal 1983, Harris 1985, van der Wal 1985, Harris 1986, Allen et al. 2003). Post hatching, migration of larvae and juveniles into freshwater likely occurs over several months (see Harris 1985). A conceptual model of the life history of the species is shown in Figure 2. Whilst Australian bass are often captured in the Snowy River, population abundance has declined dramatically. Although the cause of the decline is unknown, overfishing in addition to spawning, hatching, and/or migration failure due to alterations in flow, and subsequent effects on habitat suitability and availability may be responsible. This project aims to improve knowledge of the status of priority freshwater fish (Australian bass and grayling) in the Snowy River system. Data collected as part of this assessment will be used to 1
inform a closely associated investigation into the effects of environmental flows on priority species (see EGCMA 2013, Stoessel et al. 2014). Freshwater Estuary Sea Post-spawning migration Adult Spawning migration Larva Juvenile Figure 1. Conceptual model of the life history of Australian grayling (Koehn and Crook 2013). Freshwater Estuary Sea Adult female Post-spawning migration Spawning Spawning migration Larva Adult male Juvenile Figure 2. Conceptual model of the life history of Australian bass (Koehn and Crook 2013). 2
2 Methods and materials Study area The Snowy River is located in south-eastern Victoria (Figure 3). The river's headwaters are in southern New South Wales on the slopes of Australia s highest mountain, Mt Kosciuszko (Erskine et al. 1999). The river runs in an approximate southerly direction for 489 km, passing through mountainous terrain before flowing onto the Gippsland Plain and terminating into Bass Strait at Marlo in south-east Victoria (Erskine et al. 1999). In consultation with the EGCMA, 29 sites in the mid to lower reaches of the system were chosen for survey (Figure 3, Appendix 1). Figure 3. Location of potential survey sites within the Snowy River catchment. 3
2.2 Fish surveys A combination of survey methods were used at sites including backpack and boat mounted electrofishing, and fyke and mesh netting. Due to differing habitat complexity, flow, and size of the reach able to be accessed, the number and type of method employed was determined in the field to best suit conditions (Table 1). Where employed: 1. Fyke nets had single wings 8.9 m x 1.2 m, a first supporting hoop with a diameter of 0.5 m, and a stretched mesh size of 10 mm. Nets were randomly placed (at approximately 1.0 1.5 m depth), attached to a stake driven into the river bed (at least half a meter from the shore), set at an angle of a maximum of 45º (cod end upstream), had floats placed in all compartments, and were set late afternoon for a maximum overnight soak time of 12 hours; 2. Mesh netting a single fleet of mesh nets (25 m long by 2 m deep with square mesh sizes of 50, 62, 75, 87, 100, 112 mm, were set in water >2 m deep in close association with structure (logs, boulders etc.) just prior to dusk. Once set, nets were checked every 15 minutes and subsequently retrieved following nightfall; 3. Backpack electrofishing - a portable backpack electrofisher (Smith-Root Model 12), with standard braided wire cathode and 150 mm diameter anode, was operated at settings of 45 Hz and 150 to 250 V. Fishing was conducted in daylight hours, from just below the head of pools, working upstream into riffles; 4. Boat electrofishing due to differences in electrical conductivity (EC) from the upper to lower reaches of the catchment (which has implications for electrofishing survey efficiency), two types of boat electrofishers were employed. These were: a. A Smith-Root electrofishing boat, which is suited to EC 5500, was used upstream of Orbost at settings of 60 Hz and 200 to 250 V (Figure 3). The number of electrofishing seconds (a measure of effort) employed, was dependant on the size of the reach which could be accessed, and the complexity of habitat at each site. Sites at which larger stretches of river could be accessed, or which contained increasingly complex habitat, therefore had the most electro-fishing seconds (and therefore effort) employed. Fishing was conducted in daylight hours, from the most downstream point of a pool working upstream. All structure (rocks, timber, submerged and emergent aquatic macrophytes, woody debris) were targeted to within 50 m of the head of pools, at which point electrofishing was conducted in a zig-zag motion (from one side of the stream to the other), to herd Australian grayling into the shallower riffle area, where they were more easily captured; b. A Grassl electrofishing boat (which is designed to more effectively survey water with EC 5500) was employed downstream of Orbost (Figure 1). Due to the lack of obvious pools within this reach, effort was standardised at 1000 electrofishing seconds per site. Fishing was conducted in daylight hours from a downstream GPS coordinate, and working upstream targeting all structure (rocks, timber, submerged macrophytes, debris). Initial field assessment indicated that of the 29 potential sites, three (sites 16, 20 and 27; Figure 3; Appendix 1) could not be surveyed due to bushfire related track closures, non-contactable landowners, and/or limited boat access. Methods and date of survey for the remaining 26 sites are shown in Table 1. 4
Table 1. Methods, date and survey effort employed at survey sites. Survey method Site Date Backpack electrofishing (seconds) Boat electrofishing (seconds) Mesh net No. Soak set time (min) Fyke net No. Soak set time (min) 1 20/05/2014-1000 - - - - 2 20/05/2014-1000 - - - - 3 22/05/2014-1000 - - - - 4 21/05/2014-1000 - - - - 5 20/05/2014-1000 - - - - 6 21/05/2014 - - 6 150 - - 7 21/05/2014-1000 - - - - 8 20/05/2014-1000 - - - - 9 21/05/2014-1000 - - - - 10 19/05/2014-1000 - - - - 11 19/05/2014-1000 - - - - 12 22/05/2014-1000 - - - - 13 17/03/2014-920 - - - - 14 27/03/2014 - - 6 180 - - 15 23/03/2014 - - - - 6 1080 17 24/03/2014 - - - - 3 945 18 26/03/2014 - - 6 1020 6 300 19 07/04/2014-3795 - - - - 21 18/03/2014-936 - - - - 22 19/03/2014-1505 - - - - 23 25/03/2014 752 - - - - - 24 24/03/2014 730 - - - - - 25 24/03/2014 952 - - - - - 26 19/03/2014-1213 - - - - 28 20/03/2014-1022 - - - - 29 20/03/2014-1395 - - - - 2.3 Processing Upon capture, all fish were identified to species, measured for fork length (FL) to the nearest millimetre, and any external signs of disease (parasites, ulcers, wounds etc.) recorded. Putative Australian bass (i.e. those fish assumed to be Australian bass based on morphological attributes identified in the field) and Australian grayling in addition had weight recorded to the nearest gram, and a fin-clip (less than 5mm²) taken from the left pelvic fin using sharp, medical grade scissors (see Guy et al. 1996). Fin clips were placed into individually labelled vials containing 100% ethanol and placed into a portable fridge for future genetic analysis. In addition, sagittal otoliths from a subset of captured putative Australian bass were obtained using methods described by Secor et al. (1991). The sex of these individuals (i.e. as male, female or 5
unknown) and stomach contents were also examined. All remaining fish were released back to the site of capture. 2.4. Water parameters At each site, water parameters including electrical conductivity (EC standardized to 25 ºC µs.cm- 1), ph, dissolved oxygen (mg/l), turbidity (NTU) and temperature (ºC) were recorded in situ at a depth of 0.2 m below the water surface. 2.5 Data analysis Condition of putative Australian bass was determined according to Fulton (1904) using K= 100(W/L 3 ), where W = whole body weight in grams, and L = FL (in centimetres). 3 Results 3.1. Fish surveys A total of 2943 fish, representing 31 native and two introduced species were captured during surveys (Table 2, Appendix 2). Of the total species captured, six are classified as principle freshwater species, eight as diadromous and 19 as estuarine/marine species (Table 2). Native fish accounted by number for 98 % of the total catch. The most abundant species captured was Australian smelt Retropinna semoni (n=765), and the least (n=1) tiger flathead Platycephalus richardsoni, Australian anchovy Engraulis australis, Tailor Pomatomus saltatrix, serpent eel Ophisurus serpens and Australian grayling. The only Australian grayling measured 97 mm FL, and was recorded from site 25. The most common captured species was long-finned eel (recorded at 21 of the 26 sites surveyed). Considerable numbers of juvenile black bream Acanthopagrus butcheri, luderick Girella tricuspidata, and sand mullet Myxus elongates were captured and/or observed at sites 1 5, and 7 9 in the lower Snowy and Brodribb rivers. A total of 85 putative Australian bass were captured from 11 of the 26 sites surveyed (site 11 15, 19, 21, 22, 23, 28, and 29). Individuals ranged from 203 499 mm FL, with distinct peaks in length frequency at 270 mm, 320 mm, and 490 mm, and an absence of fish between 410 mm and 490 mm FL (Figure 4). Two bass captured at site 13 displayed stunting and deformities of the jaw (Figure 5), while an individual captured at site 15 had cloudy eyes and was in notably poor condition. Putative Australian bass found to be in the best condition were captured from site 21 (Figure 6), however, there was an overall trend of increasing condition of bass with distance upstream (Figure 6). Limited reproductive data derived from 23 individuals suggests that the proportion of female bass inhabiting sites increases with distance upstream. Stomach analysis indicated that the diet of Australian bass was likely to vary considerably, with fish from the same site found to have a diet composed entirely of terrestrial insects, while others fed exclusively on fish or aquatic insects. In addition, there was suggested differences in feeding type of Australian bass between sites, with five of 13 putative Australian bass (38 %) examined from site 14 having ingested fish, while no bass from sites 12 (n=3), 13 (n=13), and 22 (n=7) were found to have fish present in their stomachs. Overall, insects (caddis flies, small terrestrial beetles, and a dragonfly) were most commonly found in gut samples (79 % of individuals), followed by fish (common galaxias, goldfish; 16 %), and shrimp (7 %). In addition, one putative bass, captured at site 11, had the remnants of a soft plastic lure within its digestive track, while a total of 5 % of bass had guts which were empty. General observations of habitat availability suggests that a large sand slug exists upstream of Orbost (for a distance of approximately 16 km), while large woody debris is comparatively rare within much of the lower Snowy and Brodribb rivers. Where this habitat existed, however, large 6
bodied species such as Australian bass, estuary perch Macquaria colonorum, black bream and luderick were often found in considerable numbers in addition to smaller species such as the Tamar River goby, flat-headed gudgeon, tupong and Australian smelt. Table 2 Group classification of species captured. Groups: PF = principal freshwater species (inhabit freshwater for entire life cycle); D = diadromous species (migrate between fresh and saltwater for breeding); M = estuarine/marine species (usually found in marine or estuarine waters); * = alien species. Common name Scientific name Group Australian anchovy Engraulis australis M Australian bass Macquaria novemaculeata D Australian grayling Prototroctes maraena D Australian smelt Retropinna semoni PF Black bream Acanthopagrus butcheri M Bridled goby Arenigobius bifrenatus M Common galaxias Galaxias maculatus D Common silverbiddy Gerres subfasciatus M Cox's gudgeon Gobiomorphus coxii D Eastern fortescue Centropogon australis M Eastern gambusia* Gambusia holbrooki PF Estuary perch Macquaria colonorum M Flathead gudgeon Philypnodon grandiceps PF Flathead mullet Mugil cephalus M Glassgoby Gobiopterus semivestitus M Goldfish* Carassius auratus PF Gold-spot mullet Liza argentea M Large-mouth goby Redigobius macrostoma M Long-finned eel Anguilla reinhardtii D Luderick Girella tricuspidata M Port Jackson glassfish Ambassis jacksoniensis M Riffle shrimp Australatya striolata PF Sand mullet Myxus elongatus M Sand whiting Sillago ciliata M Serpent eel Ophisurus serpens M Short-finned eel Anguilla australis D Smallmouth hardyhead Atherinosoma microstoma M Striped gudgeon Gobiomorphus australis D Tailor Pomatomus saltatrix M Tamar River goby Afurcagobius tamarensis M Tiger flathead Platycephalus richardsoni M Tupong Pseudaphritis urvillii D Yelloweye mullet Aldrichetta forsteri M 7
Figure 4. Length frequency of captured Snowy River putative Australian bass. Figure 5. Putative Australian bass displaying stunting and a deformity of the upper jaw (site 13). Figure 6. Condition (diamonds) of putative Australian bass by site. 8
3.2. Water parameters On average, with increasing distance downstream, electrical conductivity and D.O. increased, while temperature decreased and ph remained relatively constant (Table 3). The higher than average turbidity readings at sites 9, 19 and 22 is most probably due to recent rains in the days just prior to sampling, which created localised areas of increased turbidity. Overall, water quality parameters were therefore within expected ranges for the catchment. Table 3. Electrical conductivity, temperature, D.O., ph and turbidity recorded by site. Site Electrical Temperature D.O. ph Turbidity conductivity (ºC) (mg/l) (NTU) (EC) 1 20600 10.9 10.7 7.6 5.0 2 22180 11.2 11.2 7.3 5.5 3 15500 9.8 9.16 6.7 3.0 4 11660 10.9 10.3 6.8 5.1 5 1436 10.6 17.1 7.5 5.0 6 2690 10.5 7.32 6.6 4.4 7 9650 10.8 7.15 7.1 5.0 8 888 8.3 12.5 7.6 5.0 9 8900 9.0 11.3 7.2 24.1 10 173 9.3 11.1 7.0 2.0 11 144 10.1 11.3 7.9 2.5 12 93.5 7.5 10.5 7.6 1.8 13 85 22.7 9.6 6.4 1.4 14 95.2 18.9 7.6 7.0 8.0 15 87 21.6 9.9 6.9 2.0 17 69 19.8 8.5 7.3 5.0 18 66 19.5 8.2 7.5 1.8 19 104 24.5 7.8 7.0 21.5 21 75 20.8 8.3 7.1 7.5 22 73.2 22.8 9.1 7.2 14.3 23 75 20.8 8.3 7.1 7.5 24 420 19.3 7.8 7.4 1.2 25 313 23.0 7.1 7.4 2.4 26 215 18.7 7.8 7 5.0 28 63 24.2 8.3 7.1 1.1 29 63 24.2 8.3 7.1 1.1 9
4 Discussion 4.1. General The survey reconfirms that the Snowy River catchment supports a large and diverse range of native fish, and a comparatively low number of alien species (see Lieschke et al. 2013). In addition, the capture of eight diadromous (Australian bass, Australian grayling, common galaxias, Cox s gudgeon, long-finned eel, short-finned eel, striped gudgeon and tupong), and juvenile estuarine/marine species (black bream, luderick, and mullet), indicates that suitable conditions and remnant habitat exist within the estuary to allow spawning and/or recruitment of a number of species. 4.2. Australian Grayling As only a single Australian grayling was recorded in the survey, resources and/or processes required for the completion of the life history of this species nevertheless, appear limited. As little data exists for the population, the reason for recruitment failure of this species is at present difficult to determine. Recent genetic analysis of four coastal river populations of Australian grayling, which spanned approximately one-quarter of the species continental range, indicates that genetics of populations is unstructured (Schmidt et al. 2011). Based on these data, the hypothesis that a single stock exists in coastal Victoria cannot be rejected (Schmidt et al. 2011). It is likely that gene flow among catchments mediated by dispersal of larvae and juveniles during the marine phase of the life cycle is responsible for this pattern (Schmidt et al. 2011). Consequently, there is no evidence to support a dispersal-limitation strategy that might develop if larvae and juveniles remained in close proximity to the natal river to minimize oceanic dispersal (Schmidt et al. 2011). Encouragingly, the research t indicates that the dispersal strategy of Australian grayling would enable recolonisation of rivers that experience localised extinction provided that connectivity between freshwater habitats and the sea is sufficient to permit migration and that enough source populations remain intact to support viability of the wider population (Schmidt et al. 2011). Ensuring that the mouth of the Snowy River is open for at least a portion of late spring to summer at a time when juveniles are recruiting to river systems (see Crook et al. 2006), may therefore allow bolstering and reestablishment of the Snowy River Australian grayling population. 4.3. Australian bass Length frequency data for Australian bass preliminarily suggests that at least three cohorts may be present, with distinct peaks at 270 mm, 320 mm, and 490 mm. Of note, was the lack of individuals captured between 410 mm and 490 mm. Future investigation as to the age frequency of individuals (derived from a portion of captured Australian bass in this study), and historic flow data may highlight possible drivers of length frequencies observed here. Based on preliminary work conducted by Douglas (2011), the results nevertheless, indicate that captured bass range from ~2 to at least 10 years of age (Figure 7). As stocking of Australian bass has occurred annually in NSW in 2007, 2008, 2009, 2010 and 2013, and in Victoria in 2008 and 2009 (Cameron et al. 2012, Ben Doolan pers. comm. 2014, Graeme Dear pers. comm. 2014, NSW Fisheries unpub. data 2014), only the largest fish captured (i.e. 490 mm) can with some certainty, be considered to have been spawned and recruited in the wild. Regardless, extrapolation of the likely age of captured individuals (based on length frequency data), suggests that additional cohorts to that stocked may exist in the Snowy River. Additional work is, however, required to determine if captured Australian bass are the result of stocking or natural recruitment, and if correlations exist between cohort strength and river 10
conditions. This work is to be undertaken in the coming months as part of the environmental flow monitoring and investigation project (see Stoessel and Arrowsmith 2014). Data presented here regarding the presence of cohorts and age of individuals captured, should therefore only be considered preliminary. Figure 7. Length at age relationship for Snowy River Australian bass (diamonds) and Australian bass/estuary perch hybrids (squares) (Douglas 2011). Investigations of the diet of the lower Snowy River Australian bass population indicates insects (particularly terrestrial) are the primary prey item for the species. Diet, however, differed considerably between individuals and locations, indicating bass are a euryphagic carnivore which exploits a wide range of animal prey. These findings are in agreement with that of Harris (1985) for a population in the Hawkesbury River in NSW. As land-use practices influence the input of terrestrial invertebrates (Edwards and Huryn 1996), the results highlight the importance of maintaining and rehabilitating riparian zones (as is occurring in the Snowy River catchment) to support the ecology of streams. The results should, however, be considered a snap-shot of the diversity of prey consumed annually given that seasonal feeding patterns have been documented elsewhere in populations (Harris 1985). As with a study on the Hawkesbury Australian bass population in NSW (Harris 1987), there appears to be partial segregation of the sexes within the catchment, with most male Australian bass remaining in estuarine or lowland habitats, while females predominate with increasing distance upstream. The data in addition follows the model of larger (and better conditioned) bass being present at more upstream sites, which is an adaptation to the energy requirements of migration (Harris 1983). As a large portion of females exist upstream, the finding highlights the importance of protecting and enhancing existing critical habitat in the upper reaches to ensure continuation of the Australian bass population. Despite habitat within the upper reaches of the catchment generally observed to be in good condition (likely due to the inaccessibility of much of the region) the lower reaches had considerable amounts of sedimentation present (in the form of a sand-slug) and a notable lack of large woody complex habitat, the latter as a result of extensive desnagging in the 1930 s (Strom 1951, Strom 1962). According to a limited study on the movement of 11 putative adult Australian bass (Brown 2009), the sand-slug does not act as a barrier to migration and movement of adults. However, as the reach offers little refuge in the form of woody debris, and beds of aquatic macrophytes, juvenile Australian bass may be exposed to increased predation (Brown 2009). 11
Woody habitat is not only used by Australian bass, but many species inhabiting (either permanently or temporarily) the lower reaches of the system. It is likely that the lack of this habitat may be affecting not only the carrying capacity of the lower reaches of these rivers, but also the completion of critical life-history stages of diadromous fish species which at times use such habitat as refuge during migration. Catchment recovery efforts, which have involved extensive replanting of riparian timber, will undoubtedly improve the availability of this habitat overtime (as trees fall into the river), however, due to the slow rate of occurrence, change is likely to occur over decades, rather than years. 5 Conclusion This survey reconfirms that Australian grayling are rare within the Snowy River catchment, however, the capture of a juvenile of the species indicates that recruitment (although limited) is occurring. Such recruitment may be improved if the mouth of the Snowy River is open for at least a portion of late spring to summer at a time when juvenile Australian grayling are recruiting. Alternatively, data suggests that multiple Australian bass cohorts may be present. It is unknown, however, as to what proportion of the population are the result of natural spawning or recent stocking. Future work (to be conducted as part of the Environmental Flow Monitoring and Investigation Project) will aim to determine the source of these individuals (i.e. stocked or naturally recruited). If a proportion of individuals are found to be resultant from natural spawning, the subsequent age of these fish will be used to determine under what flow conditions spawning and recruitment occurred. Genetic clips and otoliths collected as part of this project will therefore be instrumental in the provision of management advice regarding environmental flows delivery to the system. 12
6 References Allen, G.R., Midgley, S.H. and Allen, M. (2003). Field guide to the Freshwater Fishes of Australia, revised edition. CSIRO publishing, Collingwood, Australia. Amtstaetter, F., O Connor, J. and Pickworth, A. (2012). Thomson and Macalister rivers environmental flows monitoring and assessment program: 2012 survey results and migration of Australian grayling (Prototroctes maraena). Arthur Rylah Institute for Environmental Research. Department of Sustainability and Environment, Heidelberg, Victoria. Backhouse, G. Jackson, J. and O Conner, J. (2008). National Recovery Plan for the Australian grayling Prototroctes maraena. Department of Sustainability and Environment, Melbourne. Berra, T.M. (1982). Life history of the Australian Grayling, Prototroctes maraena (Salmoniformes: Prototroctidae) in the Tambo River, Victoria. Copeia 1982: 795 805. Bishop, K.A. and Bell, J.D. (1978). Aspects of the biology of the Australian grayling Prototroctes maraena Günther (Pisces: Prototroctidae). Australian Journal of Marine and Freshwater Research 29: 743-761. Brown, P. (2009). Australian bass movement and migration in the Snowy River. Recreational Fishing Grant Program - Research report. Department of Primary Industries, Victoria. Cameron, L., Baumgartner, L. and Miners, B. (2012). Assessment of Australian bass restocking in the Snowy River. Fisheries Final Report Series ISSN 1837-2112. New South Wales Department of Primary Industries, Cronulla, NSW. Crook, D.A., Macdonald, J.I., O Connor, J.P. and Barry, B. (2006). Use of otolith chemistry to examine patterns of diadromy in the threatened Australian grayling Prototroctes maraena. Journal of Fish Biology 69: 1330 1344. DEPI (2013). Rehabilitation of the Snowy River in Victoria: a ten year program - Draft. Department of Environment and Primary Industries Victoria, Melbourne. Douglas, J. (2011). Growth of Australian bass in the Snowy River. In: Freshwater fish resources in the Snowy River. (Eds. W. Fulton and K. Hall) pp 49 56. Fisheries Victoria Research Report Series No.25, Department of Primary Industries, Melbourne. Edwards, E.D. and Huryn, A.D. (1996). Effect of riparian land use on contributions of terrestrial invertebrates to streams. Hydrobiologia 337(1 3): 151 159. EGCMA (2013). Victorian Snowy River environmental flow monitoring and investigation program 2013/14 2015/16. East Gippsland Catchment Management Authority, Bairnsdale. Erskine, W.D., Terrazzolo, N. and Warner, R.F. (1999). River rehabilitation from the hydrogeomorphic impacts of a large hydro-electric power project: Snowy River, Australia. Regulated Rivers: Research and Management 15: 3 24. Fulton, W. and Hall, K. (eds.) (2011). Freshwater fish resources of the Snowy River, Victoria. Fisheries Victoria Research Report Series No. 25. Department of Primary Industries, Victoria. Fulton, T.W. (1904) The rate of growth of fishes. Twenty-second Annual Report, Part III. Fisheries Board of Scotland, Edinburgh, pp. 141 241. Green, D. (2009). The Snowy River rehabilitation project. Final report to New South Wales Environmental Trust. Southern Rivers Catchment Management Authority, Cooma. 13
Guy, C., Blankenship, H. and Neilsen, L. (1996). Tagging and Marking. Pp 353-384 In Murphy, B.W. and D.W. Willis (eds.) Fisheries techniques - 2nd edition. American Fisheries Society, Bethesda, USA. Harris, J.H. (1983). The Australian bass Macquaria novemaculeata. Doctor of Philosophy Thesis, University of New South Wales, Sydney. Harris, J.H. (1985). Diet of the Australian bass Macquaria novemaculeata (Perciformes: Percichthyidae), in the Sydney Basin. Australian Journal of Marine and Freshwater Research 36: 219 234. Harris, J.H. (1986). Reproduction of the Australian bass, Macquaria novemaculeata (Perciformes: Percichthyidae) in the Sydney Basin. Australian Journal of Marine and Freshwater Research 37: 209 235. Harris, J.H. (1987). Demography of Australian bass Macquaria novemaculeata (Perciformes: Percichthyidae) in the Sydney Basin. Australian Journal of Marine and Freshwater Research 39: 355 369. Koehn, J.D. and Crook, D.A. (2013). Movements and migration In: Humphries, P. and Walker, K. (eds.), Ecology of Australian Freshwater Fishes. Collingwood: CSIRO, pp. 105-130. Koster, W., Dawson, D. and Crook, D. (2013). Downstream spawning migration by the amphidromous Australian grayling (Prototroctes maraena) in a coastal river in south eastern Australia. Marine and Freshwater Research 64: 31 4. Lieschke, J.A., Dodd, L., Stoessel, D., A., Raadik, T., Steelcable A., Kitchingman, A. and Ramsey, D. (2013). The status of fish populations in Victorian rivers 2004 2011 Part A. Arthur Rylah Institute for Environmental Research Technical Report Series No. 246. Department of Sustainability and Environment, Heidelberg, Victoria. Llewellyn, L.C. and MacDonald, C.M. (1980). Family Percichthyidae: Australian freshwater basses and cods. Pp.142 149 In: MacDonald, R.M. (ed.), Freshwater fishes of south-eastern Australia. Reed, Sydney. Lugg, A., Harris, J. and Fredrickson, J. (2006). Snowy River native fish recovery plan. New South Wales Department of Primary Industries, Sydney. McCarraher, D.B. (1986). Distribution and abundance of sport fish populations in selected Victorian estuaries, inlets, coastal streams and lakes. 1. Orbost region. Arthur Rylah Institute for Environmental Research Technical Report Series No. 43, Department of Conservation, Forests and Lands, Victoria. Morton, S., Green, D. and Williams, S. (2010). Hydrological changes attributed to environmental flow release to the Snowy River, 2002-2005. Snowy River Recovery: Snowy flow response monitoring and modelling, NSW Office of Water, Sydney. Musgrave, W. (2008). Historical development of water resources in Australia: Irrigation in the Murray-Darling Basin. Pp. 28 43 In: Crase, L. (ed) Water Policy in Australia: the impact of change and uncertainty. Resources for the Future Press, Washington. O'Connor, J., Raymond, S. and Dodd, L. (2012). Offsets for Conservation of the EPBC Act-listed Australian Grayling, Prototroctes maraena. Arthur Rylah Institute for Environmental Research Technical Report Series No. 233. Department of Sustainability and Environment, Heidelberg, Victoria. 14
Raadik, T. (1992). Aquatic fauna of east Gippsland: fish and macroinvertebrates. VSP Technical Report no. 16. Freshwater Ecology Branch, Flora and Fauna Division, Department of Conservation and Environment, Heidelberg, Victoria. Raadik, T. (1995). An assessment of the significance of the fishes and freshwater decapods in three areas of east Gippsland. Flora and Fauna Technical Report no. 140. Department of Conservation and Natural Resources, Melbourne. Raadik, T.A. and O Connor, J.P. (1997). Fish and decapod crustacean survey, and habitat assessment of the lower Snowy River, Victoria. Freshwater Ecology Division, Marine and Freshwater Resources Institute, Heidelberg. Raadik, T. A., Close, P. G. and Conallin, A. J. (2001). Lower Snowy River fish recruitment study 2000/2001: pilot project report. Report to the Department of Land and Water Conservation. Arthur Rylah Institute for Environmental Research, Heidelberg, Victoria. Schmidt, D.J., Crook, D.A., O Connor, J.P. and Hughes, J.M. (2011). Genetic analysis of threatened Australian grayling Prototroctes maraena suggests recruitment to coastal rivers from an unstructured marine larval source population. Journal of Fish Biology 78, 98 111. Secor, D. H., Dean, J. H., and Laban, E. H. (1991). Manual for otolith removal and preparation for microstructural examination. Electric Power Research Institute and Belle W. Baruch Institute for Marine Biology and Coastal Research, Columbia, SC. Stoessel, D., Arrowsmith, C., Hinwood, J., Raadik, T. and Lyon, J. (2014). Snowy River environmental flow monitoring design plan. Arthur Rylah Institute for Environmental Research Unpublished Client Report for East Gippsland Catchment Management Authority, Department of Environment and Primary Industries, Heidelberg, Victoria. Stoessel, D. and Arrowsmith, C. (2014) Snowy River environmental flow monitoring and investigation project: implementation plan. Arthur Rylah Institute for Environmental Research Unpublished Client Report for the East Gippsland Catchment Management Authority, Department of Environment and Primary Industries, Heidelberg, Victoria Strom, H.G. (1951). River improvement in Victoria. Journal of Institution of Engineers Australia 23: 129 139. Strom, H.G. (1962). River Improvement and Drainage in Australia and New Zealand. State Rivers and Water Supply Commission, Victoria, Melbourne. van der Wal, E. J. (1983). NSW bass breeding program well established. Australian Fisheries 42(12): 21 3. 7 Personal communication Doolan, B., Department of Primary Industries, Port Stephens, New South Wales. Dear, G., East Gippsland Catchment Management Authority, Bairnsdale, Victoria. 15
Appendix 1 Site Waterbody Site description Latitude Longitude 1 Snowy River 1st and 2nd Islands -37.78652 148.50948 2 Lake Corringle Mouth to 500 m along northern shore -37.78014 148.50243 3 Brodribb River From 1 km above junction to Brodribb Boat -37.77850 148.52560 Ramp 4 Brodribb River 3-4 kms downstream of Lake Curlip -37.77922 148.55365 5 Snowy River 400 m upstream of junction with Brodribb -37.77316 148.51627 River to junction with Little Snowy River 6 Cabbage Tree 2nd lagoon, upstream of bridge on Healeys -37.76894 148.60077 Creek Road 7 Brodribb River 1-2 kms downstream of Lake Curlip -37.76671 148.57051 8 Snowy River 1-2 km downstream from Lochend boat ramp -37.76284 148.53835 9 Lake Curlip Lake Curlip mouth to Brodribb Cut -37.75352 148.57272 10 Snowy River Boat ramp at Lochend to 1 km upstream -37.75264 148.52020 11 Snowy River Mid-point between Lochend boat ramp and bridge on Princess Highway -37.73109 148.50414 12 Brodribb Channel 300 m downstream to 200 m upstream of bridge on Sandy Flat Road -37.72894 148.54517 13 Snowy River 750 m section behind the Butter Factory -37.70884 148.44987 14 Brodribb River 1 km upstream of Princess Highway Bridge -37.69644 148.56978 15 Snowy River Behind tennis courts, Bete Belong -37.69978 148.39616 16 Snowy River Woods point -37.64185 148.32106 17 Snowy River At end of Long Point Track -37.60460 148.34680 18 Snowy River At end of Sandy Point Track -37.58884 148.34947 19 Snowy River At end of Jonkers Road -37.55017 148.29110 20 Snowy River Downstream of Buchan River junction -37.54936 148.29056 21 Snowy River From ford on private property on Westlea -37.50993 148.26951 22 Snowy River 420 m section on private property on -37.51450 148.26337 Westlea Road (formerly Dargans Road) 23 Snowy River 800 m section on private property on -37.50993 148.26951 Westlea Road (formerly Dargans Road) 24 Buchan River Orbost/Buchan Road Bridge to 300 m -37.50607 148.22243 downstream 25 Buchan River 300 m downstream of Lanes Road Bridge to -37.50232 148.20306 100 m upstream 26 Buchan River 470 m upstream of Buchan Caves to bridge -37.49009 148.16888 27 Snowy River At end of West Track -37.44173 148.30607 28 Snowy River From ford on Jacksons Crossing to 530 m -37.39385 148.33420 downstream 29 Snowy River From ford on Jacksons Crossing to 640 m upstream -37.39385 148.33420 16
Appendix 2 Table 4. Species captured by site. Site Common name Australian anchovy Australian bass Australian grayling Australian smelt Black bream Bridled goby Common galaxias Common silverbiddy Cox's gudgeon Dwarf flathead gudgeon Scientific name Engraulis australis Macquaria novemaculeata Prototroctes maraena Retropinna semoni Acanthopagrus butcheri Arenigobius bifrenatus Galaxias maculatus Gerres subfasciatus Gobiomorphus coxii Philypnodon macrostomus 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 17 18 19 21 22 23 24 25 26 28 29 Total 1 1 1 3 29 13 1 14 2 7 5 4 6 85 1 1 1 1 170 9 21 8 106 101 10 70 9 28 28 6 56 70 694 17 31 11 9 5 1 7 4 16 1 1 3 106 19 4 9 1 33 4 2 8 41 12 7 409 42 55 120 23 10 7 8 11 6 765 2 2 1 1 1 1 * = alien species. 17
Table 4. Cont d Site Common name Eastern fortescue Eastern gambusia Estuary perch Scientific name Centropogon australis Gambusia holbrooki Macquaria colonorum 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 17 18 19 21 22 23 24 25 26 28 29 Total 2 1 3 1 6 7 9 25 27 1 1 2 65 Flathead gudgeon Flathead mullet Philypnodon grandiceps Glassgoby Gobiopterus semivestitus Goldfish Gold-spot mullet Largemouth goby Longfinned eel Luderick Port Jackson glassfish 17 4 14 5 12 25 52 12 1 8 7 3 160 Mugil cephalus 1 5 2 2 10 Carassius auratus 33 4 1 38 1 22 1 27 4 2 57 Liza argentea 10 10 6 1 27 Redigobius macrostoma Anguilla reinhardtii Girella tricuspidata Ambassis jacksoniensis 2 2 5 7 11 21 7 6 5 6 50 4 5 3 15 43 18 3 17 25 44 7 6 308 13 9 61 18 9 14 3 9 1 2 2 141 2 2 Riffle shrimp Australatya striolata * = alien species. 4 4 18
Table 4. Cont d Site Common name Sand mullet Sand whiting Scientific name Myxus elongatus Serpent eel Ophisurus serpens Shortfinned eel Smallmouth hardyhead Striped gudgeon Tailor Tamar River goby Tiger flathead Tupong Yelloweye mullet 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 17 18 19 21 22 23 24 25 26 28 29 Total 11 10 5 5 31 Sillago ciliata 3 3 Anguilla australis Atherinosoma microstoma Gobiomorphus australis Pomatomus saltatrix Afurcagobius tamarensis Platycephalus richardsoni Pseudaphritis urvillii Aldrichetta forsteri * = alien species. 1 1 1 1 2 1 3 4 1 1 2 1 2 1 1 4 1 3 17 1 1 27 17 63 19 11 51 36 27 5 256 1 1 1 7 1 1 15 5 5 2 2 4 1 18 7 10 1 4 84 10 2 6 11 1 30 19
1