Creating a new fishery for south‐western

Part 1: Assessment of the suitability of five lakes for stocking with perch

Paul Hamer and Camille White

April 2013 Fisheries Victoria Department of Primary Industries

If you would like to receive this Author Contact Details: Paul Hamer information/publication in an Fisheries Management & Science Branch, accessible format (such as large Fisheries Victoria print or audio) please call the PO Box 114, Queenscliff Victoria 3225 Customer Service Centre on: Authorised by the Victorian Government, 136 186, National Relay Service/ 2a Bellarine Hwy, Queenscliff, Victoria 3225 TTY: 133 677, or email Printed by DPI Queenscliff, Victoria [email protected] Published by the Department of Primary Industries. Copyright  The State of Victoria, Department of Primary Industries, 2013. Copies are available from the website: www.dpi.vic.gov.au/fishing This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968. General disclaimer This publication may be of assistance to you but Preferred way to cite: the State of Victoria and its employees do not Hamer, P., White, C. (2013) Creating a new guarantee that the publication is without flaw of fishery for south‐western Victoria. Part 1: any kind or is wholly appropriate for your Assessment of the suitability of five lakes for particular purposes and therefore disclaims all stocking with estuary perch. Fisheries Victoria liability for any error, loss or other consequence Technical Report No. 174, 25 pages. Department which may arise from you relying on any of Primary Industries, Queenscliff, Victoria, information in this publication. Australia.

ISSN 1835‐4785

ISBN 978‐1‐74326‐273‐x3

Suitability assessment of western Victorian lakes for stocking with estuary perch ii

Executive Summary

To date, salmonids have been the primary option and access. While all lakes possessed some for stocking of fish for recreational fishing desirable features for a trial stocking of estuary purposes in lakes of south‐western Victoria. A perch, three lakes: Hamilton, Struan and Beaufort number of lakes in this region are, however, not were selected after review of the rapid well suited to salmonid stocking due to water assessment by the FV/stakeholder reference chemistry, temperature and salinity issues. group to progress to development of a formal Estuary perch, Macquaria colonorum, is potentially stocking plan. Lake Bridgewater was rejected due an ideal candidate species for stocking western to the presence of a ‘listed’ fish species (Yarra Victorian lakes because it is native to Victoria, pygmy perch) and Lake Rosine was deferred for tolerates a range of salinities and temperatures, future considerations due to a lack of larger prey, has diverse and flexible diet and is a highly and the current absence of suitable public access. prized recreational fishing species with excellent Lake Hamilton was previously stocked with 1000 eating qualities. estuary perch in 1999. Notably, a large (47 cm The suitability of five western Victorian lakes total length, 13 years age) estuary perch was was assessed for trial stocking of estuary perch. captured in Lake Hamilton during the current The five lakes: Beaufort, Struan, Rosine, sampling, indicating that the species can cope Hamilton and Bridgewater were selected after an with the long‐term environmental variation of initial review of 16 western Victorian lakes by FV this lake. Lake Struan has never been stocked project officers, scientists and a stakeholder with estuary perch or any other fish, but had an reference group. The five candidate lakes were abundance of small invertebrate and fish (i.e. visited in April 2012 and underwent a rapid common jolly tail, Galaxias maculatus) prey and assessment of water quality, predator, competitor no evidence of predator species. Lake Beaufort and prey communities, as well as accessibility, has been previously stocked with trout, with infrastructure and general environmental/habitat variable success, and had a variety of prey features. species, along with an abundant population of red fin perch (a large proportion less than 10 cm Water quality, although variable across the five length). lakes, was generally acceptable in all lakes, with ideal salinities of 2‐5 ppt in Lakes Struan and The ecological and environmental variation Hamilton. The lakes varied considerably in their across the three chosen lakes will provide a predator, competitor and prey communities and valuable contrast for the trial program of estuary the availability of in‐water habitat, infrastructure perch stocking in western Victoria.

Suitability assessment of western Victorian lakes for stocking with estuary perch v

Table of Contents

Executive Summary ...... v

Introduction ...... 1 Estuary perch ‐ background ...... 1 Overviews of candidate lakes ...... 3 Lake Beaufort ...... 3 Lake Struan ...... 5 Lake Rosine ...... 6 Lake Bridgewater ...... 7 Lake Hamilton ...... 8

Material and Methods ...... 10 Water quality assessment ...... 10 Fish community assessment ...... 10 Invertebrate prey ...... 10

Results and Discussion ...... 11 Water quality ...... 11 Fish communities ...... 14 Invertebrate prey ...... 17

Summary and recommendations ...... 19 Final stakeholder workshop and recommendations ...... 20

Acknowledgments ...... 22

References ...... 23

Appendix 1 ...... 25

Suitability assessment of western Victorian lakes for stocking with estuary perch vi

List of Tables Table 1. Summary of water quality parameter data collected at five western Victorian lakes in April 2012...... 13 Table 2. Summary of fish species detected by different methods and their relative abundance at five western Victorian lakes. (MN = mesh net, S = seine, BT = bait trap)...... 16 Table 3. Size composition summary for potential predator and recreational interest species sampled...... 17 Table 4. Suitability assessment scores for the five western Victorian lakes informed by rapid on‐site assessments...... 21

List of Figures

Figure 1. Estuary perch, Macquaria colonorum ...... 2 Figure 2. Map of western Victorian showing locations of the five candidate lakes...... 2 Figure 3. Aerial view of Lake Beaufort with sampling areas indicated by blue dots and boat launching sites by white arrows...... 3 Figure 4. Images of Lake Beaufort, April 2012. a) south western shoreline swimming area, b) eastern shoreline fringing rushes, c) western shore boat ramp within caravan park, d) view to rock wall at northern end of lake, e) view of western shoreline and caravan park, f) fishing and jetty in south western corner...... 4 Figure 5. Aerial view of Lake Struan with sampling sites indicated by blue dots and access point by white arrow...... 5 Figure 6. Images of Lake Struan. a) boat launching area, b) view north from Lower Darlington Rd. c) Lower Darlington Rd access point...... 6 Figure 7. Aerial view of Lake Rosine with sampling sites indicated by blue dots and access point used for the sampling, white arrow...... 6 Figure 8. Images of Lake Rosine. a) sorting of seine net sample at south‐western end, b) north eastern shoreline, c) boat launching site...... 7 Figure 9. Aerial view of the Bridgewater Lakes, blue dots indicate sampling areas, white arrow indicates boat launching site...... 8 Figure 10. Images of Lake Bridgewater. a) shoreline with fringing reeds, b) view down lake with water skiers, c) sorting seine catch...... 8 Figure 11. Aerial view of Lake Hamilton, blue dots indicate sampling sites, white arrow boat ramp and yellow arrow location of capture of a large estuary perch...... 9 Figure 12. Images of Lake Hamilton (right): a) mesh sampling at the north eastern end near entrance of the Grange Burn Creek, b) view of lake central region, c) sorting seine net sample...... 9 Figure 13. Lake Beaufort: large 35 cm TL (top) and small 10 cm TL (bottom) red fin perch ...... 14 Figure 14. Lake Struan: galaxids (common jollytail) in seine net...... 14 Figure 15. Lake Bridgewater: seine net sample, small mouth hardy head and Australian smelt...... 15 Figure 16. Lake Hamilton: large (47cm, 13 year old) estuary perch sampled by mesh net, 12/04/2012...... 15 Figure 17. Lake Struan: a) siene net with ostracods and gastropods, b) scoop net sample with masses of copepods...... 17 Figure 18. Lake Rosine: siene net with water boatman and amphipods ...... 18

Suitability assessment of western Victorian lakes for stocking with estuary perch vii

Introduction

To date, salmonids have been the primary  Food sources option for stocking of fish for recreational  Predators and competitors fishing purposes in lakes of south‐western Victoria. A number of lakes in this region are,  Local environment and habitat features however, not well suited to salmonid stocking  due to water chemistry, temperature and Access and management arrangements. salinity issues. Estuary perch ‐ background Estuary perch, Macquaria colonorum (Fig. 1), is Estuary perch is distributed from northern NSW potentially an ideal candidate species for to the mouth in , stocking western Victorian lakes because it is and northern (Allen et al., 2002). The native to Victoria, tolerates a range of salinities species is widely distributed in coastal rivers and temperatures, has diverse and flexible diet and in eastern and western Victoria and is a highly prized recreational fishing (Gomon et al., 2008) and can grow to at least 60 species with excellent eating qualities. cm in length and reach 40 years of age (Kirwin, This project has two parts that will contribute to 2000; Gomon et al., 2008; Walsh et al., 2010a). the overall objective of creating new stocking‐ Although the species is long‐lived, individuals based estuary perch fisheries in selected south‐ are more commonly captured up to the age of western Victorian lakes that are not well suited 15 years by which time they are typically 40‐50 to trout. This report deals with Part 1, which has cm in length and at least 2 kg in weight (Walsh the key objective of: et al., 2010a; Kent et al., 2011). Estuary perch reach sexual maturity at 3‐4 years of age and  Identification and evaluation of suitable approximately 22‐25 cm length (Walsh et al., locations for stocking estuary perch in south‐ 2010b). western Victorian lakes. Estuary perch are most commonly found in There is a need to undertake initial assessments estuarine environments, typically in the upper of candidate waters to determine their suitability more brackish reaches of estuaries, but can occur for stocking. Five candidate waters were initially in salinities ranging from fully marine to fully short‐listed through a workshop involving freshwater (Allen, 1989; Koehn and OʹConnor Fisheries Victoria and a stakeholder reference 1990; McDowall, 1996; Howell et al., 2004; group in April 2012. This workshop considered Douglas, 2010). Adult fish migrate to the lower the potential suitability of 16 lakes based on reaches of estuaries to spawn in the late winter eight features: water quality, water security, and spring when water temperatures range size, accessibility, competition with other between 14‐19°C (Allen, 1989; Koehn and species, in‐lake habitat, infrastructure and OʹConnor, 1990; Douglas, 2010; Walsh et al., salinity, see Appendix 1. 2010b). Structured habitats such as snags, rocks From the initial set of 16 lakes the following five and reed beds provide important habitat for lakes were chosen as candidates for stocking estuary perch with spawning reported to occur and were subject to additional on‐site suitability over aquatic vegetation and/or rocky habitat assessments (Fig. 2): (McCarraher and McKenzie, 1986; Douglas, 2010; van der Muelen et al. 2011). The ability of  Lake Beaufort estuary perch to breed successfully without  Lake Struan access to the estuarine/marine environment (i.e. in lakes) is unclear, but would seem highly  Lake Rosine unlikely.  Lake Bridgewater Estuary perch have a broad and flexible diet  Hamilton Lake. often dominated by shrimps, prawns, and fish, but also including other such as This report describes the assessment of each of crabs, bivalve molluscs, worms and insect larvae the five candidate lakes in relation to: (McCarraher and McKenzie, 1986; Howell et al.,  Suitability of water quality 2004). A study in the Hopkins River, south‐

Suitability assessment of western Victorian lakes for stocking with estuary perch 1

western Victoria indicated that diet composition freshwater locations within the Hopkins River varied between freshwater and estuarine (Howell et al., 2004). locations, with length of fish, and across seasons, The wide salinity tolerance and ability of estuary indicating the flexibility of the species to perch to respond opportunistically to different respond to variable prey fields and availability prey communities suggest it is a highly suitable (Howell et al., 2004). Interestingly, glass shrimp candidate for a stocking in a range of aquatic (Parataya australiensis) was the major prey item environments. in estuarine locations where as caddis fly larvae (Trichoptera) were a dominant prey item for

Figure 1. Estuary perch, Macquaria colonorum

Lake Hamilton Lake Beaufort

Lake Struan Lake Rosine

Lake Bridgewater

Figure 2. Map of western Victorian showing locations of the five candidate lakes.

Suitability assessment of western Victorian lakes for stocking with estuary perch 2

common catch is currently red fin perch, many of Overviews of candidate lakes which are reported to be very small. Water hens and cormorants are common around the lake. Lake Beaufort Access Local environment and habitat Lake Beaufort has good access, with two public Lake Beaufort (Fig. 3) is a small lake access boat ramps (one is unsealed) and a boat approximately 500 m long and 340 m wide ramp within the adjacent caravan park (Fig. 3). (approx. 4 ha. and 172 ML. capacity), situated on There are good facilities (e.g. public toilets and the outskirts of the town of Beaufort, information) close to the main boat ramp in the approximately 30 km west of Ballarat (Fig. 2). north‐western corner of the lake. Public usage is The lake is relatively shallow with most of the predominantly for fishing and water skiing, and lake area not exceeding approximately 2 m there are limits to the number of water ski vessel depth. There is a deeper hole (approximately 3 m permitted on the lake at any one time. depth) at the northern end of the lake adjacent to Management the outflow pipe. The major inflow is a small Lake Beaufort is surrounded by public land and stream originating from a forest/marshland area is a local recreational camping and fishing at the southern end of the lake. There is a rock attraction. There is a caravan park and recreation weir built along the northern end of the lake. reserve on the south‐western shore of the lake Most of the lake substrate is sandy/muddy and the remainder is fringed by a nature reserve bottom. (Figs. 3, 4 e,f). Lake Beaufort is within the The lake is reported by local anglers to be boundaries of the Glenelg Hopkins Catchment typically tannin stained but was turbid and rusty Mangement Authority but is managed by the brown in colour when sampled in April 2012 Pyrenees Shire Council. Occasional water (Fig. 4a). There is an abundance of fringing in‐ extraction for irrigation is reported to occur. water rush and reed vegetation around the lake (predominantly on the southern and eastern margins) (Figs. 4 b,c). Small areas of submerged ribbon weed (Vallisneria sp.) were also present N around the lake (Fig. 4c). Local anglers indicated that the lake can at times become choked with ribbon weed, but also that expansion of aquatic plants is limited by damage from propellers of water ski vessels. Water level in Lake Beaufort fluctuates. The lake was almost dry in 2009, with a small pool, reportedly full of redfin perch, remaining at the northern end of the lake near the outlet pipe. The lake filled rapidly after the abundant rain in 2010, and as a result it was stocked by Fisheries Victoria with 2,000 rainbow trout fry in November 2010. However, it is thought that this stocking was not very successful, possibly due to high summer temperatures resulting in low survival rates of young fish and or the impact of the lake being flooded and breaching the weir in January 2011 (i.e. stocked fish may have been lost from the lake). Predation by red fin may have also been a contributing factor. At the time of sampling in April 2012, the lake level had reduced slightly after being at full capacity in early 2011.

Local anglers report historically catching redfin Figure 3. Aerial view of Lake Beaufort with perch, tench, goldfish, and rainbow sampling areas indicated by blue dots and boat trout, but the main target species and most launching sites by white arrows.

Suitability assessment of western Victorian lakes for stocking with estuary perch 3

b) a)

c) d)

e) f) )

Figure 4. Images of Lake Beaufort, April 2012. a) south western shoreline swimming area, b) eastern shoreline fringing rushes, c) western shore boat ramp within caravan park, d) view to rock wall at northern end of lake, e) view of western shoreline and caravan park, f) fishing and jetty in south western corner.

Suitability assessment of western Victorian lakes for stocking with estuary perch 4

Lake Struan surrounding the lake. The main public use is thought to be for duck shooting. Local environment and habitat Management Lake Struan is situated off the Lower Darlington Lake Struan is within the Corangamite Road, approximately 10 km south of Lismore and Catchment Management Authority, and is the Hamilton Highway (Fig. 5). The lake is managed as a State Game reserve by Parks approximately 60 ha and 700 m across at its Victoria. widest point with two narrower arms projecting to the north. Each of these arms is fed by an intermittent feeder stream. The surrounding catchment is farm land primarily used for sheep grazing. There is a drain/culvert running N underneath the Lower Darlington Road, which takes over flow from the lake. N The lake is shallow, with an average depth of approximately 1‐1.5 m when sampled in April; 2012. There was no evidence of significant deeper areas within the lake. Local farmers indicated that Lake Struan was dry during the last major drought period (mid‐late 2000s), but has been full to overflow after the 2010 rains. The lake was highly turbid.

There are some sections of fringing rock shoreline, but very little other structural habitat was observed in the lake, and no fallen trees or significant woody debris around the lake shoreline (Figs. 6 a,b,c). Macro‐algae and other aquatic plants were limited to small amounts of benthic weed (possibly Ruppia) in the shallows Figure 5. Aerial view of Lake Struan with around the shoreline, and there were no areas of sampling sites indicated by blue dots and access freshwater macrophytes such as ribbon weed, or point by white arrow. fringing in‐water reeds/rushes.

Lake Struan appeared to be highly productive in a) the lower trophic levels, with extremely high densities of small gastropods, ostracods and insect larvae observed in the water column and benthic habitats. Prior to this survey there was no information on the fish community present in the lake, and there is no known history of fish stocking. Some grebes were observed on the lake but few ducks were present, and no cormorants. Eel fishing has historically occurred in the lake. b)

Access There is no boat launching ramp at Lake Struan. Best access is adjacent to the Lower Darlington Road (Fig. 6 a). However, boat launch and retrieval is difficult due to the soft, volcanic clay sediment that forms the lake bank. Minor earthworks could improve access for boat launching in the absence of a concrete ramp. There was no public usage observed during the Figure 6. see caption below sampling period and no public facilities

Suitability assessment of western Victorian lakes for stocking with estuary perch 5

Various species of duck were highly abundant on the lake, but no cormorants were observed. c) Prior to this survey there was no information

available on the fish populations of Lake Rosine, and there is no known history of fish stocking. Access Access to Lake Rosine was problematic. It was difficult to find an appropriate launching site for a boat due to the steep nature of the surrounding bank. The soft clay sediment also made launching and retrieval of even a small dinghy challenging. It is also difficult to find a suitable place to launch without accessing private land.

There was no public usage observed during the Figure 6. Images of Lake Struan. a) boat sampling period and no facilities surrounding launching area, b) view north from Lower the lake. Darlington Rd. c) Lower Darlington Rd access Management point. The majority of the land surrounding Lake Rosine is privately owned farmland to the shoreline, with no public access the lake. The lake Lake Rosine is within the jurisdiction of the Corangamite Catchment Management Authority. PV/DSE is Local environment and habitat also involved in management of the lake which is Lake Rosine is situated on the Lower Darlington considered an important habitat for ducks, Road, approximately 5 km west of Cressy. The particularly, blue‐billed duck listed as lake is a round basin approximately 1.4 km in ‘endangered’ in Victoria under the Flora and diameter and 150 ha area (Fig. 7). There is an Fauna Guarantee Act 1988. intermittent stream feeding into the north‐west corner of the lake (not flowing in April 2012). The lake was virtually dry during the last major drought (mid 2000s). There are no outflows from Lake Rosine as the lake is formed within a basin N of surrounding hills. The lake reaches at least 3 m depth in the central region. The banks along the south and west side of the lake slope more steeply than along the north side, with depths reaching 1‐2 m approximately 10‐20 m from shore. The water is less turbid than Lake Struan. Similar to Lake Struan there is very little in the way of submerged structure in the lake, with no woody debris around the shore, and no fringing reeds, rushes or significant areas of aquatic macrophytes. There were some small rocks and boulders at the southern end. Similar to Lake Struan the lower trophic levels appear to be highly productive. Amphipods, cladocerans, ostracods and insect larvae were present in Figure 7. Aerial view of Lake Rosine with exceptionally high numbers. Gastropods were sampling sites indicated by blue dots and access also present, although in lower densities than point used for the sampling, white arrow. Lake Struan.

Suitability assessment of western Victorian lakes for stocking with estuary perch 6

collectively as the “Bridgewater Lakes” (Fig. 9). It is approximately 5 km to the north of Cape a) Bridgewater and 10 km west of Portland.

Lake Bridgewater is long (approximately 1.5 km, and 40 ha) and narrow, with several arms and branching sections. There are no significant

inflows, and whilst all of the Bridgewater Lakes are interconnected, there are no significant outflows from this system. The Bridgewater Lakes are almost entirely spring‐fed and there are only minor fluctuations in water level. The water in the lakes was exceptionally clear.

The majority of Lake Bridgewater is deep (greater than 6 m), with an artificial sandy beach at the southern end. With the exception of the b) beach area, all banks are covered in dense vegetation, mainly reeds and rushes. There is a reasonable amount of structured habitat available in the lake, with several tea‐tree stands creating “snaggy” areas along the shoreline. The bottom is covered in a high density of aquatic plants.

There were very few macro‐invertebrates observed in the water column, with the exception of some insects (water boatman) and dragon fly larvae (mud‐eyes).

Historically, red fin perch have been caught in the Bridgewater Lakes and brown trout were stocked into the lakes in the 1970s (Backhouse c) and Gooley, 1980). Yarra pygmy perch is reported to be present in the lakes (Backhouse and Gooley 1980) and is a listed species under the Flora and Fauna Guarantee Act 1988 (also vulnerable IUCN, vulnerable EPBC Act 1999). Access Access to Lake Bridgewater is good. There is a well maintained boat‐ramp, jetty and toilets. Lake Bridgewater is home to an active water sports club and several water‐skiers utilised the

lake throughout the survey period (Fig. 10). There were also several recreational fishers, paddle‐boarders and general tourists.

Management Figure 8. Images of Lake Rosine. a) sorting of Lake Bridgewater is situated in a coastal reserve, seine net sample at south‐western end, b) north with some areas of private land adjacent to the eastern shoreline, c) boat launching site. northern margin of the lake reserve. The Bridgewater Lakes are mostly Crown Land within the Discovery Bay Coastal Park (Fig. 9). Lake Bridgewater The scarp and catchment area are mainly in private land. The lakes are within the jurisdiction of the Glenelg Hopkins Catchment Management Local environment and habitat Authority and the Glenelg Shire and are Lake Bridgewater is the largest in managed by these agencies in conjunction with a series of interconnected coastal lakes known Parks Victoria.

Suitability assessment of western Victorian lakes for stocking with estuary perch 7

c) N

Figure 10. Images of Lake Bridgewater. a) shoreline with fringing reeds, b) view down lake with water skiers, c) sorting seine catch.

Lake Hamilton

Local environment and habitat Lake Hamilton is situated within the township of Hamilton and is a long (approximately 1 km) Figure 9. Aerial view of the Bridgewater Lakes, narrow lake of approximately 38 ha area, blue dots indicate sampling areas, white arrow surrounded by 25 ha of parkland. This lake was indicates boat launching site. created in 1977 by damming of the Grange Burn Creek which feeds into the lake at the northern end. There is a weir at the southern end of the a) lake, which acts as a spillway during floods and periods of major rainfall.

The lake is reasonably shallow, although it reaches depths of approximately 3 m at the southern end near the spillway. The northern end of the lake has a shallow gradient and

marshland near the feeder stream. The lake water was clear in April 2012. Water level can fluctuate but the lake did not dry out in the last period of

prolonged drought (2000‐2010). Algal blooms often occur in the lake due to high nutrient loads. In autumn 2011 algal blooms resulted in the lake

being temporally closed to boating, swimming and fishing. b) ) There is a variety of structured habitat existing around the shoreline of Lake Hamilton. Large stretches of shoreline are covered in rushes and reeds, and there are also rocky patches (near the weir), snags, jetties and beaches. The bottom of the lake has a dense coverage of macrophytes, including ribbon weed. Cladocerans (

Suitability assessment of western Victorian lakes for stocking with estuary perch 8

spp.) were observed in the water column in high densities. a) The lake is stocked regularly with brown trout and rainbow trout. The lake was reported to have been stocked with golden perch in 1983‐88, with poor returns to anglers. In 1999 the lake also received a trial stocking of 1000 estuary perch fingerlings, but the success of this stocking is unclear and estuary perch appear to be a rare catch in the lake. Access Access to Lake Hamilton is exceptionally good. There is a well maintained boat ramp, a beach and several jetties and fishing platforms. The lake is heavily utilised by the local community, for water sports such as water skiing as well as b) fishing, canoeing, rowing and jet‐skiing. There was a high level of public usage, and interest in the sampling activities throughout the sampling period. Management Lake Hamilton is within the jurisdictions of the Glenelg Hopkins Catchment Management Authority and the Southern Grampians Shire Council.

N c)

Figure 12. Images of Lake Hamilton (right): a) mesh sampling at the north eastern end near entrance of the Grange Burn Creek, b) view of lake central region, c) sorting seine net sample.

Figure 11. Aerial view of Lake Hamilton, blue dots indicate sampling sites, white arrow boat ramp and yellow arrow location of capture of a large estuary perch.

Suitability assessment of western Victorian lakes for stocking with estuary perch 9

Material and Methods

sampled with mesh nets over night (>12 h soak Water quality assessment times), and Lakes Beaufort, Hamilton and Assessment of water quality suitability involved Bridgewater were also sampled with separate measurements of important physico‐chemical mesh net deployments during daylight (1.5‐2 hr parameters for fish survival: temperature, soak times). For logistical reasons separate mesh salinity, dissolved oxygen and pH. These net sampling during the day was not conducted parameters will vary over time, and this at Lakes Struan and Rosine. Rather, for these assessment provides a snap‐shot of water two lakes the mesh nets were deployed once; quality to indicate current or future potential for with deployment several hours before sundown poor water quality. Where available we have and retrieval several hours after sunrise, thereby also sourced other relevant information on encompassing both day and night conditions water quality in the five lakes to provide (approximate 15‐16 h soak time). The long soak additional perspective on lake water quality. time was acceptable in these two lakes due to Further assessment of water quality will likely the lack of public access/usage and low risk of be important prior to and following any enmeshing large numbers of fish or other stocking activities. wildlife (i.e. platypus). Temperature, salinity, and dissolved oxygen Seine netting were measured by a Hydrolab DataSonde4X multiprobe at multiple sites and depths in each Seine netting occurred in areas free of snags or lake. Chlorophyll a (Chl a) was also measured large rocks, in water depth of generally 1‐1.5 m. by the same instrument as an indicator of Each seine net sampling consisted of deploying primary production for comparisons across the the net and 10 m hauling ropes and then, where five lakes and to assist in interpretation of possible, with one person on each hauling rope variation in other key parameters such as separated by approximately 20 m, the net was dissolved oxygen and pH. The Chl a data are dragged approximately 10 m, after which the only indicative and have not been calibrated two people came together and hauled the net against laboratory analysis of field collected and into the floating storage bin for sorting. All fish filtered water samples (this was logistically not were identified to species, and samples were possible due to remoteness of sampling stored in ethanol. Where more than 30 fish of a locations). species were collected by the seine, 30 fish were retained for measurements and the remainder counted and returned to the water. Depending Fish community assessment on availability of suitable sites for seine netting, Rapid assessment of fish communities in each 2‐8 seine net samples were taken across at least 3 lake was conducted using three sampling tools: different areas in each lake. 40 m long multi‐panel mesh nets (5 x 8 m panels, 1.5, 2.5, 3.5, 4.5, 5.5 inch monofilament), a seine Bait traps net (15m long x 2 m deep, 2 mm body mesh, 1 Bait traps were baited with a mixture of SPAM mm mesh codend, 10 m hauling ropes), and box and cat food and a small light stick. Five bait style bait traps (2 mm mesh). traps were deployed over night in each lake in Mesh nets conjunction with the night mesh net sampling. Sampling with mesh nest was aimed at Invertebrate prey detecting the presence of potential piscivorous predators and potential competitors with A qualitative assessment of small invertebrate estuary perch in the event that stocking was to prey was made from observations of occur. invertebrates collected by bait traps and seine net, and additional sampling with a small scoop The sampling schedule with mesh nets varied net (250 μm mesh, mouth 30 x 35 cm). slightly among the five lakes. All lakes were

Suitability assessment of western Victorian lakes for stocking with estuary perch 10

Results and Discussion

at Warrnambool they may be exposed to a Water quality temperature range of 7–26°C (Newton, 1996). Temperature Salinity Water temperatures measured in early April 2012 were lower in Lakes Hamilton and Bridgewater Lakes Beaufort, and Bridgewater were fresh (<1 (15‐16°C) compared to Lakes Beaufort, Struan ppt), lakes Hamilton and Struan were slightly and Rosine (18‐20°C) (Table 1). This variation brackish (approximately 2 and 5 ppt may partly relate to differences in sampling dates respectively), and Lake Rosine was the most and air temperature (i.e. a cold front passed saline (approximately 11) (Table 1). Previous through the region between the sampling of lakes salinity measurements in lakes Rosine and Struan Beaufort, Struan and Rosine and sampling of in 2006 during the last drought period indicated lakes Bridgewater and Hamilton), but also likely a salinity of 17 ppt in Lake Struan, and > 45 ppt in reflects general differences in heating and cooling Lake Rosine, which at the time was virtually dry of these lakes due to their different depths, (Barton et al., 2006a; Barton et al., 2006b). The lack shading, and local climate. Lake Bridgewater is of outflow/flushing of Lake Rosine during high also part of a complex of lakes that are rainfall periods may explain the higher salinity of replenished largely by ground water seeps that this lake. Historical data on salinity for Lake would further buffer against water temperature Bridgewater reported in (Backhouse and Gooley, fluctuations, particularly summer time maxima. 1980) indicated a salinity of 0.65 ppt (similar to current measurements) confirming that salinity Temperature extremes for the five lakes are of the lake is very stable. For Lake Hamilton unclear. However, the successful stocking of small fluctuations of salinity are likely, but brown and rainbow trout in Lake Hamilton, and would not be expected to provide an impediment previous successful stocking of trout in Lake to survival of estuary perch. For Lakes Struan Bridgewater (Backhouse and Gooley, 1980) and Rosine, salinity of the lakes when relatively would indicate that the temperature maxima in full would appear quite suitable for estuary these two lakes is generally less than 22°C, above perch, however, low water levels particularly in which survival of trout is compromised (Molony, Lake Rosine would lead to hypersaline 2001). Based on this we do not expect that high conditions which may be outside the tolerance water temperature in these two lakes presents a range for estuary perch. risk to survival of estuary perch. Dissolved oxygen Lakes Struan and Rosine have previously been measured for water temperature in 2006 by Dissolved oxygen (DO) levels were highest in another sampling program (Barton et al., 2006a). Lake Rosine (110‐166% saturation, 10‐15 mg/L), However, during this earlier sampling lake levels followed by Lake Struan (109% saturation, 10 were very low and measurements were taken in mg/L), Lake Hamilton (88‐98% saturation, 9‐10 winter (July) when a temperature of 11°C was mg/L), Lake Bridgewater (74‐84% saturation, 7‐8 recorded in both lakes (Barton et al., 2006a). mg/L) and Lake Beaufort (73‐81% saturation, 7‐ These two lakes were again sampled in October 7.5 mg/L) (Table 1). Australian water quality 2006, when Lake Rosine was reported to be guidelines for cultured fish recommend the DO dry/mud and Lake Struan was measured at levels are > 5 mg/L(Anon, 2000), and all lake met 15.6°C (Barton et al., 2006b). While minimum this criteria. temperatures in these lakes are likely in the order The high DO levels in lakes Rosine and Struan of 8‐10°C, peak summer temperatures are are consistent with the higher Chl a levels unclear. Reported summer temperatures for indicating a high level of oxygen producing similar shallow typically primary production. The high primary range from 22‐25°C, with minimum temperatures production in these lakes is likely the result of of around 9‐11°C (De Deckker and Williams, recent filling after being virtually dry during the 1988; Anon, 2005; Barton et al., 2006a). recent drought. It is a common feature of Temperature tolerances are unclear for estuary intermittent lakes to have productivity booms perch, but in natural populations in western when they fill after dry spells (Puckridge et al., Victorian estuaries such as the Hopkins estuary 2010).

Suitability assessment of western Victorian lakes for stocking with estuary perch 11

The minimum DO level recommended for good primary production was occurring in the recently survival and growth of trout (brown and filled Lakes Rosine and Struan, followed by Lake rainbow) is suggested to be around 7 mg/L Beaufort (Table 1). The lower levels in Lakes (Molony, 2001). The DO requirements of estuary Bridgewater and Hamilton (Table 1) likely reflect perch are unclear. However, as the oxygen lower productivity of these lakes and the greater demands of trout are considered relatively high trophic complexity (abundance of higher trophic compared to other species, we would expect that levels consumers) of these lakes. a DO level of at least 7 mg/L, the minimum observed across the five lakes, would not present an impediment to growth and survival of estuary perch. pH

The pH of lakes Struan, Rosine, Bridgewater and Hamilton were all neutral to slightly alkaline (7.4–8.3). Lake Beaufort had neutral pH (7.1) for the surface waters, but was slightly acidic (6.7) for the bottom waters (Table 1). It is unclear whether the slight acidity of this lake is a common feature or may be linked to the recent major flooding of the catchment and lake (i.e. acid sulphate soils being flushed after a long dry period). It is also unclear whether or not the lake may have been more acidic prior to sampling in April 2012. pH of natural freshwaters will typically range between 7.5 and 8.5 (Tibby et al., 2003). However, in the deeper or less productive zones pH can be lower, i.e. 6.5 to 7.5. Importantly, pH of all five lakes was within the Australian water quality guidelines for shallow inland lakes and reservoirs which recommend that a pH range of 6.5–8.5 is preferred (Anon, 2000; 2010).

Fish survival and growth can be influenced significantly by low pH, but this is species dependent (Howells et al., 2006; Locke, 2008). For brown and rainbow trout optimal pH for growth is 7‐8, and survival may be affected below 6 (Molony, 2001). pH may also have synergistic effects with other stressors such as metal concentrations in the water. In the case of Lake Beaufort, the rusty brown colour observed may be indicative of high Fe (iron) that in combination with the slightly acidic conditions could have been stressful to resident fish species. Effects of low pH on invertebrate prey are unclear, but may also be significant. Further monitoring of pH and analyses of metal concentrations of the water is recommended for Lake Beaufort before stocking with estuary perch or other species. Chlorophyll a The Chl a measurements indicated varying levels of primary production across the five lakes at the time of sampling in April 2012. The measurements clearly indicated that higher

Suitability assessment of western Victorian lakes for stocking with estuary perch 12

2012.

April

in

lakes

Salinity (ppt) DO (% sat., mg/L) Chl a (µg/L) pH Victorian

western

five

at

collected

data

parameter

quality

water

of

Summary

. 1

Table 1 6 15.3 2.0 95.1, 9.5 4.3 7.9 7.9 7.9 7.9 4.3 3.4 3.5 9.5 8.9 8.8 7.1 11.6 (ºC) 7.6 Temperature 80.9, sites 0.15 18.5 6 7.8 7.5 No. 8.3 (m) 6.7 20.2 3.4 9.8 95.1, 16.1 6.7 11.6 89.1, 14.9 11.5 0.3 Depth 87.9, 2/4/2012 108.3, 8.3 4.8 Date 7.5 166.8, 7.1 20.5 10.7 84.7, 4 7.9 0.5 Location 79.5, 3/4/2012Beaufort 21.3 3.5 0.67 3 8.3 73.1, 0.15 0.3 8.2 16.5 4/4/2012 6 24.7 0.15 7.4 Lake 18.3 12.8 2.0 9.9 25.7 0.3 6 7.4 1 10/4/2012 4.4 Struan 17.2 10.7 2.0 1 7.4 2 4.3 2.0 7.4 134.5, 4.4 Rosine 98.8, 7.4 Lake 111.6, 5.2 8.2 2.0 10.7 7.4 5.3 8.2 10.7 15.4 7.4 Lake 5.2 18.6 8.2 6 3 1 83.0, 4.7 Bridgewater 18.5 8.0 0.3 2 12/4/2012 2 83.5, 8.0 0.67 83.9, 7.9 0.67 Lake 82.0, 16.3 7.2 6 0.67 1 82.1, 16.7 6 0.67 2 81.6, 16.7 6 0.67 3 73.9, 16.5 15.3 4 0.67 4 16.6 15.4 3 0.67 5 16.6 15.5 3 6 Hamilton 16.5 1 6 7 3 2 Lake 1 2 3

Suitability assessment of western Victorian lakes for stocking with estuary perch 13

were relatively rare, compared to the common Fish communities jollytail that were highly abundant. Seine net catches ranged from approximately 100–300 Lake Beaufort common jollytail per haul, and they were sampled throughout the lake. The fish community in Lake Beaufort was characterised by a high abundance of one predator/competitor species; red fin perch, and a few species of prey fish: Australian smelt and flathead gudgeon (Table 2). The redfin perch were mostly of small size (9‐13 cm total length), with a few larger specimens captured (35‐44 cm total length) (Fig. 13) (Table 3). A number of dead red fin perch of both large and small size were observed floating on the surface. No other species were observed to be dead. Large numbers of small fish, most likely red fin perch were observed feeding at the surface on dusk and dawn. Other species that were detected included goldfish and mosquito fish.

Figure 14. Lake Struan: galaxids (common jollytail) in seine net.

Lake Rosine

No fish were detected in Lake Rosine by any sampling method.

Lake Bridgewater Of the five lakes sampled, Lake Bridgewater had the most diverse fish community, with 8 species detected (Table 2). All species could be Figure 13. Lake Beaufort: large 35 cm TL (top) considered potential prey species for estuary and small 10 cm TL (bottom) red fin perch perch. No predator species were detected, although previous studies have reported the presence of red fin perch and brown trout Lake Struan (brown trout thought to have been last stocked in the late 1970s) (Backhouse and Gooley, 1980). Only two fish species were detected in Lake Smallmouth hardyhead, Australian smelt, blue Struan: common jollytail (galaxid) (Fig. 14) and spot goby, flathead gudgeon and pygmy perch flathead gudgeon (Table 2). Flathead gudgeon all appeared to be abundant in the lake (Fig. 15),

Suitability assessment of western Victorian lakes for stocking with estuary perch 14

consistent with the previous survey by Lake Hamilton Backhouse and Gooley (1980). Despite being There were six fish species detected in Lake common in the current sampling period, Hamilton, with three of these species: brown Australian smelt were not reported by the trout, rainbow trout and red fin perch, earlier survey of Backhouse and Gooley (1980). considered to be potential predators and or There are two species of pygmy perch suggested competitors with estuary perch (Table 2). The to occur in the Bridgewater lakes: the southern main prey species detected in high abundance pygmy perch (considered common) and the was the flathead gudgeon (Table 2). Tench were Yarra pygmy perch (considered uncommon and also detected, although they are not considered listed by the IUCN as vulnerable). While we are a predator or competitor species with estuary confident that the southern pygmy perch was perch. the dominant species that we sampled, further It was notable that one large estuary perch (47 confirmation of species identity is required cm total length) (Fig. 16) was sampled in Lake (sample to be sent to Museum Victoria). Hamilton. This fish is a survivor of the trial Other species reported to occur in the stocking of estuary perch that occurred in 1999, Bridgewater lakes by Backhouse and Gooley and therefore would be approximately 13 years (1980) that we did not detect were the dwarf old. The size at age of this fish, is consistent if galaxias (Galaxiella pusilla) and the tench (Tinca not slightly larger than similar age fish in tinca). natural estuarine populations where fish greater than 45 cm are typically rare (Walsh et al., 2010a;

Kent et al., 2011).

Figure 15. Lake Bridgewater: seine net sample, small mouth hardy head and Australian smelt.

Figure 16. Lake Hamilton: large (47cm, 13 year old) estuary perch sampled by mesh net, 12/04/2012.

Suitability assessment of western Victorian lakes for stocking with estuary perch 15

Table 2. Summary of fish species detected by different methods and their relative abundance at five western Victorian lakes. (MN = mesh net, S = seine, BT = bait trap).

Method Lake Species MN S BT Abundance (pred/prey/comp)

Beaufort Australian smelt y M (pry) Retropinna semoni Goldfish y L (pry) Carassius auratus Mosquitofish y y L (pry) holbrooki Flathead gudgeon y y H (pry) Philypnodon grandiceps Redfin perch y y H (prd/pry/ Perca fluviatilis comp)

Struan Common jollytail y y VH (pry) Galaxias maculatus Flathead gudgeon y y L (pry) Philypnodon grandiceps

Rosine No fish detected

Bridgewater Common jollytail y L (pry) Galaxias maculatus Australian smelt y VH (pry) Retropinna semoni Mosquitofish y L (pry) Gambusia holbrooki Smallmouth hardyhead y y VH (pry) Atherinosoma microstoma Pygmy perch y y VH (pry) sp. River blackfish y L (pry) Gadopsis marmoratus Flathead gudgeon y y VH (pry) Philypnodon grandiceps Bluespot goby y VH (pry) Pseudogobius olorum

Hamilton Brown trout y H (prd/pry/ Salmo trutta comp)

Rainbow trout y H (prd/pry/ Oncorhynchus mykiss comp) Tench y L

Tinca tinca Estuary perch y L (comp) Macquaria colonorum Flathead gudgeon y y VH (pry) Philypnodon grandiceps Redfin perch y H (prd/pry/ Perca fluviatilis comp)

L = low, M = medium, H = high, VH = very high, prd = predator, pry = prey, comp = competitor

Suitability assessment of western Victorian lakes for stocking with estuary perch 16

Table 3. Size composition summary for potential predator and recreational interest species sampled. NB. No predator or recreational interest species sampled in lakes Struan, Rosine and Bridgewater.

Total length (cm) Species Lake n Mean Range

Brown trout Hamilton 6 31.5 30.5 – 34

Rainbow trout Hamilton 7 35.0 32.5 – 37.5

Redfin perch Beaufort 25 13.5 8.2 – 44 Hamilton 8 26.5 22.5 – 37

Estuary perch Hamilton 1 46.5 46.5

Invertebrate prey a)

Gastropods Lake Beaufort Larger macro‐invertebrates were in low Ostracods abundance in Lake Beaufort, with only a few shrimp being collected in one bait trap and surprisingly no shrimp being observed in any seine or scoop net samples. The larger zooplankton sampled by the 250 μm scoop net were dominated by cladocera (water fleas, Daphnia sp.) with very few copepods observed. Fresh water mussels were a common bycatch of the seine net samples over the muddier b) sediments. Lake Struan Small gastropods (Coxiella striata) were abundant on the sediments. The water column community sampled by scoop net was dominated by calanoid copepods that were in exceptionally high abundance. The seine net samples also indicated exceptionally high abundance of large ostracods (Fig. 17). Midges (chironomidae) and caddis fly (tricoptera) cases were also observed in seine net samples an on Figure 17. Lake Struan: a) siene net with the water surface. No shrimp or other large ostracods and gastropods, b) scoop net sample crustaceans were detected. with masses of copepods.

Suitability assessment of western Victorian lakes for stocking with estuary perch 17

Lake Rosine The scoop net samples were dominated by cladocerans (water fleas, Daphnia sp.) similar to Lake Rosine provided an interesting contrast to Lake Beaufort, with low numbers of copepods. Lake Struan. Similar to Lake Struan no shrimp Midges and were common, as well as were detected, but the seine and scoop net water boatman, and yabbies were also detected. samples indicated exceptionally high abundances of gammarid amphipods and cladocerans which were not found in Lake

Struan. Copepods were rare in Lake Rosine, compared to Lake Struan which was dominated by copepods. Similar to Lake Struan, ostracods were also abundant. The cladoceran in Lake Rosine was also not the same species as observed in Lake Beaufort and was most likely Daphiniopsis pusilla the dominant cladoceran in saline lakes of western Victoria (Timms, 1983). Cases from recently hatched midges were abundant on the lake surface, and water boatman (Hemiptera) were highly abundant in seine net samples.

Figure 18. Lake Rosine: siene net with water boatman and amphipods

Lake Bridgewater

Shrimp (Parataya australiensis) were common in seine net samples in Lake Bridgewater and several yabbies were collected in bait traps. Small zooplankton such as cladocerans and copepods were, however, in very low abundance in the scoop net samples relative to the other lakes.

Lake Hamilton

Shrimp were common in seine net samples in Lake Hamilton, along with gastropods (snails) and various insect larvae, including mud‐eyes.

Suitability assessment of western Victorian lakes for stocking with estuary perch 18

Summary and recommendations

The five lakes varied considerably in water characterised by high abundances of smaller physico‐chemical parameters. However, for the invertebrate prey, and shrimps and yabbies key parameters of dissolved oxygen, pH, were not detected. This variation is at least temperature and salinity all lakes at the time of partly related to the variation in salinity and sampling appeared to have suitable water ephemeral nature of some lakes. The lack of quality for survival of estuary perch. Lake shrimp (Parataya sp.), a key prey item for estuary Beaufort water quality will require some further perch, in the saline lakes Struan and Rosine is assessment due to observations of slightly consistent with earlier studies of benthic depressed pH. Furthermore, observations of communities in saline western Victorian lakes, dead red fin are of some concern in Lake which similar to our sampling, indicated a lack Beaufort, although it was noted by the reference of shrimp but that ostracods and amphipods group that the numbers of dead red fin observed where highly abundant (Timms, 1983). The were low and not considered unusual. It is saline lakes appeared to be most productive in unclear if the current red fin deaths are related terms of overall invertebrate biomass. Lake to water quality issues, disease such as EHN Beaufort appeared to have the lowest (epizootic haematopoietic necrosis) known to be availability of larger macro‐invertebrate prey, carried by red fin, or an interaction of the two. with notably few shrimp, and a water column EHN virus can affect native fish species plankton community dominated by Daphnia sp. (Arthington and McKenzie 1997) and has been In terms of fish prey, Lake Bridgewater had both demonstrated to transfer to some native fish diversity and abundance of fish prey, but the species in laboratory conditions. There is, likely presence of the listed Yarra pygmy perch however, no evidence of wild populations of (listed as vulnerable, EPBC Act 1999) may be a estuary perch being subject to EHN related constraint to stocking. Lake Struan lacked mortalities. diversity of larger prey fish, but had very high Lake Beaufort catchment was heavily mined for abundance of one species of prey fish (common gold and the lake itself is reported to have been jollytail), and lower abundance of another a sluicing area. Residual contamination of Lake (flathead gudgeon). Lake Rosine had no Beaufort sediments from these activities is evidence of a prey fish community. Lakes possible. Further analyses of sediment and Hamilton and Beaufort had populations of prey water chemistry along with epidemiological fish, with flathead gudgeon being the most assessments of dead red fin may be important to common prey fish in both lakes. Interestingly further assess/eliminate these risks prior to a galaxids and smelt were not highly abundant in trial stocking of estuary perch. either of these lakes at the time of sampling, possibly related to predation pressure by red fin Long‐term security of lake water levels appears perch and trout. assured for lakes Hamilton and Bridgewater, with lakes Beaufort, Struan and Rosine all being Lakes Struan and Rosine had no predator relatively shallow and potentially subject to populations, and while Lake Bridgewater drying during extreme prolonged drought appeared to have the most diverse fish periods. Long‐term water security and declining community, none of the fish species detected by water quality during exceptionally long dry our sampling would be considered a potential periods may be a limiting factor to the long‐term predator of estuary perch. Lakes Beaufort and suitability of these three lakes for stocking of Hamilton had significant populations of red fin estuary perch. perch, and in the case of Hamilton, also brown and rainbow trout. The species of biggest All five lakes had evidence of invertebrate prey concern in relation to predation of stocked communities, however, the apparent densities juvenile estuary perch fingerlings would be red and diversity of macro‐invertebrate prey, such find perch. Red fin perch are considered to be a as shrimp, varied among the lakes. Lake voracious predator of small fish and the large Bridgewater and Lake Hamilton had larger numbers of small red fin perch in Lake Beaufort, sized invertebrate prey such as shrimp and in particular, would present a predation risk to yabbies. Lakes Struan and Rosine were newly stocked estuary perch fingerlings.

Suitability assessment of western Victorian lakes for stocking with estuary perch 19

Furthermore, competition with red fin for Access arrangements and infrastructure would limited food resources in small lakes such as have to be improved for both these lakes. Lake Beaufort is likely to be strong. Lake Beaufort has one of the best settings for a In terms of access for anglers, Lakes Hamilton, trial with good access, and a small size ideal for and Beaufort had the best access to land and assessing success of a small‐scale trail stocking. boat based anglers followed by Lake However, predation risk from the high red fin Bridgwater. Lakes Struan and Rosine would population and potential water quality and require improvement to access. Rosine in security issues are a risk. particular had no public access points. Assessment of the five candidate lakes revealed Final stakeholder workshop and that each lake possessed desirable features for a recommendations trial stocking of estuary perch, however, none of On 25th June 2012 a second meeting of the the lakes satisfied to a high degree all the FV/stakeholder reference group was held to desired attributes (Table 4). Progressing to a trial consider the information from the on‐site stocking in any lake will require further suitability assessments and initiate the consideration of how to improve lake suitability development of a draft stocking plan. by focussing on aspects indentified as limiting by the current assessment. There is also some The reference group agreed to focus the trial uncertainty as to how stocked estuary perch will stocking on Lakes Hamilton, Struan and respond to issues such as competition with Beaufort. Lake Bridgewater was discounted due resident fish such as red fin perch, limitations on to presence of a listed fish species, Yarra pygmy the amount of structural habitat and diversity of perch. Lake Rosine was rejected, with possibility larger prey. The trial stocking program will to be reconsidered at a later date, due to lack of a provide an opportunity to assess these higher trophic level prey community and lack of uncertainties. public access. Given the issue of listed species in Lake Stocking plans for lakes Struan and Beaufort Bridgewater, the access, long‐term water quality will now depend on outcomes of translocation and security uncertainties for Lake Struan, assessment and water/land manager approval. Rosins and Beaufort, the lowest risk option for a Lake Hamilton is already approved for stocking trial stocking is Lake Hamilton. The capture of of estuary perch. Other western Victorian lakes an exceptionally large estuary perch that had previously assessed and approved for estuary survived from an earlier trial stocking of Lake perch stocking (eg. Lake Bolac) will also be Hamilton in 1999 is promising for the long‐term considered for additional stocking as part of this suitability of this lake for estuary perch growth trial program. and survival. There was no follow up Fisheries Victoria will conduct a follow up assessment of the success of the previous assessment of the success of any trial stockings stocking involving 1000 estuary perch at approximately three years after the stocking fingerlings in 1999, either in relation to survival has occurred. and growth rates or targeting and capture rates by anglers. Lake Struan while having no resident predators and the potential to support high growth rates of estuary perch due to the abundance of galaxids, small invertebrate and insect prey, has the risk of low long‐term water security and some uncertainty over whether the current highly abundant galaxid population will be maintained into the future. Lake Rosine, also has no predators and potential to support rapid growth of young estuary perch due to the high abundance of small invertebrate and insect prey but may require introduction of a larger prey species (i.e. Australian smelt, common jollytail) to support larger size classes of estuary perch.

Suitability assessment of western Victorian lakes for stocking with estuary perch 20

‘listed’ species species ‘listed’ pygmy (Yarra perch) recently stocked stocked recently no trout, with barriers major access, no public blue-bill ‘listed’ lake the uses duck State reserve, game duck shooting recently stocked with trout, trout, with stocked recently local preference angler for multi-species potential trout, fishery stocked

rapid changes, minimal management barriers, reat to fish survival, potential for stress or growth orgrowth survival, stress potential reat to fish for s, no management barriers, excellent access) access) excellent barriers, no management s, assessments.

land-based jetty, jetty, land-based rock wall, boat 3 shoreline, sites launching Shoreline, boat boat Shoreline, launching land-based access access land-based road, public launching boat no no public access shoreline, boat walking launching, lake around track site ‐ on

rapid

2 1 3 16 3 1 2 by

highly abundant abundant highly and galaxid prey. invert. diverse and prey abundant invert and fish available,prey with competition fin red and trout smelt, gudgeon, redfin, small competition inverts, fin red with no large invert or or invert no large lots of prey, fish invert.small prey informed

lakes

redfin, trout, trout, redfin, cormorants no abundant no abundant predators, few cormorants red fin, fin, red cormorants no significant no significant predators or competitors no predators or or predators no competitors Predators/ Predators/ Prey Access Management Total Victorian

al or growth, likely to be stable or exhibit no rapid change rapid no or exhibit stable to be likely growth, or al lants lants p western barriers to stocking, access), 2 – acceptable (immediate minor th minor (immediate 2 – acceptable access), to stocking, barriers

uatic uatic rushes/reeds, overhang trees and snags q rock wall, wall, rock rushes/reeds, plants aquatic rock wall, wall, rock rushes/reeds, can chokedbecome with a five no significant no significant habitats structural

no significant no significant habitats, structural shoreline rocky some

the

for

scores

relatively relatively shallow, intermittent dry flow, stream in 2006 lakes is is for lakes recreation, some extraction, water dryalmost in 2009 shallow, shallow, stream intermittent last in dry flow, drought level stable stable level level remains remains level has likely stable, replenishment some groundwater from 3 4 4 4 4 4 1 24 1 4 4 4 4 4 3 24 3 4 3 2 4 4 4 3 2 1 4 4 2 3 19 3 2 4 4 1 2 3 3 2 1 4 2 3 4 1 3 4 4 21 21 2 3 4 1 3 4 4 assessment

history of algal algal of history blooms groundwater fed, fed, groundwater always fresh,and clear exceptionally subject to high high to subject water as salinity drops level shallow, subject to to subject shallow, changes, rapid high possible temp.?? summer low pH, red fin red fin pH, low further deaths, assessment recommended Suitability

. 4

Table

Bridgewater Hamilton Struan Rosine 1 – poor (high immediate threat to fish survival, significant threat survival, significant immediate to fish (high 1 – poor Location Quality Water Structural Security Water Beaufort Habitat competitors Barriers effects, management and access barriers likely resolvable), 3 – good (no immediate threat for survival or growth, potential for potential or growth, survival for threat immediate (no 3 – good resolvable), likely barriers access and management effects, to surviv threat (no suitable highly , 4 – access) to improve scope

Suitability assessment of western Victorian lakes for stocking with estuary perch 21

Acknowledgments

This suitability assessment was funded by the Victorian Government’s Recreational Fishing Initiative program. The advice/input and local knowledge of regional fisheries officers: Craig Murdoch, Steve Eddy and Charlie Cooper was much appreciated. Involvement and input from a number of knowledgeable recreational fishing stakeholders (Ray Mcleod, Phil Weigall, Bruce McInnes) was highly valuable to this assessment and its recommendations. Taylor Hunt made a valuable contribution to fieldwork and meeting discussions.

Suitability assessment of western Victorian lakes for stocking with estuary perch 22

23

‐ to ‐ to of

the

26.

perch the

trout the

and

estuary 559

of K. p. growth,

estuary

of

, the

of

south

and 28. ,

for

Books.

the

of

Fisheries

perch variable

of

34 J.R.W.

16. of

Report in

46

and p.

(1986).

dynamics

relation in

estuarine

,

and to

Victoria.

trout ) estuary

Brown reference (1990).

management

diet

requirements in 165 A.

111.

Melbourne..

Reed Sadler, No. No.

Western

‐

calcium,

in Australia. Victorian

Journal

Marine

Reid, fishes J.

O.

Fisheries

and

p.

&

(2011). for

99 the

and

estuary

Institute in

growth

& ,

review. with

Victoria.

)

37. G.

)

fish monitoring

T. Sciences ‐ A.

in

of

distribution, observations

special 47 A

survival

Agriculture J. Manuscript 29 Report Report J.F.

ecology and W. Rainbow

colonorum responses

acidity, , Sydney:

colonorum review.

marine the

Victoria, . estuary.

Research,

D. zooplankton

diet Rylah estuary.

Fisheries, Conservation

of

mykiss

fish

and Estuarine of Victoria,

with

Bruce, eastern 515 of Freshwater

fishery Age

) 28. on McKenzie,

of of Aquatic

stocking

on

& colonorum

and and Research

Environmental

&

information p. variation

Food freshwater River River, Tabulated S.

Connor, Australia: Canadian

and for Research Research wedge ʹ

B.

Arthur ‐ Costelloe, Brown, trutta

of (1996).

Effects Australia

River,

Macquaria

O

Ecological

Macquaria ( In

(1996).

(2000).

class D.

tolerances ‐ & salt D., M.

tolerance

R.

(2001). L. J.T.,

lakes native a

(2008). D. G. Salmo

G.

B.

Oncorhynchus Macquaria ( ichthyoplankton spawning size

Conron, M.

and ( Western eastern Department hydrology Fisheries in Australia, Observation Hopkins Science Recreational productivity—a Environment, Bemm Victoria Department (:Percichthyidae) perch Biological of Environmental waters. Freshwater

biota. pH Victoria 570. aluminium (2006).

( (2010) perch Hopkins Hydrobiologia

J.

A.

J.,

Victorian Molony, McCarraher, McDowall, Newton, Koehn, Kirwin, Locke, Kent, Puckridge, Howells,

western

. of

of

P. In

and

and

P.

‐

lakes lakes Reed

In

Review Water

(2).

The Fishes

&

(2002). of of eleven,

in

Waters),

of

Australia

Report Report

H.

waters. quality

of

Museum. guidelines M.

of Naturalist

J.

Program

temporal Lakes, Dahlhaus, Victoria. Zealand

(1997).

(1988). region. region

River.

assessment the

(1980). (2008).

Dahlhaus,

Marine lakes

Sydney:

movement

Fishes Protection & .

F.

Guidelines, L. of &

D. (Inland analysis water R. analysis

Science Science

inland

286.

Environment Victoria. Fishes Allen,

Publications.

‐

D. J.

Grant and quality New

Myers, G.

Environment CMA CMA

W.

coast &

The Victorian

Australia perch Spatial, and and the

Snowy

275

limnology

J.,

Australia.

1

with

, Fisheries

Series Water Water H. and

Cox, Cox,

of

Kuiter, L.

Fresh T.F.H.

the

Suitability S.

permanent

Bridgewater 162

displaced/introduced Freshwater lakes.

& Fishing

Canberra.

A., A., and and McKenzie,

in

Gooley,

(2004). for

to Freshwater Victoria. of of

southern Authority, 4. Modewarre

Department State Estuary

Paper D. &

Victoria.

Western &

Williams, report. s City:

L.

Volume Environmental ʹ : chemical Victoria, Sampling

Sampling

use

‐

238.

saline Land Land & H.

‐

N.

P. No. associated Corangamite Corangamite

Holland. 05. Lake Australian Environmental . . Guide

fauna P.

Midgley, ‐

Bray,

A.

(1989).

G.

Laurenson, Victorian

232 (2010).

Herczeg, Herczeg,

impacts the the ,

J. R. R.,

fish habitat M., T.,

96 Hydrobiologia western Neptune Portland, CSIRO 34/06 Physico mostly Australia New

Canberra, (2006a). in Protection for 2004 (2006b). in CSIRO xx/06

Recreational Research Field Australia Paper Guidelines Jones, Environment. of fauna Australia: Technical Authority, Quality:

A., A.,

G. G. (2005). (2000). (2010).

Deckker,

Barton, Anon Barton, Douglas,

Allen, Allen, References

Howell, De Gomon, Anon Arthington, Anon Backhouse,

S it bilit t f t Vi t i lk f tki ith t h

water regimes in arid‐zone : Coongie Lakes, Australia. Marine and Freshwater Research 61, 832‐841. Tibby, J., Reid , M., A, Fluin , J., Hart , B. T. & Kershaw, P. A. (2003). Assessing long‐ term pH change in an Australian river catchment using monitoring and palaeolimnological data. Environmental Science and Technology 37, 3250‐3255. Timms, B. V. (1983). A study of benthic communities in some shallow saline lakes of western Victoria. Hydrobiologia 105, 165‐177. van der Meulen, D.E., Walsh, C.T., Gray, C.A. and Taylor, M.D., 2011. Investigating fine‐scale spawning habitat and reproductive dynamics of estuarine‐ dependent fishes. Abstract: 1st International Conference on Fish Telemetry, 12 – 18 June, 2011, Sapporo, Hokkaido, Japan. Walsh, C. T., Gray, C. A., West, R. J., van der Meulen, D. E. & Williams, L. F. (2010a). Growth, episodic recruitment and age truncation in populations of a catadromous percichthyid, Macquaria colonorum. Marine and Freshwater Research 61, 397‐407. Walsh, C. T., Gray, C. A., West, R. J. & Williams, L. F. G. (2010b). Reproductive biology and spawning strategy of the catadromous percichthyid, Macquaria colonorum (Gunther, 1863). Environmental Biology of Fishes 91, 471‐ 486.

Suitability assessment of western Victorian lakes for stocking with estuary perch 24

officers,

f=fresh, b=brackish f f f b f b project

69 63 60 59 55 54 48 48 47 45 44 43 38 38 36 33 Victoria

Fisheries

by

lakes

Victorian

Infrastructure Score Weighted score Salinity western

16

of

Habitat

(other species present) assessment

stakeholders.

preliminary

fishing a

from

Size Access Competition Inlake recreational

derived

and Security

333 3333 1 3 3333 2 3 3 19 3333 1 3 3 20 2322 3 2 3 19 3323 2 2 1 17 2323 3 2 3 17 1132 2 2 1 16 2221 3 1 1 14 3321 2 2 2 14 2321 2 2 3 15 2221 1 2 1 13 2122 3 1 2 13 1212 3 1 1 12 1113 3 2 1 11 1112 3 1 1 12 1 3 1 1 11 1 10 scores

553 3 34 2

scientist 1

(within species tolerances) Water qualityWater Water assessment

officers,

fisheries suitability

of

regional Appendix Table

Lake Weighting Lakes Bridgewater Hamilton Struan Bolac Rosine Buninjon Murdeduke Colac Norval Burrumbeet Gnarpurt Colongulac Terangpom Milangil Bookar Beaufort

Suitability assessment of western Victorian lakes for stocking with estuary perch 25