Category Archives: Fish

Piccaninnie Ponds Conservation Park, South Australia

Mark Bachmann

Key words: wetland restoration, Ramsar, rising springs, drainage, hydrology

Piccaninnie Ponds Conservation Park is situated 30 km south east of Mt Gambier in South Australia. For 15-20 years after the park was proclaimed in 1969, there was considerable local interest in trying to address previous changes that had been made to the hydrology of the wetland system.

Although it was protected, reserved and supporting a diverse suite of habitats and range of resident threatened species, Piccaninnnie Ponds was far from intact from a hydrological perspective. Prior to European settlement, water that discharged from the karst, rising-spring wetlands in the system flowed eastward across the State border into the Glenelg River Estuary, in far South West Victoria.

This is how the system remained until 1906, when the first of several attempts to drain the wetlands of Piccaninnie Ponds directly to the sea occurred. What ensued was a turbulent 9 year period during which the fishermen successfully lobbied to have the creek re-directed to the Glenelg River in 1915; a step which was ultimately unpopular with affected landholders and resulted in an alternative flow path again being cut to the sea two years later in 1917. Subsequent ad hoc drainage and development of portions of the wetland system continued and by the time the Piccaninnie Ponds Conservatioon Park was proclaimed in 1969, a new main artificial outlet drained the ponds directly to the sea.

The first attempts at advocacy to restore environmental flows to the Glenelg River in the 1970s and 80s to counter this long-term drying trend in the Park were unsuccessful, until the concept was revisited and a series of steps undertaken, starting in 2001, to achieve hydrological restoration. These steps culminated in the following actions.

 Fig. 1 – Stage 1 weir and fishway under construction in 2006.

Fig. 1,  Stage 1 weir and fishway under construction in 2006.

Actions taken to correct hydrology

  1. 2006 – Stage 1 weir and fishway constructed at Piccaninnie Ponds (Figure 1) regulated outflows on the artificial outlet. This had the effect of increasing inundation in a small area immediately upstream of the structure, under the direct influence of the weir pool created by the new structure, as shown in Fig 2.
  2. 2013 – The stage 2 weir and fishway upgrade (Fig 3) resulted in the structure height being lifted to increase future management flexibility, including providing the future ability to completely block outflows, should the option of re-instating the original flow path one day become a reality.

The stage 2 upgrade was completed at the same time as providing a new flow path to physically reconnect the isolated eastern and western basins at Piccaninnie Ponds. These wetlands had been separated for several decades by a combination of lower water levels, sand drift and the impact of the Piccaninnie Ponds Road. An aerial photographic view of the new flow path is shown in Fig 4.

These works within the original Conservation Park, have occurred in in a complementary way with those that have occurred in the neighbouring, newly reserved area at Pick Swamp, each contributing to the wider vision for restoration of this wetland complex.

Fig. 2. Drained condition of habitat in 2006

Fig. 2a. Drained condition of habitat upstream of the Stage 1 weir (prior to construction  in 2006).

Fig. 3. The upstream inundation and habitat change caused by the stage 1 weir, 2012.

Fig. 2b. The upstream inundation and habitat change caused by the stage 1 weir, 2012.

Results to date.

  • Increase in quality and area of available habitat for native freshwater fish, including the nationally threatened Dwarf Galaxias (Galaxiellla pusilla)
  • Protection of hydrological processes that support a wide range of other threatened species, from a number of taxonomic groups
  • A positive trajectory of change in the distribution of wetland habitats in the vicinity of the works (increased aquatic habitat and reversal of a drying trend that was causing terrestrialisation of vegetation communities)
  • Re-establishment of connectivity between the western and eastern wetlands in the Park for the first time in several decades
Figure 4 – The lifted and redesigned stage 2 weir and fishway on the main artificial outlet at Piccaninnie Ponds – upon completion in 2013.

Fig. 3. The lifted and redesigned stage 2 weir and fishway on the main artificial outlet at Piccaninnie Ponds – upon completion in 2013.

Fig 5a. Piccaninnie

Fig. 4a. Before works – in January 2003

Figure 5 – TOP – Before works image: January 2003. BOTTOM – Post-construction/restoration image: January 2014.

Fig, 4b. After construction/restoration – in January 2014.

Future directions. The works and outcomes described here were delivered by staff working for the South Australian Department of Environment, Water and Natural Resources (DEWNR)

  • Ongoing management of the works and associated ecological monitoring in Piccaninnie Ponds Conservation Park is managed by DEWNR
  • Nature Glenelg Trust staff continue to provide specialist ecological advice and monitoring for the site when required by the site manager, DEWNR

Acknowledgements. The outcomes of the restoration project described can be attributed to a wide range of people who, in addition to the author (see current contact details below), worked at the South Australian Department of Environment, Water and Natural Resources during the period described. DEWNR project ecologists overseeing the works described here include Ben Taylor (stage 1 weir) and Steve Clarke (stage 2 weir and associated works).

The project was generously funded and supported by a range of different grants and programs administered by the South Australian Government, Australian Government and the South East Natural Resources Management Board.

Contact. Mark Bachmann. Nature Glenelg Trust, PO Box 2177, Mt Gambier, SA 5290 Australia; Tel +61 (0)8 8797 8181; Mob+61 (0) 421 97 8181; Email: mark.bachmann@natureglenelg.org.au Web| www.natureglenelg.org.au

See also:

Bradys Swamp EMR short summary

Long Swamp EMR short summary

Long Swamp, Discovery Bay Coastal Park, Victoria

Mark Bachmann

Key words: wetland restoration, Ramsar, hydrology, Glenelg River, drainage

Long Swamp is a 15 km long coastal freshwater wetland complex situated in Discovery Bay Coastal Park, approximately 50 km north-west from Portland in south-western Victoria. The wetland system supports a diverse suite of nationally threatened species and is currently undergoing a Ramsar nomination process. Despite its size, reserved status and impressive biodiversity values, including recognition on the Directory of Important Wetlands in Australia, the local community in Nelson had expressed concern for over a decade about the impact that two artificial outlets to the ocean were having on wetland condition. The outlets were cut during an era when the swamp was grazed, many decades before being dedicated as a conservation reserve in the 1970s.

The wetland originally discharged into the ocean via Oxbow Lake and the Glenelg River mouth at Nelson. These changes to hydrology caused an interruption of flows, contributing to a long-term drying trend within the wetland complex.    This was not immediately obvious to many as the gradual drying of wetlands in a natural area is often less noticeable than in a cleared agricultural area, driven by a seamless and gradual shift towards more terrestrial species within the composition of native vegetation (Fig. 1).

Figure 1. Shrub (Leptospermum lanigerum) encroachment into sedgeland underway in Long Swamp.

In 2012, Nature Glenelg Trust (NGT) became actively involved in Long Swamp, working closely with Parks Victoria, the Nelson Coast Care Group, and the Glenelg Hopkins CMA. The initial involvement was to undertake a scientific review of the aquatic ecological values that might be impacted by the ecological shifts anecdotally observed to be underway. This early work identified that the more remote artificial outlet to the sea (White Sands) had in fact naturally closed, with a dune forming in front of the former channel several years earlier during the Millennium Drought (c. 2005). This formed an area of aquatic habitat immediately upstream of the former outlet that is now home to a diverse native freshwater fish community, including two nationally threatened fish species, the Yarra Pygmy Perch (Nannoperca obscura) and Dwarf Galaxias (Galaxiella pusilla). This observation and other investigations led to the planning of a restoration trial aimed at regulating or possibly blocking the second and final artificial outlet at Nobles Rocks to increase the availability, diversity and connectivity of aquatic habitats throughout Long Swamp, in order to benefit a wide range of wetland dependant species.

As well as undertaking basic monitoring across a broad range of taxonomic groups (birds, vegetation, frogs), the project has a particular emphasis on native freshwater fish populations as a primary indicator of project success.

Figure 2 – Aerial view of Nobles Rocks artificial outlet, detailing the location of the three trial sandbag structures.

Figure 2 . Aerial view of Nobles Rocks artificial outlet, detailing the location of the three trial sandbag structures.

Figure 3 - NGT staff members celebrate the completion of the third and final sandbag structure with some of the many dedicated volunteers from the local community.

Figure 3. Nature Glenelg Trust staff members celebrate the completion of the third and final sandbag structure with some of the many dedicated volunteers from the local community.

Reversal of artificial outlet impact over three phases.

The first two stages of the restoration trial in May and July 2014 involved 56 volunteers from the community working together to construct low-level temporary sandbag structures, initially at the most accessible and technically feasible sections of drain under flowing conditions. Tackling the project in stages enabled us to learn sufficient information about the hydrological conditions at the site in 2014, before commencing the third and final stage of the trial in March 2015. On the 27th April 2015, the main structure was completed, following two days of preparation and nine days of sandbagging (using about 6,600 sandbags), which were put in place with the dedicated help of over 30 volunteers (see Figs 3 and 4). To achieve our target operating height, the structure was raised by a further 30 cm in August 2015.

A series of gauge boards with water depth data loggers were also placed at key locations in the outlet channel and upstream into Long Swamp proper, to monitor the change in water levels throughout each stage of restoration and into the future.

Fig 4a. Long swamp

Figure 4a. View of the Phase 3 Restoration Trial Structure location prior to construction in March 2015.

Fig 4b. Long swamp

Figure 4b. Same location in June 2015, after construction of the Restoration Trial Structure.

Results to date.

Water levels in the swamp immediately upstream of the final structure increased, in the deepest portion of Long Swamp, from 34 cm (in April 2015) to 116 cm (in early September 2015). Further upstream, in a shallower area more representative of the impact on Long Swamp in the adjacent wider area, levels increased from being dry in April 2015, 14 cm deep in May, through to 43 cm deep in early September 2015, as shown in Figure 5. This is a zone where the shrub invasion is typical of the drying trend being observed in Long Swamp, and hence will be an important long-term monitoring location.

To evaluate the response of habitat to short and longer-term hydrological change, we also undertook longer-term landscape change analysis through GIS-based interpretation of aerial photography. This showed that we have currently recovered approximately 60 hectares of total surface water at Nobles Rocks, not including larger gains across downstream habitats as a result of groundwater mounding, sub-surface seepage and redirected surface flows that have also been observed.  These initial results and longer-term outcomes for targets species of native plants and animals will be detailed fully in future reports.

Fig 5a. Long swamp

Figure 5a. Further inland in the swamp after the Phase 3 structure was complete, shown here in May 2015. Depth – 14 cm.

Fig 5b. Long swamp

Figure 5b. Same photopoint 4 months later in September 2015. Depth – 43 cm.

Lessons learned and future directions.Meaningful community participation has been one of the most critical ingredients in the success of this project so far, leading to a strong sense of shared achievement for all involved. Monitoring will continue to guide the next steps of the project, with the ultimate aim of informing a consensus view (among those with shared interest in the park) for eventually converting the trial structure to a permanent solution.

Acknowledgements. Project partners include Parks Victoria, Nelson Coast Care Group, the Glenelg Hopkins CMA and the Friends of the Great South West Walk. Volunteers from several other groups have also assisted with the trials. Grant funding was generously provided by the Victorian Government.

Contact. Mark Bachmann, Nature Glenelg Trust, PO Box 2177, MT GAMBIER, SA 5290 Australia, Tel +61 8 8797 8181, Mob 0421 97 8181, Email: mark.bachmann@natureglenelg.org.au  Web: www.natureglenelg.org.au

See also:

Bradys Swamp EMR short summary

Picanninnie Ponds EMR short summary

Dewfish Demonstration Reach: Restoring native fish populations in the Condamine Catchment

Key words: native fish, riparian habitat, fish passage, aquatic habitat, Native Fish Strategy

The Dewfish Demonstration Reach is a 110 kilometre stretch of waterway in the Condamine catchment in southern Queensland consisting of sections of the Condamine River, Myall Creek and Oakey Creek near Dalby. The Reach was established in 2007 with the purpose of promoting the importance of a healthy river system for the native fish population and the greater river catchment and demonstrating how the restoration of riverine habitat and connectivity benefits native biodiversity and local communities. Landholders, community groups, local governments and residents have worked together to learn and apply new practices to improve and protect this part of the river system.

The purpose of the project is to demonstrate how the restoration of riverine habitat and connectivity benefits native biodiversity and promote the importance of a healthy river system for native fish and the greater river catchment. The goal is to restore native fish populations to 60% of pre-European settlement levels and improve aquatic health within the Reach.

Image 3 - Adding structural timber to Oakey Creek

Fig 1. Adding structural timber to Oakey Creek

Image 4 - Installing a fish hotel into Oakey Creek

Fig 2. Installing a fish hotel into Oakey Creek

Works undertaken. A range of activities to improve river health and native fish communities have been undertaken primarily at seven key intervention sites within the Dewfish Demonstration Reach. These include:

  • Re-introduction of large structural habitat at five sites, involving the installation of 168 habitat structures consisting of trees, fish hotels, breeding pipes and Lunkers (simulated undercut banks).
  • Improvement of fish passage (by more than 140 km) with the upgrade of the fishway on Loudoun Weir and the installation of two rock-ramp fishways on crossings in Oakey Creek.
  • Ongoing management of pest fish, involving carp angling competitions, carp specific traps, electrofishing and fyke nets.
  • Rehabilitation of the riparian vegetation over 77 km of the Reach using stock exclusion fencing, off-stream watering points, weed control and replanting of native vegetation. In Dalby, a 1 metre wide unmown buffer was established on the banks Myall Creek.

Twice-yearly monitoring using a MBARCI model (multiple-before-after-reference-control-intervention) was undertaken to detect the local and reach-wide impacts of the intervention activities. Surveys involved sampling of the fish assemblage at fixed sites and assessment of the instream and riparian habitat.

Image 5 - Wainui crossing before the fishway

Fig. 3 Wainui crossing before the fishway

Image 6 - Wainui crossing after installation of the rock-ramp fishway

Fig 4. Wainui crossing after the installation of the rock ramp fishway

Results. The surveys indicated many of the intervention activities had a positive impact. The fish assemblage and riparian habitat improved at all intervention sites in the Dewfish Demonstration Reach since rehabilitation activities commenced.

The fish assemblages at introduced habitat structures were very similar to those found on natural woody debris, suggesting the introduced habitat is functioning well as a surrogate.

There were significant increases in the abundance of larger fish species, including Golden Perch (Macquaria ambigua) (up to 5-fold), Murray Cod (Maccullochella peelii peelii) (from absent to captured every survey), Spangled Perch (Leiopotherapon unicolor) (up to 9-fold) and Bony Bream Nematolosa erebi (up to 11-fold) in intervention sites following re-snagging. Murray Cod and Golden Perch are now consistently being caught from introduced woody structures and local anglers are reporting that the fishing has improved greatly. Despite this increase there is still limited evidence of recruitment in the area. There have also been small increases in Eel-tailed Catfish (Tandanus tandanus) and Hyrtls Tandan (Neosilurus hyrtli) abundances and a limited amount of recruitment has been observed for these species.

The abundance of smaller native fish has improved significantly in response to the intervention activities undertaken, especially where bankside and instream vegetation was improved. In Oakey Creek Carp Gudgeon (Hypseleotris spp.) abundance increased 1200-fold, Murray-Darling Rainbowfish (Melanotaenia fluviatilis) increased 60-fold and the introduced species Mosquitofish (Gambusia holbrooki) increased 9-fold following intervention activities.

Establishment of a bankside unmown buffer on Myall Creek has enabled natural regeneration of vegetation and resulted in significant increases in aquatic vegetation and native trees. This has led to substantial increases in the smaller bodied native fish assemblage, including a 3-fold increase in Bony Bream, 237-fold increase in Carp Gudgeon, 60-fold increase in Murray-Darling Rainbowfish and a 35-fold in the introduced Mosquitofish.

The abundance of pest fish remains low, except for Mosquitofish which have increased in abundance with the improvements in the aquatic vegetation. There is little evidence of Carp recruitment (Cyprinus carpio), suggesting active management may continue to suppress the population and minimise this species impacts in the Reach.

Image 1 - Myall Creek prior to restoration

Fig 5.  Myall Creek prior to restoration

Image 2 - Myall Creek after restoration

Fig 6. Myall Creek after restoration

Lessons learned and future directions. Improvements of the waterway health and ecosystems can lead to positive responses from native fish populations.

  • Targeting rehabilitation activities to specific classes of fish has been very effective.
  • Introducing habitat structures has been effective for larger fish, and
  • Re-establishing healthy bankside and aquatic vegetation has been vital in boosting the abundance of juveniles and smaller species.

Improvements in the extent of aquatic vegetation have unfortunately also resulted in increased numbers of the introduced pest, Mosquitofish. However, the overall benefits to native fish far outweigh impacts from the increase in the Mosquitofish population.

Stakeholders and Funding bodies. A large number of stakeholders have been involved in this project. The project’s success is largely due to the high number of engaged, involved and committed stakeholders. Without this broad network, costs to individual organizations would be higher and strong community support less likely.

Major funding has been provided by the Murray Darling Basin Authority, Condamine Alliance, Queensland Department of Agriculture and Fisheries and Arrow Energy.

 

Contact. Dr Andrew Norris, Senior Fisheries Biologist, Queensland Department of Agriculture and Fisheries, Bribie Island Research Centre, PO Box 2066, Woorim, QLD 4507; Tel (+61) 7 3400 2019; and Email: andrew.norris@daf.qld.gov.au

READ MORE:

Finbox demonstration reach toolbox: http://www.finterest.com.au/finbox-a-demonstration-reach-toolbox/

Native Fish Strategy – first 10 years. http://onlinelibrary.wiley.com/enhanced/doi/10.1111/emr.12090

Demonstration reaches – Looking back, moving forward http://onlinelibrary.wiley.com/enhanced/doi/10.1111/emr.12092

Monitoring in demonstration reaches https://site.emrprojectsummaries.org/2014/01/25/establishing-a-framework-for-developing-and-implementing-ecological-monitoring-and-evaluation-of-aquatic-rehabilitation-in-demonstration-reaches/

 

Understanding the original distribution and abundance of fish fauna in the Murray-Darling Basin.

Key words: Oral history, native fish, Native Fish Strategy

Threats and Impacts: One of the main goals of the Native Fish Strategy (NFS) was to return native fish communities in the MDB to 60% of that prior to European settlement. Fundamental to realising this goal is knowledge of the original distribution and abundance of fish fauna in the MDB. However, there has been limited readily available information on the rivers and their fish populations at the time of European settlement.

Broad aim and specific objectives: The aims of this project were to:

  1. collect, collate and analyse historical information on native fish in the southern half of the Murray-Darling Basin;
  2. identify the original distribution and habitat preferences of Trout Cod (Maccullochella macquariensis) and resolve the ongoing debate on this issue;
  3. identify the original distribution and habitat preferences of the other large fish species, primarily those of interest to anglers;
  4. collect general historical information on native fish, in particular aspects of their biology;
  5. document changes or events that may have contributed to the decline of native fish;
  6. present the information collected in a format to assist scientists and managers engaged in the recovery of native fish but also accessible to the general public so as to increase community awareness of the plight of Trout cod and other native fish species.

Methods: Photographs, written accounts and oral history were collected on the past distribution and abundance of Trout Cod and other large native fishes of the Basin. For Trout Cod, records held in museum databases were located and used, and nearly 400 photographs of catches of Cod and other native fish were located and examined, most of them predating 1950 and the oldest dating from 1862. Photographs were sourced from anglers, angling clubs, individuals, historical societies, books and newspapers.

An extensive search of old written accounts of native fish captures was also undertaken, including writings of early settlers, naturalists and anglers, newspaper records, hand-written manuscripts, indigenous accounts, and reports and appendices.

Figure 1. A 124 pound Murray Cod shot in the Barr Creek near Kerang 1939. On the left is Eddie Ashton, older brother of Mick Ashton who stands on the right. (Photo courtesy of Mick Ashton)

Figure 1. Brothers Eddie Ashton (left) and Mick Ashton – with a 124 pound Murray Cod shot in the Barr Creek near Kerang 1939.  (Photo courtesy of Mick Ashton)

Local historical societies and angling clubs were contacted to help identify senior residents who may possess knowledge relating to native fish. Participants were interviewed to gather information on their personal history, fish captures, locations and timing, and the changes they observed over the years. Photographs were used to aid validation of species caught. Interviews were recorded and provided to the individual for correction and confirmation. Over 140 people were contacted with the two oldest being 95 years of age whose memories extended back into the 1920s.

The reliability of individual pieces of historical evidence relating to the presence of native fish in specific waters was assessed and rated as high, moderate or low. From the information collected maps were created for each catchment recording the locations of historical accounts for each species considered to be of high quality. Historical material was collated and summarised for each catchment.

Figure 2. Photo of fish caught from the Goulburn River at McGee’s Beach, Alexandra, 1924. Fish include trout cod, Murray cod, Macquarie perch and catfish. Young Russell Stillman is visible in the foreground. (Photo courtesy of Russell Stillman)

Figure 2. Fish caught from the Goulburn River at McGee’s Beach, Alexandra, 1924. Fish include Trout Cod, Murray Cod, Macquarie Perch and Catfish. Young Russell Stillman is visible in the foreground. (Photo courtesy of Russell Stillman)

Figure 3, The Murray River near Corryong c1910. Changes are already evident including a bank covered in Scotch Thistles (Photo courtesy of Bob Whitehead)

Figure 3, The Murray River near Corryong c1910. Changes are already evident including a bank covered in Scotch Thistles (Photo courtesy of Bob Whitehead)

Findings: From all of the historical sources, including newspaper records, journal entries, indigenous accounts, naturalist’s notes and personal photographs, a wealth of information from across the MDB has been collected on Trout Cod, with much also on the other larger fish species e.g. Murray Cod (Maccullochella peelii), Golden Perch (Macquaria Ambigua), Silver Perch (Bidyanus bidyanus), Macquarie Perch (Macquaria australasica), Catfish (Tandanus tandanus) and River blackfish (Gadopsis marmoratus). For each of these species the following information is presented:

  •          European discovery
  •          Aboriginal and European names
  •          Distribution and habitat associations
  •          Translocations
  •          Size
  •          Community value
  •          Current conservation status
  •          Map of former distribution and abundance

From this information a reliable indication of the pre-European settlement distribution and abundance of the larger native fish species of the MDB was constructed.

Lessons learned and future directions:  This project has provided an indication of the distribution and abundance of Trout Cod and other large native fish species in the MDB prior European settlement. By examining this information, researchers and managers can get an idea of what populations of Trout Cod used to be like and set targets for rehabilitation efforts to achieve the goal of the NFS to return native fish populations back to 60% of their pre-European settlement condition.

Stakeholders and Funding bodies: This project was funded through the Murray-Darling Basin Authority’s Native Fish Strategy.

Contact: William Truman, Tel: + 61 7 4042 4800, Email: williamtrueman@bigpond.com.

Link: http://australianriverrestorationcentre.com.au/mdb/troutcod/book.php

Assessing the effectiveness of Integrated Pest Management in Queensland

Key words: Integrated Pest Management, pest fish control, Native Fish Strategy

Threats and Impacts: Carp (Cyprinus carpio) are believed to impact on native fish communities by increasing turbidity, up-rooting delicate shallow-rooted vegetation, competing with native fishes and other aquatic fauna for food and space, and indirectly promoting the development of toxic algal blooms.

All of the currently available methods for Carp control have limitations. Integrated Pest Management (IPM) involves the application of a range of technologies applied simultaneously, and focussing on achieving broader objectives (e.g. improved habitat) rather than simply reducing pest numbers.

Broad aim and specific objectives: The objectives of this project were to apply a range of Carp control techniques, as an integrated package, to:

  • intensively reduce Carp at a particular location, and measure the response;
  • achieve a significant reduction in damage caused by Carp using existing techniques; and,
  • demonstrate to the community the commitment to on-ground control.

The study was conducted at four lagoon sites, two in the Condamine River catchment, and two in the Macintyre river catchment.

Methods: One lagoon in each catchment was selected as an experimental site for intensive carp removal, and the other was used as a reference site which received no carp treatment.

Each site was sampled on eight occasions for the following response variables: water quality (temperature, pH, conductivity, turbidity, dissolved oxygen, light penetration, available forms of nitrogen and phosphorus); phytoplankton biovolume and diversity; zooplankton biomass and diversity; benthic macroinvertebrate abundance and diversity; native fish abundance, biomass and diversity; carp abundance, biomass and size distribution; and abundance of piscivorous birds and turtles.

One sampling event was conducted before the carp reduction treatment and a further seven samples were performed after Carp reduction. Carp removal employed a variety of methods based on boat electrofishing, gill nets, fyke nets, angling, commercial-scale netting and traps, and screens to prevent re-entry of Carp.

Figure 1: electrofishing during carp removal at rainbow lagoon. (Photo courtesy Peter Gehrke)

Figure 1: electrofishing during carp removal at rainbow lagoon. (Photo courtesy Peter Gehrke)

Figure 2: Researcher Sarah St Pierre live picking macroinvertebrates (Photo courtesy of Nissa Murphy)

Figure 2: Researcher Sarah St Pierre live picking macroinvertebrates (Photo courtesy of Nissa Murphy)

Findings: In Rainbow Lagoon (one of the experimental sites), Carp removal achieved an estimated 51% reduction in abundance and 43% biomass reduction, compared with 41% abundance and 33% biomass reductions in Warra Lagoon (the other experimental site). Reduction of Carp biomass by approximately 30 kg per ha allowed a threefold increase of more than 90 kg per ha in native fish that are eaten by larger fish species and fish-eating birds.

The size and weight of Carp removed differed markedly between Warra Lagoon and Rainbow Lagoon. Rainbow Lagoon had large numbers of small Carp, while Warra Lagoon had relatively large numbers of big Carp, with relatively few small individuals. The differences in Carp populations between lagoons are likely to result in different ecosystem responses over time.

Boat electrofishing was the most effective method of Carp removal used; fyke nets were the second most effective method, while the number of Carp removed by angling was far lower than other methods.

A succession of ‘transient’ responses to Carp reduction was observed in treatment lagoons. Whilst the exact nature of succession differed between lagoons, the generalised pattern following Carp reduction was evidenced as (i) an increase in biomass of large zooplankton; (ii) an increase in abundance of benthic macroinvertebrates; and (iii) increased biomass of gudgeons (Hypseleotris spp.) and Bony Herring (Nematalosa erebi).

These results suggest that of the full set of potential ecosystem responses to Carp reduction, only a subset may be demonstrated in individual locations because of the influence of local drivers and constraints. Due to a range of factors, the environmental responses of several variables, including water quality, macrophytes, zooplankton and macroinvertebrates, could not be linked to Carp control.

Lessons learned and future directions:Modest reductions in Carp biomass can provide significant benefits for native fish and, if continued, may be expected to translate into longer-term increases in native fish populations.

  • Carp in turbid wetlands interact strongly with native fish through pelagic food web pathways involving zooplankton, as well as benthic macroinvertebrate pathways.
  • Carp reduction has the potential to contribute significantly to restoring populations of native fish by increasing food availability.
  • Environmental outcomes of Carp reduction include direct conservation benefits to native fish, potential increases in popular recreational species and improved aquatic ecosystem health.
  • Piscivorous fish (e.g. Murray cod, Maccullochella peelii) are likely to have increased prey availability as a result of Carp reduction.
  • Improving native fish populations in key wetlands by reducing Carp biomass may strengthen the value of permanent lagoons as drought refuges for native fish.

Stakeholders and Funding bodies: This project was funded through the Murray-Darling Basin Authority’s Native Fish Strategy.

Contact: Sarah St Pierre, SMEC. Tel: + 61 (07) 3029 6600.

Link: http://www.finterest.com.au/wp-content/uploads/2013/07/MD923%20Integrated%20pest%20management%20QLD.pdf

The identification and protection of drought refuges for native fish in the Murray-Darling Basin.

Key words: drought, refuge, native fish, Native Fish Strategy

Threats and Impacts: From 1996 to 2009, the Murray-Darling Basin (MDB) experienced severe drought conditions. As the impacts of the drought worsened, the need for improved and co-ordinated management responses became increasingly important to protect key ecological assets and critical aquatic habitats and ecosystems. Within the MDB it was uncertain whether an adequate network of drought refuges (e.g. flowing perennial river reaches, deep waterholes) remained to preserve native fish species/populations through extended drought. This project was established to address this knowledge gap.

Aims: The broad aims of the project were to:

  • define, identify and explore the current status and management of drought refuges in the MDB (Figs 1 and 2); and,
  • develop guidelines and an approach to identify, prioritise and protect drought refuges for native fish that can be implemented across the MDB.
Figure 1: A drying refuge (Photo courtesy of Luke Pearce)

Figure 1: A drying refuge (Photo courtesy of Luke Pearce)

Figure 2: Drought refuge on the Condamine River (Photo courtesy of Michael Hutchison)

Figure 2: Drought refuge on the Condamine River (Photo courtesy of Michael Hutchison)

Methods: The current status and management of refuges were explored using a number of techniques including questionnaires, an expert/management workshop and a review of relevant literature and management programs. This process identified the types of habitats that serve as drought refuges across the MDB, the key native fish species that have been targeted for protection under drought response programs, key threats and the current management responses/actions undertaken for refuge protection. In order to catalogue refuge sites, a preliminary list of critical sites was developed in collaboration with managers and experts.

An approach to identify and protect refuges was developed in conjunction with regional agencies and jurisdictions from two pilot valleys: the Goulburn Broken catchment in northern Victoria and the Moonie catchment in south-eastern Queensland. Under this phase of the project, definitions and criteria for identifying and prioritising refuges were developed in conjunction with management agencies. A management tool was developed for collating refuge values and habitat attributes, as well as threats to the maintenance and improvement of these important characteristics. This approach may be used for the prioritisation of interventions based on key management principles, including: threatened species, protection of habitat biodiversity, water allocation, catchment management actions, fisheries management actions and restoration.

Based on the information elicited from the pilot valley analyses, a template was produced to assist in refuge identification and management across the MDB. This template documents a process that can be integrated into regional natural resource management frameworks across the MDB, acknowledging that different states and regions are subject to various legislative and policy environments and possesses varying levels of information, data, planning structures and intervention opportunities that relate to aquatic habitat protection.                                                                

Findings: A wide range of aquatic habitats were considered important as drought refuges, with unregulated waterways the most commonly identified habitat type, and of the greatest concern to managers. In some instances, key native fish species were used to identify particular drought refuges. The protection and/or management of the refuges for these species either followed a ‘single species’ approach (more common in the drier, southern MDB) or ‘multi-species/community’ approach (more common in the northern MDB).

Refuges were defined and identified at larger spatial scales in the northern MDB and at smaller, site-specific scales in the southern MDB. The reason for these different approaches reflects the varying intensity of drought impacts across the MDB. These different approaches to the management and protection of drought refuges reflect the different aspects of native fish ecology, in terms of resistance versus resilience.

This study concluded that a holistic approach to drought management was required with drought refuge protection plans incorporating enough flexibility to identify and invest in emergency short-term responses during peak drought periods as well as having guidelines in place aimed at broader scales to promote long-term resilience in native fish populations.

Lessons learned and future directions:  This study has reinforced that priority areas which act as drought refuges require adequate management to ensure the long term survival of native fish populations. This study identified the two scales at which drought management operates and the strengths of each scale to address both short and long-term impacts of drought on native fish and their habitats. This information will ultimately lead to better drought management regarding native fish and their habitats, which will minimise the risk of loss of native fish species and populations and preserve native fish habitats.

Stakeholders and Funding bodies: This project was funded through the Murray-Darling Basin Authority’s Native Fish Strategy.

Contact: Dr Dale McNeil, South Australian Research and Development Institute. Tel: + 61  8 8207 5342, Email:  dale.mcneil@sa.gov.au

Captions

 

Figure 2: A drying refuge (Photo courtesy of Luke Pearce)

LINK: http://www.sardi.sa.gov.au/__data/assets/pdf_file/0006/186702/Drought_Refuges_for_Native_Fish.pdf

The potential for Mozambique Tilapia to invade the Murray–Darling Basin and the likely impacts: a review of existing information

Key words: Tilapia, pest fish, invasion risk, Native Fish Strategy

Threats and Impacts: Mozambique Tilapia (Oreochromis mossambicus) is a major pest fish species in Australia (Fig 1). A successful invader, it has managed to dominate natural waterways into which it has been introduced. It is not currently found in the Murray–Darling Basin; however, it has established thriving populations in catchments neighbouring the Basin. In some places, it is only a short distance from the northern headwaters. There is a high risk that this species will be introduced to the Basin.

Project aims and methods: Despite the high risk of introduction, prior to this project minimal work had been done to estimate the potential range Tilapia might occupy in the Basin, or to predict its possible impacts on natural, economic or social assets. This project set out to review available literature and assess likely impacts in an attempt to provide some information about these potential threats.

In order to estimate the potential range of Tilapia in the Murray–Darling Basin, this project set out to to:

  • predict the range in the Basin where Tilapia may survive through colder winter temperatures;
  • determine the length of the feasible breeding season (including the number of broods possible in that time) in different ranges; and,
  • determine the portion of the year in which Tilapia may feed and is therefore likely to have impacts on ecological processes through the food web.

This included:

  • estimating the lower temperature tolerance for Tilapia based on literature and survival rates of populations already infesting locations in Queensland;
  • identifying the minimum winter temperatures recorded at different locations throughout the Basin; and,
  • using the distribution of native fish with similar temperature tolerances to Tilapia as a surrogate.
Figure 1. Female Mozambique Tilapia carrying juveniles in her mouth (Photo courtesy of QLD DAFF)

Figure 1. Female Mozambique Tilapia carrying juveniles in her mouth (Photo courtesy of QLD DAFF)

Figure 2. male Mozambique Tilapia (Photo courtesy of QLD DAFF)

Figure 2. male Mozambique Tilapia (Photo courtesy of QLD DAFF)

Figure 3. Stunted Tilapia (male top, female bottom) mature at only a few centimetres in length, (Photo courtesy of QLD DAFF)

Figure 3. Stunted Tilapia (male top, female bottom) mature at only a few centimetres in length, (Photo courtesy of QLD DAFF)

Findings: Tilapia has a wide and varied diet and can occupy a diverse range of habitats, however, the one factor that appears to affect Tilapia is its vulnerability to cold temperatures. Based upon minimum temperature tolerated by Tilapia and the minimum water temperature data available, Tilapia have the potential to infest the northern Basin in Queensland and parts of New South Wales, through the western inland catchments of NSW and down to the Lower Lakes and lower Murray in South Australia. This equates to a distribution occupying approximately half of the MDB.

Tilapia is capable of sustaining reproducing populations under the conditions found in much of the MDB, as breeding and feeding can occur for significant portions of the year. In the northern parts of the Basin, and many southern parts, median water temperatures could see a breeding season of at least 3–6 months in duration with around 4–6 broods for each female in each breeding season.

Tilapia impacts have been recorded in a number of locations both in Australia and overseas. The key impacts recorded include major declines in commercial and traditional fisheries, fish extinctions, destruction of beds of aquatic plants) and declines in water quality. Some of the predicted direct impacts of Tilapia on the Murray–Darling Basin include:

  • direct predation by Tilapia;
  • competition for resources (food, habitat);
  • destruction of macrophytes and other aquatic plants used as breeding or nursery habitat by native species;
  • habitat disturbance;
  • transmission of diseases and parasites;
  • competitive exclusion of native fish from favourable habitat by tilapia’s aggressive behaviour;
  • increase of blue-green algal blooms (through resuspension of nutrients);
  • winter die-offs of tilapia (polluting waterways); and,
  • undermining river banks due to destruction of river plants and nesting behaviour.

Review of recent studies indicate that Tilapia consume juvenile native fish, including members of genera that occur in the Murray–Darling Basin, such as Rainbowfishes (Melanotaeniidae), Carp Gudgeons (Hypseleotris spp.), Hardyheads (Atherinidae), Bony Herring (Nematalosa erebi) and Glassfish (Ambassidae). It is possible that the potential preying of tilapia on native fish has been underestimated. 

Lessons learned and future directions: This project highlighted that invasion of the MDB by Tilapia could be disastrous for many (up to 18) native fish species of the MDB. Areas and species most at risk from Tilapia and the likely impacts if invasion occurred were identified. The study recommends a ‘prevention is better than cure’ approach with respect to Tilapia invasion and highlights education and awareness as a key factor. This review should be most pertinent in areas close to current distribution of wild tilapia populations (i.e. north-eastern MDB). 

Stakeholders and Funding bodies: This project was funded through the Murray-Darling Basin Authority’s Native Fish Strategy.

Contacts: Dr Michael Hutchison, Queensland Department of Agriculture Fisheries and Forestry. Tel: + 61 7 3400 2037, Email: Michael.Hutchison@daff.qld.gov.au

Link http://www.mdba.gov.au/sites/default/files/pubs/Tilapia-report.pdf

Assessment of an infrared fish counter (Vaki Riverwatcher) to quantify fish migrations in the Murray-Darling Basin

Key words: infrared, fish counting, VAKI Riverwatcher, fish migration, Native Fish Strategy

A number of fishways have been constructed under the auspices of the NFS to help reinstate passage of fish past a number of barriers in the Murray-Darling Basin (MDB). Because it is too expensive to continuously trap fishways to gather information on migratory behaviour, using an electronic monitoring unit to continuously monitor fish migrations is an attractive option for monitoring fish movement and fishway effectiveness. The Vaki Riverwatcher technology has been successfully used in Northern Hemisphere rivers to count and measure the size, date and shapes of fish which pass through an infrared scanner. Prior to this project, this technology had not been trialled on Australian rivers and species to evaluate utility for monitoring purposes.

Broad aim and specific objectives: This study aimed to perform a field study on the effectiveness of an infrared fish counter, the Vaki Riverwatcher in anticipation of wider application throughout the Murray-Darling Basin. The limitations and advantages of the system were fully explored in both controlled and field environments.

The objectives of this project were to:

  • perform a field assessment of an infrared fish counter in the Basin;
  • determine if turbidity reduces the accuracy of an infrared fish counter; and
  • determine how fish behave in relation to an infrared fish counter and fish trap.

Methods: Laboratory trials were undertaken to determine the ability of the Riverwatcher (Figs 1-3) to cope with different turbidity and fish migration rates. Silver Perch (Bidyanus bidyanus) were passed through the unit under a range of turbidity between 0 and 100 Nephelometric turbidity units (NTU).

Field trials were undertaken at Lock 10, on the Murray River (near Wentworth), which had been retro-fitted with a vertical slot fishway in 2006. The unit was used in conjunction with a DIDSON sonar unit and a standard fish trap, to assess the ability of the Riverwatcher to distinguish different species, count migrating fish, estimate the size of migratory fish and to assess fish behaviour in and around the unit.

Field trials were also performed to test the Vaki Riverwatcher system under river conditions. The unit was used in conjunction with other electronic monitoring gear, and also fish traps, to assess the ability of the Riverwatcher to distinguish different species, count migrating fish, estimate the size of migratory fish and to assess fish behaviour in and around the unit.

Figure 1. The Vaki Riverwatcher (Photo courtesy of Lee Baumgartner)

Figure 1. The Vaki Riverwatcher (Photo courtesy of Lee Baumgartner)

Figure 2. Installing the vaki riverwatcher into the lock 10 fishway (Photo courtesy of Lee Baumgartner)

Figure 2. Installing the vaki riverwatcher into the lock 10 fishway (Photo courtesy of Lee Baumgartner)

Figure 3. Manipulating turbidity to quantify vaki effectiveness (photo courtesy of Lee Baumgartner)

Figure 3. Manipulating turbidity to quantify vaki effectiveness (photo courtesy of Lee Baumgartner)

Findings: The Riverwatcher performed well and counted hundreds of migrating fish. Fish counts from the unit roughly corresponded with those caught within a fish trap upstream of the unit. However, the unit tended to underestimate fish size and some fish avoided contact with the unit.

Experimental trials on the impacts of turbidity on the Riverwatcher revealed that the unit generally overestimated fish counts during low turbidity but underestimated during high turbidity. It was also difficult to identify fish that actively avoiding passage through the unit.

Lessons learned and future directions: The Riverwatcher unit provided a powerful mechanism to monitor fish movement but often underestimated fish numbers and lengths which detracted from the quality of the hardware. If these limitations are overcome, or at least quantified, the unit would represent a cost effective mechanism to count and measure migrating fish.

The unit has a range of potential applications including within fishways, at floodplain regulators, within supply channels or other points of suspected fish movement. It is flexible in terms of operation, but is limited by the restricted width of the scanner unit. Where width or depth is an issue, additional scanner units can be linked together to create an array which can give wider spatial coverage of the target area. Provided the site of application is a known point of fish movement, obtaining count and size data on migrants would be possible and should be considered for a long-term deployment at a key site of fish migration in the Basin. Additional trials would help to determine if the gear is suitable for determining trends in fish movement over a longer time period.

Stakeholders and Funding bodies: This project was funded through the Murray-Darling Basin Authority’s Native Fish Strategy. 

Contact: Dr Lee Baumgartner, New South Wales Department of Primary Industries. Tel: + 61 2 6958 8215, Email: lee.baumgartner@dpi.nsw.gov.au

LINK: http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0005/322970/AE_2010_Output-1629_Baumgartner-et-all_Vaki-Riverwatcher-report_REPORT.pdf

Scoping study to determine the methodologies and data availability for identifying native fish hotspots in the Murray-Darling Basin

Key words: hotspots, resilience, native fish, Native Fish Strategy

Recent ecological research at the landscape scale suggests that there may be key locations, or “hotspots”, that play a disproportionate role in sustaining species and ecological communities. The identification of native fish “hotspots’ in the Murray-Darling Basin (MDB) would greatly assist managers in protecting biodiversity and maintaining important ecological processes for native fishes.

Broad aim and specific objectives: This scoping study was undertaken to help guide future investment in the identification of “hotspots” in the Basin, by conducting broad reviews of the literature and available data, and consulting extensively with a range of relevant experts to:

  • develop an appropriate definition for what constitutes a native fish hotspot in the MDB;
  • identify the requirements of resource managers and other stakeholder groups including the Authority to maximise utility and adoption of the hotspots project;
  • identify information already available which may be useful to identify native fish ‘hotspots’;
  • determine appropriate metrics/methodologies to identify geographical areas or ‘hotspots’ across the MDB that are significant for native fishes in terms of species diversity, population densities and key ecological processes;
  • develop an appropriate experimental design for a large-scale project to demonstrate the applicability of the hotspots concept and subsequently enable the extrapolation across the whole of the MDB; and,
  • provide a template for similar studies to be undertaken on other fish species in the Basin.
Figure 1. A healthy stretch of the Murrumbidgee with plenty of habitat for native fish (Photo courtesy of Jamin Forbes)

Figure 1. A healthy stretch of the Murrumbidgee with plenty of habitat for native fish (Photo courtesy of Jamin Forbes)

Figure 2. Identification of native fish 'hotspots' would greatly assist in the management of native fish communities (Photo courtesy of Jamin Forbes)

Figure 2. Identification of native fish ‘hotspots’ would greatly assist in the management of native fish communities (Photo courtesy of Jamin Forbes)

Methods:  The first stage of the scoping study was to define the hotspots concept and management applicability of the project for key stakeholders within the MDB. This was achieved through an extensive review of the background literature of the hotspots concept (both within Australia and globally) and an expert panel workshop to:

  • clearly define the hotspots concept for use in the MDB and within the project, with particular reference to types of criteria;
  • explore spatial and temporal variability within existing datasets for identifying hotspots; and,
  • explore the management applicability and use of MDB hotspots for native fish.

A second expert panel workshop was held to review relevant ecological information for the priority species and communities, sampling methodologies and the spatial and temporal coverage of existing data and with the aims of:

  • determining appropriate sampling methodologies for identifying hotspots of priority species and communities; and,
  • using this methodology and data availability to develop an appropriate study design which could be used in Stage II of the of the project to identify ‘hotspots’ across the MDB that are significant for native fish.

Findings: The study mainly focussed on four high priority native fish species; Murray Cod (Macculochella peelii), Silver Perch (Bidyanus bidyanus), Golden Perch (Macquaria ambigua) and Freshwater Catfish (Tandanus tandanus), though some consideration was also given to some other species of conservation concern. The study defined a “hotspot” as being “areas within riverscapes that have extraordinary importance for fish or processes that sustain native fish populations”.

The study highlighted the importance of understanding the processes underlying hotspots in order to maximise the efficiency of management actions and conservation measures to ensure cost-effective return on interventions. To achieve this, a suite of suitable metrics were developed which encompassed both direct measures of fish and measures of the ecological drivers supporting them for each of the priority species and communities.

The study concluded that insufficient data currently exists to adequately identify hotspots across the MDB. However, this project provided an approach and suitable methods to collect relevant data that could then be used with current data to determine and describe hotspots in the MDB.

It was recommended that the next step should be to investigate large-scale patterns in focus species abundance using existing datasets, determine the applicability of the hotspots concept for all metrics in a subset of river valleys, then expand on observed trends to other valleys to identify hotspots throughout the MDB.

Lessons learned and future directions:

The identification of “hotspots’ in the Murray-Darling Basin (MDB) would greatly assist managers in protecting biodiversity and maintaining important ecological processes for native fishes. This study provides a pathway by which to engage the next step in the process of validating the hotspot concept in the MDB. This will identify critically important habitat required for protecting or rehabilitation to support priority native fish species.

Stakeholders and Funding bodies:  This project was funded through the Murray-Darling Basin Authority’s Native Fish Strategy.

Contacts: Zeb Tonkin, South Australian Research and Development Institute. Tel: + 61 3 9450 8600, Email: zeb.tonkin@depi.vic.gov.au.

Behavioural aggression in Gambusia holbrooki is conditional upon temperature and relative abundance.

Key words: Eastern Gambusia, aggression, pest fish, Native Fish Strategy.

Threats and Impacts: Introduced to Australia in 1925 as a potential mosquito control agent, the fish Gambusia (Gambusia holbrooki) (Figs 1 and 2) is now present in almost every major Australian drainage, including the Murray-Darling Basin. Gambusia are extremely aggressive, harassing, predating and attacking native fish; and are thought to also pose a significant threat to many amphibians and invertebrates.

Broad aim, specific objectives and methods: This project explored in aquaria how aggressiveness of Gambusia changed according to the relative abundance of two native fish species (western carp gudgeon Hypseleotris spp. and juvenile Golden Perch Macquaria ambigua). Five treatments were run involving  combination of Gambusia to native fish ratios and temperatures. The project was designed to improve understanding of how Gambusia might behave when it colonises new areas and how behavioural responses might be affected by efforts to control their numbers.

Figure 1: Female Gambusia. Note that all fish are in gravid condition. (Photo courtesy of Tarmo Raadik.)

Figure 1: Female Gambusia. Note that all fish are in gravid condition. (Photo courtesy of Tarmo Raadik.)

Figure 2: Mature female Eastern Gambusia (photo courtesy of Tarmo Raadik)

Figure 2: Mature female Eastern Gambusia (photo courtesy of Tarmo Raadik)

Findings: The study found that Gambusia were highly aggressive towards both species of native fish and that aggressiveness increased when Gambusia were outnumbered by native fish. The study also found that the type of aggressive behaviour by Gambusia (e.g. biting or chasing) was specific to the native species it was interacting with. Gambusia were shown to dominate the available habitat within the tank very shortly after introduction. The high aggression and dominance behaviour exhibited by Gambusia when outnumbered assist this species when invading new habitats and may also have implications for eradication efforts aimed at this invasive species.

Lessons learned and future directions: The increased aggression by Gambusia when outnumbered potentially means that control efforts that reduce the abundance of Gambusia but don’t fully eradicate them may not be beneficial to native fish in some cases. The research suggested that aggressive interactions from Gambusia may not decrease as a result of eradication efforts.

Stakeholders and Funding bodies: This project was funded through the Murray-Darling Basin Authority’s Native Fish Strategy.

Contacts: Dr Andy Moore, Department of Agriculture Fisheries and Forestry. Tel: + 61 2 6272 3090, Email: anthony.moore@daff.gov.au.

Link: http://www.finterest.com.au/wp-content/uploads/2013/07/MD1224%20Gambusia%20Aggression.pdf