Lake Condah Restoration Project - Biodiversity Assessments
The Budj Bim landscape near Portland, Victoria, is listed nationally as a region of natural and cultural significance. Rock formations shaped by ancient volcanic activity allowed the traditional owners, the Gunditjmara, to harvest ‘kooyang’ (Short-finned Eels Anguilla australis) during their migration phases. Eels and other fish such as Tupong (Pseudaphritis urvilli) were trapped, and eels were held in ponds prior to consumption or trade. The natural flooding/drying cycles within the region’s largest water body, Lake Condah, was crucial to this traditional fishery. However, since construction of the Condah Drain in 1954 to mitigate flooding of the surrounding land, the frequency and duration of lake inundation has markedly declined.
As part of a program to restore the natural and cultural values of Lake Condah, a biodiversity assessment was undertaken to determine the ecological responses of fish to flow in Lake Condah and its major tributary Darlot Creek, prior to restoration of water to the lake. In collaboration with the Winda Mara Aboriginal Corporation, fish surveys were conducted each season from winter 2007 to autumn 2008. Important findings were the high abundance and species diversity of native fish species compared with introduced fish species, and the discovery of relatively widespread and abundant populations of the threatened Yarra Pygmy Perch and Dwarf Galaxias. Acoustic telemetry technology was used to monitor the critical movements (e.g. to spawning grounds) of eels and Tupong in relation to environmental variables (e.g. flow, lake inundation). Eels were often tracked moving long distances (>30 km) during high flows. Tupong generally migrated downstream to the associated estuary and out to sea during the spawning season, suggesting that spawning occurs in the marine environment rather than in the estuary as previously thought.
A major outcome of this project has been skill sharing between researchers and members of the local indigenous community. Members of the Winda Mara Corporation have been trained in aquatic research, and ARI staff have gained an insight into indigenous issues and the cultural heritage of the Lake Condah region. Funding has been secured through the Glenelg-Hopkins Catchment Management Authority to continue the fish tracking component of the study.
For more information contact David.Crook@dse.vic.gov.au
The following report is available:
 ARI Technical Report 180 - Lake Condah restoration project - biodiversity assessments (PDF - 1.6 MB)
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Watering Floodplain Wetlands for Native Fish - Murray-Darling Basin
Floodplain wetlands are wetlands that are situated on a river’s floodplain, receiving the majority of their water from the river. The flow of the river heavily influences when a floodplain wetland receives its water, how much water it receives, and how long it stays wet for. These wetlands are utilised by fish species that inhabit the associated river, and are thought to play an important role in their spawning, growth and survival. Aside from the ARI project examining Environmental Water Allocations and Fish Spawning and Recruitment - Barmah-Millewa Forest, there is limited information available on the relationships between characteristics of inundation (or watering) of floodplain wetlands (such as timing) and fish productivity. For example, if inundation does not coincide with the preferred fish spawning period, or if it occurs during winter months when food production is low, native fish populations may not be able to take full advantage of the influx of water.
Such information is particularly important for managing wetlands associated with rivers whose flow patterns have been altered by water extraction for irrigation and retention in dams, and whose native fish populations are in decline. The Murray River is an example of one such system. A recent workshop with wetland managers highlighted that many do not consider general benefits to native fish when allocating environmental water to floodplain wetlands. Most environmental water is used to target other ecosystem attributes such as floodplain vegetation communities, waterbird breeding, or the survival of a particular endangered fish species during drought.
A study is underway to determine optimal wetting protocols for native fish of floodplain wetlands to aid in management of the river systems in the Murray-Darling Basin. Wetlands in the mid-Murray River region will be studied to document the relationships between the timing, depth, scale and duration of wetland inundation and wetland productivity, to fish abundance and condition, nutrients and zooplankton density. Movements of fish between wetlands and the river will also be investigated. Native fish species that occur in high abundances in these wetlands and that will be monitored during the study include the Carp Gudgeon species complex (Hypseleotris spp.), Australian Smelt (Retropinna semoni) and the Un-specked Hardyhead (Craterocephalus stercusmuscarum fulvus).
This research is a collaborative effort with the Murray-Darling Freshwater Research Centre and is funded by the National Water Commission.
For more information contact: Leah.Beesley@dse.vic.gov.au
The following report is available:
ARI Technical Report 189 - Watering Floodplain Wetlands in the Murray-Darling Basin to Benefit Native Fish: a discussion with managers (PDF - 2.8 MB)
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Regulators and Movements of Native Fish - Barmah-Millewa Forest
The Barmah-Millewa Forest is a large red-gum forest on the Murray River floodplain near Echuca, downstream from the Hume Dam and Yarrawonga Weir. It has high environmental, cultural, social and economic values and is a wetland of international importance under the Ramsar convention. It is characterised by low-lying river banks and complex mosaics of creeks, flood-runners, anabranches, wetlands, and floodplains. Most of the waterways are controlled by regulators (about 30), which protect the forest from unnatural flooding caused by high irrigation flows. Research over the past several years has found, however, that these regulators negatively impact upon the river-floodplain movements of native fish.
The movements of native fish were followed using a variety of techniques including radio-telemetry, t-bar tag returns (from anglers recapturing tagged fish), sampling waterways using electrofishing and netting, and pumping out waterbodies isolated by receding waters. It was found that in regulated systems fish move into offstream creeks when regulator gates are open, but then become trapped when water levels drop and gates close. Fish stranded this way are subjected to a range of threats including reduced water quality, and increased angling and predation pressure.
To improve the movements of native fish in this system it is recommended that;
- fishways be installed on large floodplain regulators to facilitate fish movement;
- regulator gates be left open and flows in floodplain creeks be allowed to recede with the Murray River - allowing unrestricted access to the River
- the Murray River be kept at a lower level to cope with unexpected within-bank river rises - reducing the need to open floodplain regulators (to prevent unwanted flooding) and so reducing the incidence of fish moving into floodplain creeks and becoming stranded;
- environmental water allocations be delivered during spring-summer months, the known spawning period for native fish, during which fish would most benefit from increased water flow
For further information contact Matthew.Jones@dse.vic.gov.au
The following report is available:
Impact of Flow Regulation Structures on Fish in the Barmah-Millewa Forest 2004 (PDF - 1.9 Mb)
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Environmental Water Allocations and Fish Spawning and Recruitment - Barmah-Millewa Forest
The Barmah-Millewa Forest, the largest River Red Gum forest in Australia, is situated on the Murray River floodplain, and contains a wide variety of habitats required for all aspects of fish life history. A long history of flow regulation of the Murray River (via the Hume Dam and Yarrawonga Weir) has significantly altered the frequency and extent of natural flooding of the Forest. Such changes have had negative impacts on the health of the system, including a decrease of nutrient input due to a loss of connectivity between the floodplain and riverine systems. In an attempt to alleviate some of these impacts, volumes of water have been allocated to the site (environmental water allocation) and released into the system. Such releases have occurred on three separate occasions since their introduction in 1993. Whilst these environmental water allocations are broadly aimed at enhancing spawning and recruitment of native fish, little is known of their effectiveness. Since 2003, the Murray Darling Basin Commission has funded research to investigate the effect of such water allocations on these aspects of fish breeding in the Forest.
Each year during the spring-summer spawning season, a sampling program collected information on where fish species are breeding, foraging and sheltering. Ten species of native fish, utilising a wide variety of habitat types, have been found to both reside and recruit in the Forest, during flood and non-flood conditions. Abundant breeding populations of five introduced fish were also found.
In spring of 2005, the largest environmental water allocation in Australia (513GL) was released into the Forest. This was also the first time fish were monitored during such an event. This flooding event led to a large increase in recruitment for Murray Cod and Trout Cod, probably due to the large volume of water bringing in a more abundant food supply. Flood events are known to act as a spawning cue and species such as Silver Perch and Golden Perch, showed an increase in such activity. These four fish are regarded as iconic species of conservation and recreational significance, making these responses to the flooding event an important outcome. This research will be used to help make decisions on the timing and volume of future allocations that will be most beneficial to native fish populations.
For more information contact: Zeb.Tonkin@dse.vic.gov.au
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