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Risk of inter-basin water transfer to the aquatic fauna of the Denmark and Hay Rivers. Report to the Water Corporation of Western Australia.
Abstract
This report describes the fishes and freshwater crayfishes of the Denmark and Hay
River catchments and provides a risk assessment to these fauna of the proposed
extraction of water from the Mitchell River (a tributary of the Hay River) and
subsequent transfer to the Quickup River Dam (within the Denmark River catchment).
Three sites for the pumpback facility (and dam) are under investigation, one in the
vicinity of the present gauging station site (Site 1), one just upstream of the Denmark
- Mt Barker Rd (Site 2) and one just upstream of the confluence with the Hay River
(Site 3) (see Plate 1). The project aims to divert peak flows from the Mitchell River
and pump the water to Quickup River Dam (opened in 1990) in the adjacent Denmark
River catchment. The size and shape of the interception structure is yet to be
determined, but early estimates for the scheme are based on a concrete weir <5 m high
to produce a reservoir of up to 20 ML capacity.
A total of 22 sites in these catchments were sampled for fish and freshwater
crayfishes. These data were collated with additional historical information on the
fishes and crayfishes of the rivers. Marron, Gilgies and Koonacs were found in both
catchments, while the Restricted Gilgie was only recorded within the Hay River
catchment (predominantly within the Mitchell River). Seven species of fish were
recorded during the current study, including five strictly freshwater species that are
endemic to the south-west region of Australia (i.e. Western Minnow, Western Mud
Minnow, Western Pygmy Perch, Balston’s Pygmy Perch and Nightfish), one
introduced freshwater species (Eastern Mosquitofish), and one typically estuarine
species (i.e. Swan River Goby). Additionally, Morgan et al. (1998) recorded a second
estuarine species from the Hay River and the larval Pouched Lamprey from the
Denmark River catchment. Both Balston’s Pygmy Perch and Western Mud Minnow
are listed as Schedule 1 under the Wildlife Protection Act 1950 and Balston’s Pygmy
Perch is listed as vulnerable under the Environment Protection and Biodiversity
Conservation Act 1999.
Potential impacts to the ecology of the system will depend largely on the selection of
the site to be regulated on the Mitchell River. Threats to fish and freshwater crayfish
include altered flow and environmental regimes, introduction of parasites, impact on
spawning migrations and transfer of potentially genetically discrete populations
between catchments. The site that poses the least threat to maintaining the quality of
freshwater fish and crayfish populations is Site 1, which is already regulated by the
Mitchell River gauging station. The highest threat to the aquatic fauna would be if a
weir was constructed near to the mouth of the Mitchell River (Site 3), as this could
potentially limit the access to the river for fishes that utilise the Hay River during
periods of low flow, then move into the Mitchell River for spawning, and the
subsequent offspring utilise it as a nursery area. Fishway construction at any new dam
would reduce some of the impacts to fish migrations.
... Such utilisation of large water supply dams by native freshwater fishes in the region has previously been documented (e.g. Beatty et al. 2003;Morgan et al. 2008). ...
Instream barriers are known to have major negative impacts on aquatic ecosystems; particularly on migratory fishes. These impacts include exclusion from critical habitats (particularly spawning habitats), reduced colonisation, genetic fragmentation, and increased rates of density dependent mortality below barriers. Construction of fishways can overcome many of the impacts of barriers on migratory fishes by providing passage over, through, or around artificial barriers. In southwestern Australia, instream barriers are one of several major stressors on highly endemic (82%) freshwater fishes; many of which are potamodromous and migrate to spawn during the seasonal high flow period. Moreover, climate change has made the allocation of surface water more challenging due to a severe (~50%) reduction in surface flow over the past ~40 years. This study describes the design and construction of the largest fishway system built to date in this region and
tests its functionality. The rock-ramp fishway system was located on Rushy Creek (an ephemeral tributary of the Blackwood River) and included a bypass and spillway fishway with an overall lift of 4.5 m. In spring 2010 and 2011, three of the eight native fishes (Western Minnow (Galaxias occidentalis), Western Pygmy Perch (Nannoperca vittata), and the Blue-spot Goby (Pseudogobius olorum)) in Rushy Creek were shown to pass upstream and downstream on the fishway system. Higher and more sustained flows in 2011 likely resulted in greater upstream fish passage in that year compared with 2010; highlighting the flow dependence of successful fish passage through fishways, which will have implications in terms of their functionality in drying climatic regions both in terms of changes in migration cues and fishway passage success. However, hydrological conditions during peak flow in both years also probably exceeded the swimming performance of the Western Pygmy Perch thereby preventing it negotiating the system during the early part of its spawning period, as opposed to the Western Minnow and the Blue-spot Goby both of which successfully negotiated the system during August and September. The findings highlight the importance of understanding species life-histories and swimming abilities, and have implications for future planning and design of fishways in this region to ensure they are appropriate for fish passage under future flow scenarios.
Following the complete eradication of the alien piscivorous perch Perca fluviatilis from a potable reservoir, the abundance of the endemic western minnow Galaxias occidentalis, which was previously undetectable prior to the initial eradication event, increased dramatically. The study reveals the potential of reservoirs to act as ecological refuges and has implications for understanding the relative effects of alien fishes v. habitat alteration on native freshwater fishes. Journal of Fish Biology
This is the first overview of stream salinity across the south-west of Western Australia since 1988. More than half of the rivers analysed in this study are now marginal in quality, brackish or saline, and only 44% of the south-west rivers are still fresh. Stream salinity was still rising at many of the sites analysed. Sixty-six percent of the analysed rivers had higher salinities in the last 10 years (1993–2002) than in the previous 10 (1983–92). Part of the reason for the higher salinity was lower rainfall over the last 10 years.
This book is the second edition of the first of three proposed volumes on diseases and disorders in freshwater and marine fishes (fin and shellfish). Since the publication of the first edition, a tremendous volume of research has been conducted on parasites, especially those that cause morbidity and mortality in fish. Like the first edition, this book deals with parasitic infections caused by protozoans and metazoans and each chapter deals with a specific disease/disorder or a group of closely related diseases. Its primary objective is to produce a comprehensive and authoritative review from experts who are actively working in the area or have contributed to the understanding of fish diseases/disorders. Significant changes to this second edition include the addition of three new chapters and four of the original chapters have new authors. All other chapters have been thoroughly updated since the first edition was published in 1995. The book will be of significant interest to researchers and students of aquaculture, fisheries, parasitology and veterinary medicine.
Within Western Australia, Perca fluviatilis is restricted to the south-western corner and is found in the Swan, Murray, Harvey, Collie, Capel, Carbunup, Margaret, Blackwood, Donnelly and Warren river systems. Age data suggest it was released into Big Brook Dam (Warren River) in 1992 or 1993, where it has since played a role in eliminating the native teleosts. Its success here is attributed to a young age at maturity, rapid growth (compared with populations elsewhere), predatory nature, large size (compared with native fish), broad environmental and habitat tolerances, and absence of predators. Gonadal development initiates in late summer, with peak spawning between August and September. Males and females attained maturity in their first and second years, respectively, which is earlier than reported for most Northern Hemisphere populations and can be attributed to their rapid growth here because of the warmer climate. At ages 1, 2, 3, 4 and 5, males, on average, attained 102, 159, 206, 246 and 280 mm total length (TL) and females had attained 104, 166, 228, 290 and 351 mm TL at the respective ages. Diets of fish 50-200 mm TL comprised mainly small aquatic invertebrates, whereas larger fish preyed almost exclusively on decapods, mainly marron (Cherax tenuimanus), and teleosts.
A one-dimensional hydrodynamic reservoir model is coupled with a stochastic fish population model to examine the impacts of cold water pollution (CWP) on the Australian freshwater fish, Murray cod, downstream of Hume Dam, Australia. Mitigation of CWP through the introduction of selective withdrawal capabilities to access near-surface water is predicted to increase discharge temperatures during the crucial spring-early summer post-spawning period by 4–6°C for normal operating conditions, that is, a full reservoir in early spring. No improvement in discharge temperature was predicted for drought conditions characterized by relatively low storage levels in early spring. The predicted temperature increase using selective withdrawal increased the predicted average minimum female population abundance by 30–300% depending on the assumed spawning behaviour. Increased discharge temperatures appear to be achievable and are expected to reduce the stress currently impacting Murray cod populations due to CWP during crucial post-spawning periods. This provides evidence that mitigation of this problem may assist in rehabilitating Murray cod populations in the Murray River downstream of Hume Dam. Copyright © 2007 John Wiley & Sons, Ltd.
This paper reviews briefly recent studies of estuarine ecosystems of southwestern Australia. Specifically, the paper (A) assesses the meteorologic and physiographic features which determine the unusual environmental characteristics of these estuaries, especially the extreme variation in salinity; (B) classifies the estuaries according to frequency and duration of bar closure, with consequent different hydrological characteristics; (C) discusses the more important aspects of the flora and fauna of the estuaries as related to these environmental differences; and (D) describes in general terms their nutrient status, as an introduction to the paper by McComb et al. (10) in this Symposium on the Peel-Harvey estuarine system.
The reproductive biology, growth and diet of Galaxiella munda McDowall in a south-western Australian river are described. Monthly trends in gonadosomatic indices, stages in ovarian development and the size and maturity of oocytes show that spawning extended from July to October and peaked in late August to early September. Histology of ovaries indicated that G. munda produced clutches of eggs which it released at intervals. Data on length-frequencies, otoliths and gonads demonstrate that G. munda typically died in the few months after spawning. By age I, the females and males of G. munda had reached 47 mm (≡ 0.54 g) and 43 mm (≡ 0.42 g), respectively. The respective von Bertalanffy growth curve parameters for L., K and to were 48.6 mm, 3.702 and -0.0014 for females and 44.3 mm, 4.217 and -0.0012 for males. Galaxiella munda fed predominantly on terrestrial fauna on the water surface, cladocerans and copepods in the water column, and dipteran larvae in the benthos. Comparisons are made between the above aspects of the biology of G. munda and those recorded for three other locally endemic species (Galaxias occidentalis Ogilby, Bostockia porosa Castelnau and Edelia vittata Castelnau) and wherever possible with other Galaxiella species. Such comparisons have emphasized the relationship between size and age at first maturity and spawning mode.
The effects of cold water releases, as a by-product of storing irrigation water in large dams, has been a source of great concern for its impact on native freshwater fish for some time. The Mitta Mitta River, northeast Victoria, is impacted by altered thermal regimes downstream of the fourth largest dam in Australia, Dartmouth dam, with some daily temperatures 10–12°C below normal. Murray cod (Maccullochella peelii peelii) were endemic to the Mitta Mitta River; however, resident Murray cod have not been found in this river since 1992. The response of eggs and hatched larvae from Murray cod to different temperature gradients of water were measured and the post-spawning survival recorded. As a case study, post-spawning survival was then inferred from flow data for each year of operation of Dartmouth Dam, recorded since first operation in 1978, and included in a stochastic population model to explore the impact of the altered (historical) thermal regime on population viability. Experimental results revealed no egg and larval survival below 13°C and predicted historical temperature regimes point to more than 15 years of low temperatures in the Mitta Mitta River. Population modelling indicates that the impact of cold water releases on post-spawning survival is a significant threatening process to the viability of a Murray cod population. Additionally, we consider changes to the thermal regime to explore how the thermal impact of large dams may be minimized on downstream fish populations through incrementally increasing the temperature of the releases. The modelled Murray cod population responds to minor increases in the thermal regime; however, threats are not completely removed until an increase of at least 5–6°C. Copyright © 2005 John Wiley & Sons, Ltd.
1.The history of river conservation has largely focused on preservation of the physical and structural properties of lotic ecosystems in an attempt to ensure safe and potable water supplies for human consumption. Such strategies are increasingly being implemented at the catchment or basin scale.2.Although these reflect positive developments in the conceptualization of conservation issues pertaining to lotic systems and provide the logical economic, sociological and/or political units for management, we question whether they represent the appropriate scale for the protection of lotic biodiversity and biological processes. We argue that this requires considerations that extend beyond the protection of physical habitat to ensure protection of population processes.3.Although many species can be successfully conserved using the catchment as the basic management unit, many others cannot. We review evidence from genetic studies of aquatic populations to examine movement in relation to catchments, recognizing that organisms with poor dispersal characteristics during their life cycles exhibit a high degree of genetic structure, whilst organisms with robust dispersal characteristics typically exhibit a homogeneous genetic structure.4.Species with poor dispersal characteristics are more easily conserved at the catchment level, whereas those with high dispersal characteristics can only be safely conserved at bio-regional supra-catchment levels.5.Modern technological advances aimed at redistributing water from areas with perceived surpluses to those with perceived deficits (inter-basin water transfers), demonstrated to transfer organisms between historically isolated catchments, pose a potential threat to the conservation of biodiversity by mixing genetically distinct populations and hence altering evolutionary processes and pathways.6.If our arguments hold, then it appears that conservation authorities need to reappraise the current dominant paradigm of the catchment as the basic unit for conservation and management, and incorporate broader, strategic landscape planning in water resource management. Copyright © 2003 John Wiley & Sons, Ltd.