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Introducing the Murray-Darling Basin Native Fish Strategy and initial steps towards demonstration reaches

2004; Wiley; Volume: 5; Issue: 1 Linguagem: Inglês

10.1111/j.1442-8903.2004.00177.x

1839-3330

Jim Barrett,

Fish Ecology and Management Studies

Ecological Management & RestorationVolume 5, Issue 1 p. 15-23 Introducing the Murray-Darling Basin Native Fish Strategy and initial steps towards demonstration reaches Jim Barrett, Jim BarrettSearch for more papers by this author Jim Barrett, Jim BarrettSearch for more papers by this author First published: 18 March 2004 https://doi.org/10.1111/j.1442-8903.2004.00177.xCitations: 35 Jim Barrett is the Manager of the Native Fish Strategy for the Murray-Darling Basin Commission (Tel. + 61-2 6279 0154, Email: jim.barrett@mdbc.gov.au). This feature follows the launch of the Murray-Darling Native Fish Strategy, the first comprehensive strategy of its kind in Australia, and explores potential directions for planning and implementing 'demonstration reaches', a fundamental recommendation of the Strategy. Opinions expressed in this article are those of the author, not necessarily the MDBC. Box 1. What is the Murray-Darling Basin Commission?: The MDBC was set up in 1992 to provide advice on the planning, development and management of the Basin's resources to the Murray-Darling Basin Ministerial Council. It has a direct role in river management through its responsibility for the operation and management of structures along the Murray River and Lower Darling, including allocation of environment flows and arrangements for fishways. The MDBC also plays a role in information exchange and public awareness activities, and seeks to ensure consistency across State boundaries. Actions by the Commission that aim to rehabilitate fish populations in the Basin include: • developing policies and strategies and providing policy advice about significant natural resource management issues in riverine environments; • on-ground actions, including general water management/operational activities, fishway construction, and support and advice to partner governments on fish-related projects; • funding research projects in the Basin to generate knowledge; and • ensuring effective cooperation between departments and adequate involvement and ownership of issues. Box 2. Reduction of native fish populations from presettlement levels: Native fish populations in the Murray-Darling Basin are currently estimated to be about 10% of their pre-European settlement levels. This estimate has been based on scientific research, fishing records, Aboriginal oral history and anecdotal evidence and takes into account the naturally variable nature of fish populations ( Phillips 2003). This decline has been demonstrated by many indicators, including: • localized extinction of some native fish species — for example, Trout cod (Maccullochella macquariensis), Murray Cod (Maccullochella peelii peelii) and Macquarie Perch (Macquaria australasica). These species have become locally extinct in the Mitta Mitta River for 100 km downstream of Dartmouth Dam ( Koehn 2001); • threats to other species — nine of the 35 native fish species in the Basin are nationally 'threatened' (as listed by the Australian Society for Fish Biology) and at least two are 'critically endangered'; 16 species are listed as threatened under State jurisdictions; • rapid decline in the conservation status of 'flagship' species such as Silver Perch (Bidyanus bidyanus), Freshwater Catfish (Tandanus tandanus) and Murray Cod (Maccullochella peelii peelii) across the Basin ( Harris & Gehrke 1997; Kearney et al. 1999); • presence of 11 alien species of fish that now make up one-quarter of the Basin's total fish species ( Harris & Gehrke 1997). Examples are Carp, Gambusia (Gambusia holbrooki), Oriental Weatherloach (Misgurnus anguillicaudatus), Roach (Rutilus rutilus), Tench (Tinca tinca), Goldfish (Carassius auratus), Redfin Perch (Perca fluviatilis), Brown Trout (Salmo trutta), Brook Char (Salvelinus fontinalis), Rainbow Trout (Oncorhynchus mykiss), and Atlantic Salmon (Salmo salar). Carp now make up an estimated 60–90% of the total fish biomass at many sites, with densities as high as one Carp per square metre of river surface area ( Harris & Gehrke 1997); • presence of two native fish species that are not native to the Basin rivers, i.e. Broad-finned Galaxias (Galaxias brevipinnus) and Spotted Galaxias (Galaxias truttaceus); • loss of most commercial fisheries and observed declines in recreational angling success — native fish species make up just 4.4% of the total recreational catch in the River Murray region ( Kearney et al. 1999). The magnitude of the decline of native fish populations has been most significant in the past 100 years, with the greatest declines in the past 50 years ( Phillips 2003). For example, following the construction of the Dartmouth Dam in 1980, the loss of Trout Cod, Macquarie Perch and Murray Cod from the Mitta Mitta River was at least partly due to the cold water releases that inhibited spawning and favoured the cold water alien species especially Brown Trout ( Koehn 2001). Although native fish populations are very low Basin-wide, some anglers are reporting improved catches in some river reaches (M. Lintermans, pers. comm., 2003). Fish numbers are highly variable, both over time as well as among reaches, valleys and rivers, due to factors such as environmental conditions and recruitment success. Good numbers of fish in some reaches can be a short-term reflection of successful local stocking programs. On the other hand, the presence of certain large angling species such as Murray Cod or Golden Perch does not necessarily indicate that the entire fish community is doing well. Many of the smaller fish species such as gudgeons, galaxiids and hardyheads are declining at alarming rates, but this would not be reflected by recreational catches in the short term. Box 3. Will it work?: Experts have agreed that interventions must be undertaken in an integrated way if they are to be effective. If undertaken singly, the capacity of interventions to recover the native fish populations of the Basin beyond 25% of their pre-European level is questionable. If a number of interventions (such as allocation of environmental flows, habitat rehabilitation, abatement of cold water pollution, improved land-use management practices, provision of fish passage, creation of a Habitat Management Area system, and control of alien fish) are implemented in an integrated way, then experts believe the goal of the Strategy is achievable. There have been some success stories to date. There are a number of examples where the sort of 'interventions' mentioned in the Strategy have led to increased native fish populations. For example: Resnagging: has been conducted experimentally at 14 sites on the River Murray with the addition of over 300 large River Red Gum (Eucalyptus camaldulensis) snags. Results show that a range of native fish species use the new snags in the same proportions as would have been expected in natural snag piles ( Nicol et al. 2002). The snags were favoured by native species such as Murray Cod, Trout Cod and Golden Perch, but were not heavily used by Carp. Different locations were more successful than others, indicating designs to maximize environmental benefit. Similarly, different locations were used by different species. Fishways: built on overseas designs have been largely unsuccessful in Australia. Redesign of prototypes directly based on experiments on the swimming ability of native fish led to the construction of the first fishway at Torrumbarry in 1990, which opened up 350 km of river to Yarrawonga Weir upstream. From the moment it was opened, native fish used it and in the first 2 years the fishway allowed the passage of over 20 000 native fish from seven species. Above the weir, numbers of Silver Perch increased and juvenile Golden Perch were seen for the first time in decades. Tagged Golden Perch moved all the way to Yarrawonga Weir and also entered the Goulburn River. Short-headed Lamprey, a very uncommon native species that migrates thousands of kilometres from the sea, was found to use the fishway. Threatened species recovery: . Before Googong Dam was constructed on the Queanbeyan River in 1978, there was a small population of the threatened Macquarie Perch in the river. After the dam was built, a fish monitoring program revealed that Macquarie Perch were present in the reservoir, but were not breeding (possibly due to the flooding of all available spawning sites) and were unable to migrate upstream due to a waterfall ( Lintermans 2002). Fifty-seven adult Macquarie Perch were netted from the reservoir and transported upstream past the waterfall, and released at two sites on the Queanbeyan River. There is now a thriving population of Macquarie Perch, with regular breeding occurring ( Lintermans 2002). Box 4. Hume-Yarrawonga: The first demonstration reach?: The Hume-Yarrawonga section of the Murray River has been proposed as the first demonstration reach under the Strategy as its fish community (the 'Aquatic Community of the Lower Murray River Drainage') has been listed as 'endangered' under of the NSW Fisheries Management Act 1994 (Part 7A). Several factors warranted its selection, including the wide variety of land uses and resultant impacts on the riverine environment, the heterogeneity of land tenure, and the diversity of both alien and native fish species, the latter including nine threatened taxa. It complies with all of the criteria of a demonstration reach. More specifically, it is: degraded by several different threats but able to demonstrate rehabilitation arising from well monitored trials; substantial, visible and in close proximity to a significant population which could supply resources and strong community support (i.e. Albury/Wodonga); characteristic of other sites so solutions are potentially transferable; and able to use an adjoining downstream river reach as a reference community. Potential actions Land acquisition — impact of flow regulation.: The MDBC has produced a Summary Report Scoping Study — Waterway Management Plan for the Hume to Yarrawonga Reach which recommends a range of short- and long-term actions, in cooperation with landowners. To confirm the Commission's right to continue to make regulated flow releases from Hume Dam up to channel capacity of 25 000 mL/day, a key management program 'Land Management and Land Tenure' was outlined in the Scoping Study. Resnagging.: A feasibility study is being undertaken prior to funding for resnagging up to 100 km in this section of the River. This proposal is underpinned by a major associated project, conducted between Yarrawonga and Tocumwal and now in its fourth year, which sets out the methodologies and logistics required for resnagging and measures the response of fish communities to this effort. The resnagging project could well be the centrepiece of the suite of projects that together will define this demonstration reach. Improving fish passage.: At the bottom end of the section, funds are available to upgrade the fishlock at Yarrawonga. In line with the recommendations of a recent MDBC workshop on downstream movement, Yarrawonga may also provide a prime test structure to examine engineering solutions for downstream movement. Thermal mitigation: engineering options are being investigated at Hume Dam to counter cold water pollution. This is a long-term feasibility and design phase (at least 6–7 years) before structural works begin. Riparian restoration works: designed to improve biodiversity and natural processes will soon be the subject of formal experimentation. This may include an adaptive management habitat reconstruction experiment on the Hume-Yarrawonga demonstration reach. Community involvement may be facilitated by the findings of a recent Land & Water Australia funded research project into assessing community capacity for riparian restoration. Control of alien species.: A workshop will soon identify and prioritize 'management units' within the demonstration reach from which a plan will be developed to control Carp in the reach. Threatened species recovery program.: The reach previously supported a number of threatened native species including Freshwater Catfish, Trout Cod, Murray Cod and Macquarie Perch. Most of these species are now severely reduced or absent from the reach, largely as a result of river regulation, thermal pollution and other habitat modification. A national recovery plan has been prepared for Trout Cod and Basin recovery plans have been prepared for Freshwater Catfish and Silver Perch, with national recovery plans soon to be prepared for Macquarie Perch and Murray Cod. Restocking of native fish species.: Restocking should be undertaken in accordance with the principles and objectives outlined in the Strategy, and in the proceedings of the recent 2002 workshop 'Managing Fish Translocation & Stocking in the Murray-Darling Basin'. However, great care will have to be taken with stocking programs if they are to not mask true recovery of the fish community in response to the other interventions in the demonstration reach. 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