Freshwater fish conservation in the face of critical water shortages in the southern Murray–Darling Basin, Australia

Abstract

Abstract. The lower reaches of the expansive Murray-Darling Basin, Australia, are a hotspot for freshwater biodiversity. The regional ecosystem, however, has been significantly altered by river regulation, including local and catchment-wide water abstraction. Freshwater fishes have suffered from the resultant altered flow regime, together with other threats including habitat degradation and alien species. Impacts reached a critical point (imminent species extinction) during a prolonged drought (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)) that lead to broad-scale habitat loss and drying of refuges during 2007-2010, and urgent conservation measures were subsequently instigated for five threatened small-bodied fish species. A critical response phase included ad hoc interventions that were later incorporated within a broader, coordinated multi-agency program (i.e. the Drought Action Plan and Critical Fish Habitat projects). On-ground actions included local translocation, alien species control, in situ habitat maintenance (e.g. earthworks, environmental water delivery), fish rescues, artificial refuge establishment and captive breeding. Improved river flows signalled an initial phase of recovery in 2011-2012 that included reintroductions. The present paper aims to document the actions undertaken in the Lower Murray, and review successes and lessons from practical examples that will help guide and inform management responses to conserve fish in modified systems subjected to severe water decline.

Landscape genetics informs mesohabitat preference and conservation priorities for a surrogate indicator species in a highly fragmented river system

“…Many native MDB species have poor or moderate dispersal potential and a relatively high degree of habitat specialization. These characteristics, in combination with humandriven fragmentation and disturbance of the basin (Lintermans, 2007;Hammer et al, 2013), account for the high population structure and isolation typically detected in population genetic studies of MDB fishes (see, for example, Faulks et al, 2011;Brauer et al, 2013;Attard et al, 2016;Cole et al, 2016;Sasaki et al, 2016). Therefore, our microsatellite results support the proposal that G. marmoratus represents a valuable surrogate indicator species of how fragmentation might affect co-occurring low dispersal species in affected riverine ecosystems.…”

“…In spite of using controlled trials in a dedicated aquaculture facility, most spawning attempts proved unsuccessful and only eight captive-reared juveniles were produced (Westergaard and Ye, 2010), emphasizing the need for further research into G. marmoratus captive breeding . Because of these issues, we propose that conservation agencies should instead focus on maintaining and restoring core habitat (for example, environmental water allocation, riparian restoration and enhancement of water quality; sensu Hammer et al, 2013) and that these in situ management actions should be done at the level of catchments.…”

A review of on-ground recovery actions for threatened freshwater fish in Australia

“…However, in recent years, breeding programs for small-bodied fish have been developed (Table 3; see Ellis et al 2013;Hammer et al 2013). Innovative approaches using artificial refuges (farm dams and created wetlands) were used for Yarra pygmy perch, Nannoperca obscura, Murray hardyhead, and southern pygmy perch, Nannoperca australis, allowing relatively small numbers of captive-bred fish to produce thousands of offspring for reintroduction .…”

Recovering threatened freshwater fish in Australia

“…The importance of a translocation as recovery action is evident for several species, particularly small-bodied species whose reproductive ecology was poorly known, where captive breeding facilities were unavailable, or where natural habitats had been rendered uninhabitable (Chilcott et al 2013;Ellis et al 2013;Hammer et al 2013;Kerezsy and Fensham 2013). The popularity of translocation as a freshwater recovery action in recent years is apparent for other freshwater species both nationally and internationally (e.g.…”

“…Emergency responses associated with prolonged drought were critical components for several species, with desiccation and/or declining water quality the key drivers of emergency recovery activities (Ellis et al 2013;Hammer et al 2013). For Murray hardyhead, Craterocephalus fluviatilis, which largely rely on off-channel habitats for persistence, recovery activities initially revolved around delivery of water to such habitats to prevent desiccation and manage water quality issues such as increasing salinity (Ellis et al 2013).…”