Lintermans, M., Geyle, H.M. Beatty, S., Brown, C., Ebner, B., Freeman, R., Hammer, M.P., Humphreys, W.F., Kennard, M.J., Kern, P., Martin, K., Morgan, D., Raadik, T., Unmack, P.J., Wager, R., Woinarski, J.C.Z., and Garnett, S.T. (2020) Big trouble for little fish: identifying Australian freshwater fishes in imminent risk of extinction. Pacific Conservation Biology, Vol. 26, Iss. 4, 365-377. DOI: https://doi.org/10.1071/PC19053 1 Big trouble for little fish: identifying Australian freshwater fishes in 2 imminent risk of extinction 3 4 Mark LintermansA,B,O, Hayley M. GeyleC, Stephen BeattyD, Culum BrownE, Brendan 5 EbnerB,F, Rob FreemanB,G, Michael P. HammerB,H, William F. HumphreysI, Mark J. 6 KennardJ, Pippa KernK, Keith MartinL, David MorganB,D Tarmo A. RaadikB,M, Peter J. 7 UnmackA, Rob WagerN, John C.Z. WoinarskiC, Stephen T. GarnettC. 8 9 Author affiliations 10 A Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, 11 ACT 2601, Australia. 12 B Australian Society for Fish Biology Threatened Fishes Committee. 13 C Threatened Species Recovery Hub, National Environmental Science Program, Research 14 Institute for the Environment and Livelihoods, Charles Darwin University, NT 0909, 15 Australia. 16 D Freshwater Fish Group & Fish Health Unit, Centre for Sustainable Aquatic Ecosystems, 17 Harry Butler Institute, Murdoch University, WA 6150, Australia. 18 E Department of Biological Sciences, Macquarie University, NSW, 2109, Australia. 19 F TropWATER, James Cook University, Townsville, QLD 4811, Australia. 20 G Inland Fisheries Service, New Norfolk, TAS 7140, Australia. 21 H Museum and Art Gallery of the Northern Territory, Darwin, NT 0801, Australia. 22 I School of Biological Sciences, University of Western Australia, Crawley, WA 6009, 23 Australia. 24 J Northern Australia Environmental Resources Hub, National Environmental Science 25 Program, Australian Rivers Institute, Griffith University, QLD 4111, Australia. 1 26 K Bush Heritage Australia, Level 1, 395 Collins St, Melbourne, VIC 3000, Australia. 27 L PO Box 520 Clifton Beach QLD 4879, Australia. 28 M Arthur Rylah Institute for Environmental Research, Department of Environment, Land, 29 Water and Planning, Heidelberg, VIC 3084, Australia. 30 N “Rockatoo” 281 Falls Road, Esk, QLD 4312, Australia. 31 OCorresponding author. Email: [email protected]. 32 33 Summary text 34 Australian freshwater fishes have typically been neglected in conservation planning, despite 35 evidence of catastrophic declines. Here we use structured expert elicitation to identify the 36 Australian freshwater fishes in imminent risk of extinction. All 22 taxa considered had 37 moderate to high (> 40%) likelihoods of extinction in the next two decades. Using 38 conservation progress metrics, we identify priority management needs for averting future 39 extinctions. 40 41 Abstract 42 Globally, freshwater fishes are declining at an alarming rate. Despite much evidence of 43 catastrophic declines, few Australian species are listed as threatened under national 44 legislation. We aim to help redress this by identifying the Australian freshwater fishes that 45 are in the most immediate risk of extinction. For 22 freshwater fishes (identified as highly 46 threatened by experts), we used structured expert elicitation to estimate the probability of 47 extinction in the next ~20 years, and to identify key threats and priority management needs. 48 All but one of the 22 species are small (<150 mm total length), 12 have only been formally 49 described in the last decade, with seven awaiting description. Over 90% of these species were 50 assessed to have a >50% probability of extinction in the next ~20 years. Collectively, the 2 51 biggest factor contributing to the likelihood of extinction for the freshwater fishes considered 52 is that they occur in small (distributions ≤44 km2), geographically isolated populations, and 53 are threatened by a mix of processes (particularly alien fishes and climate change). Nineteen 54 of these species are unlisted on national legislation, so legislative drivers for recovery actions 55 are largely absent. Research has provided strong direction on how to manage approximately 56 35% of known threats to the species considered, and of these, about 36% of threats have 57 some management underway (although virtually none are at the stage where intervention is 58 no longer required). Increased resourcing, management intervention and social attitudinal 59 change is urgently needed to avert the impending extinction of Australia’s most imperilled 60 freshwater fishes. 61 62 Additional Keywords: alien species, anthropogenic mass extinction crisis, biodiversity 63 conservation, climate change, Delphi, IDEA, introduced species, threatening processes 64 65 Running head: big trouble for little fish 66 67 Introduction 68 Global extinctions are occurring at an accelerating rate in response to a mix of human-driven 69 threats (Johnson et al. 2017), and this is likely to continue to increase over time (Ceballos et 70 al. 2015). Freshwater fishes are the largest vertebrate group (~17,750 species), and freshwater 71 habitats are arguably the most imperilled globally (Dudgeon et al. 2006; Dudgeon 2011; 72 Vorosmarty et al. 2010; Reid et al. 2019). Therefore, the conservation of freshwater fishes 73 and their habitats should be of major concern in maintaining our biological inheritance. 74 3 75 Freshwater environments are imperilled for several reasons: (i) they are limited in extent— 76 only ~3% of the water on earth is fresh and only ~0.29% of global freshwaters are liquid (i.e. 77 not frozen in polar ice caps) and available for most fishes (i.e. not underground) (Gleick 78 1996); (ii) they are subject to escalating water extraction and regulation (domestic, 79 agricultural, aquaculture, hydropower, industry and urban uses); (iii) the quality of 80 freshwaters continues to decline as a result of anthropogenic use and alteration (e.g. habitat 81 loss and water extraction). Freshwaters are the ‘receiver’ of sundry terrestrial perturbations 82 and degradation (i.e. they are at the bottom of landscapes and so receive elevated levels of 83 sediment and pollutants); (iv) river systems are linear with large edge to area ratios and so 84 are extremely prone to fragmentation; (v) they are spatially isolated (limiting fauna 85 movements between adjacent catchments), and often fragmented; and (vi) they are 86 increasingly invaded and occupied by alien species (Dudgeon 2011; Reid et al. 2019).. 87 88 Each of these factors is contributing to the decline of freshwater fishes, which has been 89 catastrophic in some parts of the world. For example, the Living Planet Index (LPI) shows a 90 decline in monitored freshwater vertebrate populations (mostly fishes) of 84% between 1970 91 and 2014 (WWF 2016; WWF 2018). Likewise, in Australia, freshwater fishes have fared 92 poorly, with many species suffering from catastrophic declines since the 1950s (Lintermans 93 2013a; Lintermans 2013b). This decline has been attributed to habitat loss, introduced 94 species, alteration to natural flow regimes, fragmentation, water pollution and 95 overexploitation (Duncan and Lockwood 2001; Dudgeon et al. 2006; Vorosmarty et al. 96 2010); threats which are unsurprisingly similar (with the exception of altered flow regimes) 97 to those facing terrestrial environments. However, many additional threats to freshwater 98 environments are emerging (e.g. climate change, expanding hydropower, infectious diseases), 4 99 and so the need to ameliorate the dynamic pressures on freshwater environments is even more 100 pressing (Reid et al. 2019). 101 102 Along with other signatories to the Convention on Biological Diversity, the Australian 103 government has committed to avoiding further extinctions (United Nations 2015; Department 104 of Environment and Energy 2016), a task that first requires identification of the species at 105 most immediate risk. Typically, this is achieved using statutory threatened species lists, but 106 such lists are reactive rather than proactive; i.e. they usually require considerable time to 107 update, and so may not be the best way to prioritise urgent actions (Possingham et al. 2002; 108 Wilcove and Master 2005). Furthermore, these lists are often not comprehensive or up-to- 109 date. For example, in August 2019, the number of freshwater fishes listed under the 110 Australian Government’s Environment Protection and Biodiversity Conservation Act 1999 111 (EPBC Act), was 38, whereas the non-statutory national threatened species list of the 112 Australian Society for Fish Biology (ASFB) contained 61 species (Lintermans 2017) out of 113 the 315 freshwater fish species so far accepted as occurring in Australia. Not only are few of 114 Australia’s imperilled freshwater fish species listed under the EPBC Act, but the addition of 115 fish species to that list has been especially slow since the mid-2000s. In particular, small- 116 bodied species are often neglected, with larger species (usually targets for commercial, 117 artisanal and recreational angling) capturing the most public attention (Reynolds et al. 2005; 118 Ellis et al. 2013; Saddlier et al. 2013). 119 120 Imperilment can be recognised not only in the size and composition of official lists of 121 threatened species, but also through mathematical models that estimate extinction risk based 122 on life history parameters and population growth rates (e.g. Population Viability Analysis, 123 PVA). However, this approach