Summary New evidence of impacts by feral horses in Australia's alpine parks systems confirms they endanger threatened species and extensively damage critically endangered bog communities that could take millennia to recover. These impacts are not confounded by effects of deer and accumulate over time, even when only a small number of feral horses (~100) are present. With protected areas representing only a small proportion of the area of the Australian states of New South Wales (9.3%) and Victoria (17%), allowing feral horses to degrade reserves is not a reasonable management compromise, is contrary to the purpose of the protected area system and conflicts with international obligations. Modelling and decades of management experience indicate that trapping alone does not control feral horse numbers. Trapping and fertility control can work in small populations, but not when there are several thousand horses in remote areas. Aerial culling is needed to cost‐effectively and humanely control feral horse populations. The relatively small amount of suffering feral horses experience during a cull is outweighed by (i) avoiding suffering and death of horses from starvation and thirst, (ii) avoiding the suffering of native animals displaced by horses and (iii) avoiding the ethical concerns of driving threatened species towards extinction. Objections to aerial culling on welfare and cultural grounds are contradicted by evidence. Improving knowledge in the general community about what is at stake is long overdue because without this knowledge, small groups with vested interests and unfounded claims have been able to dominate debate and dictate management actions. As a result of ineffective management, horse populations are now expanding and causing well‐documented damage to Australia's alpine parks, placing at risk almost $10M spent on restoration after livestock grazing ended. The costs of horse control and restoration escalate the longer large horse populations remain in the alpine parks. It is crucial that feral horse numbers are rapidly reduced to levels where ecosystems begin to recover. Aerial culling is needed as part of the toolbox to achieve that reduction.

Recent advances in PIT technology have led to smaller tags, meaning that this technology can be used to mark and monitor smaller‐bodied species, many of which are threatened. We examined the effects of 9‐mm PIT tags on the survival and growth of the Mountain Galaxias Galaxias olidus, using this fish as a surrogate for several threatened, small‐bodied galaxiids. We measured survival, growth, and tag retention in 34 tagged and 34 untagged fish held in aquaria for 90 d posttagging. Fish were randomly assigned to a treatment (tagged or untagged) and were weighed just prior to tagging and then at 7, 14, 21, 28, 42, and 90 d after tagging, with observations made 5–7 times per week to check for survival and tag loss. Survival did not differ significantly between tagged and untagged groups (79% and 88%, respectively), and there was no difference in weight gain or loss between the two groups over time. Tag retention rate was high (96%), with only one tag expelled by the smallest tagged fish (73 mm length to caudal fork). Our findings show that Mountain Galaxias are capable of successfully retaining 9‐mm PIT tags in aquarium conditions, suggesting that this technology is suitable for the monitoring of similar small‐bodied fish in the wild.

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Stocky galaxias Galaxias tantangara is a newly described freshwater fish restricted to a single population, occupying a 3 km reach of a small headwater stream in the upper Murrumbidgee River catchment of southeastern Australia. This species is listed as critically endangered under IUCN Red List criteria, and knowledge of the species' ecology is critical for future conservation efforts to establish additional populations by translocation and captive breeding. This study details the first account of spawning and reproductive ecology of G. tantangara, including reproductive development, timing of spawning and a description of one spawning site. Peak gonadosomatic index was observed in March/April in males and in October in females. Absolute fecundity ranged from 211 oocytes for a 76 mm length to caudal fork (LCF) fish to 810 oocytes for a 100 mm LCF fish. The observation of spent females in mid-November 2017 and discovery of an egg mass 8 days later suggest that spawning had occurred, and over a relatively short period. Larvae were subsequently detected in monthly electrofishing surveys in December 2017. Findings from this study provide new understanding of existing and future threats to G. tantangara and have important implications for conservation management of not only this species but also other closely related threatened Galaxias species.

Monitoring is critical for conservation, to track the status of threatened species, assess the relative impacts of threats, inform management responses and prioritise them according to their efficacy. Globally, freshwater fish are impacted by a range of threats including deterioration in water quality, climate change, habitat loss and degradation, introduced predators and herbivores, and wildfire. Monitoring of freshwater fish can be challenging because aquatic conditions can make detecting and identifying population trends difficult for many species. Galaxiidae is the most speciose family of Gondwanandistributed freshwater fishes, and over 75% of species assessed by the IUCN Red List have been classified as threatened. Many Australian galaxiids are highly imperilled and monitoring effort and adequacy is low. We prepared a detailed monitoring plan for the Stocky Galaxias (Galaxias tantangara) that is representative of the conservation status and level of threat facing many congeneric and other similar species. Our protocol provides details of species biology, pertinent threats, and management options with sampling methods to gather these data, and options to link with management actions for maximum benefit. Improved monitoring linked with threat management should improve the conservation status of Stocky Galaxias. By providing this example, we have sought to improve monitoring for range-restricted freshwater fishes more generally.

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Context. Improved tracking technologies increase understanding of fish movement, but care is required when comparing studies of different design. Aims. We used an approach that allowed fine-scale tracking to compare results from individual-tracking designs to simulated batchmarking designs. Methods. Adult Galaxias tantangara (a small freshwater fish) individuals were tagged with 9-mm PIT tags in a small headwater stream and tracked with an accuracy of 1 lineal metre. To evaluate differences between common study designs, data were re-analysed to simulate both batch-marking section size and tracking resolution between 1 and 250 m. Key results. Homerange estimates decreased with a smaller section size and tracking resolution. Batch-marking simulations differed in 99% of cases, whereas individual tracking simulations differed in only 17% of comparisons. Comparisons between different methods were rarely statistically equivalent, being so only when section size or resolution was less than 4 m. Implications. Importantly, batch-marking studies are often likely to overestimate home-range size, and results from different studies may be comparable only when resolution is very fine or identical, even if the same method was used.