Conserving the iconic and highly threatened mahseer fishes of South and Southeast Asia.

This thesis and supporting papers constitute the submission for an award of a PhD research degree by publication and consists of a cohesive synthesis linking a total of eight published papers across seven peer review journals and an IUCN Red List assessment. The mahseers (Tor spp.) represent an iconic group of large-bodied cyprinid fishes found throughout the fast-flowing rivers of South and Southeast Asia. Due to the considerable religious, cultural and recreational significance of these fishes, and the anthropogenic pressures they face, they are of high conservation concern and represent flagship and umbrella focal species for the sustainable management of river systems throughout their biogeographic range. Based on research conducted since 2012, considerable advances in the taxonomic and human dimension aspects of mahseer conservation have been acheived. Engagement with the recreational angling community has demonstrated the high value, and future potential for this rapidly expanding stakeholder group to impact positively on the conservation of mahseer and rivers more generally. This has been evidenced through the development of economic incentivised community habitat protection initiatives. Specifically, community level recognition that a live fish captured and released by paying anglers has a renewable value over the single revenue value of a harvested fish, has been shown to offer employment opportunities and support the sustainable stewardship of aquatic ecosystems. Where such incentives are lacking however, fisheries continue to be subject to high levels of exploitation, due to limited alternative livelihood opportunities available within impoverished rural communities. Further, and due to a combined lack of political will and the difficulties associated with sampling large fishes in large and remote monsoonal rivers, records from catch-and- release angler logs have provided the only available insight to the temporal performance of mahseer populations. Over a 12 year period, angler derived data not only revealed a collapse (>90% reduction) in the River Cauvery’s endemic mahseer population, but also evidenced the establishment and rapid invasion of the non-indigenous blue-finned mahseer, thus highlighting the previously under-appreciated risks of stocking mahseer species into novel systems beyond their natural distribution range. With particular focus on the mahseers of South India’s River Cauvery, this work has afforded the largest of all mahseer species, the hump-backed mahseer, with a valid scientific name (Tor remadevii) and, through extensive analysis of angler catch data, has highlighted its high extinction risk, with it now assessed as ‘Critically Endangered’ on the IUCN Red List of Threatened Species. This has in turn impacted on regional and national fishery and wildlife policy and affected a concerted international effort to apply a multidisciplinary and multiple stakeholder approach to saving this iconic species of megafauna from extinction. In the absence of these works, it is highly probable that the species would have remained on a trajectory towards rapid extinction. Instead, the first major steps to safeguarding its future have been taken. In achieving these research highlights, this work has also resulted in an extensive gap analyses to identify and address some of the many knowledge gaps which have been constraining the effective direction and efficacy of international efforts to conserve species across the genus. With specific reference to previous taxonomic uncertainties, a comprehensive synthesises and critique of species descriptions and subsequent morphological and molecular focused literature, has resulted in the previously listed 24 species of Tor, being revised to just 16 valid species. Additional collation of available data to inform distribution ranges, population trends and threats across the genus, has facilitated the revision of IUCN Red List assessments, with one species now ‘Critically Endangered’, three as ‘Endangered’ one as ‘Vulnerable’, three as ‘Near Threatened’, and eight remaining ‘Data Deficient’. In discussing residual uncertainties, population threats, conservation prospects and the role of stakeholders across the region, this submission concludes with an overarching synthesis of the current knowledge base pertaining to the genus Tor. In discussing taxonomic clarifications, emerging research priorities and potential mechanisms to effect species conservation, this also represents a first point of reference for researchers, while encouraging further research to challenge and enhance the knowledge base necessary to conserve and promote these freshwater icons as focal species to support the ecological integrity of South Asian rivers

A Case Study of the Population Ecology of a Topmouth Gudgeon (Pseudorasbora parva) Population in the UK and the Implication for Native Fish Communities

1. The topmouth gudgeon Pseudorasbora parva is a small Asian cyprinid species that has proved invasive throughout many European countries. Following an initial introduction into the wild in 1996, the species is now proving invasive in the UK, with at least 25 infested waters in England and Wales, of which 10 are known to have direct connection to a major river catchment. 2. To demonstrate the threat of P. parva to fisheries in the UK, a case study is presented on a lake located in the Lake District of England where the species was introduced in 2000. The species rapidly established a breeding population that, by 2003, was the dominant species in size classes <70 mm. In 2004, they were the only species in the lake that produced young-of-the-year. 3. Individual P. parva adopted the reproductive tactics of early maturity, multiple spawning, male dominance and male nest guarding; sexual dimorphism was manifested in larger body size of males. These traits were in contrast to the resident, native species of the lake, including roach Rutilus rutilus and gudgeon Gobio gobio, which adopted traits of later maturity and single spawning. 4. This case study, therefore, revealed relatively rapid establishment of a P. parva population, their subsequent numerical dominance of the fish community, and the impediment of the recruitment of native fish. The implications for UK fisheries are concerning: should P. parva continue to disperse and individuals adopt similar traits as those in this case study, there may be few waters immune from their invasion, numerical dominance and subsequent impacts

Length-weight relationships of two conservation-concern mahseers (Teleostei: Cyprinidae: Tor) of the river Cauvery, Karnataka, India

Length-weight (LW) relationships are presented for two conservation-concern species of mahseer (Tor spp.) from southern India’s river Cauvery. Constructed from angler catch data, these are the first available LW relationships for the Critically Endangered Tor remadevii and the non-native and locally invasive Tor khudree. For T. remadevii, the value of b, the allometric parameter, was 2.94 (95% CI: 2.75–3.14) and was not significantly different from 3.0, indicating isometric growth (t = 0.61, P = 0.54). For T. khudree, b was greater at 3.18 (95% CI: 3.01–3.38), but with this also not significantly different from 3.0 (t = 1.91, P = 0.06). Outputs are discussed with reference to species conservation and recreational catch-and-release fisheries

Are well‐intended Buddhist practices an under‐appreciated threat to global aquatic biodiversity?

Abstract 1. The inherently pro‐conservation and humane Buddhist practice of ‘live release’, entailing the release into the wild of creatures destined for slaughter, poses potentially significant conservation consequences if inappropriate, invasive species are procured for release. 2. This article collates evidence, citing one legal case and other examples, about the risks of the live release of potentially invasive aquatic species that may result in serious, possibly irreversible, conservation threats to aquatic biodiversity and natural ecosystems, with ensuing adverse ecological and human consequences. 3. It is essential that practitioners are aware of these risks if their actions are not to work diametrically against the pro‐conservation and humane intents of the practice. 4. Ensuring that live release occurs safely necessitates raising awareness, with guidance informed by science, to ensure that good intentions do not result in perverse, environmentally destructive outcomes. 5. We propose four simple principles to achieve this, for dissemination to the global adherents of these otherwise entirely laudable practices

A desk review of the ecology of heather beetle

The heather beetle Lochmaea suturalis is a naturally occurring species in the heather dominated landscapes of the United Kingdom. When the heather beetle population density increases dramatically it can cause significant damage to heather plants. It has been suggested that burning heather outside the permitted heather-burning season will promote the regeneration of heather following heather beetle damage. There is also some discussion as to whether burning outside the permitted season might also help control heather beetle. For these reasons Natural England regularly receives applications for licences to burn outside the permitted season. However, burning at this time of year may have effects on a wide range of biodiversity. Therefore, Natural England commissioned this report, and (NEER009 - Desk review of burning and other management options for the control for heather beetle) to ensure the best available evidence is being used. This report is based on an extensive literature review to determine the current state of knowledge of the ecology of the heather beetle. Some of the older references, which appear to form the basis for much current thinking on the subject, are now out of print and were not accessible for this review. A flurry of work was published in the 1980s and early 1990s, but much of this was either: • based at the same experimental plots; • involved relatively low levels of replication; or • did not report heather beetle damage as a central focus of the work. More recently, there have been some PhDs quantifying the ecology of heather beetles in more detail, but these have rarely been published in the peer-reviewed literature. Therefore, current thinking may be influenced by out-of-date information and experimental work that does not truly back up the conclusions of authors. This makes it difficult both to confidently discern patterns over time in frequency and severity of attacks (such as might be caused by climate change or changing nutrient deposition loads) and to be certain which factors control population levels in most year’s at most heather-dominated sites. Much more, and higher quality, monitoring and experimental work needs to be carried out to be able to predict the likely population dynamics of this species under different scenarios. The potential for parasites and parasitoids to control population numbers is particularly worthwhile. More detailed spatial analyses based on citizen science records, combined with carefully designed laboratory studies, might also be used to more clearly elucidate the relationship between beetle numbers and climatic conditions, enabling prediction of the relative likelihood of outbreaks occurring in the future

Desk review of burning and other management options for the control for heather beetle (NEER009)

The heather beetle Lochmaea suturalis is a naturally occurring species in the heather dominated landscapes of the United Kingdom. When the heather beetle population density increases dramatically it can cause significant damage to heather plants. It has been suggested that burning heather outside the permitted heather-burning season will promote the regeneration of heather following heather beetle damage. There is also some discussion as to whether burning outside the permitted season might also help control heather beetle. For these reasons Natural England regularly receives applications for licences to burn outside the permitted season. However, burning at this time of year may have effects on a wide range of biodiversity. Therefore, Natural England commissioned this report, and (NEER008 - A desk review of the ecology of heather beetle) to ensure the best available evidence is being used. An extensive literature review was carried out to determine the effectiveness of burning and other management options in managing heather-dominated systems for the heather beetle Lochmaea suturalis. In general, the quantity of relevant studies was low, and the quality of most was also poor, with very low levels of replication and/or a lack of controls or comparators being very common. There are three potential ways that management could be used. The first way is to reduce the likelihood of outbreaks. There is currently no evidence that burning is useful for this, due to a lack of relevant studies. Other management options that could be considered to achieve this are biological control and drainage of wetter areas, as well as general moorland management such as mowing, rotovating and sod cutting. The second way that burning could be used is by burning infested areas to reduce the numbers of heather beetles present. There has been some discussion as to whether it would be necessary to do this outside the current burning season, but there is currently no reliable evidence available to show whether this is effective, nor a cost-benefit analysis to take account of the additional risks of burning during the summer months. This is again due to a total lack of relevant studies. Other management options at this stage are to use insecticides on the affected areas, but there are also risks associated with this and again there is a lack of evidence as to how effective it would be. The potential for biocontrol at this stage has also not yet been explored. The third way is in encouraging regeneration of damaged areas. The available evidence for this is generally poor quality, and there is some suggestion that management techniques other than burning might be more effective at encouraging regrowth. In addition, some sites have been observed to regenerate naturally, in the absence of management, so there is a question as to whether management is necessary. Some trials are currently under way in Scotland and the Peak District with the aim of determining which management techniques are best for restoring damaged heather, but again the level of replication and lack of control areas appears to be a problem. The following are recommended in order to be better able to advise managers in the future: • Management actions should be carefully monitored so as to establish the effects of decisions (including whether to burn out of season or not). This monitoring should use properly designed experiments with adequate levels of replication and control plots. The effectiveness of management in controlling heather beetles and the effects on biodiversity as a whole and on ecosystem functioning should all be recorded. • Further research should be undertaken into the relationship between the heather beetle and its natural enemies. • Further research should be undertaken into the other factors that might affect the likelihood of outbreaks occurring