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Barriers to the migration of fish limit access to suitable habitat and have been identified as a major contributor to the decline of freshwater fish species. GIS and fine scale elevation data were used to create a model to identify physical barriers to fish migration on the Cotter River in the ACT, Australia. The effect of spatial resolution on the efficacy of the model was also examined. Elevation data gridded at 1m, 5m, 10m and 20m were used to simulate the terrain. Two types of models were analysed for barrier identification: logistic regression and non-hierarchical clustering. Logistic regression based on 1m resolution terrain data was found to create the best models. The 1m model using transect averages predicted 88% of the barriers identified in the field. The relative steepness parameter was found to be a key variable for predicting barriers. A general trend of increased accuracy of barrier prediction of field surveyed barriers with a decrease in grid cell size was found for grid spacing less than 20m. The model allows for a semi-automated process to rapidly assess catchments for instream barriers to fish passage. The predictions from the model provide the means for prioritizing areas containing possible physical barriers in the Cotter River. It is intended to be used in conjunction with traditional barrier identification.
Many of the native freshwater fish species are not well known to the general public whilst some of the introduced species are so familiar that they are occasionally mistakenly thought to be native to the state. The Tasmanian freshwater fish fauna consists of 25 species of native fish and a further 8 introduced species. At least 15 further species which are predominately marine or estuarine inhabitants, may be found some distance inland at certain times of the year. Some of these are more frequent invaders than others and the listing of species as freshwater is somewhat arbitrary. The lampreys are included in this and other fish guides by tradition, although they are not fishes in the strict sense.
This edited volume reviews our past and present understanding of the ecology of Australian freshwater fishes. It compares patterns and processes in Australia with those on other continents, discusses the local relevance of ecological models from the northern hemisphere and considers how best to manage our species and their habitats in the face of current and future threats. In view of these challenges, the need for redress is urgent. The chapters are written by some of our foremost researchers and managers, developing themes that underpin our knowledge of the ecology, conservation and management of fish and fish habitats. For each theme, the authors formulate a synthesis of what is known, consider the need for new perspectives and identify gaps and opportunities for research, monitoring and management. The themes have an Australian context but draw upon ideas and principles developed by fish biologists in other parts of the world. The science of freshwater fish ecology in Australia has grown rapidly from its roots in natural history and taxonomy. This book offers an introduction for students, researchers and managers, one that the authors hope will carry Australian fish biology and resource management to new levels of understanding.
Abstract: "Given that conservation introductions are essentially biological invasions, researching the main factors which influence them will provide insight for both conservation and management. The factors affecting invasion success in small-bodied Australian freshwater fishes are largely unstudied. From a conservation-oriented perspective this is worrying as small-bodied freshwater species are more likely to become threatened than large-bodied species. It is equally concerning from an invasive species management perspective as many species have the potential to negatively impact native species and ecosystems. This thesis consists of two data chapters preceded by a general introduction and followed by a synthesis.The first data chapter examines potential pre and post zygotic barriers to hybridisation between the Running River rainbowfish (RRR) and eastern rainbowfish (Melanotaenia splendida). Eastern rainbowfish is a widespread native fish of northern Australia with an alien population in Running River (a tributary of the Burdekin River, Queensland). Hybridisation between RRR and eastern rainbowfish has been detected and in the absence of barriers to further hybridisation and introgression will likely lead to the loss of pure RRR from the wild. Dichotomous mate choice experiments and egg survival experiments were used to determine the presences of pre and post-zygotic barriers to hybridisation between RRR and eastern rainbowfish. The findings of this study do not support the presence of barriers to hybridisation between the two species. Mate choice experiments suggested that males and females of both species examined did not exhibit preferential mate choice, which is most unusual. Similarly, egg survival experiments found no differences in fertility or reproductive success between hybrid and pure crosses. The chapter is presented as a stand-alone article and has been accepted for publication by the journal Ethology.The second data chapter focuses on conservation introductions conducted for RRR into refuge habitats free of eastern rainbowfish. Releases made into one of these release sites (Deception Creek) were used to examine the impact of predator avoidance training on the survival of captive bred RRR after release. Deception Creek received approximately 2500 fish while Puzzle Creek received approximately 1500 fish. RRR bred for release into Deception Creek exposed to a novel predator found within the release sites (spangled perch, Leipotherapon unicolor) using repeated controlled exposures prior to release. Experiments regarding predator training were ended prematurely due to unexpected weather conditions. This reduced the number of replicates and prevented any reliable statistical analysis of collected data. However, analysis of collected data suggested there was no difference between the survival of trained and untrained fish. Despite this, anecdotal observations suggest that pre-exposure to predators may have some beneficial effects on the survival of captive fish. This chapter also discusses movement data gained from these releases, something which is lacking for most native small-bodied fish species. This chapter is presented as a stand-alone article that will form part of a larger publication covering the discovery, description and conservation of RRR."
Indexes journal articles in ecology and environmental science. Nearly 700 journals are indexed in full or in part, and the database indexes literature published from 1982 to the present. Coverage includes habitats, food chains, erosion, land reclamation, resource and ecosystems management, modeling, climate, water resources, soil, and pollution.