Dissertations / Theses on the topic 'Fish movements'

Movement patterns and space use by mature fishes are critical in determining the effectiveness of marine reserves in conserving spawning stock biomass and/or providing biomass to adjacent fisheries through 'spillover'. Home range sizes, activity patterns, site fidelity and habitat preferences were determined for acoustically-tagged snappers and groupers using a rigorously-calibrated array of omnidirectional hydroacoustic receivers deployed in the diverse coral reef environments of a no-take marine reserve (NTMR) network in the Dry Tortugas, Florida. An individual-based localizing tendency model of reef fish movement was parameterized from fine-scale acoustic telemetry data and integrated into a Spatial Management Performance Assessment (SMPA) simulation model for reef fish populations developed to quantitatively evaluate performance of no-take marine reserves in the Dry Tortugas, Florida. Spatially-explicit SMPA models were parameterized for three overfished stocks in the lucrative snapper-grouper fishery: red grouper (Epinephelus morio), black grouper (Mycteroperca bonaci), and mutton snapper (Lutjanus analis). SMPA models were used to evaluate the impacts of a variety of life histories, movement strategies and speeds, and management regulations upon long-term stock sustainability, as measured by annual changes in spawning potential ratio (SPR), and long-term stock productivity, as measured by annual changes in fisheries yield-in-weight per recruit (Yw/R). Under assumptions of constant regional fishing pressure, constant recruitment, and 'realistic' fish movement, SMPA simulation runs from initial conditions in 2000 suggested that by 2014, the Tortugas NTMR network should function to restore red grouper populations to 30% SPR, a Federal management benchmark for sustainability. Mutton snapper were the most mobile of the species investigated; if mutton snapper movements are ignored, their population is predicted to attain 30% SPR by 2014, but given 'realistic' mobility, they may not attain this target by 2021 without additional protections. Black grouper are currently fished at over 9 times sustainable levels. SMPA simulations suggest coupling an increase in minimum size at capture of 20 - 25 cm with NTMR implementation would result in substantial short term losses in yield, but would restore both black grouper and mutton snapper populations to 30% SPR by 2021 and lead to increased long-term yields. Although marine reserve sites are often chosen opportunistically, these findings strongly suggest that reserve designs (e.g. proper sizes and configurations) must take into account the scales and patterns of movement exhibited by the exploited stocks they are intended to protect. These modeling efforts also suggested reserves are not a panacea; in order to promote sustainability for severely depleted stocks, they must be accompanied by an overall reduction in fishing capacity. Although important questions remain concerning the movements of reef fish in response to habitat and density dependent processes, our analyses of realistic reef fish behaviors suggest that the NTMRs of the Dry Tortugas promote substantial gains in SPR, promoting long-term stock sustainability and enhanced egg production. Increased rates of movement diminish these benefits, but may also mitigate short-term losses in yield associated with NTMR establishment.

Dams and weirs are widely implicated in large-scale declines in both the range and abundance of aquatic fauna. Although many factors are involved, such declines are commonly attributed to the prevention or reduction of migration, reductions in available habitat, alteration of natural flow regimes and changes to physicochemical characteristics. In Australia, studies into the ecological effects of these impacts are limited, and have concentrated mainly on species of recreational and commercial importance. Subsequently, the adverse effects of dams and weirs, and suitable methods of mitigation, remain largely unknown for many other taxa. Therefore, the major aim of this thesis is to investigate the ecological effects of dam and weir construction on previously unstudied migratory assemblages of fish and macroinvertebrates in the Murray-Darling Basin. It is anticipated that the results of these studies will feed back into improved management strategies that help arrest the previously observed declines of aquatic fauna. Initially, fish communities were sampled, by boat electrofishing, from both reference sites and downstream of Balranald and Redbank weirs on the lower reaches of the Murrumbidgee River, Australia. Sampling was stratified over large spatial and temporal scales to gain a comprehensive understanding of species most affected by the presence of these two barriers. In general, the weirs obstructed fish migrations during summer and autumn and many species of small-bodied fish such as Australian smelt, western carp gudgeon, fly-specked hardyhead and crimson-spotted rainbowfish accumulated downstream of Balranald Weir. In addition, downstream accumulations of juveniles of larger-bodied species such as bony herring, common carp and goldfish were also detected. Although many previous studies had either documented or hypothesised that upstream migrating fish accumulate downstream of migration barriers, none attempted to quantify the size of such populations. Therefore, a simple but efficient method to estimate the size of migratory populations was assessed at the Balranald Weir site. The application of two commonly used estimation techniques yielded relatively reliable results for seven species that accumulated downstream of the weir. Population size estimates were greatest for most species during summer and autumn, where accumulations as high as 800 fish per day were detected. The largest calculated population size estimates, in addition to the greatest temporal variation, of any individual species was observed in bony herring. Given the simplicity of the technique and the relative accuracy of population estimates, it was concluded that these methods could easily be applied to other weirs where the size of migratory populations is of particular interest. A study investigating the effects of Yanco Weir on the diets of three migratory percichthyid species, Murray cod, trout cod and golden perch was also conducted. Observed spatial variation in a number of trophic processes strongly implicated Yanco Weir as a major contributor to increased competition among percichthyid species on the Murrumbidgee River. The greater relative abundance of percichthyids from downstream samples, combined with increases in dietary overlap and a greater percentage of empty stomachs, also suggested percichthyids may be significantly affecting the relative abundance of potential prey items such as freshwater prawns and Australian smelt. These significant changes in dietary composition were likely related to migratory behaviour, as these species accumulated downstream of the weir, and could be readily expected at other sites where passage is obstructed. It was suggested that the construction of suitable fish passage facilities would effectively reduce the probability of migratory fish accumulating and, subsequently, potential effects of dams and weirs on trophic processes. Since it was established that dams and weirs of the Murrumbidgee River were significantly affecting migratory fish communities, an innovative but relatively inexpensive fishway design, the Deelder fish lock (after Deelder, 1958), was constructed and assessed for wider application throughout the Murray-Darling Basin. The Deelder lock was effective at mitigating the effects of Balranald Weir by providing passage for a wide range of size classes and species of fish; but importantly, the structure enabled the passage of most species previously observed to accumulate downstream of the structure. Most significant was the ability of the fish lock to pass substantial numbers of small-bodied fish, which were previously not considered migratory, suggesting that these species should be considered when developing options to mitigate the effects of other dams and weirs throughout the Murray-Darling Basin. A significant finding of this study was the realisation that substantially more species and size classes of Australian native fish are migratory than previously thought. Subsequently, it is recommended that, when designing facilities to mitigate the effects of a dam or weir, the structure of the entire migratory community is considered when developing operating parameters. Various options for mitigating the effects of dams and weirs are discussed, but it was concluded that the construction of effective fishways would be the most appropriate means of restoring migration pathways to Australian native fish. A strategic approach for assessing and adaptively mitigating the effects of dams and weirs is presented and discussed.

This study examined whether movements of fishes across reserve boundaries reduced the difference in density and size of fish between reserve and non-reserve areas. Visual censuses, experimental trapping, habitat measurements and tagging were performed at 10 sites on two nearly contiguous fringing coral reefs at the northern edge of the Barbados Marine Reserve and at 10 sites on the two fringing reefs closest to the boundary in the non-reserve. The visual censuses showed that overall density and size of fishes large enough to be caught in Antillean fish traps were higher on reserve reefs than on non-reserve reefs. The differences in density and size varied considerably among species and were not statistically significant for individual species. In contrast to a previous study, experimental trap catches were not higher in the reserve than in the non-reserve. Visual censuses, trap catches, and their ratio (trappability) were affected by habitat variables. Species mobility, estimated by the maximum distance between locations at which an individual was captured, corrected for the sampling effort at that distance, was highly variable among species (medians 0--116m). For the more mobile species, movements within fringing reefs and between the nearly contiguous reserve reefs was high but extremely rare among reefs separated by expanses of sand and rubble. For this discrete fringing reef system, there is no evidence that movement across the reserve boundary influences the relative density or size of fish between the reserve and non-reserve.

The Scottish salmon industry is facing challenges in the control of aquatic infectious disease, as is the case in other countries such as Chile and Norway. Disease outbreaks can have an enormous economic impact and possibly affect wild fish populations. Disease transmission in an aquatic environment is complex and there are several transmission routes (vertical transmission, natural reservoirs, hydrodynamic transmission and long-distance movements). Effective control methods such as vaccines are not available in all cases and therefore disease prevention remains a priority. In livestock, epidemiological network models have been proven to be a highly useful tool to investigate the role of different transmission routes on the course of epidemics and have the potential to provide the same utility for aquatic networks. Understanding the complex contact network will result in more effective disease prevention, surveillance systems and control strategies. The aim of this thesis was to investigate the Scottish live fish movement network and its consequences for pathogen transmission between farms in order to develop and optimize control strategies for epidemics. The main objective of chapter 3 was to investigate the effect of different fallowing strategies on the spread of diseases with different transmission properties. A network model was constructed that included both local transmission and long-distance transmission. The basic structure of this network was a ring model where neighbours within a management area could infect each other and non-local transmission occurred at random. The results showed that when long-distance transmission was under reasonable control in comparison with local transmission risk, synchronized fallowing at the management area level was potentially a highly effective tool in the control of infectious diseases. Chapter 4 presents a detailed description of the number of live fish movements and their timing for Atlantic salmon (Salmo salar) in Scottish aquaculture. For this, movement records from 2002 to 2004 were provided by Marine Scotland, Aberdeen. Salmon are anadromous and have a freshwater (FW) and seawater phase (SW). Scottish live fish movements can be divided in FW-FW, FW-SW, SW-SW, SW-FW and “other” movements. The latter are mainly movements from and to research sites. This study showed that the contact structure and timing of live fish movements are seasonal and differ largely between production phases. Disease control measures should take these differences into account to optimize their strategies. In chapter 4, live fish movements were shown to be seasonal; therefore in chapter 5 the main aim was to quantify the effects of seasonality of live fish movements on the course of epidemics. The results showed that the sequence of salmon movements is important for the course of an epidemic. Seasonality is important when local transmission is higher than 0.05 per contact per week and when the movements are not clustered and when movements do not occur in a specific order based on the specific assumptions made in this model. In conclusion, this thesis described the complex live fish movement structure of salmon in Scotland and showed that biosecurity in SW farms is good but could be further improved if all management areas apply synchronized fallowing. The results of this study suggest that biosecurity between freshwater sites could be improved by the application of a system similar to management areas in SW farms.

Master of Science
Department of Biology
Keith B. Gido
Recognizing habitat needs of fishes across space and time is increasingly important for managing altered stream networks, such as in the Colorado River basin. Recent work on warm-water fishes suggest they might benefit from access to tributaries and their confluences. Fish movements or distributions within tributaries relative to distance from mainstem confluences in two streams with different network types (linear versus dendritic) were investigated in the San Juan River basin, USA. Upstream distance from the San Juan River resulted in species declines (Chaco Wash, linear network) or turnover (McElmo Creek, dendritic network). McElmo Creek movement patterns were likely attributed to spring spawning migrations of flannelmouth sucker (Catostomus latipinnis), spawning aggregations of razorback sucker (Xyrauchen texanus), foraging or refuge seeking by Colorado pikeminnow (Ptychocheilus lucius), and monsoon-related movements for channel catfish (Ictalurus punctatus) and razorback sucker. Razorback sucker and Colorado pikeminnow dominated movements at Chaco Wash, suggesting this backwater-like tributary supplied thermal or current refuge, foraging habitat, or both. Within McElmo Creek, a second study explored the importance of confluences by characterizing habitat use and movements of fishes at the junction of McElmo and Yellow Jacket creeks. Native fish dominated the confluence community composition. The reach downstream of the confluence had consistently higher abundances, species richness, and more frequent detections of tagged fishes relative to upstream reaches. Movement behaviors inferred by detection frequency of tagged fish among reaches surrounding the confluence differed among species. Small flannelmouth sucker (< 300 mm) and roundtail chub (Gila robusta) were commonly detected in Yellow Jacket Creek whereas large flannelmouth sucker (> 300 mm), bluehead sucker (C. discobolus), and channel catfish used McElmo Creek reaches. Monsoons increased McElmo Creek discharge which triggered upstream movements of channel catfish and displaced large flannelmouth sucker and bluehead sucker. Monsoons increased movements between McElmo and Yellow Jacket creeks by roundtail chub, small flannelmouth sucker, and black bullhead (Ameiurus melas). Combined, these two field studies emphasized using links between patterns and processes of tributary fish communities. Conservation, rehabilitation, and maintenance of connectivity and habitat heterogeneity at confluence zones likely can be a localized management strategy with expansive ecosystem effects.

Short-term immigration via home range relocation has important implications for metapopulation dynamics, sustainable harvest and pest control strategies, and conservation in populations experiencing high localized mortality. Despite its importance, no suitable theory is available to predict immigration in response to harvest near an adjacent protected area. There is also little information about the factors that influence the magnitude of immigration. I developed a compensatory immigration model to predict the effect of harvesting on immigration under different assumptions about the factors limiting immigration. The model predicts that immigration from protected areas can contribute importantly to total yield and population recovery in the harvest area and can strongly affect demography in the protected area. Immigration and total yield can show complex non-linear relationships with harvesting as the size of the protected area, initial rate of replacement, mobility and behavioral interactions vary. I carried out field experiments to validate the model and assess the relative influence of limiting factors to immigration (i.e. population size in the protected area, the relative habitat quality and functional connectivity between the harvest and protected area). I used longfin (Stegastes dienaceus) and dusky damselfish (S. adustus) as a model system. I first examined functional connectivity by translocating damselfish to investigate which habitat or social features represent a barrier to movement during homing. Small sand gaps constitute a partial barrier to movement, but the effect of sand gap width varies with reef configuration, and fish minimize travel over conspecific territories. I carried out replicated, experimental, incremental reduction of damselfish populations to examine the mechanisms behind home range relocation at the scale of the territory and to evaluate immigration at the landscape scale. At the territory scale, the probability that a territory would be recolonized decreases with local density. Territories tend to be reoccupied by individuals of the same species, sex and size as the original occupant, but territories occupied by larger individuals are more likely to be recolonized. At the landscape scale, models assuming a constant but partial replacement of removed individuals predict immigration much better than models that include either no replacement or complete replacement. In several sites, the best fitting model also included parameters describing density dependence that changed in direction and magnitude with cumulative harvest. Total yield and the proportion of removed individuals replaced by immigrants were correlated with the combined effects of relative habitat quality and connectivity of replicate sites. Overall, my thesis proposes and tests a new compensatory immigration model to predict immigration from protected to harvested areas and suggests that variation in mobility, habitat quality, functional connectivity and behavioral interactions must be considered when predicting the effects of immigration in a harvesting context on metapopulation dynamics, sustainable harvest and conservation.
Dans les populations qui sont soumises à une forte mortalité locale, l'immigration à court terme - via la relocalisation du domaine vital - a d'importantes implications pour la dynamique des métapopulations, l'exploitation soutenable des ressources, la lutte contre les espèces introduites et invasives et la conservation. Malgré son importance, il n'existe pas de théorie prédisant l'immigration dans une zone exploitée à partir d'une zone protégée adjacente. Il existe aussi très peu d'information sur les facteurs influençant l'intensité de l'immigration. J'ai développé un modèle d'immigration compensatoire afin de prédire les effets d'une réduction locale de la densité sur l'immigration en utilisant des scénarios hypothétiques variant dans l'inclusion de facteurs limitant. Le modèle prédit que l'immigration peut contribuer à la récolte totale et à la récupération des populations exploitées et peut affecter la démographie dans la zone protégée. L'immigration et la récolte totale sont reliées de façon complexe et non-linéaire avec l'exploitation cumulative en relation avec la taille de l'aire protégée, le taux initial de remplacement des individus récoltés, la mobilité et les interactions comportementales. Des expériences sur le terrain m'ont permis de valider le modèle et d'estimer l'influence relative de facteurs limitant à l'immigration (i.e. la taille de la population dans la zone protégée, la qualité de l'habitat relative et la connectivité fonctionnelle entre la zone exploitée et la zone protégée). J'ai utilisé la demoiselle noire (Stegastes dienaceus) et la demoiselle brune (S. adustus) et leur habitat comme système modèle. J'ai examiné en premier lieu la connectivité fonctionnelle en relocalisant des demoiselles afin d'investiguer quelles caractéristiques de l'habitat ou caractéristiques sociales peuvent représenter une barrière au mouvement lors du comportement de retour au territoire (ang. « homing »). Les petites étendues de sable constituent une barrière partielle au mouvement mais l'effet de la taille de l'étendue de sable varie en fonction de la configuration des récifs. Les poissons minimisent les mouvements au-dessus des territoires de leur conspécifiques. J'ai également entrepris une réduction expérimentale, incrémentée et répliquée de populations de demoiselles qui a servi à examiner les mécanismes régissant la relocalisation du domaine vital à l'échelle du territoire et l'immigration à l'échelle du paysage. À l'échelle du territoire, la probabilité qu'un territoire soit recolonisé diminue avec une réduction de la densité. Les territoires ont tendance à être recolonisés par des individus de la même espèce, du même sexe et de taille comparable à celle de l'occupant original. Les territoires occupés initialement par les individus les plus gros ont une probabilité plus forte d'être recolonisés. À l'échelle du paysage, les modèles qui assument un remplacement constant mais partiel des individus récoltés ont un meilleur support statistique que les modèles incluant soit un remplacement incomplet ou une absence de remplacement. Dans plusieurs sites où la densité à été manipulée, le modèle ayant le meilleur support statistique incluait également des paramètres modélisant de la densité dépendance (i.e. changement de direction et d'intensité en relation avec la récolte cumulative). La récolte totale et la proportion des individus récoltés qui étaient remplacés par les immigrants étaient corrélées avec l'effet combiné de la qualité de l'habitat et de la connectivité fonctionnelle. En conclusion, ma thèse propose et test un modèle d'immigration compensatoire prédisant l'immigration d'individus habitant les aires protégées vers les zones exploitées. Ce modèle considère la variation de la mobilité, la qualité de l'habitat, la connectivité fonctionnelle et les interactions comportementales afin de prédire les effets de l'immigration dans un contexte d'exploitation soutenable et de conservation à l'échelle de la métapopulation.

Habitat use of mesophotic coral reefs by sharks is largely unknown. However, it is well established that mesophotic reefs are the site of spawning aggregations for many species of teleost fish. These aggregations represent seasonal concentrations of potential prey biomass that may influence the habitat use of predatory species such as large sharks. I employed acoustic monitoring to examine the movements of three shark species [lemon shark (Negaprion brevirostris), tiger shark (Galeocerdo cuvier), and Caribbean reef shark (Carcharhinus perezi)] to determine 1) the comparative spatiotemporal patterns of mesophotic reef habitat use by the three shark species and 2) the spatiotemporal relationship between these sharks and grouper spawning aggregations at a fish spawning aggregation (FSA) site (Hind Bank and Grammanik Bank) along the southern reef shelf edge off St. Thomas, United States Virgin Islands (USVI). Tiger and lemon sharks were detected across nearly the entire acoustic array, which spanned ~ 1060 km2. When present, Caribbean reef sharks used a much smaller activity space, composed exclusively of mesophotic reef habitat located within FSA sites. Individuals from all three species were typically detected for stretches of several consecutive days, while periods without detections usually lasted less than one week. Lemon sharks were present at the FSA site more often during the grouper spawning season (Dec-May) than the non-spawning season (Jun-Nov), but showed no preference toward specific areas within the FSA site, which varied by location and grouper species composition. In contrast, there was no relationship between the presence of tiger and Caribbean reef sharks at the FSA site and the grouper spawning season. My results suggest that despite different habitat use 5 patterns and varying degrees of fidelity, this mesophotic reef serves as an important habitat to all three shark species.

Habitat use of mesophotic coral reefs by sharks is largely unknown. However, it is well established that mesophotic reefs are the site of spawning aggregations for many species of teleost fish. These aggregations represent seasonal concentrations of potential prey biomass that may influence the habitat use of predatory species such as large sharks. I employed acoustic monitoring to examine the movements of three shark species lemon shark (Negaprion brevirostris), tiger shark (Galeocerdo cuvier), and Caribbean reef shark (Carcharhinus perezi)] to determine 1) the comparative spatiotemporal patterns of mesophotic reef habitat use by the three shark species and 2) the spatiotemporal relationship between these sharks and grouper spawning aggregations at a fish spawning aggregation (FSA) site (Hind Bank and Grammanik Bank) along the southern reef shelf edge off St. Thomas, United States Virgin Islands (USVI). Tiger and lemon sharks were detected across nearly the entire acoustic array, which spanned ~ 1060 km2. When present, Caribbean reef sharks used a much smaller activity space, composed exclusively of mesophotic reef habitat located within FSA sites. Individuals from all three species were typically detected for stretches of several consecutive days, while periods without detections usually lasted less than one week. Lemon sharks were present at the FSA site more often during the grouper spawning season (Dec-May) than the non-spawning season (Jun-Nov), but showed no preference toward specific areas within the FSA site, which varied by location and grouper species composition. In contrast, there was no relationship between the presence of tiger and Caribbean reef sharks at the FSA site and the grouper spawning season. My results suggest that despite different habitat use patterns and varying degrees of fidelity, this mesophotic reef serves as an important habitat to all three shark species.

Limited information exists on how southern Californian restored estuaries affect fish habitat use. I used the movements of five predatory fishes in two guilds (ambush and roving predators) to assess juvenile habitat use within estuaries and across landscapes at two spatial scales. Translocating fishes between two discrete estuaries located approximately I 0 km apart revealed that connectivity potential between sites differed between foraging guilds. Despite habitat design differences, fishes did not appear to prefer one site over the other. However on a smaller scale (e.g., within a single estuary), differences in microhabitat conditions affected the habitat use by California Halibut (Paralichthys californicus). Individuals selected habitat based on water flow velocity, temperature and eelgrass coverage, but utilized habitat conditions in a size-segregated manner. Since restoration habitat design influences available microhabitat conditions, differences in design likely alters space use within restored estuaries although perhaps not estuary selection itself.

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The political organization of fishermen configures itself from a series of changes in the fishing industry over the history of the region, the internal dynamics of the communities sobredeterminadas generated by the socio-economic and political environment of the region. From this understanding, the present study is to examine the purpose political organization of fishermen in the community Tauarú in the municipality of Tabatinga / Am. The cut methodology considers the people who participate in studies as important actors in the formulation of new knowledge. The approach of stamp investigative and analytical, characterized as a case study, covering the combination of quantitative and qualitative data collected from the formal and informal representatives of fishermen in the community Tauarú. In this study, adopted is a set of tools and techniques mutually complementary, as application forms, semi-structured, formal and informal conversations, home visits, systematic observation and assistemática, registration fonográfico and photographs. The discussion about the political organization, links to the configuration of social movements in the search for alternatives and strategies for answering the real demands of organized groups. Thus, the study indicates that the fishermen in the Amazon region, began to organize itself in the quest to defend the right to use and management of fish stocks. Therefore, the political organization of fishermen, engendered by changes in the fishery, where despite the difficulties, there is as a strategy to mobilize to have access to fishery resources and property and social services.
A organização política dos pescadores configura-se a partir um conjunto de mudanças ocorridas no setor da pesca ao longo da história da região, da dinâmica interna das comunidades sobredeterminadas geradas pelo contexto sócio-econômico e político da região. A partir dessa compreensão, o presente estudo tem como intuito analisar a organização política dos pescadores na comunidade Tauarú no município de Tabatinga/Am. O recorte metodológico considera as populações que participam dos estudos como agentes importantes na formulação de novos saberes. A abordagem de cunho investigativo e analítico, caracterizou-se como um estudo de caso, abrangendo a associação de dados quantitativos e qualitativos coletados junto aos representantes formais e informais dos pescadores na comunidade Tauarú. Neste estudo, adotou-se um conjunto de instrumentos e técnicas complementares entre si, como aplicação de formulários, entrevistas semi-estruturadas, conversas formais e informais, visitas domiciliares, observação sistemática e assistemática, registro fonográfico e fotográfico. A discussão acerca da organização política, articula-se com a configuração dos movimentos sociais na busca de alternativas e estratégias para o atendimento às reais demandas dos grupos organizados. Assim, o estudo indica que os pescadores na região Amazônica, passaram a organizar-se na busca de defender o direito de uso e gestão dos recursos pesqueiros. Portanto, a organização política dos pescadores, engendrada pelas mudanças no contexto da pesca, em que pese às dificuldades, vislumbra-se como estratégia de mobilização tenham para o acesso aos recursos pesqueiros e aos bens e serviços sociais.

Tese(doutorado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2010.
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O presente estudo teve como objetivo investigar as consequencias da construção Barragem Eclusa na estrutura das assembléias de peixes marinha, estuarina e de água doce que habitam o sistema lagunar Patos-Mirim. A área de estudo foi o Canal São Gonçalo, o qual interliga a Lagoa dos Patos com a Lagoa Mirim. As amostragens foram conduzidas mensalmente durante os anos de 2005 (12 meses), 2006 (6 meses), 2007 (12 meses) e 2008 (2 meses) abrangendo a região sudoeste do Canal denominada de limnica, sem a presença de salinidade, e na região nordeste, com influência sazonal da salinidade. As amostragens foram realizadas com métodos ativos de pesca: Arrasto de praia em profundidades (1,5m) e o Arrasto de fundo, em profundidades (>2m) totalizando 384 e 768 amostras, respectivamente. O trabalho foi dividido em três capítulos: I) Evidência de Fragmentação de Habitat afetando a movimentação de peixes entre as Lagoas Patos – Mirim, no Sul do Brasil; II) Distribuição espacial da assembléia de peixes em uma região de transição entre o estuário da Lagoa dos Patos e a Lagoa Mirim, Canal São Gonçalo, RS, Brasil; III) Padrões Ambientais influenciando a similaridade espacial da assembléia de peixes em uma região de transição entre estuário e água doce. No total foram capturadas 98 espécies, com 52.020 indivíduos no arrasto de praia e 155.972 indivíduos no arrasto de fundo. Os principais resultados demonstram que as conseguencias da Barragem Eclusa provocaram uma mudança na condição ambiental deste Sistema Lagunar envolvendo três aspectos para assembléia de peixes: i) a perda de habitat para as espécies Marinho Vagante, Estuarino Dependente e Estuarino Residente, ii) o Aumento do habitat para as espécies Primárias e Secundárias de água doce na região da Lagoa Mirim e iii) a fragmentação do habitat para as espécies Primárias e Secundárias de água doce entre as regiões Limnica e Estuarina do Canal. As medidas propostas para mitigar o impacto da Barragem Eclusa estão relacionadas a aumentar a passagem das espécies Estuarino Dependente para região Límnica do Canal São Gonçalo para a Lagoa Mirim, via o aperfeiçoamento da operação do sistema de comportas da Barragem Eclusa.
The present study aimed to investigate the consequences of the São Gonçalo channel dam-lock in the structure of the marine, estuarine and freshwater fish assemblies that inhabit the Patos-Mirim lagoon system. The study area was the São Gonçalo channel that connects the Patos Lagoon with the Mirim Lagoon. Sampling took place monthly during years 2005 (12 months), 2006 (6 months), 2007 (12 months) and 2008 (2 months), covering the southwestern part of the channel – the limnic region without salinity, and the northeastern part, influenced by saline waters. Samples were taken by means of active gears: beach-seine in depth up to 1.5 m and bottom-trawl at depth higher than 2 m, totaling 384 and 768 samples, respectively. The present wor was divided in three chapters: I) Evidence of habitat fragmentation affecting fish movement between Patos and Mirim coastal Lagoons in Soutthenr Brazil, II) Spatial distribution of the fish assembly in a transition zone between Patos Lagoon's e estuary and Mirim Lagoon: São Gonçalo channel, RS, Brazil; III) Environmental patterns influencing the spatial similarity of the fish assembly of a transition zone between estuarine and freshwater. In total, 98 species, with 52,020 individuals were collected by the beach-seine and 155,972 by bottom-trawl. Main results demonstrate that the building of the dam-lock caused a change in the environment of this lagunar system with three aspects: i) habitat loss for the marine vagrant, the estuarine-resident and the estuarine-depentent species, ii) an increase of habitat for primary and secondary freshwater species in the Mirim lagoon region, and iii) habitat fragmentation for primary and secondary freshwater species in the limnic and estuarine regions of the channel. The proposed measures to mitigate the impact of the dam-lock are related to increase the passage of estuarine-dependent species towards the limnic region of São Gonçalo channel and to Mirim lagoon, by improving the operation of the dam-lock gates.

Modifications to Brandon Road Lock and Dam (BRLD), located on the Des Plaines River in northeastern Illinois, have been proposed to prevent the upstream transfer of aquatic invasive species, particularly Asian carps, into the Great Lakes Basin. These modifications, including the installation of an electric barrier, acoustic fish deterrent, and air bubble curtain, are designed to completely eliminate all upstream fish passage and may negatively impact native fish populations in the Des Plaines River by reducing upstream movement and potentially fragmenting populations. BRLD is situated just 21 km upstream of the Des Plaines River mouth, and fish are only able to pass upstream via the lock chamber. Fish species richness within the Des Plaines River watershed has increased over the last 35 years. It has been suggested that the majority of new species to the upper Des Plaines River have migrated upstream past Brandon Road Lock and Dam (BRLD), from the Illinois, Kankakee, and lower Des Plaines rivers. However, documentation of emigration needed to support that contention is lacking and there is limited knowledge of the current rate of BRLD passage by native species. To assess native fish passage through the lock, a microchemical study was conducted using fin rays from fish collected from the Des Plaines, Illinois, and Kankakee Rivers. The edge of each fin ray, which contained the most recently deposited material, was assumed to contain a microchemical signature reflective of residency in the river where the fish was sampled. Fin ray edge strontium:calcium ratio (Sr:Ca) was used to define taxonomic and river-specific signature ranges for four taxonomic groups: centrarchids, catostomids, ictalurids, and lepisosteids. Fin ray edge Sr:Ca data were input into a random forest classification model, and the classification accuracy of fish to their river of capture based on their fin ray edge Sr:Ca was > 97% in each taxonomic group. The classification model was then applied to the entire fin ray of each fish sampled upstream of Brandon Road to infer retrospective environmental history. Upstream BRLD lock passage was suggested by the presence of Sr:Ca signatures indicative of prior downstream residency in the Illinois or Kankakee rivers in a fish sampled upstream of BRLD. Results indicated some evidence of downstream residency that suggested upstream BRLD lock passage for centrarchids, catostomids, ictalurids, and lepisosteids, ranging from 15 – 37% of individuals sampled depending on taxa. An additional 19 – 80% of individuals within each taxonomic group were classified as fish with uncertain downstream residency, whereby the possibility of BLRD lock passage could not be rejected, but there was higher uncertainty in establishing downstream residency in the Illinois or Kankakee rivers. The impact of BRLD modifications and passage restriction on Des Plaines River fish populations is unknown and merits further investigation.

Master of Science
Biology
Keith B. Gido
Negative interactions with nonnative fish are often cited as a leading cause of declining native fish populations, but quantifying these interactions is difficult. Movement ecology and consumptive demand estimates of nonnative fish predators is needed to better understand potential impacts these organisms are having on native species. The objective of this thesis were to estimate the consumptive demand of Flathead Catfish Pylodictis olivaris on native fishes across an elevational gradient, and characterize the movement at hourly, daily, and seasonal scales of this introduced predator. This research was conducted in the upper Gila River basin of southwestern New Mexico. Bioenergetics modeling was used to estimate consumptive demand; model results were coupled with measured densities and size structure of Flathead Catfish populations, and water temperatures, to predict its predatory threat. Potential consumption was highest at lower elevation sites because of higher water temperatures, but actual consumption was highest at mid-elevation sites because of the prevalence of large-bodied individuals. Potential annual consumptive demand of Flathead Catfish on native fish across our nine sampling sites ranged from 0.0 to 3.1 g/m²/yr, which exceeded native fish productivity at one site. To characterize the movement of Flathead Catfish, we used radio telemetry and tracked individuals from May 2014 to June 2015. Movement behaviors varied among individuals with a majority moving <150 m from capture location and some more mobile, moving substantial distances (692-42,840 m). During the course of the study, activity was greatest in summer and fall, and individuals moving substantial distances moved downstream to warmer river reaches before the winter. Nightly movements only involved short distances (5 m) and no fish exceeded a single movement >80 m. Daily activity was greatest during evening but late afternoon activity was observed in summer and fall. Results from this study identify areas within the upper Gila River where introduced Flathead Catfish consumption is likely to negatively impact native fish populations and managers can use this information to understand potential overlap with native species, target future removal efforts in areas where these fish are concentrated, and avoid stocking native fishes in reaches where Flathead Catfish tend to aggregate.

Mongolia is currently undergoing a rapid socioeconomic transition with extensive development driven by increased mineral resource extraction and large scale agriculture and pastoral expansion. There has also been unprecedented urbanisation and continued population growth that has placed added pressure on the ageing public infrastructure including power stations and waste water treatment plants. As a result, the country’s pristine landscapes, including its vast freshwater ecosystems, are now facing widespread degradation, contamination and species losses in the most impacted regions. The proposed large-scale dams and imminent climate change effects will further damage these fragile ecosystems. With a number of rivers and lakes deteriorating, resident aquatic communities, including unique fish species, have suffered significant population declines. However, a more substantial threat currently facing these fish populations is the rapid and largely unregulated rise in fishing activities within an emerging recreational fishery. Although historically fish capture and consumption has not been a traditional part of the Mongolian diet or culture, this is changing rapidly. Therefore a comprehensive set of research projects were developed and implemented across Mongolia, to gather essential information on this new fishery, while also addressing existing knowledge gaps regarding the spatial ecology and genetic structure of the main target species. In addition, a potential human health risk was evident due to the increased consumption of locally caught fish species from a heavily impacted river basin, and thus this was also investigated. Overall, the collective aim of this fisheries research was to increase the scientific understanding and knowledge across a range of issues and ultimately advise authorities on improving current management regulations and conservation strategies. It is hoped that the recommendations can assist in safeguarding the future sustainability and resilience of the threatened fish populations and the emerging recreational fishery across Mongolia for the future. A total of five fisheries related research projects were completed between 2011 and 2014, with the results from each used to formulate the conservation and management recommendations presented in this thesis. Due to the lack of knowledge regarding the emerging recreational fishery, roving creel surveys were conducted across three river basins and covered five key topics including angler demographics, fishing practices, current fishing trip data, fishing gear and costs, and angler knowledge and opinions. Fifty-eight fishing groups (n = 154 anglers) were interviewed and two angler types were identified: rural anglers with no or low incomes, who reside in the basin, fish alone or in smaller groups, fish frequently for shorter periods, and consumed fish more regularly; and urban anglers who have medium to high incomes, live in larger cities, spent more money on fishing gear / trips and fished for multiple days at a time. B. lenok was identified as the most targeted and caught species in the fishery. The results of the creel surveys confirmed increased fish consumption in the Kharaa River basin, which was identified as a potential human health risk due to the widespread heavy metal contamination from both past and present mining activities. Thus heavy metal contaminates in river water, sediment and five consumed fish species were examined at 11 sites across the basin. Heavy metals were evident in all five sampled species, with maximum muscle contents of chromium (Cr), arsenic (As), mercury (Hg) and lead (Pb) detected in fish from the middle and lower reaches, while zinc (Zn) was highly elevated in B. lenok from the upper tributaries. Elevated median contents of Cr, copper (Cu), Hg and Pb increased with trophic level, with the bioaccumulation of Hg posing the greatest threat to human health with over 10 % of all fish sampled exceeded the internationally recommended threshold for Hg in consumable fish tissue (> 0.5 µg g-1 ww). This bioaccumulation in resident fish species could lead to chronic toxicity in people who consume them regularly and have additional exposure to other sources of contamination e.g. gold mining. A further two projects were conducted that utilised passive acoustic telemetry to describe the spatial and temporal autecology, habitat use and behaviour of B. lenok in the Eroo River and H. taimen in the Onon/Balj rivers under Mongolia’s extreme seasonal conditions. The maximum longitudinal movements (home ranges) detected were more extensive than previously reported for both species with 45.3 km for B. lenok and 126.1 km for H. taimen. Increased movements were recorded in spring and summer, with individuals entering surrounding tributaries and remaining there for between four and 85 days before returning to the main river channel. The results highlighted the importance of maintaining the integrity and connectivity of tributary habitats for spawning, feeding and overwintering, as well as hydrological and thermal refuges, which will be increasingly important for these species in the region with the pending impacts of climate change. This increased knowledge relating to the spatial ecology of these threatened species can guide the design and implementation of new protective measures such as the introduction of Freshwater Protected Areas (FPAs) across Mongolia. Further research was conducted to gain a broader, multigenerational understanding of the interconnectedness between conspecific populations of H. taimen, B. lenok and T. baicalensis across the major river basins. Both molecular and nuclear markers were used to demarcate the population’s genetic structure and define Evolutionary Significant Units (ESUs) and priority populations for these species across their Mongolian distributions. Across all species, the most prominent pattern was a strong differentiation among major basins with low differentiation and weak patterns of isolation by distance within basins, which indicates high within-basin connectivity between populations, although exact patterns were not completely concordant among species. The extensive results produced from the current scientific research has facilitated the development of a comprehensive set of key recommendations for implementing new, and enhancing existing, management and conservation measures relating to Mongolia’s threatened salmonid species and its emerging recreational fishery. These recommendations include: 1. Establishing a series of Freshwater Protected Areas (FPAs) throughout Mongolia’s major river basins, with their design and location based upon the spatial ecology and genetic population structure determined by the current research results; 2. Shifting the opening date of the fishing season to encompass the entire spawning period of B. lenok (the fishery’s main target species), which appears to currently not be the case; 3. Adding the blunt-snouted lenok (B. sp.) to the prohibited species list, as it has been genetically proven to be an independent species and has a restricted distribution and low abundance in Mongolia; and 4. Introducing minimum (and potentially maximum) size limits for B. lenok and T. baicalensis, to better protect immature and pre-spawning individuals from being removed from the population. In addition, it is highly recommended to commence fisheries dependent and independent assessments in key river basins and conduct biomonitoring programs (using a bioindicator species) to track toxic heavy metal contamination and identify potential human health risks associated with consuming resident fish species from the more heavily impacted regions. The lack of knowledge of the current fishing regulations by anglers as well as the observed and reported widespread illegal fishing activities demands a wide-ranging angler education program to improve understanding and compliance within the fishery. The future survival of these threatened salmonids and the sustainability of the emerging recreational fishery in Mongolia currently hangs in the balance. However, if these scientifically based recommendations are implemented in full, and can be adequately enforced, then the responsible authorities can take a huge step forward towards reversing the current trends and preserving the country’s imperilled freshwater fish populations and their valuable aquatic ecosystems. Mongolia can be a model for freshwater species conservation and management throughout the region and the world.:DECLARATION OF CONFORMITY I TABLE OF CONTENTS II ACKNOWLEDGMENTS V LIST OF ABBREVIATIONS VI LIST OF FIGURES VII LIST OF TABLES VIII SUMMARY IX SUMMARY IN GERMAN / ZUSAMMENFASSUNG AUF DEUTSCH XII SUMMARY IN MONGOLIAN / ХУРААНГУЙ XVI INTRODUCTION 1 1 RESEARCH OBJECTIVES AND HYPOTHESES 1 1.1 OVERALL THESIS OBJECTIVES 6 2 MONGOLIA’S NATURAL ENVIRONMENT 7 2.1 GEOGRAPHIC ECOREGIONS 7 2.2 CLIMATIC CONDITIONS 7 2.3 HYDROLOGICAL NETWORKS 8 2.4 FRESHWATER FISH FAUNA 9 3 ANTHROPOGENIC FORCINGS 11 3.1 CURRENT SOCIOECONOMIC TRANSITIONS 11 3.2 INTENSIFYING FISHING ACTIVITIES 11 3.3 CONTAMINATION OF AQUATIC ECOSYSTEMS 12 3.4 IMMINENT THREATS 15 RESEARCH CHAPTERS 17 4 AN EMERGING RECREATIONAL FISHERY IN MONGOLIA’S URBANISING SOCIETY: A THREAT TO ITS PRISTINE FISH STOCKS? 17 4.1 ABSTRACT 17 4.2 INTRODUCTION 18 4.3 MATERIALS AND METHODS 20 4.4 RESULTS 22 4.5 DISCUSSION 29 5 REGIONAL PATTERNS OF HEAVY METAL EXPOSURE AND CONTAMINATION IN THE FISH FAUNA OF THE KHARAA RIVER BASIN (MONGOLIA) 36 5.1 ABSTRACT 36 5.2 INTRODUCTION 37 5.3 MATERIALS AND METHODS 39 5.4 RESULTS 43 5.5 DISCUSSION 49 6 MOVEMENTS AND BEHAVIOUR OF AN ARCHAIC TROUT, BRACHYMYSTAX LENOK (PALLAS, 1773) UNDER EXTREME ENVIRONMENTAL CONDITIONS IN MONGOLIA 57 6.1 ABSTRACT 57 6.2 INTRODUCTION 57 6.3 MATERIALS AND METHODS 60 6.4 RESULTS 64 6.5 DISCUSSION 71 7 SEASONAL HOME RANGE SHIFTS OF THE SIBERIAN TAIMEN (HUCHO TAIMEN; PALLAS, 1773): EVIDENCE FROM PASSIVE ACOUSTIC TELEMETRY IN THE ONON RIVER AND BALJ TRIBUTARY (AMUR RIVER BASIN, MONGOLIA) 78 7.1 ABSTRACT 78 7.2 INTRODUCTION 79 7.3 MATERIALS AND METHODS 81 7.4 RESULTS 84 7.5 DISCUSSION 88 8 FISH CONSERVATION IN THE LAND OF STEPPE AND SKY: EVOLUTIONARY SIGNIFICANT UNITS OF THREATENED SALMONID SPECIES IN MONGOLIA MIRROR MAJOR RIVER BASINS 95 8.1 ABSTRACT 95 8.2 INTRODUCTION 95 8.3 MATERIALS AND METHODS 98 8.4 RESULTS 101 8.5 DISCUSSION 108 DISCUSSION 115 9 SOLUTIONS FOR SUSTAINABLE FISHERIES IN MONGOLIA 115 9.1 OVERVIEW AND LINKAGES OF KEY RESEARCH FINDINGS 115 9.2 FRESHWATER FISH CONSERVATION IN A TRANSITIONAL SOCIETY 118 9.3 ADDRESSING MANAGEMENT SHORTFALLS TO CURB INTENSIFYING FISHING ACTIVITIES 119 9.4 BIOMONITORING TO MITIGATE HUMAN HEALTH RISKS 122 9.5 IMPROVING ANGLER COMPLIANCE WITH INCREASED EDUCATION 123 9.6 PRESERVING HYDROLOGICAL CONNECTIVITY AND RIVER INTEGRITY IN THE FACE OF IMMINENT THREATS 124 9.7 MANAGEMENT AVOIDANCES 127 9.8 TRANSFERABILITY OF RESEARCH METHODS, RESULTS AND RECOMMENDATIONS 127 9.9 FUTURE RESEARCH AND MANAGEMENT PRIORITIES 129 10 REFERENCES 132 APPENDIX 1 I APPENDIX 2 II APPENDIX 3 VI APPENDIX 4 VIII APPENDIX 5 XXI APPENDIX 6 XXII APPENDIX 7 XXIV 11 REFERENCES TO OWN PUBLISHED / SUBMITTED MANUSCRIPT IN THE PRESENT THESIS XXV 12 INDIVIDUAL CONTRIBUTIONS TO THE CURRENT THESIS XXVI 13 NOTE ON THE COMMENCEMENT OF THE DOCTORAL PROCEDURE XXVIII 14 CURRICULUM VITAE XXIX 15 LIST OF PUBLICATIONS XXXI
Die Mongolei befindet sich derzeit in einem rasanten sozioökonomischen Übergang mit tiefgreifenden Veränderungen, die v.a. durch eine Zunahme bergbaulicher Aktivitäten sowie einen Ausbau ackerbaulicher Nutzungen wie auch der Viehwirtschaft angetrieben werden. Derzeit vollzieht sich eine noch nie dagewesene Urbanisierung und ein weiteres Bevölkerungswachstum, das auf die alternde öffentliche Infrastruktur, einschließlich Kraftwerke und Abwasserbehandlungsanlagen, einen zusätzlichen Druck ausübt. Infolgedessen zeigen sich in den weitgehend unberührten Landschaften des Landes, einschließlich seiner riesigen Süßwasser-Ökosysteme, deutliche Anzeichen von Übernutzung natürlicher Ressourcen, Umweltverschmutzung und Artenverlusten. Zukünftig geplante große Staudämme werden neben den bevorstehenden Auswirkungen des Klimawandels die Hydrologie deutlich verändern. So sind bereits deutliche Beeinträchtigungen der Fluss-und See-Ökosysteme erkennbar, insbesondere in Hinblick auf ihre aquatischen Lebensgemeinschaften. Einige der weltweit einzigartigen Fischarten haben bereits erhebliche Bevölkerungsrückgänge erlitten. Eine weitere existenzielle Bedrohung für diese Fischpopulationen ist der rasche und weitgehend un-regulierte Anstieg der Fischereitätigkeiten aus einer aufstrebenden Freizeitfischerei. Obwohl Fischfang und -konsum keine traditionellen Elemente der mongolischen Ernährung oder Kultur darstellen, vollziehen sich diesbezüglich derzeit tiefgreifende Veränderungen. Daher wurden in der Mongolei umfangreiche Forschungsprojekte geplant und durchgeführt, um wesentliche Informationen über diese neue Art der Fischerei zu sammeln und gleichzeitig bestehende Wissenslücken in Bezug auf die räumliche Ökologie und die Metapopulationsstruktur der wichtigsten Zielarten zu schließen. Darüber hinaus zeigten Untersuchungen, dass sich aufgrund des erhöhten Konsums von lokal gefangenen Fischarten aus einem stark beeinträchtigten Einzugsgebiet ein potenzielles Risiko für die menschliche Gesundheit ergibt. Insgesamt ist das übergeordnete Ziel dieser Fischereiforschung, das wissenschaftliche Verständnis und Wissen zu erweitern und letztlich die derzeitigen Managementinstrumente zu verbessern und neue Erhaltungsmaßnahmen zu ergreifen, um die Nachhaltigkeit und Widerstandsfähigkeit der bedrohten Fischartenpopulationen und die aufkommende Erholung zu sichern. Insgesamt wurden zwischen 2011 und 2014 insgesamt fünf fischereibiologische Forschungsprojekte abgeschlossen, wobei die Ergebnisse dieser Arbeiten in Erhaltungs- und Managementempfehlungen münden. Wegen des Mangels an Wissen über die aufkommende Freizeitfischerei wurden Anglerbefragungen in drei Einzugsgebieten durchgeführt, welche fünf wichtige Themen wie Angler-Demographie, Fischereipraktiken, Reisetätigkeiten, Fanggeräte und Kosten sowie Anglerwissen und Meinungen umfassten. Fünfundsechzig Angelgruppen (n = 154 Angler) wurden interviewt und zwei Anglertypen identifiziert: ländliche Angler ohne oder niedrige Einkommen, die in dem Becken wohnen, alleine oder in kleineren Gruppen fischen, häufig für kürzere Zeiten fischen und regelmäßig Fisch verzehren; und städtische Angler, die mittlere bis hohe Einkommen haben, in größeren Städten leben, mehr Geld für Fanggeräte / Ausflüge ausgegeben und typischerweise für mehrere Tage am Stück fischen. B. lenok wurde als die bevorzugte und am meisten gefangene Zielarten der Fischerei identifiziert. Die Ergebnisse der Anglerbefragungen bestätigten den erhöhten Fischkonsum im Kharaa-Einzugsgebiet, das aufgrund der weit verbreiteten Schwermetallverunreinigung aus der Vergangenheit und den gegenwärtigen Bergbauaktivitäten als potenzielles Risiko für die menschliche Gesundheit identifiziert wurde. So wurden Schwermetallverunreinigungen im Flusswasser, Sediment und fünf konsumierten Fischarten an 11 Standorten im Einzugsgebiet untersucht. Schwermetalle zeigten sich in allen fünf Stichprobenarten, wobei der maximale Muskelgehalt von Cr, As, Hg und Pb in Fischen aus dem Mittel- und Unterlauf festgestellt wurde, während Zn in B. lenok in den Oberlaufregionen stark erhöht war. Der erhöhte mediane Gehalt an Cr, Cu, Hg und Pb nahm mit trophischer Ebene zu, wobei die Bioakkumulation von Hg die größte Bedrohung für die menschliche Gesundheit darstellte, wobei über 10% aller Fischproben den international empfohlenen Schwellenwert für Hg im verzehrbaren Fischgewebe überstiegen (> 0,5 μg g-1 ww). Diese Bioakkumulation in residenten Fischarten könnte zu chronischen Intoxikationen bei Menschen führen, die sie regelmäßig konsumieren und zusätzliche Exposition gegenüber anderen Kontaminationsquellen haben, z.B. im Goldbergbau. Es wurden weitere zwei Projekte durchgeführt, die eine passive akustische Telemetrie zur Beschreibung der räumlichen und zeitlichen Autökologie, des Lebensraumnutzens und des Verhaltens von B. lenok im Eroo River und H. taimen in den Flüssen Onon und Balj unter den extremen Klimabedingungen der Mongolei verwendeten. Die maximalen Längsbewegungen (Heimatbereiche) wurden -umfangreicher als bisher angenommen- für beide Arten wurden auf 45,3 km für B. lenok und 126,1 km für H. taimen ermittelt. Im Frühjahr und Sommer wurden erhöhte Bewegungen aufgezeichnet, wobei die Individuen in die umliegenden Nebenflüsse eintraten und dort zwischen 4 und 85 Tagen verblieben, bevor sie zum Hauptfluss des Flusses zurückkehrten. Die Ergebnisse zeigen die Bedeutung der Aufrechterhaltung der Integrität und der Konnektivität von Nebenflüssen für Laichen, Nahrungssuche und Überwinterung sowie hydrologische und thermische Schutzräume, die für diese Arten in der Region mit den anstehenden Auswirkungen des Klimawandels zunehmend an Bedeutung gewinnen werden. Die verbesserten Kenntnisse der räumlichen Ökologie dieser bedrohten Arten kann die Gestaltung und Umsetzung neuer Schutzmaßnahmen wie Süßwasser-Schutzgebiete in der Mongolei wissenschaftlich fundieren und leiten. Weitere Untersuchungen wurden durchgeführt, um ein breiteres, multigenerationales Verständnis der Zusammenhänge zwischen den konkreten Populationen von H. taimen, B. lenok und T. baicalensis über die großen Flusseinzugsgebiete zu gewinnen. Sowohl molekulare als auch nukleare Marker wurden verwendet, um die genetische Struktur abzugrenzen und definieren, so z.B. evolutionär signifikante Einheiten (ESUs) und eigenständige Populationen für diese Arten einschließlich ihrer räumlichen Verteilung in der Mongolei. Über alle Arten hinweg war das deutlichste Muster eine starke Differenzierung zwischen den großen Becken mit geringer Differenzierung. Dem gegenüber stehen schwache Muster der Isolation durch die Distanz in den Becken, die eine hohe einzugsgebietsinterne Konnektivität anzeigen, obwohl exakte Muster nicht vollständig unter allen Arten übereinstimmten. Die Prioritäten der Erhaltung müssen sich auf die Verbesserung des Schutzes der vorrangigen Bevölkerungsgruppen innerhalb jeder Art und ESU konzentrieren, um die begrenzten verfügbaren Ressourcen für die Arten- und Populations-Erhaltung und fischereiliche Bewirtschaftung in der Mongolei zu maximieren. Die umfangreichen Ergebnisse aus der aktuellen wissenschaftlichen Forschung ermöglichten die Ableitung umfassender Empfehlungen für die Umsetzung neuer und die Verbesserung der bestehenden Management- und Erhaltungsmaßnahmen in Bezug auf die bedrohten Lachsarten der Mongolei und die aufkommende Freizeitfischerei. Diese Empfehlungen beinhalten 1.die Gründung einer Reihe von Süßwasser-Schutzgebieten (FPA) in den großen Flussgebieten der Mongolei auf der Grundlage der räumlichen Ökologie und der genetischen Bevölkerungsstruktur, die durch die aktuellen Forschungsergebnisse untermauert wird; 2. Eine Verschiebung des Eröffnungstermins der Fangsaison, welche im Gegensatz zur aktuellen Praxis die gesamte Laichzeit von B. lenok (die Hauptzielspezies der Fischerei); umfassen sollte; 3. Hinzufügen des Stumpfschnauzen-Lenok (B. sp.) zur Liste der besonders geschützten Arten, da er sich als eine genetisch unabhängige Spezies erwiesen hat, welche eine begrenzte räumliche Verteilung und geringe Populationsdichte in der Mongolei hat; und 4. Einführung von minimalen (und potentiell maximalen) Körpergrößenbeschränkungen für B. lenok und T. baicalensis, um die unreifen und heranwachsenden Individuen besser vor menschlichen Einflüssen zu schützen. Darüber hinaus empfiehlt es sich dringend, in den wichtigsten Flussgebieten fischereilich genutzte und nicht genutzte Fischpopulationen zu erfassen und Biomonitoring-Programme (unter Verwendung von Bioindikator-Spezies) zu implementieren, um toxische Schwermetallverunreinigungen zu verfolgen und potenzielle Risiken für die menschliche Gesundheit zu identifizieren, die mit dem Verzehr Fischen aus beeinträchtigten Regionen einhergehen. Schließlich verlangt das Fehlen von Kenntnissen über die derzeitigen Fischereiverordnungen durch Angler sowie die beobachteten und gemeldeten weitverbreiteten illegalen Fischereitätigkeiten ein weitreichendes Angler-Bildungsprogramm, um das Verständnis und die Einhaltung fischereilicher Regelungen zu verbessern. Das künftige Überleben der bedrohten Salmoniden und die Nachhaltigkeit der aufkommenden Freizeitfischerei in der Mongolei sind eng miteinander verbunden. Sofern die hier dargestellten wissenschaftlich fundierten Empfehlungen in vollem Umfang umgesetzt werden und hinreichend kontrolliert werden können, würden die zuständigen Behörden einen großen Schritt in Richtung der Umkehrung der aktuellen Trends machen und die gefährdeten Süßwasserfischpopulationen des Landes und ihre wertvollen aquatischen Ökosysteme bewahren. Die Mongolei könnte dann ein Modell für die Erhaltung und Bewirtschaftung von Süßwasserarten in der ganzen Region und der Welt werden.:DECLARATION OF CONFORMITY I TABLE OF CONTENTS II ACKNOWLEDGMENTS V LIST OF ABBREVIATIONS VI LIST OF FIGURES VII LIST OF TABLES VIII SUMMARY IX SUMMARY IN GERMAN / ZUSAMMENFASSUNG AUF DEUTSCH XII SUMMARY IN MONGOLIAN / ХУРААНГУЙ XVI INTRODUCTION 1 1 RESEARCH OBJECTIVES AND HYPOTHESES 1 1.1 OVERALL THESIS OBJECTIVES 6 2 MONGOLIA’S NATURAL ENVIRONMENT 7 2.1 GEOGRAPHIC ECOREGIONS 7 2.2 CLIMATIC CONDITIONS 7 2.3 HYDROLOGICAL NETWORKS 8 2.4 FRESHWATER FISH FAUNA 9 3 ANTHROPOGENIC FORCINGS 11 3.1 CURRENT SOCIOECONOMIC TRANSITIONS 11 3.2 INTENSIFYING FISHING ACTIVITIES 11 3.3 CONTAMINATION OF AQUATIC ECOSYSTEMS 12 3.4 IMMINENT THREATS 15 RESEARCH CHAPTERS 17 4 AN EMERGING RECREATIONAL FISHERY IN MONGOLIA’S URBANISING SOCIETY: A THREAT TO ITS PRISTINE FISH STOCKS? 17 4.1 ABSTRACT 17 4.2 INTRODUCTION 18 4.3 MATERIALS AND METHODS 20 4.4 RESULTS 22 4.5 DISCUSSION 29 5 REGIONAL PATTERNS OF HEAVY METAL EXPOSURE AND CONTAMINATION IN THE FISH FAUNA OF THE KHARAA RIVER BASIN (MONGOLIA) 36 5.1 ABSTRACT 36 5.2 INTRODUCTION 37 5.3 MATERIALS AND METHODS 39 5.4 RESULTS 43 5.5 DISCUSSION 49 6 MOVEMENTS AND BEHAVIOUR OF AN ARCHAIC TROUT, BRACHYMYSTAX LENOK (PALLAS, 1773) UNDER EXTREME ENVIRONMENTAL CONDITIONS IN MONGOLIA 57 6.1 ABSTRACT 57 6.2 INTRODUCTION 57 6.3 MATERIALS AND METHODS 60 6.4 RESULTS 64 6.5 DISCUSSION 71 7 SEASONAL HOME RANGE SHIFTS OF THE SIBERIAN TAIMEN (HUCHO TAIMEN; PALLAS, 1773): EVIDENCE FROM PASSIVE ACOUSTIC TELEMETRY IN THE ONON RIVER AND BALJ TRIBUTARY (AMUR RIVER BASIN, MONGOLIA) 78 7.1 ABSTRACT 78 7.2 INTRODUCTION 79 7.3 MATERIALS AND METHODS 81 7.4 RESULTS 84 7.5 DISCUSSION 88 8 FISH CONSERVATION IN THE LAND OF STEPPE AND SKY: EVOLUTIONARY SIGNIFICANT UNITS OF THREATENED SALMONID SPECIES IN MONGOLIA MIRROR MAJOR RIVER BASINS 95 8.1 ABSTRACT 95 8.2 INTRODUCTION 95 8.3 MATERIALS AND METHODS 98 8.4 RESULTS 101 8.5 DISCUSSION 108 DISCUSSION 115 9 SOLUTIONS FOR SUSTAINABLE FISHERIES IN MONGOLIA 115 9.1 OVERVIEW AND LINKAGES OF KEY RESEARCH FINDINGS 115 9.2 FRESHWATER FISH CONSERVATION IN A TRANSITIONAL SOCIETY 118 9.3 ADDRESSING MANAGEMENT SHORTFALLS TO CURB INTENSIFYING FISHING ACTIVITIES 119 9.4 BIOMONITORING TO MITIGATE HUMAN HEALTH RISKS 122 9.5 IMPROVING ANGLER COMPLIANCE WITH INCREASED EDUCATION 123 9.6 PRESERVING HYDROLOGICAL CONNECTIVITY AND RIVER INTEGRITY IN THE FACE OF IMMINENT THREATS 124 9.7 MANAGEMENT AVOIDANCES 127 9.8 TRANSFERABILITY OF RESEARCH METHODS, RESULTS AND RECOMMENDATIONS 127 9.9 FUTURE RESEARCH AND MANAGEMENT PRIORITIES 129 10 REFERENCES 132 APPENDIX 1 I APPENDIX 2 II APPENDIX 3 VI APPENDIX 4 VIII APPENDIX 5 XXI APPENDIX 6 XXII APPENDIX 7 XXIV 11 REFERENCES TO OWN PUBLISHED / SUBMITTED MANUSCRIPT IN THE PRESENT THESIS XXV 12 INDIVIDUAL CONTRIBUTIONS TO THE CURRENT THESIS XXVI 13 NOTE ON THE COMMENCEMENT OF THE DOCTORAL PROCEDURE XXVIII 14 CURRICULUM VITAE XXIX 15 LIST OF PUBLICATIONS XXXI

The principal objective of this thesis was to gain an understanding of the movement patterns of spotted grunter Pomadasys commersonnii, an estuarine-dependent fishery species, in the turbid, freshwater dominated Great Fish Estuary. Both manual and automated telemetry methods were used to monitor the movements of spotted grunter during two separate studies conducted in summer and spring 2003 and 2004. Acoustic transmitters were surgically implanted into twenty spotted grunter with lengths between 263 and 387 mm TL in the first study and twenty spotted grunter ranging between 362 and 698 mm TL in the second study. The specific objectives were to gain an understanding of (i) the time spent in the estuarine environment (ii) the space use and home range size, and (iii) the abiotic factors governing the movement patterns of spotted grunter in the estuary. The nursery function of estuarine environments was highlighted in this study as adolescent spotted grunter spent a significantly larger proportion of their time in the estuary than adult fish (p < 0.0001; R² = 0.62). The increased frequency of sea trips, with the onset of sexual maturity, provided testimony of the end of the estuarinedependent phase of their life-cycle. Although considered to be predominantly marine, the adult spotted grunter in the Great Fish Estuary utilised the estuary for considerable periods. Adults are thought to frequent estuaries to forage, seek shelter and to possibly rid themselves of parasites. During this study, the number of sea trips made by tagged fish ranged from 0 to 53, and the duration ranged from 6 hours to 28 days. The tidal phase and time of day had a significant effect (p < 0.05) on the sea trips undertaken by fish. Most tagged spotted grunter left the estuary during the night (84%) on the outgoing tide, and most returned in the evening (77%) during the incoming tide. Sea temperature (p < 0.0001; R² = 0.34), barometric pressure (p = 0.004; R² = 0.19) and wind (p = 0.01) had a significant effect on the number of spotted grunter recorded in the estuary. Spotted grunter were more prone to return to the estuary after high barometric pressure, when low sea temperatures (upwelling events) prevailed. There was a significant positive relationship between home range size and fish length (p = 0.004; R² = 0.20). Small spotted grunter (< 450 mm TL) appeared to be highly resident, with a small home range (mean size = 129 167 m²), that was generally confined to a single core area. Larger individuals (> 450 mm TL) occupied larger home ranges (mean size = 218 435 m²) with numerous core areas. The home ranges of small and large spotted grunter overlapped considerably yielding evidence of two high use areas, situated 1.2 km and 7 km from the mouth of the Great Fish Estuary. Tagged spotted grunter were located in a wide range of salinity, turbidity and temperature, but were found to avoid temperatures below 16 ºC. The daily change in environmental variables (salinity, temperature and turbidity) had a significant effect on the change in fish position in the estuary (p < 0.0001; R² = 0.38). The distribution of tagged spotted grunter, particularly the larger individuals, in the Great Fish Estuary was influenced by the tidal phase (p < 0.05); they moved upriver on the incoming tide and downriver on the outgoing tide. This study provides an understanding of the movement patterns of spotted grunter in the estuary and between the estuarine and marine environments. Consequently, it provides information that will assist in the design of a management plan to promote sustainability of this important fishery species. The techniques used and developed in this study also have direct application for further studies on other important estuarinedependent fishery species.

Mongolia is currently undergoing a rapid socioeconomic transition with extensive development driven by increased mineral resource extraction and large scale agriculture and pastoral expansion. There has also been unprecedented urbanisation and continued population growth that has placed added pressure on the ageing public infrastructure including power stations and waste water treatment plants. As a result, the country’s pristine landscapes, including its vast freshwater ecosystems, are now facing widespread degradation, contamination and species losses in the most impacted regions. The proposed large-scale dams and imminent climate change effects will further damage these fragile ecosystems. With a number of rivers and lakes deteriorating, resident aquatic communities, including unique fish species, have suffered significant population declines. However, a more substantial threat currently facing these fish populations is the rapid and largely unregulated rise in fishing activities within an emerging recreational fishery. Although historically fish capture and consumption has not been a traditional part of the Mongolian diet or culture, this is changing rapidly. Therefore a comprehensive set of research projects were developed and implemented across Mongolia, to gather essential information on this new fishery, while also addressing existing knowledge gaps regarding the spatial ecology and genetic structure of the main target species. In addition, a potential human health risk was evident due to the increased consumption of locally caught fish species from a heavily impacted river basin, and thus this was also investigated. Overall, the collective aim of this fisheries research was to increase the scientific understanding and knowledge across a range of issues and ultimately advise authorities on improving current management regulations and conservation strategies. It is hoped that the recommendations can assist in safeguarding the future sustainability and resilience of the threatened fish populations and the emerging recreational fishery across Mongolia for the future. A total of five fisheries related research projects were completed between 2011 and 2014, with the results from each used to formulate the conservation and management recommendations presented in this thesis. Due to the lack of knowledge regarding the emerging recreational fishery, roving creel surveys were conducted across three river basins and covered five key topics including angler demographics, fishing practices, current fishing trip data, fishing gear and costs, and angler knowledge and opinions. Fifty-eight fishing groups (n = 154 anglers) were interviewed and two angler types were identified: rural anglers with no or low incomes, who reside in the basin, fish alone or in smaller groups, fish frequently for shorter periods, and consumed fish more regularly; and urban anglers who have medium to high incomes, live in larger cities, spent more money on fishing gear / trips and fished for multiple days at a time. B. lenok was identified as the most targeted and caught species in the fishery. The results of the creel surveys confirmed increased fish consumption in the Kharaa River basin, which was identified as a potential human health risk due to the widespread heavy metal contamination from both past and present mining activities. Thus heavy metal contaminates in river water, sediment and five consumed fish species were examined at 11 sites across the basin. Heavy metals were evident in all five sampled species, with maximum muscle contents of chromium (Cr), arsenic (As), mercury (Hg) and lead (Pb) detected in fish from the middle and lower reaches, while zinc (Zn) was highly elevated in B. lenok from the upper tributaries. Elevated median contents of Cr, copper (Cu), Hg and Pb increased with trophic level, with the bioaccumulation of Hg posing the greatest threat to human health with over 10 % of all fish sampled exceeded the internationally recommended threshold for Hg in consumable fish tissue (> 0.5 µg g-1 ww). This bioaccumulation in resident fish species could lead to chronic toxicity in people who consume them regularly and have additional exposure to other sources of contamination e.g. gold mining. A further two projects were conducted that utilised passive acoustic telemetry to describe the spatial and temporal autecology, habitat use and behaviour of B. lenok in the Eroo River and H. taimen in the Onon/Balj rivers under Mongolia’s extreme seasonal conditions. The maximum longitudinal movements (home ranges) detected were more extensive than previously reported for both species with 45.3 km for B. lenok and 126.1 km for H. taimen. Increased movements were recorded in spring and summer, with individuals entering surrounding tributaries and remaining there for between four and 85 days before returning to the main river channel. The results highlighted the importance of maintaining the integrity and connectivity of tributary habitats for spawning, feeding and overwintering, as well as hydrological and thermal refuges, which will be increasingly important for these species in the region with the pending impacts of climate change. This increased knowledge relating to the spatial ecology of these threatened species can guide the design and implementation of new protective measures such as the introduction of Freshwater Protected Areas (FPAs) across Mongolia. Further research was conducted to gain a broader, multigenerational understanding of the interconnectedness between conspecific populations of H. taimen, B. lenok and T. baicalensis across the major river basins. Both molecular and nuclear markers were used to demarcate the population’s genetic structure and define Evolutionary Significant Units (ESUs) and priority populations for these species across their Mongolian distributions. Across all species, the most prominent pattern was a strong differentiation among major basins with low differentiation and weak patterns of isolation by distance within basins, which indicates high within-basin connectivity between populations, although exact patterns were not completely concordant among species. The extensive results produced from the current scientific research has facilitated the development of a comprehensive set of key recommendations for implementing new, and enhancing existing, management and conservation measures relating to Mongolia’s threatened salmonid species and its emerging recreational fishery. These recommendations include: 1. Establishing a series of Freshwater Protected Areas (FPAs) throughout Mongolia’s major river basins, with their design and location based upon the spatial ecology and genetic population structure determined by the current research results; 2. Shifting the opening date of the fishing season to encompass the entire spawning period of B. lenok (the fishery’s main target species), which appears to currently not be the case; 3. Adding the blunt-snouted lenok (B. sp.) to the prohibited species list, as it has been genetically proven to be an independent species and has a restricted distribution and low abundance in Mongolia; and 4. Introducing minimum (and potentially maximum) size limits for B. lenok and T. baicalensis, to better protect immature and pre-spawning individuals from being removed from the population. In addition, it is highly recommended to commence fisheries dependent and independent assessments in key river basins and conduct biomonitoring programs (using a bioindicator species) to track toxic heavy metal contamination and identify potential human health risks associated with consuming resident fish species from the more heavily impacted regions. The lack of knowledge of the current fishing regulations by anglers as well as the observed and reported widespread illegal fishing activities demands a wide-ranging angler education program to improve understanding and compliance within the fishery. The future survival of these threatened salmonids and the sustainability of the emerging recreational fishery in Mongolia currently hangs in the balance. However, if these scientifically based recommendations are implemented in full, and can be adequately enforced, then the responsible authorities can take a huge step forward towards reversing the current trends and preserving the country’s imperilled freshwater fish populations and their valuable aquatic ecosystems. Mongolia can be a model for freshwater species conservation and management throughout the region and the world
Die Mongolei befindet sich derzeit in einem rasanten sozioökonomischen Übergang mit tiefgreifenden Veränderungen, die v.a. durch eine Zunahme bergbaulicher Aktivitäten sowie einen Ausbau ackerbaulicher Nutzungen wie auch der Viehwirtschaft angetrieben werden. Derzeit vollzieht sich eine noch nie dagewesene Urbanisierung und ein weiteres Bevölkerungswachstum, das auf die alternde öffentliche Infrastruktur, einschließlich Kraftwerke und Abwasserbehandlungsanlagen, einen zusätzlichen Druck ausübt. Infolgedessen zeigen sich in den weitgehend unberührten Landschaften des Landes, einschließlich seiner riesigen Süßwasser-Ökosysteme, deutliche Anzeichen von Übernutzung natürlicher Ressourcen, Umweltverschmutzung und Artenverlusten. Zukünftig geplante große Staudämme werden neben den bevorstehenden Auswirkungen des Klimawandels die Hydrologie deutlich verändern. So sind bereits deutliche Beeinträchtigungen der Fluss-und See-Ökosysteme erkennbar, insbesondere in Hinblick auf ihre aquatischen Lebensgemeinschaften. Einige der weltweit einzigartigen Fischarten haben bereits erhebliche Bevölkerungsrückgänge erlitten. Eine weitere existenzielle Bedrohung für diese Fischpopulationen ist der rasche und weitgehend un-regulierte Anstieg der Fischereitätigkeiten aus einer aufstrebenden Freizeitfischerei. Obwohl Fischfang und -konsum keine traditionellen Elemente der mongolischen Ernährung oder Kultur darstellen, vollziehen sich diesbezüglich derzeit tiefgreifende Veränderungen. Daher wurden in der Mongolei umfangreiche Forschungsprojekte geplant und durchgeführt, um wesentliche Informationen über diese neue Art der Fischerei zu sammeln und gleichzeitig bestehende Wissenslücken in Bezug auf die räumliche Ökologie und die Metapopulationsstruktur der wichtigsten Zielarten zu schließen. Darüber hinaus zeigten Untersuchungen, dass sich aufgrund des erhöhten Konsums von lokal gefangenen Fischarten aus einem stark beeinträchtigten Einzugsgebiet ein potenzielles Risiko für die menschliche Gesundheit ergibt. Insgesamt ist das übergeordnete Ziel dieser Fischereiforschung, das wissenschaftliche Verständnis und Wissen zu erweitern und letztlich die derzeitigen Managementinstrumente zu verbessern und neue Erhaltungsmaßnahmen zu ergreifen, um die Nachhaltigkeit und Widerstandsfähigkeit der bedrohten Fischartenpopulationen und die aufkommende Erholung zu sichern. Insgesamt wurden zwischen 2011 und 2014 insgesamt fünf fischereibiologische Forschungsprojekte abgeschlossen, wobei die Ergebnisse dieser Arbeiten in Erhaltungs- und Managementempfehlungen münden. Wegen des Mangels an Wissen über die aufkommende Freizeitfischerei wurden Anglerbefragungen in drei Einzugsgebieten durchgeführt, welche fünf wichtige Themen wie Angler-Demographie, Fischereipraktiken, Reisetätigkeiten, Fanggeräte und Kosten sowie Anglerwissen und Meinungen umfassten. Fünfundsechzig Angelgruppen (n = 154 Angler) wurden interviewt und zwei Anglertypen identifiziert: ländliche Angler ohne oder niedrige Einkommen, die in dem Becken wohnen, alleine oder in kleineren Gruppen fischen, häufig für kürzere Zeiten fischen und regelmäßig Fisch verzehren; und städtische Angler, die mittlere bis hohe Einkommen haben, in größeren Städten leben, mehr Geld für Fanggeräte / Ausflüge ausgegeben und typischerweise für mehrere Tage am Stück fischen. B. lenok wurde als die bevorzugte und am meisten gefangene Zielarten der Fischerei identifiziert. Die Ergebnisse der Anglerbefragungen bestätigten den erhöhten Fischkonsum im Kharaa-Einzugsgebiet, das aufgrund der weit verbreiteten Schwermetallverunreinigung aus der Vergangenheit und den gegenwärtigen Bergbauaktivitäten als potenzielles Risiko für die menschliche Gesundheit identifiziert wurde. So wurden Schwermetallverunreinigungen im Flusswasser, Sediment und fünf konsumierten Fischarten an 11 Standorten im Einzugsgebiet untersucht. Schwermetalle zeigten sich in allen fünf Stichprobenarten, wobei der maximale Muskelgehalt von Cr, As, Hg und Pb in Fischen aus dem Mittel- und Unterlauf festgestellt wurde, während Zn in B. lenok in den Oberlaufregionen stark erhöht war. Der erhöhte mediane Gehalt an Cr, Cu, Hg und Pb nahm mit trophischer Ebene zu, wobei die Bioakkumulation von Hg die größte Bedrohung für die menschliche Gesundheit darstellte, wobei über 10% aller Fischproben den international empfohlenen Schwellenwert für Hg im verzehrbaren Fischgewebe überstiegen (> 0,5 μg g-1 ww). Diese Bioakkumulation in residenten Fischarten könnte zu chronischen Intoxikationen bei Menschen führen, die sie regelmäßig konsumieren und zusätzliche Exposition gegenüber anderen Kontaminationsquellen haben, z.B. im Goldbergbau. Es wurden weitere zwei Projekte durchgeführt, die eine passive akustische Telemetrie zur Beschreibung der räumlichen und zeitlichen Autökologie, des Lebensraumnutzens und des Verhaltens von B. lenok im Eroo River und H. taimen in den Flüssen Onon und Balj unter den extremen Klimabedingungen der Mongolei verwendeten. Die maximalen Längsbewegungen (Heimatbereiche) wurden -umfangreicher als bisher angenommen- für beide Arten wurden auf 45,3 km für B. lenok und 126,1 km für H. taimen ermittelt. Im Frühjahr und Sommer wurden erhöhte Bewegungen aufgezeichnet, wobei die Individuen in die umliegenden Nebenflüsse eintraten und dort zwischen 4 und 85 Tagen verblieben, bevor sie zum Hauptfluss des Flusses zurückkehrten. Die Ergebnisse zeigen die Bedeutung der Aufrechterhaltung der Integrität und der Konnektivität von Nebenflüssen für Laichen, Nahrungssuche und Überwinterung sowie hydrologische und thermische Schutzräume, die für diese Arten in der Region mit den anstehenden Auswirkungen des Klimawandels zunehmend an Bedeutung gewinnen werden. Die verbesserten Kenntnisse der räumlichen Ökologie dieser bedrohten Arten kann die Gestaltung und Umsetzung neuer Schutzmaßnahmen wie Süßwasser-Schutzgebiete in der Mongolei wissenschaftlich fundieren und leiten. Weitere Untersuchungen wurden durchgeführt, um ein breiteres, multigenerationales Verständnis der Zusammenhänge zwischen den konkreten Populationen von H. taimen, B. lenok und T. baicalensis über die großen Flusseinzugsgebiete zu gewinnen. Sowohl molekulare als auch nukleare Marker wurden verwendet, um die genetische Struktur abzugrenzen und definieren, so z.B. evolutionär signifikante Einheiten (ESUs) und eigenständige Populationen für diese Arten einschließlich ihrer räumlichen Verteilung in der Mongolei. Über alle Arten hinweg war das deutlichste Muster eine starke Differenzierung zwischen den großen Becken mit geringer Differenzierung. Dem gegenüber stehen schwache Muster der Isolation durch die Distanz in den Becken, die eine hohe einzugsgebietsinterne Konnektivität anzeigen, obwohl exakte Muster nicht vollständig unter allen Arten übereinstimmten. Die Prioritäten der Erhaltung müssen sich auf die Verbesserung des Schutzes der vorrangigen Bevölkerungsgruppen innerhalb jeder Art und ESU konzentrieren, um die begrenzten verfügbaren Ressourcen für die Arten- und Populations-Erhaltung und fischereiliche Bewirtschaftung in der Mongolei zu maximieren. Die umfangreichen Ergebnisse aus der aktuellen wissenschaftlichen Forschung ermöglichten die Ableitung umfassender Empfehlungen für die Umsetzung neuer und die Verbesserung der bestehenden Management- und Erhaltungsmaßnahmen in Bezug auf die bedrohten Lachsarten der Mongolei und die aufkommende Freizeitfischerei. Diese Empfehlungen beinhalten 1.die Gründung einer Reihe von Süßwasser-Schutzgebieten (FPA) in den großen Flussgebieten der Mongolei auf der Grundlage der räumlichen Ökologie und der genetischen Bevölkerungsstruktur, die durch die aktuellen Forschungsergebnisse untermauert wird; 2. Eine Verschiebung des Eröffnungstermins der Fangsaison, welche im Gegensatz zur aktuellen Praxis die gesamte Laichzeit von B. lenok (die Hauptzielspezies der Fischerei); umfassen sollte; 3. Hinzufügen des Stumpfschnauzen-Lenok (B. sp.) zur Liste der besonders geschützten Arten, da er sich als eine genetisch unabhängige Spezies erwiesen hat, welche eine begrenzte räumliche Verteilung und geringe Populationsdichte in der Mongolei hat; und 4. Einführung von minimalen (und potentiell maximalen) Körpergrößenbeschränkungen für B. lenok und T. baicalensis, um die unreifen und heranwachsenden Individuen besser vor menschlichen Einflüssen zu schützen. Darüber hinaus empfiehlt es sich dringend, in den wichtigsten Flussgebieten fischereilich genutzte und nicht genutzte Fischpopulationen zu erfassen und Biomonitoring-Programme (unter Verwendung von Bioindikator-Spezies) zu implementieren, um toxische Schwermetallverunreinigungen zu verfolgen und potenzielle Risiken für die menschliche Gesundheit zu identifizieren, die mit dem Verzehr Fischen aus beeinträchtigten Regionen einhergehen. Schließlich verlangt das Fehlen von Kenntnissen über die derzeitigen Fischereiverordnungen durch Angler sowie die beobachteten und gemeldeten weitverbreiteten illegalen Fischereitätigkeiten ein weitreichendes Angler-Bildungsprogramm, um das Verständnis und die Einhaltung fischereilicher Regelungen zu verbessern. Das künftige Überleben der bedrohten Salmoniden und die Nachhaltigkeit der aufkommenden Freizeitfischerei in der Mongolei sind eng miteinander verbunden. Sofern die hier dargestellten wissenschaftlich fundierten Empfehlungen in vollem Umfang umgesetzt werden und hinreichend kontrolliert werden können, würden die zuständigen Behörden einen großen Schritt in Richtung der Umkehrung der aktuellen Trends machen und die gefährdeten Süßwasserfischpopulationen des Landes und ihre wertvollen aquatischen Ökosysteme bewahren. Die Mongolei könnte dann ein Modell für die Erhaltung und Bewirtschaftung von Süßwasserarten in der ganzen Region und der Welt werden

Thesis (Ph. D.) -- University of Maryland, College Park, 2006.
Thesis research directed by: Marine-Estuarine-Environmental Sciences. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

This study was part of a larger, more comprehensive project assessing the effects of culvert designs on freshwater mussel habitat. Because many freshwater mussels depend on an obligate relationship with certain fish hosts to complete their life cycle as well as sole mechanism for dispersal, it is critical to identify obstacles to fish movement that, in turn, could negatively impact dispersal success of mussels. The primary goal of our study was to quantify the impact of four commonly used road crossings (bridge, arch culvert, box culvert, and pipe culvert) on stream fish abundance and diversity, as well as movement. We conducted a mark-recapture study in 16 streams located in the Piedmont region of the Cape Fear River Basin of North Carolina during the summer of 2004. Following electrofishing surveys, all fish were identified to species and measured to the nearest millimeter. Fish ¡Ü 30 mm total length (TL) were individually marked elastomer paint. These procedures were repeated four, eight, and 12 weeks after the initial sampling period. With the exception of species richness, all response variables: estimates of population size, species diversity, fish index of biotic integrity (FIBI), and Conditional Percent Movement (CPM) did not vary significantly with crossing type, position (upstream and downstream), or month. Downstream reaches of box culverts contained significantly higher species richness of stream fish than other crossing types. High diversity of stream fish downstream of box culverts may have been due to a scouring effect common below box and pipe culverts which results in pool formation and a possible change from benthic to pool fish species on a local level. The general lack of stream fish abundance and diversity responses to road crossings may be due to: the insensitivity of stream fish community variables (FIBI and diversity index) to anthropogenic effects, the overall resilience of fish communities, or the shifting baseline theory--fish communities having shifted to an impacted community prior to sampling. There were extremely low numbers of individuals that moved between stream reaches in the first study, therefore we conducted a second mark-recapture study using Passive Integrated Transponder (PIT) tags with remote antenna arrays on six streams, three streams with bridges and three streams with box culverts, during the summer of 2005. We surveyed each stream using electrofishing and marked all fish measuring ¡Ý 60 mm TL with an ISO PIT tag. Custom built antenna arrays, with weir nets to direct fish passage through the antenna loop, were installed in each stream either upstream or downstream of a given crossing and detected tagged fish continuously for 30 days. Estimates of mean percent movement of fish through box culverts (28.27% ¡À 12.24% SE) was almost half that of bridges (44.35% ¡À 8.77% SE); however, the percent tagged fish detected by the antenna for bridges and culverts showed no significant difference between the two crossing types. These results suggest that a larger study might detect a significant difference in fish movement through culverts as opposed to bridges. This application of PIT tags and remote antenna arrays proved a more effective and efficient use of research funding to assess stream fish movement through culverts and we recommend the antenna systems for further non-game fish research.

Includes abstract.
Includes bibliographical references (leaves 67-71)
Experts in both the line-fisheries and fisheries science sectors specialise in tracking the movement of fish. The knowledge thus gained is integral to both fishing practice and fisheries research, yet the two have often been posited against each other on opposite sides of a spectrum. This dissertation problematises the modernist divide between two different ways of knowing the sea by looking at the points of partial connections between them. It aims to perhaps change the conversations about ways of knowing the sea, so that different sectors may be able to collaborate in research with a view towards positively influencing management decisions. Skipper's logbooks represent one of the primary points of connection between two of the pivotal actors in the line-fishery and offer insight into how communication between them is currently characterised.

Animals that live in groups face a dual challenge of effectively exploiting their environment while at the same time maintaining cohesion with other group members. Maintaining cohesion requires group members to come to consensus about when and where to move, despite the fact that they may not always agree. In this thesis, I investigate how individuals in groups make movement decisions, and how these individual decisions scale up to group-level properties. Using a laboratory experiment with golden shiners (Notemigonus crysoleucas ), I first investigate the interaction network over which information spreads, finding that decisions are better predicted by whom individuals can see rather than whom they are close to, with potential consequences for the global spread of information (Chapter 2). I then investigate collective movement behavior in the wild using high-resolution GPS data from members of a troop of olive baboons (Papio anubis). I first show that baboons are consistent in the spatial positions they occupy within the group, and that the observed patterns may be understood based on a very simple mechanism by which individuals maintain cohesion with different numbers of their neighbors (Chapter 3). By quantifying how group members move relative to one another, I then show that baboon movement decisions are consistent with a shared decision-making process, rather than despotic leadership by dominant individuals, and that the patterns of decision-making are consistent with simple models of collective motion (Chapter 4). Finally, by incorporating a fine-scale, three-dimensional reconstruction of the habitat through which the baboons move, I show that habitat structure, in addition to social factors, also exerts an important influence on individual movement decisions, resulting in changes in the emergent structure and movement of the group (Chapter 5). Taken together, these results highlight that by combining high-resolution animal tracking, remote sensing, and analytical methods, we can begin to extend our understanding of collective animal movement from laboratory studies to complex animal societies living in the wild.

Inshore tropical and subtropical estuaries harbor a relatively high abundance and diversity of organisms. Specifically within estuaries, mangrove and seagrass habitats provide shelter and food for a plethora of organisms, through some or all their life histories. Given the biological connection between offshore coral reefs and coastal estuaries, there is a critical need to understand the underlying processes that determine distribution and abundance patterns within mangrove-seagrass habitats. The predatory fish assemblage within the mangrove and seagrass beds of Biscayne Bay, Florida (USA), was examined over 24-hr. time periods along a distance and habitat gradient from the mangrove edge and nearshore environment (0–300 m) to farshore (301–700 m) seagrass beds. This thesis also investigated the occurrence, distribution and timing of reef fish movement between offshore coral reef habitat and inshore seagrass beds over 24-hr periods. Results indicate that fish predators differed over both the sampling period and with distance from mangrove edge. The results also demonstrated reef fishes move into Biscayne Bay at dusk and exit at dawn by utilizing Broad Creek Channel as a passageway. This work supports the idea of diel migration of selected reef fishes to inshore seagrass beds and highlights the importance of connective channels between habitats. The results suggest that the degradation or loss of seagrass habitat could differentially impact the life-history stages of reef fish species.

The aim of this study was to investigate population densities and dynamics of brown trout along multiple tributaries of the Taieri River, a large New Zealand river. Relationships between juvenile brown trout population dynamics and food availability, discharge and water temperature were examined in the same lowland stream. Downstream movements of juvenile brown trout were also examined. Trace element analyses of eggs aimed to identify the source of fish spawning in tributary streams. An experimental study of juvenile brown trout collected from downstream and upstream reaches compared patterns of agonistic behaviour amongst trout that were considered to be dominated by either migratory (downstream) or resident (upstream) fish. Longitudinal surveys of juvenile trout abundance were expanded across four additional streams to determine whether there were consistent patterns in population dynamics of brown trout. Large spatial and temporal variation in population dynamics of juvenile brown trout was found in Silverstream with an upstream site having significantly less temporal variation in densities than a downstream site. No effect of food availability on population dynamics was found. Discharge and temperature affected population densities of juvenile brown trout in some years, but could not solely explain the general pattern in spatial variation in population dynamics. Downstream movement was found to be a behavioural strategy used by juvenile brown trout and appeared to contribute to variation in juvenile density. Analysis of trace element signatures in brown trout eggs indicated that upstream spawning migration by anadromous females was restricted by the presence of a steep gorge along the middle reaches of the Taieri River. Patterns of spawning by migratory and resident fish along tributary streams appeared to vary. In Silverstream, spawning by anadromous fish dominated the lower reaches, whereas considerable overlap between anadromous and resident fish was observed in Big Stream. In Cap Burn distinct trace element signatures were observed for redds spawned along upstream and downstream reaches. However, it was not possible to confidently ascribe the source of the redds to main river migrants or Cap Burn resident fish. Behavioural observations of juvenile brown trout collected from upstream (resident) and downstream (migratory) reaches of Silverstream revealed differences in aggression level, with migratory fish being more aggressive. No difference in growth rates was found between fish from the two areas. Furthermore, the social organisation of resident fish was based on the formation of dominance hierarchies, whereas the competitive status of migratory fish was more even. Patterns in spatial and temporal variation in the longitudinal population dynamics and patterns of abundance of juvenile trout were repeated across the five tributaries. Populations in upstream reaches consisted of fish from multiple age classes and exhibited relatively limited variation in densities, whereas juvenile fish dominated populations along downstream reaches and densities varied greatly over an annual cycle. Taken together, these results suggest a general pattern of spatial and temporal variation in the population dynamics of brown trout sub-populations along tributaries of a large New Zealand river. Whilst various environmental factors may contribute to some of the variation, longitudinal separation into resident and migratory populations also appeared to be important. These finding are important for the management of brown trout in both main river channels and tributaries in New Zealand.

The emergence of collective patterns from repeated local interactions between individuals is a common feature to most living systems, spanning a variety of scales from cells to animals and humans. Subjects of this thesis are two aspects of emergent complexity in living systems: collective movement and transport network formation. For collective movement, this thesis studies the role of movement-mediated information transfer in fish decision-making. The second project on collective movement takes inspiration from granular media and soft mode analysis and develops a new approach to describe the emergence of collective phenomena from physical interactions in extremely dense crowds. As regards transport networks, this thesis proposes a model of network growth to extract simple, biologically plausible rules that reproduce topological properties of empirical ant trail networks.  In the second project on transport networks, this thesis starts from the simple rule of “connecting each new node to the closest one”, that describes ants building behavior, to study how balancing local building costs and global maintenance costs influences the growth and topological properties of transport networks. These projects are addressed through a modeling approach and with the aim of identifying minimal sets of basic mechanisms that are most likely responsible of large-scale complex patterns. Mathematical models are always based on empirical observations and are, when possible, compared to experimental data.

Telemetry methods were used to investigate the influence of selected environmental variables on the position and movement of an estuarine-dependent haemulid, the spotted grunter Pomadasys commersonnii (Lacepède 1801), in the Great Fish Estuary, South Africa. Forty individuals (263–698 mm TL) were surgically implanted with acoustic coded transmitters and manually tracked during two periods (7 February to 24 March 2003; n = 20 and 29 September to 15 November 2003; n = 20). Real-time data revealed that spotted grunter are euryhaline (0–37) and are able to tolerate large variations in turbidity (4–356 FTU) and temperature (16–30 °C). However, the fish altered their position in response to large fluctuations in salinity, temperature and turbidity, which are characteristic of tidal estuarine environments. Furthermore, tidal phase had a strong influence on the position of spotted grunter in the estuary.

Bull trout are a fish species listed as threatened under the Endangered Species Act.Historically, they ranged from Northern California at the southernmost extent, into Canada at the northern most extent, and east into Nevada and Montana. Bull trout are highly migratory and require large, unfragmented habitats to persist and are thus highly susceptible to human induced land-use practices. The goal of my thesis was to obtain a better understanding of bull trout movement patterns in the Walla Walla River, Washington using complimentary techniques; Passive Integrated Transponder (PIT)technology and otolith microchemistry. PIT tags can be injected into a fish body cavity, similar to how pets are “chipped”, and as the fish swim through antennas placed in the river, their location and movements are be documented.Otolith microchemistry is a technique that is similar to analysis of tree rings. The otolith, a hard bony structure of a fish’s ear, develops over a lifetime and as the rings of the otolith are created the chemical signature in the water in which they live is recorded and can be compared to chemical makeup of water samples collected through the river system. Using these two techniques, I found that the age or size of a fish and the season are important factors to explain both a fish’s movements and where in the river a fish might be located at a given time. Knowing at what size, age and season a fish is attempting to migrate allows managers to provide the best possible river conditions (e.g., temperatures, flow) to allow for unimpeded migrations to occur and to foster conservation and recovery of bull trout populations.

Tracking an individual specimen can be a difficult task especially when one also has to keep track of the environmental factors that affect the tracked specimen’s behavior. The task of tracking these animals becomes impossible when they become submerged in water and their number increases to more than just one. The aquatic species that are being tracked by this project in Lake Pontchartrain and the Gulf of Mexico are: tarpon, scalloped hammerhead, whale shark, tiger shark, yellowfin tuna, spotted seatrout, redfish, and bull shark. We are tracking these fish using acoustic and satellite transmitters. The insertion of transmitters in the fish was handled by the Louisiana Department of Wildlife and Fisheries biologists. The acoustic transmitters were implanted on smaller fish that only swam in Lake Pontchartrain. Due to this, receivers were only implanted at locations across the lake on various types of attachments such as buoys, PVC pipes, and pilings. These receivers were positioned at more than ninety locations in order to maximize the acquisition of detections. These species were tracked in Lake Pontchartrain and the Gulf of Mexico. After this preliminary setup, a constant batch of data was generated on a regular basis and this data was process by the application developed in this project. A Ruby on Rails application was then setup in order to store this data and manipulate it to display an animated track. The application utilizes: Ruby, Rails, HTML, CSS, SQL, JavaScript and multiple third part libraries. Many optimizations were performed in order to ensure reliability and performance when loading a high volume of fish or if a high volume of users were to use the application.

Sharks are particularly vulnerable to over-exploitation. Although catsharks are an important component of the near-shore marine biodiversity in South Africa and most of the species are endemic, little is known about their movement patterns, home range and population size. With an increasing number of recreational fishers this information is crucial for their conservation. The aims of this study were threefold. Firstly, to identify and analyze existing data sources on movement patterns and population dynamics for four catshark species: pyjama (Poroderma africanum), leopard (P. pantherinum), puffadder (Haploblepharus edwarsii) and brown (H. fuscus). This highlighted a number of shortcomings with existing data sets, largely because these studies had diverse objectives and were not aimed solely at catsharks. Secondly, a dedicated study was carried out for a limited area, testing a number of methods for data collection, and where appropriate the data was analyzed to determine movement patterns and population numbers. Thirdly, the most appropriate methodology for future studies (with similar objectives) was identified, and the results of the study were used to propose a number of conservation measures. All species of catsharks exhibited strong site fidelity and limited dispersal for extended periods. A few individuals did, however, travel distances in excess of 150 km. Significant trends in temporal abundance were not observed, nevertheless, there was some evidence for higher catches from September to December. Population estimates for the study area were low, with P. africanum having the smallest population size while H. fuscus had the highest population size within the restricted study area. Limited movements, high site fidelity and small population sizes emphasize their vulnerability and suggest that catsharks would benefit from no-take marine protected areas.

This thesis investigates the movement behaviour of South African two coastal fish species and evaluates the effectiveness of marine protected areas (MPAs) in their protection and management. Its primary focus is on resolving the movement patterns of roman Chrysoblephus laticeps (Sparidae) in and around the Goukamma and Castle Rock MPAs in the Western Cape province of South Africa. A pilot study of the methodology investigated the movement behaviour of spotted grunter Pomadasys commersonnii (Haemulidae) in the sheltered East Kleinmonde Estuary in the Eastern Cape province. The application of different tagging methods was tested in a controlled tank experiment. Tagged roman were monitored over a 198-day period. Barbed dart, t-bar anchor and Visible Implanted Fluorescent Elastomer (VIFE) tags were compared. Application techniques and underwater visibility of VIFE tags were tested on roman and on fransmadam Boobsoidia inornata in a pilot study. Needles of gauge 25 were found to be optimal for VIFE tag application. Whereas VIFE tagging caused fin rot in fransmadam, it had no negative effect on roman. VIFE tagged fish could be identified by divers from a distance of three metres under ambient light in an observation tank in five metres water depth. There was no significant difference in growth rate between groups of roman with different tags and controls after 198 days. High tag loss rates were experienced for barbed dart and t-bar anchor tags, although barbed dart tags performed better than t-bar anchor tags. Although some of the VIFE marks had deteriorated, all VIFE tagged fish were individually recognised at the end of the study. Conventional dart and VIFE tags are feasible methods to tag roman. However, the high tag loss rate of conventional tags must be taken into account in the design of a tagging study. Previous mark and recapture studies on roman are beset with a number of problems. Poor experimental design and low precision of capture positions resulted in equivocal results of limited value. A tagging experiment was designed to eliminate ambiguity in data interpretation and to produce a dataset that could be used to model roman residency and dispersal. A combination of conventional barbed dart tags and Visible Implanted Fluorescent Elastomer tags was used to tag roman in the Goukamma Marine Protected Area (GMPA) on the temperate South African south coast. Sixty one percent of roman were recaptured within 50 m of the tagging position. A small proportion moved considerable distances of up to four kilometres. The extent of these movements was not dependent on fish size or sex. Data from this experiment and from a previous tagging study in the Tsitsikamma National Park (TNP) were used to model the resident behaviour of roman. The model suggests a probability of 91% (GMPA) and 94% (TNP) of residency within a 10000 m² cell. This result suggests that individual roman will benefit from protection in small MPAs. A different experimental approach was required to investigate the exact home range of this species. Firstly the feasibility of using acoustic telemetry to study the movement of coastal fish in South Africa was investigated. The telemetry equipment comprised two VEMCO V8 transmitters and a VEMCO VR60 receiver linked to a directional hydrophone. A tank experiment was conducted to examine the effects of the transmitter implantation. A tracking experiment was conducted on spotted grunter Pomadasys commersonnii in the East Kleinmonde Estuary. Operated fish recovered quickly and, with respect to swimming behaviour and growth rates, no differences were found between fish with implants and controls. The maximum detection range in the estuary was 400 m. Interference between different transmitter frequencies was negligible. Transmitter location recordings were found to be accurate within five metres. Two fish were tracked over a seven-day period. The fish preferred the lower reaches of the estuary where they made repeated and prolonged use of specific areas. The success of the initial experiments allowed this method to be used to investigate the spatial utilisation and activity patterns of roman Chrysoblephus laticeps. Surgically implanted VEMCO V8, V13 and V16 transmitters were used to track 13 roman inside the Castle Rock MPA in False Bay. Transmitters implanted into C. laticeps in tanks had no apparent effects on growth and physiology. Manual boatand diver-based tracking experiments covered a 17-month period. A VEMCO VRAP radio acoustic positioning system was used over two one-month periods during and after the spawning season of roman. Analysis of data using a 95% fixed kernel algorithm suggests that roman are resident throughout their adult life, occupying home ranges between 1000 and 3000 m². Activity was lower at night. During periods of cold-water upwelling, fish retreated into caves. During the spawning season, females extended their home ranges, possibly to mate with different males. These results confirm that this species is well suited for protection and management with small MPAs. The effect of two MPAs on the South African south coast on the population of C. laticeps was simulated with a spatially explicit individual based model (IBM). Life history parameters determined in recent studies and the effect of fishing on the size of sex change was taken into account. Fish densities and size frequencies were based on recent underwater visual census. The distribution of suitable habitat in the study areas was also incorporated. The results show a rapid recovery of the fish size frequency spectrum and sex ratio to pre-exploitation levels inside both MPAs. Little 'spillover' of fish into the fished areas occurred resulting in negligible improvement of catches. The results suggest that for resident species like roman, even small MPAs offer sufficient protection.

White steenbras Lithognathus lithognathus (Pisces: Sparidae) has been a major target species of numerous fisheries in South Africa, since the late 19th century. Historically, it contributed substantially to annual catches in commercial net fisheries, and became dominant in recreational shore catches in the latter half of the 20th century. However, overexploitation in both sectors resulted in severe declines in abundance. The ultimate collapse of the stock by the end of the last century, and the failure of traditional management measures to protect the species indicate that a new management approach for this species is necessary. The species was identified as a priority for research, management and conservation in a National Linefish Status Report. Despite knowledge on aspects of its biology and life history, little is known about juvenile habitat use patterns, home range dynamics and movement behaviour in estuaries. Similarly, the movement and migration of larger juveniles and adults in the marine environment are poorly understood. Furthermore, there is a complete lack of information on its genetic stock structure. Such information is essential for effective management of a fishery species. This thesis aimed to address the gaps in the understanding of white steenbras movement patterns and genetic stock structure, and provide an assessment of its current conservation status. The study adopted a multidisciplinary approach, incorporating a range of methods and drawing on available information, including published literature, unpublished reports and data from long-term monitoring programmes. Acoustic telemetry, conducted in a range of estuaries, showed high site fidelity, restricted area use, small home ranges relative to the size of the estuary, and a high level of residency within estuaries at the early juvenile life stage. Behaviour within estuaries was dominated by station-keeping, superimposed by a strong diel behaviour, presumably based on feeding and/or predator avoidance, with individuals entering the shallow littoral zone at night to feed, and seeking refuge in the deeper channel areas during the daytime. Conventional dart tagging and recapture data from four ongoing, long-term coastal fish tagging projects, spread throughout the distribution of this species, indicated high levels of residency in the surf zone at the late juvenile and sub-adult life stages. Consequently, juvenile and sub-adult white steenbras are vulnerable to localised depletion, although they can be effectively protected by suitably positioned estuarine protected areas (EPAs) and marine protected areas (MPAs), respectively. It has been hypothesized that adult white steenbras undertake large-scale coastal migrations between summer aggregation areas and winter spawning grounds. The scale of observed coastal movements was correlated with fish size (and age), with larger fish undertaking considerably longer-distance coastal movements than smaller individuals, supporting this hypothesis. Given the migratory behaviour of adults, and indications that limited spawning habitat exists, MPAs designed to protect white steenbras during the adult life stage should encompass all known spawning aggregation sites. The fishery is plagued by problems such as low compliance and low enforcement capacity, and alternative management measures, such as seasonal closure, need to be evaluated. Despite considerable conventional dart tagging effort around the coastline (5 782 fish tagged) with 292 recaptures there remains a lack of empirical evidence of fish migrating long distances (> 600 km) between aggregation and spawning areas. This uncertainty in the level of connectivity among coastal regions was addressed using mitochondrial DNA sequencing and genotyping of microsatellite repeat loci in the nuclear genome, which showed no evidence of major geographic barriers to gene flow in this species. Samples collected throughout the white steenbras core distribution showed high genetic diversity, low genetic differentiation and no evidence of isolation by distance or localised spawning. Although historically dominant in several fisheries, analysis of long-term commercial and recreational catch data for white steenbras indicated considerable declines and ultimately stock collapse. Improved catch-per-unit-effort in two large MPAs subsequent to closure confirmed that MPAs can be effective for the protection of white steenbras. However, the current MPA network encompasses a low proportion of sandy shoreline, for which white steenbras exhibits an affinity. Many MPAs do not prohibit recreational shore angling, which currently accounts for the greatest proportion of the total annual catch. Furthermore, EPAs within the juvenile distribution protect a negligible proportion of the total available surface area of estuaries – habitat on which white steenbras is wholly dependent. Despite some evidence of recent increases in abundance in estuaries and the surf zone in certain areas, white steenbras meets the criteria for “Endangered” on the IUCN Red List of Threatened Species, and for “Protected species” status on the National Environmental Management: Biodiversity Act of South Africa. The species requires improved management, with consideration for its life-history style, estuarine dependency, surf zone residency, predictable spawning migrations and its poor conservation status. The multidisciplinary approach provides valuable information towards an improved scientific basis for the management of white steenbras and a framework for research that can be adopted for other overexploited, estuarine-associated coastal fishery species.

Individuals within a species often compete for resources in both space and time. In dominance hierarchies individuals with the greatest competitive ability will occupy prime locations during optimal periods to increase efficiency in gathering a resource. Subdominant individuals with low competitive abilities may be forced to reside in habitats of poor quality relative to dominant individuals. In this study I examined the long term patterns of giant kokopu distribution, movement, growth, habitat use, and social interaction between fish in relation to invertebrate drift (food supply). The habitat quality and abundance of food along a one km section of Alex�s Creek was monitored for a two year period. Though the physical structure of Alex�s Creek was relatively homogenous there were significant spatial differences in the density of drifting invertebrates sampled between riffles and pools over this long temporal period. In general, more drifting invertebrates were sampled in riffles of relatively long length and area. Within Alex�s Creek the distribution of giant kokopu, Galaxias argenteus, was determined by patchy distributions of food supply, specific physical factors of pools, and interactions between fish in dominance hierarchies. Over the 20 month study period, the most important biotic factor determining fish biomass was the total number of drifting invertebrates within pools while the most important abiotic factor determining fish abundances within pools was the pool size (surface area). The growth rate of individual fish correspondingly varied between fish residing within pools of different quality. Growth rates were higher for individual fish residing in pools with a relatively high density of drifting invertebrates. The differences in individual growth rates of giant kokopu may determine when fish leave a particular habitat patch (pool) and move to a new one. Fish that moved had lower growth rates (before moving) than fish that remained resident within home pools. Overall the movement of giant kokopu within Alex�s Creek was very restricted due to a relatively consistent distribution of food, however there were differences in the mobility of giant kokopu among different social ranks. The most dominant fish in pools were largely sedentary while fish ranked directly below fish 1 (i.e. fish 2 and 3 in social hierarchies) were relatively mobile. The ability of dominant fish to exclude subdominant fish from the most preferred feeding positions during optimal feeding times had consequences for overall giant kokopu activity. Under normal food supply conditions dominant fish were predominantly nocturnal and maintained large home ranges at night. Conversely subdominant fish occupied large home ranges by day, but were generally not observed at night. When the food supply was limited the utilization of pools was determined by social rank. Dominant fish from each pool increased daytime activity, home range size, aggressiveness, and the capture of food items offered by day while simultaneously reducing the spatial and temporal activity and habitat use of subdominant fish. These results indicate that behavioral changes in large dominant fish influence and reduce the amount of resources available to subdominant fish.

Marine Protected Areas (MPA) are broadly used to protect marine ecosystems, restore biomass, and increasingly as tools in fisheries management for benthic stocks. Nevertheless, MPAs are seldom used to target pelagic species due the challenges of designing an effective MPA in a highly dynamic environment. It is believed that highly mobile organisms will get few benefits, since they leave the protected area too frequently. One possible solution is to compensate for such movement with larger MPAs. Nevertheless, uncertainty about the benefits in the face of vagaries about fish movement make it unlikely that such efforts would be successfully pursued.

Although it is a generally accepted that MPAs provide multiple benefits if well designed, empirical demonstrations of benefits from MPA are hard to obtain. They require long term evaluations, and as a consequence, comparisons between alternative MPA designs are almost nonexistent. Simulation models provide an alternative to empirical approaches that allow tests of designs and forecasts of potential outcomes. To date, most of the simulation models of MPAs have been developed for benthic systems, where simplified assumptions about fish and fisherman movement are reasonable. Fortunately, with the advent of more realistic fish movement models, new approaches are now possible that can combine complex individual-based models of movement, population dynamics and virtual MPA systems. The use of these new complex simulation models can guide the optimization of MPA design to increase both stock sizes and fisheries yields.

The goal of the research presented in this dissertation is to study the potential of a large MPA to protect a pelagic stock and determine how fish movement characteristics and complex environmental dynamics influence the optimal design criteria for a successful pelagic MPA. The findings are timely given increasing interest in developing large no fishing zones to protect overfished pelagic stocks, especially for those taxa whose distribution spans more than one exclusive economic zone or resides in international waters. For this purpose I implemented a simulation model that incorporates detailed fish movement and their responses to complex environmental forcing to study the effect of fish movement on the efficacy of MPAs of different size and location. (Abstract shortened by ProQuest.)

Since the discovery of Viral Hemorrhagic Septicemia (VHS) in the Great Lakes in 2005, the assessment of its ability to spread amongst connected watersheds has been at the forefront of VHS management. This project was designed to determine a rate of passage of VHS-susceptible fish species between coastal Lake Michigan and its harbors and the artificial waterways in the Chicago metropolitan area. This information can be used to assess the potential for VHS to spread into the waterways, which drain into the Illinois River watershed. Although fishes (e.g. Round Goby and occasionally salmonids) are known to have moved from Lake Michigan into the Illinois River via the Chicago Area Waterway System (CAWS), the rate of fish passage from the lake into the waterway system is unclear. To directly assess fish movement, a total of 1216 fish were collected, tagged, and returned to Lake Michigan harbors (532, 43.8% of total) and Lake Calumet (684, 56.2%), an adjacent lake connected to Lake Michigan via the CAWS. Fishermen reports, Illinois Department of Natural Resources (IDNR) sampling, and subsequent electrofishing sampling trips yielded 51 recaptured fish (4.2% of tagged fish). Of these, 2 fish were recaptured below the O¡¯Brien Lock and Dam in the Calumet River (south of Lake Michigan and Lake Calumet) and 49 fish were recaptured in the location at which they were originally tagged. To further assess movement of VHS susceptible species between Lake Michigan and the CAWS, otoliths were collected from 375 small-bodied fish (<150 mm total length) captured in the CAWS and analyzed for ¥ä©ö©øC to determine the origin (Lake Michigan or CAWS) of these fish. Fifty-six percent of small-bodied fishes collected from the Calumet River were immigrants from Lake Michigan, whereas 35% of fish collected from the Chicago River and 28% of fish collected from the North Shore Channel were immigrants. Results indicate that fishes (particularly small-bodied species such as Round Goby) move between VHS-positive Lake Michigan into the VHS-negative Chicago area waterways and represent a potential vector for VHS to spread into the inland waters of Illinois. However, the lack of movement of fishes from Lake Michigan into the Des Plaines River and further downstream waters also indicates a watershed-based approach to managing VHS in Illinois waters rather than simply designating the entire state as VHS-affected due to positive samples in Lake Michigan, may be valid. VHS surveillance should be continued in the CAWS to ensure the status of these water bodies as ¡°VHS positive¡± or ¡°VHS negative¡± is accurate, as this is useful for informing the public and creating policies and regulations to attempt to slow the spread of this disease.

The Staunton River is a high gradient, second order stream approximately 6 km in length located on the eastern slope of the Blue Ridge Mountains in Shenandoah National Park, VA. In June 1995, a catastrophic flood and debris flow altered the instream habitat and Salvelinus fontinalis population of the Staunton River. The debris flow scoured the streambed, deposited new substrate materials, removed trees from the riparian zone, and eliminated fish from a 1.9km section of the stream. By June 1998, both young-of-year (YOY) and age 1+ S. fontinalis had recolonized the debris flow affected area. The event provided a rare opportunity to examine recovery of the S. fontinalis population and instream habitat in addition to addressing potential effects of the debris flow on movement, activity, and growth of fish in the debris flow affected and unaffected areas of the stream. Post-recolonization movement and activity were monitored using two-way fish traps (weirs), mark-recapture techniques, and radio telemetry. The weirs failed to produce any movement data. Most fish (91%) in the mark-recapture study had range sizes less than 100m, however biases common to mark-recapture study designs (low recapture rate, flawed logic, etc.) hampered interpretation of results. For example, subsequent recapture of individually marked fish indicated that as many as 54% of marked fish confirmed to have been alive at the time of a recapture session were not recaptured. Radio telemetry provided information on S. fontinalis movement and activity at seasonal and diel scales during summer and fall. Differences in movement and activity between the debris flow affected and unaffected areas were minimal when compared to seasonal variations. During summer, range sizes were near 0m and crepuscular activity patterns were observed. During the fall range size increased and diel activity was concentrated in the mid-afternoon with a much higher peak than during summer. Basin-wide visual estimation technique (BVET) fish population surveys performed each spring and fall from 1993 = 1999 provided pre- and post-event fish population abundance and density estimates. Post-event fish growth in the debris flow affected and unaffected areas was monitored using mark-recapture techniques. Abundance and density of both YOY and age 1+ S. fontinalis exceeded pre-event levels within 2-3 years. Growth of YOY and age 1+ fish was significantly greater in the debris flow affected area until spring 1999. Population density appeared to have a strong negative influence on growth. The observed changes in fish growth and differences in fish size associated with population density would be of minimal importance to the typical angler but may suggest a mechanism by which S. fontinalis populations can quickly recover from catastrophic events. BVET habitat surveys provided information on total stream area, number of pools and riffles, pool and riffle surface area and depth, substrate composition, and large woody debris (LWD) before (1993), immediately following (1995), and four years post-event (1999). Immediately following the debris flow, the stream channel was highly disordered which resulted in an increase in the total number of habitat units and a decrease in average habitat unit surface area, total stream area, and average depth when compared with pre-event conditions. In addition, substrate composition had shifted from small to large diameter particles and LWD loading had increased in both debris flow affected and unaffected areas. Four years after the event, the total number of habitat units, average habitat unit surface area, total stream area, and average depth had all returned to near pre-debris flow levels and substrate composition had begun to shift towards smaller particle sizes. Changes in LWD loading from 1995-1999 reflected changes in the riparian zone following the debris flow. In the unaffected area, where riparian trees remained intact, LWD loading increased, whereas in the debris flow affected area, where riparian trees were eliminated, LWD loading decreased. For the most part the effects of the debris flow, although immediately dramatic, were in the long term minimal. The debris flow affected area was recolonized rapidly and abundance and density quickly rebounded past pre-event levels. Differences in fish growth between the affected and unaffected area were short lived. Any effect the debris flow affected area may have had on movement or activity was minimal when compared with seasonal variations. Most habitat characteristics reverted to near pre-event levels just four years after the flood and debris flow. Although a number of factors will influence recovery time from such events, these results indicate that immediate management action, such as stocking or habitat modifications, are not necessary in all cases.
Master of Science

Die Besiedlung von Gewässern durch Fische, ist neben abiotischen Lebensraumbedingungen auch von der Erreichbarkeit d.h. von der art-spezifischen Ausbreitungsfähigkeit sowie von Wanderhindernissen abhängig. Der erste Teil dieser Arbeit bietet die erste umfangreiche quantitative Analyse von Ausbreitungsmustern und -distanzen von Flussfischen. Aus der Fachliteratur wurden 160 empirische Datensätze aus 71 wissenschaftlichen Studien zur Ausbreitung von 62 Fischarten in Flüssen extrahiert und an leptokurse Wahrscheinlichkeits-Dichte-Funktionen (Dispersal kernel) angepasst. Es konnte bei Fischpopulationen zwischen einer stationären (ca. 2/3) und einer mobilen Komponente (ca. 1/3) unterschieden werden deren Ausbreitungsdistanzen von vier Faktoren abhängig sind: Fischlänge, Form der Schwanzflosse, Fließgewässergröße, betrachtete Zeitspanne. Der zweite Teil dieser Arbeit widmet sich dem neu entwickelten Fischausbreitungsmodell FIDIMO einem GIS-Softwareprogramm zur Modellierung und Simulation der räumlichen und zeitlichen Ausbreitungsmuster von Fischen in Flüssen unter Berücksichtigung von Wanderhindernissen. FIDIMO verknüpft konzeptionelle Überlegungen zu Ausbreitungsmodellen in verzweigten Fließgewässernetzwerken mit empirisch bestimmten leptokursen Fischausbreitungskurven unter ausschließlicher Verwendung von Free and Open Source Software. Im dritten Teil der Arbeit wurde FIDIMO zur Modellierung der Ausbreitung von 17 Fischarten angewendet um die Einflüsse von (i) Habitatqualität, (ii) Ausbreitungsfähigkeit und (iii) Fließgewässer-Fragmentierung auf die Besiedlungsmuster durch Fische zu bestimmen. Die Ergebnisse zeigen, dass die artspezifische Habitatqualität und Ausbreitungsfähigkeit die Besiedlung maßgeblich bestimmen. Dagegen wurde kein signifikanter Einfluss von Barrieren auf das Vorkommen einer Art gefunden. Über längere Zeiträume sinkt der Einfluss von Fischausbreitung auf das lokale Vorkommen einer Fischart während die Habitatqualität relativ wichtiger wird.
The colonisation of rivers by fishes is directly linked to abiotic habitat conditions but often impaired by dispersal abilities of fishes and movement constraints such as barriers. The first part of this thesis provides the first comprehensive quantitative analysis of freshwater fish movement while considering fish populations consisting of differently mobile specimens. 160 empirical datasets from 71 studies on the movement of 62 riverine fish species were analysed based on refitted leptokurtic probability-density functions (dispersal kernels). A share of one third and two thirds emerged as a general pattern of the mobile and stationary component of a fish population, respectively. Moreover, four variables were identified primarily determining dispersal distances: fish length, aspect ratio of the caudal fin, river size and time. In the second part of the thesis, the novel fish dispersal model FIDIMO is introduced. FIDIMO provides a GIS-tool for predicting and simulating spatio-temporal patterns of fish dispersal in dendritic river networks considering movement barriers. The fish dispersal model FIDIMO links conceptual considerations on dispersal modelling with empirically observed leptokurtic fish movement patterns and the strengths of geographically explicit modelling in Free and Open Source GIS. In the third part of the thesis, FIDIMO was applied for modelling dispersal of 17 fish species to disentangle the effects of (i) habitat suitability, (ii) dispersal constraints and (iii) network fragmentation on the distribution of river fishes. The results show significant positive effects of both, local-scale habitat quality and species-specific dispersal ability on the distribution of river fishes, whereas no significant effect of barriers influencing the presence of a species could be found. Over longer time periods the importance of dispersal decreased in favour of habitat suitability becoming relatively more relevant in determining species'' presence.