Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 26 for “"Small pelagic"”.
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Multidisciplinary investigation into stock structure of small pelagic fishes in southern Africa
Three abundant small pelagic fish species co-occur in the Benguela upwelling ecosystem off southern Africa: sardine (Sardinops sagax), anchovy (Engraulis encrasicolus) and round herring (Etrumeus whiteheadi). It is hypothesised that populations of these species have a complex structure that …
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Developing dynamic energy budget (DEB) models for small pelagic fishes in the Southern Benguela
… between ecosystems. Differential responses of small pelagic fish species to environmental factors help in understanding the variable population dynamics of these species and can help predict the impacts of climate change.
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Investigating the trophic ecologies of early life stages of small pelagic fishes in the Benguela upwelling ecosystem
… Africa, harbours large biomasses of three small pelagic fishes; anchovy Engraulis encrasicolus, sardine Sardinops sagax and west coast round herring Etrumeus whiteheadi. Despite fisheries management interventions, stocks of sardine have been low for the past decade following consecutive …
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Comparative dietary analysis of four small pelagic fish species from presumed mixed shoals off South Africa's east coast
Stomach contents of sardine (Sardinops sagax), anchovy (Engraulis encrasicolus), west coast redeye (Etrameus whiteheadi) and east coast redeye (E. teres) were collected from presumed mixed shoals off South Africa's east coast. The stomach contents were analysed to 1) determine the diet composition …
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Using seasonal mass-balanced models of the Algoa Bay ecosystem to investigate African penguin and small pelagic fish interactions
… order to investigate the interaction between the small pelagic fish and penguin population, mass-balanced trophic models of the Algoa Bay ecosystem were constructed using the software Ecopath with Ecosim. Input parameters were derived from data compiled from published literature and survey data …
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Modelling regime shifts in the southern Benguela : a frame-based approach
Small pelagic fish populations in productive upwelling systems are characterised by long-term patterns of alternating dominance. Sardine and anchovy are the most important small pelagic species in the southern Benguela ecosystem, which has been shown to have undergone regime shifts during the past …
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Seasonal and spatial variability of pelagic fishes in relation to environmental variability in St Helena Bay
… that are significant to early life history of small pelagic fish. Environmental, acoustic and zooplankton data have been collected along the SHBML to obtain information on ocean environment, pelagic fish abundance and also zooplankton abundance. This study used an interdisciplinary approach, …
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Misunderstandings in fisheries: an ethnography of regulative categories and communication around Gansbaai and Dyer Island
… in Gansbaai partly rely on the availability of small pelagic fish (sardine and anchovy). However, fishers also hand-line and angle actively, and more recently practiced a range of other fishing techniques. Ten weeks of fieldwork in Gansbaai allowed the intertwined lived reality of fishers’ …
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Trophic models of the Benguela upwelling system : towards an ecosystem approach to fisheries management
… 1990s. However, because stocks and catches of small pelagic fish and model zooplankton biomass were larger in the 1990s, the ecosystem was less tightly constrained by predators and food availability than in the 1980s. An extension ofOdum's development theory also suggests that the ecosystem was …
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Tracking African penguins (Spheniscus demersus) outside of the breeding season: Regional effects and fishing pressure during the pre-moult period
… shift may be exacerbated by pressure from the small-pelagic fishery targeting these species. A lack of knowledge regarding foraging areas when not breeding has been identified as a deficiency in management planning for African penguins. Satellite transmitters were deployed on 20 adults during …
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Investigating the foraging ecology and energy requirements of a seabird population increasing in an intensely exploited marine environment
… Benguela upwelling ecosystem that rely on small pelagic fish have decreased dramatically over the last decade. In contrast, the population of the greater crested tern Thalasseus bergii has increased. To understand these conflicting trends, I investigated the foraging ecology and energy …
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Bycatch in the South African midwater trawl fishery for horse mackerel (Trachurus capensis) as established from observer records
… volumes and temporal and spatial patterns. Small fauna were analysed by extrapolation of sample weights and large fauna were counted. The midwater trawl fishery was estimated to have caught 25 415 t annually, with a bycatch rate of 6.9% of the total catch, by weight. Bycatch species with the …
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Environmental drivers of the abundance and distribution of forage fishes on the Northeast US shelf, with a particular emphasis on northern sand lance
Small pelagic fishes, also termed forage fishes, represent a critical link between secondary production and myriad top predators in marine ecosystems, including the Northeast US shelf. In this dissertation, I analyze the drivers of forage fish distribution throughout the Northeast US shelf and the …
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Environmental drivers of the abundance and distribution of forage fishes on the Northeast US shelf, with a particular emphasis on northern sand lance
Small pelagic fishes, also termed forage fishes, represent a critical link between secondary production and myriad top predators in marine ecosystems, including the Northeast US shelf. In this dissertation, I analyze the drivers of forage fish distribution throughout the Northeast US shelf and the …
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Assessing the implementation efficacy of an ecosystem approach to Fisheries management in the South African sardine fishery
… implementation of an EAF in the South African small pelagic fishery and provide a model for other fisheries.
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Observer effects on pelagic fleet operations and Bayesian-based explorations of the mass balance model ECOPATH
… deals with the analysis of observer data from pelagic commercial vessels with a particular focus being to examine whether there is any indication of dumping (discarding) that is provided by these data. The second section investigates the ability of constraints associated with the ECOPATH …
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Modelling South African cold-water coral habitats
… cold-water corals are linked to the overlying pelagic ecosystems is also poorly understood. Observational studies have indicated that fish abundance is greater in the waters surrounding coldwater coral reefs compared to nearby waters over barren seafloor, implying enhanced productivity in the …
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Assessing the effects of internal (trophic structure) and external (fishing and environment) forcing factors on fisheries off central Chile : basis for an ecosystem approach to management
… (Chilean hake-red squat lobster and Chilean hake-small pelagic fish) to test hypothesis of top-down and bottom-up control versus alternative hypotheses of fishing and/or environmental control in the same populations, and iv) simulation experiments to test hypotheses of ecosystem change and …
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The Development of Spring-Actuated Mechanisms in Mantis Shrimp (Stomatopoda) and Snapping Shrimp (Alpheidae)
… larval stage when they transition into the pelagic zone and begin feeding on plankton. Mathematical and physical models of LaMSA kinematics suggest that smaller mechanisms generate greater accelerations. Therefore, I hypothesized that larval mantis shrimp would accelerate their strikes …
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The diet, reproductive biology age and growth of yellowtail, Seriola lalandi, in South Africa
… cephalopods, polychaetes and bivalves. Small pelagic fish were the dominant prey type, followed by crustaceans. The remaining taxa were of negligible importance. Some dietary differences were observed between sample areas. Most notable was the increased importance of crustaceans at …
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