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Marengo, Amy Elizabeth. "Shark Heart." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/73493.
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Shark Heart is a manuscript of poems that maneuver between fearlessness and tenderness at the drop of a dime. In the same way that many sharks need to survive by constantly swimming in order to extract oxygen from the water streaming between their gills, the heart muscle needs to constantly pump blood throughout a body to sustain life: there is no rest for either fish or organ until death. These poems, too, keep pushing forward; they are not afraid to explore the small beats of childhood and hidden desire, or the larger mysteries of illness and death.Master of Fine Arts
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Filmalter, John David. "Movements of sub-adult sicklefin lemon sharks Negaprion acutidens in a remote Indian Ocean atoll." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1018229.
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The sicklefin lemon shark Negaprion acutidens is a large-bodied (> 3m) coastal shark species, widely distributed in tropical and sub-tropical Indo-Pacific waters. Despite its large size and wide distribution, very little is known about its movement behaviour throughout ontogeny. The primary aim of this thesis was to gain an understanding of the movements of sub-adult N. acutidens, in and around the St. Joseph Atoll, Republic of Seychelles, to facilitate the effective conservation of this vulnerable species. A total of 22 sharks (139 – 202 cm TL) were equipped with coded acoustic transmitters and passively monitored using moored acoustic receivers for a period of 20 month from March 2009 to October 2010. The use of passive acoustic telemetry arrays to study behavioural ecology has increased in popularity in recent years and been successfully applied to study a host of teleost and elasmobranch species in a diversity of habitats, ranging from sheltered estuaries to the offshore pelagic environment. However, the practicalities of designing an effective network of receivers to optimally monitor animal movements can be challenging. In this study the receiver array was optimised through a series of incremental steps to achieve an efficient design that allowed for the specific objectives to be addressed. The specific objectives of this study were to i) gain an understanding of the long term space use patterns and site fidelity of sub-adult N. acutidens within degree of use of the St. Joseph Atoll lagoon and surrounding habitats, and ii) investigate their short term behavioural patterns in response to natural rhythmic cycles. The important role the atoll plays in the sub-adult stage of this species was demonstrated by the very low numbers of detections outside the atoll compared to the very large numbers of detections inside the atoll. Over the course of a year the tagged sharks showed a high degree of site fidelity to the atoll, with 79 – 100% of the individuals detected during each month and 50% being detected on a near daily basis. This result provides testimony of the nursery role of the atoll and importance of these habitats in the early life history for this species. Individual area use was generally found to be restricted to the eastern part of the atoll incorporating a portion of the central deep lagoon and a nearby adjacent area of the sand flats. The movements of sub-adult N. acutidens on and off of the shallow flats surrounding the central lagoon (likely for foraging) were found to be strongly influenced by the tidal height and the diel cycle. Tagged sharks were found to utilise the flats more regularly when the tidal height was greater than 90 cm and particularly more so during the night and early morning than during daylight times. The combined results of this study expose the vulnerability of this species to rapid local depletion. Similarly, the effectiveness of spatial management measures, such as no-take marine protected areas is highlighted as an efficient tool for the future conservation of this species. In the St. Joseph Atoll in particular, the use of a multi-levelled protection approach, where the eastern portion on the atoll is completely restricted while the remaining area is utilized for non-consumptive tourism activities, could be highly effective. Future research should investigate changes in area use throughout the ontogeny of this species as well improve the understanding of the breeding site fidelity and population size of reproductive females using the St. Joseph Atoll.
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Andreev, Plamen Stanislavov. "The early evolutionary history of sharks and shark-like fishes." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5491/.
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The Middle Ordovician to Late Silurian represents an interval of approximately 50 million years, which has been recognised as the initial, cryptic, period in the evolutionary history of chondrichthyan fish. The fossil remains attributed to early chondrichthyans are dominated by isolated dermal scales that predate the appearance of undisputed chondrichthyan teeth and articulated skeletons in the Lower Devonian. Investigation of the inter-relationships of these scale taxa and their systematic position relative to high- ranked chondrichthyan clades has been hampered by the lack of developed scale-based classification schemes for jawed gnathostomes, coupled with the limited use of scale characters in phylogenetic studies of Palaeozoic Chondrichthyes. Here, all previously documented scale types of alleged Lower Palaeozoic chondrichthyans were examined using a combination of X-ray microtomography, SEM and Nomarski DIC optics. These were found to exhibit a set of characteristics (symmetrical trunk scales, areal crown growth and lack of hard-tissue resorption, cancellous bone and enamel) recognised as specific to the dermal skeleton of chondrichthyans among derived gnathostomes. The collected data permitted the establishment of a hierarchy of scale characters for separate taxonomic ranks, leading to the recognition of three Orders (Mongolepidida, Elegestolepida ordo nov. and Altholepida ordo nov.) of early chondrichthyans, differentiated by distinct types of scale-crown morphogenesis. A scale-based cladistic analysis of jawed gnathostomes corroborated these results by recovering a chondrichthyan clade that incorporates all examined taxa and ‘acanthodians’ with non-superpositional crown growth patterns. It is thus proposed that chondrichthyan dermoskeletal characters carry a phylogenetic signal, allowing to interpret the documented diverse types of scale morphogenesis as evidence for a major radiation of chondrichthyan lineages in the Lower Palaeozoic.
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O'Bryhim, Jason. "Public knowledge, attitudes, and behavior towards sharks and shark conservation." Fairfax, VA : George Mason University, 2009. http://hdl.handle.net/1920/4571.
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Thesis (M.S.)--George Mason University, 2009.Vita: p. 127. Thesis director: Chris Parsons. Submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Science and Policy. Title from PDF t.p. (viewed Oct. 11, 2009). Includes bibliographical references (p. 121-126). Also issued in print.
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Queiroz, Nuno. "Diving behaviour, movement patterns and population structure of blue sharks, Prionace glauca (L. 1758) in the North-east Atlantic." Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=158318.
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This project provided an exceptional opportunity to describe diving behaviour, movements and to characterise critical habitats of blue sharks in the North-eastern Atlantic using satellite and archival telemetry. Tracked blue sharks displayed southward movements away from the tagging areas, exhibiting pronounced site fidelity to localised high-productivity frontal regions. Blue sharks also displayed a high degree of variability in vertical movements. Shifts in diving behaviour were detected both within and between individuals, whereas behavioural phases were linked to the thermal structure of the water column in coastal areas, and to changes in prey distribution or type in offshore regions. High resolution data showed that blue sharks shift between Brownian (in productive habitats) and Lévy (less productive waters) behaviours. Vertical movements ranged from the surface to 1160 m, and water temperatures varied between 7.2-27.2°C. Behavioural data was also crucial in determining the degree of spatial and temporal overlap, and thus vulnerability, between blue sharks and high-seas longliners. Confirmed fishing mortality was ~11% with four tagged sharks caught by surface longliners. Simulations showed that boats/sharks overlap was higher in winter and early spring, with the majority of simulated sharks (~88%) at risk at least one day year-1. Our results indicate that, depending on which geographical regions are occupied at specific times, different segments of the blue shark population face differential risk from longlines. Sequencing of mitochondrial DNA suggested an absence of spatial genetic differentiation throughout the North Atlantic, providing strong evidence that blue sharks comprise a single population in this region.
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McCandless, Camilla Thomas. "Juvenile abundance in a summer nursery and ontogenetic changes in the distribution and migrations of sandbar sharks/." View online ; access limited to URI, 2007. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3276995.
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Heithaus, Michael R. "Habitat use decisions by bottlenose dolphins (Tursiops aduncus) and tiger sharks (Galeocerdo cuvier) in a subtropical seagrass ecosystem." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61648.pdf.
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Bethea, Dana M. "Foraging ecology of the early life stages of four shark species (Rhizoprionodon terraenovae, Carcharhinus limbatus, Carcharhinus isodon, and Carcharhinus brevipinna) in Apalachicola Bay, Florida." Connect to this title online, 2003. http://www.lib.ncsu.edu/theses/available/etd-04252003-160742/unrestricted/etd.pdf.
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Huang, Katie. "Soup, Fins, and Exploitation: An Analysis of the Current State of Shark Finning." Scholarship @ Claremont, 2014. http://scholarship.claremont.edu/scripps_theses/506.
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Despite being one of the most recognizable sea creatures in the world, sharks remain widely misunderstood by the public. Media coverage often sensationalizes them as dangerous creatures, when in reality, humans pose a much more significant threat to sharks than vice versa. Over the past few decades, overfishing has decimated populations worldwide as demand increases for byproducts such as meat, cartilage, and fins in particular, a crucial ingredient in the Chinese delicacy of shark fin soup. Finning, a particularly inefficient practice that promotes overfishing and waste, occurs when fishers cut off fins at sea and throw carcasses overboard. As sharks play an important role in marine ecosystems as apex predators and are slow to reproduce, increased attention to shark conservation is urgently needed. Although there have been attempts by international organizations such as the United Nations and by individual countries, current legislation has proven to be inadequate in combating shark exploitation. Though public awareness is on the rise thanks to increased media coverage and environmental advocacy, sharks still need greater protection in the face of overharvest and stock depletion. This thesis details the current state of shark exploitation, including shark biology, public perceptions of sharks, and current levels of shark finning, as well as the economics behind the trade. It also analyzes previous actions taken both at the international and national levels. Finally, it recommends further actions to be undertaken in order to preserve declining shark populations and keep them from extinction.
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Han, G. Z. "Extensive retroviral diversity in shark." BioMed Central, 2015. http://hdl.handle.net/10150/610330.
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BACKGROUND: Retroviruses infect a wide range of vertebrates. However, little is known about the diversity of retroviruses in basal vertebrates. Endogenous retrovirus (ERV) provides a valuable resource to study the ecology and evolution of retrovirus. FINDINGS: I performed a genome-scale screening for ERVs in the elephant shark (Callorhinchus milii) and identified three complete or nearly complete ERVs and many short ERV fragments. I designate these retroviral elements "C. milli ERVs" (CmiERVs). Phylogenetic analysis shows that the CmiERVs form three distinct lineages. The genome invasions by these retroviruses are estimated to take place more than 50 million years ago. CONCLUSIONS: My results reveal the extensive retroviral diversity in the elephant shark. Diverse retroviruses appear to have been associated with cartilaginous fishes for millions of years. These findings have important implications in understanding the diversity and evolution of retroviruses.
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Merly, Liza. "Immunomodulation by Shark Cartilage Extracts." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/420.
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The immune system is composed of innate and adaptive mechanisms. Innate immune responses are significantly modulated by immunomodulatory factors that act through the induction of specific patterns of cytokine production in responding cells. Human leukocytes have been shown to respond to substance(s) present in acid extracts of commercial shark cartilage (SC). Shark cartilage is a food supplement taken by consumers as a prophylaxis and for the treatment of conditions ranging from arthritis to cancer. No reliable scientific evidence in the literature supports the alleged usefulness of shark cartilage supplements, but their use remains popular. Cartilage extracts exhibit immunomodulatory properties by inducing various inflammatory, Th1-type cytokines and potent chemokines in human peripheral blood leukocytes (HPBL) in vitro. The objectives of the study were to (1) to determine the nature of the active component(s), (2) to define the scope of cellular response to SC extract, and (3) to elucidate the molecular mechanisms underlying bioactivity. Results showed that there are at least two cytokine-inducing components which are acid stable. One anionic component has been identified as a small (14-21 kDa) glycoprotein with at least 40% carbohydrate content. Shark cartilage stimulated HPBL to produce cytokines resembling an inflammatory, Th1 polarized response. Leukocyte-specific responses consist of both initial cytokine responses to SC directly (i.e., TNF-a) and secondary responses such as the IFN-γ response by lymphocytes following initial SC stimulation. Response of RAW cells, a murine macrophage cell line, indicated that TNF-α could be induced in macrophages of another mammalian species in the absence of other cell types. The results suggest that the human monocyte/macrophage is most likely to be the initial responding cell to SC stimulation. Stimulation of cells appears to engage at least one ligand-receptor interaction with TLR 4, although the role of TLR 2 cannot be ruled out. Initial activation is likely followed by the activation of the JNK and p38 MAPK signal transduction pathways resulting in activation, release, and translocation of transcription factor nuclear factor κB (Nf-kB). This dissertation research study represents the first in-depth study into characterizing the bioactive component(s) of commercial shark cartilage responsible for its immunomodulating properties and defining cellular responses at the molecular level.
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Blizard, Katherine S. "Shark Sim: A Procedural Method of Animating Leopard Sharks Based on Raw Location Data." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/938.
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Fish such as the Leopard Shark (Triakis semifasciata) can be tagged on their fin, released back into the wild, and their location tracked though technologies such as autonomous robots. Timestamped location data about their target is stored. We present a way to procedurally generate an animated simulation of T. semifasciata using only these timestamped location points.
This simulation utilizes several components. Input timestamps dictate a monotonic time-space curve mapping the simulation clock to the space curve. The space curve connects all the location points as a spline without any sharp folds that are too implausible for shark traversal. We create a model leopard shark that has convincing kinematics that respond to the space curve. This is achieved through acquiring a skinned model and applying T. semifasciata motion kinematics that respond to velocity and turn commands. These kinematics affect the spine and all fins that control locomotion and direction. Kinematic- based procedural keyframes added onto a queue interpolate while the shark model traverses the path.
This simulation tool generates animation sequences that can be viewed in real-time. A user study of 27 individuals was deployed to measure the perceived realism of the sequences as judged by the user by contrasting 5 different film sequences. Results of the study show that on average, viewers perceive our simulation as more realistic than not.
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Pires, Natalia de Medeiros. "Economy of the island of eco-tourism: the role of shark-diving and shark harvesting." Universidade Federal do Rio Grande do Norte, 2015. http://repositorio.ufrn.br/handle/123456789/20503.
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Beyond its importance in maintaining ecosystems, sharks provide services that play important socioeconomic roles. The rise in their exploitation as a tourism resource in recent years has highlighted economic potential of non-destructive uses of sharks and the extent of economic losses associated to declines in their population. In this work, we present estimates for use value of sharks in Fernando de Noronha Island - the only ecotouristic site offering shark diving experience in the Atlantic coast of South America. Through the Travel Cost Method we estimate the total touristic use value aggregated to Noronha Island by the travel cost was up to USD 312 million annually, of which USD 91.1 million are transferred to the local economy. Interviewing people from five different economic sectors, we show shark-diving contribute with USD 2.5 million per year to Noronha?s economy, representing 19% of the island?s GDP. Shark-diving provides USD 128.5 thousand of income to employed islanders, USD 72.6 thousand to government in taxes and USD 5.3 thousand to fishers due to the increase in fish consumption demanded by shark divers. We discover, though, that fishers who actually are still involved in shark fishing earn more by catching sharks than selling other fish for consumption by shark divers. We conclude, however, that the non-consumptive use of sharks is most likely to benefit large number of people by generating and money flow if compared to the shark fishing, providing economic arguments to promote the conservation of these species.
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Gubili, Chryssoula. "Application of molecular genetics for conservation of the great white shark, Carcharodon carcharias, L. 1758." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources. Restricted: no access until Dec. 31, 2009, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=26045.
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Gray, Teagen K. "Global Population Structure of the Dusky Shark and Geographic Sourcing of Shark Fins from Commercial Markets." NSUWorks, 2014. http://nsuworks.nova.edu/occ_stuetd/53.
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The dusky shark, Carcharinus obscurus, is a globally distributed, coastal-pelagic species subject to an apparent high level of exploitation. The International Union for the Conservation of Nature (IUCN) lists this species as “Vulnerable” globally, and “Endangered” within western North Atlantic and Gulf of Mexico waters due to an over 80% decline in this region, with no evidence of population recovery. The extensive exploitation of dusky sharks may partly be attributed to the high market value of its fins, but the contribution of individual dusky shark stocks to the fin markets is unknown. This knowledge would be helpful to detect if specific stocks are experiencing disproportionate levels of exploitation. Due to its susceptibility to overfishing, current dire conservation status and need for additional information on its population dynamics, we analyzed the genetic population structure and genetic diversity of the dusky shark (n = 415) across 8 globally distributed locations utilizing 10 nuclear microsatellite loci. The nuclear marker analyses support and extend previously published mitochondrial marker work, identifying a strong divergence among Atlantic and Indo-Pacific samples. Furthermore, nuclear marker results indicate the presence of six genetically discrete management units for dusky sharks, with significant genetic differentiation between the western North Atlantic, South African, and each of three Australian site collections (N, E and W coasts). Discovery of these nuclear microsatellite-defined, smaller geographic scale management units provides a basis for the assignment of market-derived fins to their population of origin with the use of genetic assignment techniques.
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Biery, Leah Elisabeth. "Using shark catch data to estimate the magnitude and global distribution of the shark fin trade." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43285.
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China’s economic growth in recent years has led to a rapid increase in shark fin soup consumption, fueling the demand for shark fins and encouraging fishers worldwide to engage in shark finning. Such practices have led to the overfishing and biomass decline of numerous shark species. Globally, shark catches are poorly reported both quantitatively and taxonomically, and legislation to protect sharks is insufficient. Additionally, data on the international trade of shark fins and other shark products are sparse and, when available, lack descriptive details, making effective shark fishery management challenging.
In this thesis, shark-related legislation is reviewed on a global scale, and the legitimacy of the 5% wet fin to body weight ratio commonly specified in legislation is examined through an analysis of 50 species-specific wet fin to body weight ratios. Official FAO shark catch statistics were supplemented with outside information, and Best Catch Estimates (BCEs) of mean yearly shark catches were calculated for each EEZ between the years 2000 and 2009. Missing values for EEZs and the High Seas were estimated. Appropriate conversion factors were applied to BCEs to estimate the total weight of dry fins traded yearly. Results indicate that both legislation and official FAO shark catch statistics are inadequate and improved regulation, data collection, and monitoring of shark fisheries is necessary on a global scale.
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Lam, Yan-yan Vivian, and 林因恩. "The shark fisheries of Southern China and the reproductive biology of the spadenose shark, Scoliodon laticaudus." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43278541.
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Sheridan, Katherine. "Human safety and shark conservation: an analysis of surfer risk perceptions and attitudes towards shark management." Master's thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33023.
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South Africa has a history of human conflict with sharks and shark safety management. Management of this conflict differs throughout the country, with Cape Town opting for a non-lethal approach in the form of the Shark Spotters programme, and Kwa-Zulu Natal (KZN) opting for a lethal approach using shark nets and drumlines. Lethal management of sharks stems from a belief that without it, people would be too afraid to go in the water, leading to adverse effects on tourism and other associated industries. I assessed surfers' perceptions of risk from sharks, how they value sharks, their knowledge of sharks, and their attitudes towards shark management. I surveyed surfers at Muizenberg Beach in Cape Town, and North Beach and Bay of Plenty Beach in Durban by asking them to answer questions in a questionnaire. A conjoint analysis assessed how likely respondents were to go in the water under various scenarios using situational factor levels related to shark presence, surf/sea and spotting conditions, and whether other people were in the water. The questionnaire results showed no support for lethal shark control and only 8.3% of respondents were aware the nets used in KZN were a lethal form of shark control. Respondents had good knowledge of shark ecology and a positive perception of sharks, both of which have been shown to benefit shark conservation in previous studies. A multiple linear regression model showed a positive correlation between perception of shark risk and perception of other risks, such as car accidents and natural disasters, with respondents perceiving other risks as greater than shark risks. In the conjoint analysis, shark presence was the most influential factor for surfers deciding to go in the water, but respondents were more likely to go in under good surf conditions and spotting/sea conditions even if a shark had been seen recently. Overall, sharks do not deter people from going in the ocean. Implications of these results undermine the longstanding argument that lethal shark management is necessary to protect tourism. Furthermore, the lack of knowledge that lethal shark control is being practised in South Africa coupled with the opposition to lethal management found in this study highlights a clear disconnect between water users and shark managers in KZN.
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Lam, Yan-yan Vivian. "The shark fisheries of Southern China and the reproductive biology of the spadenose shark, Scoliodon laticaudus." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43278541.
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Chapman, Clint Allan. "Anoxia Survival Strategies in the Grey Carpet Shark (Chiloscyllium punctatum) and the Epaulette Shark (Hemiscyllium ocellatum)." Thesis, Griffith University, 2009. http://hdl.handle.net/10072/366452.
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Most vertebrates exhibit a negligible tolerance to anoxic conditions. The epaulette shark (Hemiscyllium ocellatum), however, is exposed to severe hypoxia in its natural environment and has developed adaptive strategies to cope with these conditions, making this species the only currently known anoxia tolerant elasmobranch. The grey carpet shark (Chiloscyllium punctatum) is a closely related species inhabiting ecologically similar environments. Anecdotal evidence suggests some degree of tolerance to low oxygen conditions occurs in this species. This thesis examined the degree of anoxia tolerance in the grey carpet shark along with the haematological and physiological responses of the grey carpet shark and the epaulette shark to anoxia and re-oxygenation.
The effect of seasonal temperature on the duration of anoxia tolerance in both species was examined. Both species were exposed to a number of anoxic regimes and re-oxygenation at moderate (23°C), intermediate (25°C) and high (27°C) temperatures. Total time to loss of righting reflex (LRR) and ventilation rates were measured in adult epaulette sharks, along with adult and juvenile grey carpet sharks. Anoxia tolerance times of both species were temperature dependent, with a significant reduction in the time to LRR occurring at higher temperatures. While both species had similar times to LRR at 23°C, epaulette sharks had a significantly greater time to LRR at higher temperatures. Juvenile grey carpet sharks appear to possess little tolerance to anoxia. Neither juvenile nor adult grey carpet sharks entered into ventilatory depression.
Clint Chapman v The haematological responses of wild and captive populations of both species were examined in response to anoxia and re-oxygenation. The epaulette shark showed evidence of erythrocyte swelling, while the grey carpet shark had a significant increase in erythrocyte concentrations due to a release of erythorcytes into the circulation and/or haemoconcentration of the blood in response to anoxia. Plasma glucose concentrations were maintained in epaulette sharks and wild grey carpet sharks during anoxia but increased significantly during re-oxygenation. Captive grey carpet sharks had an immediate increase in plasma glucose concentrations after anoxia, which was sustained during the re-oxygenation period. Lactate concentrations significantly increased in all animals after anoxia, reaching a peak at 2 hours of re-oxygenation.
Since anoxia compromises the supply of ATP, the maintenance of ion homeostasis may be compromised during prolonged anoxia. A significant increase in plasma potassium concentrations were observed in the grey carpet shark immediately following anoxia and in the epaulette shark after 2 hours of re-oxygenation. No differences in plasma sodium concentrations were observed in either species, although a decrease in plasma chloride occurred after 2 hours of re-oxygenation in the grey carpet shark. Plasma magnesium concentrations significantly increased in both species immediately following anoxia and for 2 hours of re-oxygenation, while plasma calcium only increased in the epaulette shark during re-oxygenation. With the exception of chloride in the grey carpet shark, all plasma electrolyte concentrations were restored during re-oxygenation in both species.
One plausible hypothesis for the increase in erythrocytes observed in the grey carpet shark in response to anoxia is the release of erythrocytes from a storage site. Changes in spleen and liver weight and haemoglobin concentrations were measured to determine if they Clint Chapman vi function as erythrocyte stores. While significant increases in haematological parameters were observed, no significant differences were observed in organ weights or haemoglobin concentrations in response to anoxia.
The up-regulation of protective proteins has been observed to protect vital organs during events of cellular stress in many vertebrates. The heat shock protein 70 kDa (Hsp70) response to anoxic stress was characterised in both species using two different protocols. Hsp70 concentrations of both species were determined via western blotting on the plasma separated blood and additionally in the cerebellum and the ventricle of the heart of the grey carpet shark. No significant differences in Hsp70 concentrations were observed in the blood of either species. Furthermore, no significant differences in Hsp70 concentrations were observed in the cerebellum or the ventricle of the grey carpet shark in response to anoxia.
This study reported for the first time a significant tolerance to anoxia in the grey carpet shark and demonstrated the effect of temperature on the duration of anoxia tolerance in both species. A reduction in the duration of anoxia tolerance was identified in both species at higher temperatures, although the effect was more pronounced in the grey carpet shark. This study identified unique changes in haematological parameters and plasma constituents in both species in response to anoxia and normoxic re-oxygenation. While the epaulette shark possesses energy conserving strategies present in other anoxia tolerant vertebrates, such as metabolic and ventilatory depression, the grey carpet shark does not. This study concluded that the grey carpet shark possesses an intermediate tolerance to anoxia, which would prolong survival during events of naturally occurring hypoxia encountered from the ambient environment on coral reef flats, mangrove swamps and seagrass beds.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Physiotherapy and Exercise Science
Faculty of Health Sciences
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Dicken, Matthew Laurence. "Population dynamics of the raggedtooth shark (Carcharias taurus) along the east coast of South Africa." Thesis, Connect to this title online, 2006. http://eprints.ru.ac.za/247/.
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Gardiner, Jayne M. "Multisensory Integration in Shark Feeding Behavior." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4046.
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Multimodal sensory input directs simple and complex behaviors in animals. Most research to date has been limited to studies of individual senses rather than multiple senses working together, leading to important advances in our comprehension of the sensory systems in isolation, but not their complementary and alternative roles in difficult behavioral tasks, such as feeding. In the marine environment, a prey item might emit an odor, create a hydrodynamic disturbance, such as from gill movements or swimming, be visible to the predator, produce a sound, and/or produce a weak electrical field. Therefore, the goal of this study was to investigate the integration of olfaction, mechanoreception by the lateral line system, vision, and electroreception in a marine animal. Sharks were chosen as a model organism in which to investigate multisensory integration because of their sensitivity and acuity, the presence of the same suite of sensory modalities in all species, the availability of experimental animals from different species, habitats and ecologies, and the rich literature on sharks' prey capture behavior. Two approaches were used: controlled artificial stimuli, delivered to the animals, were used to determine the spatial and concentration characteristics of odor encounters that guide the initial orientation to an odor plume in the far field in a model elasmobranch, the smooth dogfish, Mustelus canis; and sensory deprivation was used to restrict the availability of natural cues emanating from live prey items in order to elucidate the complementary and alternating roles of the senses in detecting, tracking, orienting to, striking at, and ultimately capturing prey. In the latter experiments, three species of sharks from different ecological niches were investigated: benthic, suction-feeding nurse sharks (Ginglymostoma cirratum) that hunt nocturnally for fish; ram-biting bonnetheads (Sphyrna tiburo) that scoop crustaceans off the bottom of seagrass beds; and ram-feeding blacktip sharks (Carcharhinus limbatus) that rapidly chase down midwater teleost prey. In orienting to odor patches, bilateral time differences between the nares are more important than concentration differences, such that animals turn toward the side stimulated first, even with delayed pulses of higher concentration. This response would steer the shark into each oncoming odor patch, helping the animal maintain contact with an odor plume. Sensory deprivation experiments revealed similarities and differences among species in terms of which senses they choose to focus on for particular behaviors, likely as a result of differences in the environments that they hunt in, type of prey consumed, and foraging strategies used, as well as anatomical differences in the central nervous system and the sensory organs. In most cases, multiple senses can be used for the same behavioral task. Thus, sharks are capable of successfully capturing prey, even when the optimal sensory cues are unavailable, by switching to alternative sensory modalities, which indicates that feeding behavior is plastic. Nurse sharks rely primarily on olfaction for detection. Olfaction in combination with vision, the lateral line, or touch is required for tracking. Nurse sharks orient to prey using the lateral line, vision, or electroreception, but will not ingest food if olfaction is blocked. Capture is mediated by the electrosensory system or tactile cues. Bonnetheads normally detect prey using olfaction, rely on olfactory-based tracking until they are close to the prey, then vision to line up a strike, and finally electroreception to time the jaw movements for capture. They can detect, orient, and strike visually in the absence of olfactory cues. Blacktip sharks also detect prey using olfaction or vision. Olfaction is used in combination with vision or the lateral line system for tracking. Long-distance orientation and striking is visually mediated, but strike precision relies on lateral line cues and an increase in misses occurs when this system is blocked. In the absence of vision, short-range orientation and striking can occur using lateral line cues. Capture is mediated by electroreception or tactile cues. Collectively, these results were used to develop species-specific sensory hierarchies for shark feeding behavior in a captive environment, the first such hierarchies to cover a complete behavioral sequence in a vertebrate.
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Horn, Rebekah L. "Applying a Molecular Genetics Approach to Shark Conservation and Management: Assessment of DNA Barcoding in Hammerhead Sharks and Global Population Genetic Structuring in the Gray Reef Shark, Carcharhinus amblyrhynchos." NSUWorks, 2010. http://nsuworks.nova.edu/occ_stuetd/218.
Full textAbstract:
Chapter 1
DNA barcoding based on the mitochondrial cytochrome c oxidase subunit I (COI) gene sequence is emerging as a useful tool for identifying unknown, whole or partial organisms to species level. However, the application of only a single mitochondrial marker for robust species identification has also come under some criticism due to the possibility of erroneous identifications resulting from species hybridizations and/or the potential presence of nuclear-mitochondrial psuedogenes. The addition of a complementary nuclear DNA barcode has therefore been widely recommended to overcome these potential COI gene limitations, especially in wildlife law enforcement applications where greater confidence in the identifications is essential. In this study, we examined the comparative nucleotide sequence divergence and utility of the mitochondrial COI gene (N=182 animals) and nuclear ribosomal internal transcribed spacer 2 (ITS2) locus (N=190 animals) in the 8 known and 1 proposed cryptic species of globally widespread, hammerhead sharks (family Sphyrnidae). Since hammerhead sharks are under intense fishing pressure for their valuable fins with some species potentially set to receive CITES listing, tools for monitoring their fishery landings and tracking trade in their body parts is necessary to achieve effective management and conservation outcomes. Our results demonstrate that both COI and ITS2 loci function robustly as stand-alone barcodes for hammerhead shark species identification. Phylogenetic analyses of both loci independently and together accurately place each hammerhead species together in reciprocally monophyletic groups with strong bootstrap support. The two barcodes differed notably in levels of intraspecific divergence, with average intraspecific K2P distance an order of magnitude lower in the ITS2 (0.297% for COI and 0.0967% for ITS2). The COI barcode also showed phylogeographic separation in Sphyrna zygaena, S. lewini and S. tiburo, potentially providing a useful option for assigning unknown specimens (e.g. market fins) to a broad geographic origin. We suggest that COI supplemented by ITS2 DNA barcoding can be used in an integrated and robust approach for species assignment of unknown hammerhead sharks and their body parts in fisheries and international trade.
Chapter 2
The gray reef shark (Carcharhinus amblyrhynchos) is an Indo-Pacific, coral reef associated species that likely plays an important role as apex predator in maintaining the integrity of coral reef ecosystems. Populations of this shark have declined substantially in some parts of its range due to over-fishing, with recent estimates suggesting a 17% decline per year on the Great Barrier Reef (GBR). Currently, there is no information on the population structure or genetic status of gray reef sharks to aid in their management and conservation. We assessed the genetic population structure and genetic diversity of this species by using complete mitochondrial control region sequences and 15 nuclear microsatellite markers. Gray reef shark samples (n=305) were obtained from 10 locations across the species’ known longitudinal Indo-Pacific range: western Indian Ocean (Madagascar), eastern Indian Ocean (Cocos [Keeling] Islands, Andaman Sea, Indonesia, and western Australia), central Pacific (Hawaii, Palmyra Atoll, and Fanning Atoll), and southwestern Pacific (eastern Australia – Great Barrier Reef). The mitochondrial and nuclear marker data were concordant in most cases with population-based analysis showing significant overall structure (FST = 0.27906 (pST = 0.071 ± 0.02), and significant pairwise genetic differentiation between nearly all of the putative populations sampled (i.e., 9 of the 10 for mitochondrial and 8 of the 10 for nuclear markers). Individual-based analysis of microsatellite genotypes identified at least 5 populations. The concordant mitochondrial and nuclear marker results are consistent with a scenario of very low to no appreciable connectivity (gene flow) among most of the sampled locations, suggesting that natural repopulation of overfished regions by sharks from distant reefs is unlikely. The results also indicate that conservation of genetic diversity in gray reef sharks will require management measures on relatively local scales. Our findings of extensive genetic structuring suggests that a high level of genetic isolation is also likely to be the case in unsampled populations of this species.
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Ryklief, Rabiah. "Population dynamics of the white shark, Carcharodon carcharias, at Mossel Bay, South Africa." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1012077.
Full textAbstract:
Mossel Bay is internationally recognised as one of the centres of abundance of white sharks in South Africa. During 2008 – 2010 there were four sites within the bay i.e. Seal Island, Hartenbos, Kleinbrak and Grootbrak, which were sampled to gain insight into the population dynamics of this species. Currently, life history information on white sharks in this area is limited. This study used a combination of mark-recapture using photographic identification techniques and sight per unit effort methods. Inter-annual, seasonal and spatial patterns in abundance are assessed. The effects of environmental parameters on abundance are also investigated. Photographic identification techniques were employed to identify unique individuals within the sampled population. This modified mark-recapture approach is therefore non-invasive and cost-effective. Open population POPAN parameterization was used to analyse the data in software program MARK. The total population was estimated at 389 sharks (351 – 428; 95 percent CI). Over the three year period, a marginal (yet non-significant) decline in numbers was observed, in terms of both monthly and seasonal population estimates. Sightings per unit effort data were collected during sampling trips. The relative abundance and body size composition of white sharks demonstrated significant spatial and seasonal variation. The highest and lowest relative abundance was observed at Seal Island and Hartenbos, respectively, and is likely attributed to prey availability. Although white sharks were present year-round in Mossel Bay, the highest relative abundance occurred during summer and the lowest relative abundance occurred during spring. White sharks were grouped into three main size classes based on estimated total length (TL): Young of the year (YOY) (125 – 174cm), juvenile (175 – 324cm) and adult (325 – 524cm). YOY white sharks were most prevalent at Grootbrak, with juvenile and adult individuals concentrating at Seal Island. Although most size classes were present throughout the year, seasonal differences were observed. YOY individuals were most abundant in the autumn months, juvenile size-classes appeared to concentrate in the study area during winter, and the adult individuals were most abundant in the spring months. Overall, there was a high concentration of white sharks ranging in size between 175 – 324cm TL, and it was thus hypothesised that Mossel Bay represents an interim nursery or grow out area for white sharks in South Africa. Data collected from 2008 and 2009 was used to investigate the relationship between specific environmental parameters, i.e. sea surface temperature and vertical water clarity, in relation to the relative abundance of white sharks. Sea surface temperature and vertical water clarity observed in this study ranged from 9.3 - 22.7°C and 0 – 10m, respectively. Sea surface temperature did not have a significant influence on the relative abundance of white sharks and this may be attributed to the thermoregulatory capacity of the species. Vertical water clarity, however, did significantly influence the relative abundance. Furthermore, the combined effect of site and season significantly influenced the relative abundance of white sharks and is probably linked to the distribution and abundance of inshore prey resources.
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Davis, Christopher. "Prey Selection by Young Lemon Sharks (Negaprion brevirostris) at Chandeleur Island Nursery Habitats with a Comparison to Three Other Co-Occurring Shark Species." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1281.
Full textAbstract:
The Chandeleur Islands (Louisiana) contain nursery habitats for lemon sharks that provide abundant prey and protection from predation. Other local shark species (Atlantic sharpnose, bull, and blacktip sharks) co-occur with lemon sharks in the same region, including the nearby Biloxi Marshes. To better assess how lemon sharks use these nursery habitats, I measured diet and prey availability of young of the year and juvenile lemon sharks from 2009 to 2010. Young lemon sharks at the Chandeleur Islands have a relatively reduced diet breadth in comparison to those from nurseries in Bimini (Bahamas) and the Florida Keys. At the Chandeleur Islands, young lemon sharks appear to be opportunistically feeding on the most abundant prey items, resulting in high prey abundance and low diversity in their diet. Opportunistic feeding by young lemon sharks suggests minimal dietary overlap with other local shark species, resulting in minimal competition for resources.
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Strid, Anna. "Organohalogen contaminants in Greenland shark (Somniosus microcephalus)." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-45828.
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The remote sub-Arctic/Arctic environment has due to human activities become a sink for organohalogen contaminants (OHCs). These OHC include traditional contaminants such as polychlorinated biphenyls (PCBs), DDTs and technical mixtures of polybrominated diphenyl ethers (PBDEs), all included in the Stockholm Convention list of persistent organic pollutants (POPs). Other OHCs, currently under evaluation to be included among the POPs i.e. short chain chlorinated paraffins (SCCPs) and hexabromocyclododecane (HBCDD) are also found in these environments as well as a whole range of other OHCs. The main objective of this thesis is to increase the knowledge about the presence of OHCs in a high trophic Arctic shark species, the Greenland shark (Somniosus microcephalus). The Greenland shark is an opportunistic feeder, occasionally feeding at the top of the Arctic marine food chain. Furthermore may this species have a life span in excess of 100 years and is probably among the oldest of any fish species. These traits make the shark prone to accumulate elevated concentrations of OHCs. This has shown to be true for the Greenland sharks studied and most of the targeted OHCs were determined in the species. The highest concentrations were observed for the DDTs, ranging up to 26 μg/g fat. Other OHCs reported that are of special interest are SCCPs and brominated flame retardants used as replacement products to PBDEs; pentabromoethylbenzene (PBEB) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE). Also a range of OHCs whose origin is assumed to be natural, were shown to be present in Greenland sharks. This thesis is stressing the fact that even though the use of certain OHCs has been banned for decades they are still present at high concentrations in the deep waters of the Arctic. Therefore it is of major importance to continue to monitor the fate of traditional and emerging OHCs in the environment, and for this purpose the Greenland shark is an excellent species.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.
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Rodda, Kate. "Development in the Port Jackson shark embryo /." Title page, table of contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phr686.pdf.
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Clarke, Shelley Catherine. "Quantification of the trade in shark fins." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408811.
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Polaha, Jodi, and Jennifer Funderburk. "Shark Tank: Competition to Evaluate Collaborative Care." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/6650.
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Polaha, Jodi, Jennifer Funderburk, Tina Studts, Lesley Manson, J. D. Smith, Nadiya Sunderji, and Mark Vosvick. "Shark Tank: Clinician Innovators to Clinician Scientists." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/6659.
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Whitenack, Lisa Beth. "The biomechanics and evolution of shark teeth." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002678.
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Jewell, Oliver Joseph David. "Global seascape ecology of the white shark." Thesis, Jewell, Oliver Joseph David (2022) Global seascape ecology of the white shark. PhD thesis, Murdoch University, 2022. https://researchrepository.murdoch.edu.au/id/eprint/63107/.
Full textAbstract:
The movements of predators are inherently connected to their prey and environment. Yet, quantifying the movements of predators in inaccessible areas, such as the marine environment, has traditionally been challenging. In recent years, technical advancements in the development and miniaturisation of biologgers and their attachment and retrieval devices have seen an unprecedented increase in our ability to answer questions addressing the movement ecology of highly mobile marine animals.
White sharks Carcharodon carcharias are long-lived, top marine predators that feed on a variety of prey in a range of environments. Despite being globally distributed, rare and threatened, they are found to seasonally aggregate in areas of high and predictable prey abundance. These aggregations offer a unique setting to answer questions on the movement ecology of a large marine predator, as many individuals, often varying in size and sex, are found in comparatively small areas that often serve as foraging grounds. In this thesis, I assess the seascape ecology of white sharks at local, regional and global scales using novel biologging tools and exploring their interactions with prey and the environment.
At a local scale, I used animal-borne video and environmental data collection devices (AVEDs) to determine how white sharks interact with their preferred prey in a complex marine seascape in South Africa. Previous studies identified white sharks forage diurnally in this seascape, and in response, Cape fur seals Arctocephalus pusillus pusillus refuge in kelp forest. The use of AVEDs revealed white sharks make repeated movements into kelp forest throughout the day while raising their activity and turning rates. Cape fur seals were seen in footage grouping in numbers, hunkering to the seafloor, and blowing bubbles as white sharks approached. Though no predation events were captured in the footage, the results combined with the previous studies revealed white sharks are capable of foraging in kelp forests.
At a regional scale, in the Northeast Pacific, I used biologging data from white sharks of three size-classes in four contrasting habitats in a multivariate statistical framework to elucidate both the internal and external determinants of movement and behaviour. I reveal distinct hierarchical similarity in movement characteristics, primarily driven by habitat, bathymetry in particular, and secondarily driven by size. Sharks in all habitats revealed distinct movement and behaviour between day and night, characteristic of a diurnal activity rhythm irrespective of circumstance. The availability of prey and access to deep water between these habitats are likely drivers of these differences. The two island habitats provide more elephant seal Mirounga angustirostris prey and are situated closer to the continental shelf edge. The other areas are either far from it and contain more harbour seals Phoca vitulina, or only host juvenile, piscivorous white sharks.
Finally, I tested if the diurnal activity rhythm detected in the Northeast Pacific white shark population was characteristic of the species globally. I used scale-free estimates of activity derived from accelerometers deployed on 104 white sharks of four populations and eight aggregation areas to test for local adaptations in activity rhythms. Overall, linear modelling revealed consistent diurnal activity rhythms, irrespective of size or population, suggesting strong conservation of activity rhythms in this species. Despite the overall conservation of diurnal activity, generalised additive mixed models revealed some degree of site-specific plasticity, with peak activity differing between sites. I suggest that strong conservation in the diurnality of white sharks is driven by sensory specialisation for foraging in well-lit environments. In contrast, behavioural plasticity in the peak of activity is driven by the availability of prey at a given location.
Together, my thesis reveals the major external and internal factors driving the movements and routines of white sharks. While white sharks display moderate plasticity in their movements and behaviours between different habitats, they also appear to be constrained to diurnal foraging, possibly due to the evolution of their sensory system making them diurnal specialists. As a threatened species that require protection yet can be potentially dangerous to water users, balanced management strategies involving multiple stakeholders are required in areas the species frequents. These strategies should consider the internal and external factors found influential on the movements and behaviours of white sharks. Given the results of this thesis, white sharks have a conserved diurnal circadian rhythm; potential challenges remain, as the time white sharks are more likely to be active reflects the time when people are more likely to be using coastal waters.
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Pělucha, Jiří. "Výpočet zatížení kluzáku HPH 2 Twin Shark." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229315.
Full textAbstract:
The object of diploma thesis is a loading determination for strength calculation of HPH 2 Twin Shark glider matching the requirements of Certification Specification for Sailplanes (CS-22). Loading of the wing, tail section, fuselage and undercarriage is determined in this work.
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Krmela, Luděk. "Aerodyanmický návrh a výpočet kluzáku "Twin Shark"." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229321.
Full textAbstract:
The thesis contains determination of real aerodynamics characteristics of PW09-135 flap airfoil with help of calibration method via CFD, followed by accomplishment of CFD analysis of parts and the whole Twin Shark glider. Detailed research and optimization was made to flow field quality of fuselage and wing fuselage junction. On the basis of CFD solution was determine a stability control, static margin and angle of attack of a horizontal stabilizer. The thesis concludes an evaluation of results applicability in praxis.
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Thorpe, Teresa Mary. "The shark faunal assemblage of North Carolina, USA and assessment of a gillnet modification intended to reduce shark bycatch." Thesis, University of London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536785.
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Daly, Ryan. "Feeding ecology, residency patterns and migration dynamics of bull sharks (Carcharhinus leucas) in the southwest Indian Ocean." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1017802.
Full textAbstract:
Bull sharks (Carcharhinus leucas) are globally distributed top predators that play an important ecological role within coastal marine communities. However, little is known about how the spatial and temporal scales of their habitat use are associated with their ecological role. In this study, a population of sub-adult and adult bull sharks were investigated within a remote subtropical marine community in the southwest Indian Ocean off the coast of southern Mozambique. The main objectives of the study were to test a minimally invasive remote biopsy sampling method; to investigate the feeding ecology of bull sharks; and to investigate the temporal and spatial scales of bull shark residency patterns and migration dynamics. Biopsy tests on free-swimming bull sharks showed that the devised sampling technique provided a minimally invasive and consistent method (biopsy retention rate = 87%) to obtain muscle tissue samples sufficiently large enough (310±78mg, mean ± SD) for stable isotope analysis. Results from the stable isotope analysis showed that adult bull sharks appeared to exhibit a shift towards consistentlyhigher trophic level prey from an expanded foraging range compared to sub-adults, possibly due to increased mobility linked with size. Additionally, bull sharks had significantly broader niche widths compared to top predatory teleost assemblages with a wide and enriched range of δ13C values relative to the local marine community, suggesting that they forage over broad spatial scales along the east coast of southern Africa. Results from the passive acoustic telemetry investigation, conducted over a period between 10 and 22 months, supported these findings showing that the majority of tagged adult sharksexhibited temporally and spatially variable residency patterns interspersed with migration events. Ten individuals undertook coastal migrations that ranged between 433 and 709km (mean = 533km) with eight of these sharks returning to the study site. During migration, individuals exhibited rates of movement between 2 and 59km.d-1 (mean = 17.58km.d-1) and were recorded travelling annual distances of between 450 and 3760km (mean = 1163km). These findings suggest that adult bull sharks are not the sedentary species once thought to be but rather, consistently move over broad spatial scales on the east coast of southern Africa and play an important predatory role shaping and linking ecological processes within the southwest Indian Ocean.
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Ha, Daniel Stuart. "Ecology and conservation of Virginia shark species: Analysis of thirty years of Virginia long-line shark census data, 1974--2004." W&M ScholarWorks, 2006. https://scholarworks.wm.edu/etd/1539616679.
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Sharks of the Atlantic coast of the United States have suffered increased fishing pressure in last three decades. Commercial and recreational catches jumped in the mid to late 1980's, leading to regulation by the National Marine Fisheries Service in the early 1990's. The Virginia Institute of Marine Sciences' shark long-line survey, begun in 1974, and continuing to the present day, is thus well positioned to look at the effects of this fishing mortality on sharks. Using GAM modelling, six of ten shark species analyzed, including the most common species, Carcharhinus plumbeus, suffered declines of from 98-99% of early abundances in the survey. Only two species showed no significant trends, and only one (C. obscurus) showed signs of recovery. Analysis of size changes showed that both C. plumbeus and C. obscurus have suffered declines in both mean and variance of their size distribution since 1974. Analyses of mass changes showed that five of thirteen species have shown biologically significant declines in mass per shark since 1974. Six of the remaining eight showed no trend in mass per shark. Habitat analyses showed that few species showed effects of climate scale variables such as the North Atlantic Oscillation index, Chesapeake Bay discharge, or the Palmer Drought Index. Many species showed significant changes in patterns in abundance with local environmental variables, such as temperature, salinity, and water depth. These patterns, when combined, revealed several groupings of species, including deep-water species, Bay-abundant species, and near-shore species. Another group consisted of species that occur in this area only as they move north and south en route to more northerly areas for summer months. One group was made up of two species (S. acanthias and M. canis) that occurred almost exclusively in cold water (April and May). Analysis of New Jersey long-line data from 1961-62 with a resample of many of the same sites revealed that abundances off New Jersey show a trend in both mass and abundance similar to that found in the VIMS survey data. Overall, this study demonstrated many trends in shark distribution and ecology not previously shown in any way other than anecdotally.
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Ford, Ryan Michael. "Diet and Reproductive Biology of the Blacknose Shark (Carcharhinus Acronotus) from the Southwestern Atlantic Ocean." UNF Digital Commons, 2012. http://digitalcommons.unf.edu/etd/347.
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The blacknose shark (Carcharhinus acronotus) is a common small coastal shark species found in nearshore waters along the southeast coast of the United States, from North Carolina into the Gulf of Mexico and extending further south into the Bahamas. There has been some debate in recent years over the reproductive periodicity of C. acronotus in waters off the U.S. coast. Earlier studies have suggested that Gulf C. acronotus reproduce on an annual basis whereas the Atlantic populations of this species may reproduce biennially. Additionally, there have been no known studies on the diet of C. acronotus. The goal of the present study was to re-evaluate the reproductive biology of the Atlantic populations of C. acronotus with the intent on clarifying discrepancies in reproduction as well as provide information on dietary trends. This was accomplished by examining male and female reproductive tracts and gut contents in animals caught throughout the Atlantic range of C. acronotus. Based on these data, spermatogenesis occurs between late May to early July with peak sperm production occurring in June and July. In females, follicular development is complete by late June-early July with ovulation occurring shortly afterwards. Mating occurs between mid-June and early July based on the presence of fresh mating scars on females captured during this time. Current data suggests that gestation begins late July with parturition occurring late May to early June the following year. As observed in earlier studies, reproductive periodicity appears to be largely biennial. However, evidence for concurrent follicular development and pregnancy was observed in several females, suggesting that at least a portion of the Atlantic population may reproduce on an annual basis. Dietary data shows a dominance of teleost prey items in the diets of C. acronotus with scianids making up the majority of the identifiable teleosts.
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Jacoby, David. "A network analysis approach to understanding shark behaviour." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/4093.
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The mechanisms and functions of shark grouping behaviour have received relatively little scientific attention to date. The current widespread use of social network analysis to study animal groups, in concert with rapid advances in animal tracking technology, now allows us to test specific hypotheses about how and why sharks form groups. This thesis uses replicated laboratory experiments to investigate some of the mechanisms underpinning aggregation in a model species of benthic, oviporous elasmobranch, the small spotted catshark (Scyliorhinus canicula L. 1758; Scyliorhinidae). Acoustic tracking of this species in the wild is also conducted to explore how network analyses can be adopted to study the localized movements, habitat connectivity and ranging behaviour of adult sharks. Groups of juvenile S. canicula were characterized by non-random social preferences, crucially, only when individuals were familiar with one another suggesting social recognition is important in young sharks of this species. Genetic analyses of parent and offspring DNA revealed very high levels of multiple paternity in this species, likely due to male sexual harassment and multiple mating, which leads to increased genetic diversity between juvenile sharks. Perhaps unsurprisingly, there was no evidence of kin relatedness structuring social interactions between conspecifics. Furthermore, testing the effects of environment on social behaviour provided evidence that these juveniles aggregated more in structurally complex environments than simple ones. However, at the individual level sharks showed consistency in their social network positions through time and across different habitat types. This result is indicative of personality traits in S. canicula. Using data gathered via passive acoustic telemetry of wild shark behaviour, network analysis provided a useful tool with which to quantify movement between receivers. One chapter has been dedicated to the application of these methods, highlighting a number of different analyses for predicting movement behaviour from such data. Finally, these methods were adopted to address ecological questions in this sexually segregated species. Persistent site fidelity to a localised inshore area by both male and female sharks suggested that segregation occurred at a relatively small spatial and temporal scale. Despite strong evidence of segregation, analyses of movement networks and individual co-occurrences revealed distinct periods of behavioural synchronicity during the months of March, April and May. In addition, habitat complexity appeared to be a significant driver of female behavioural strategy. Enhancing our knowledge of the social and environmental drivers of aggregation and movement in sharks is of great importance given the ecological threat facing many of our ocean’s top elasmobranch predators.
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Morris, Alexandra H. "Preying on the predator : the shark fin controversy." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92635.
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Thesis: S.M. in Science Writing, Massachusetts Institute of Technology, Department of Humanities, Graduate Program in Science Writing, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 23-25).
The consumption of shark fin soup dates back to the Ming Dynasty in China, when it was served to emperors. Today, the cultural delicacy represents wealth, status, and power. Over the past 30 years, with the rising middle class in China, the demand for shark fins has surged. To address the increasing demand, a group of fishermen came to realize there was little value in carting massive shark bodies to shore when all they needed were the highly valued fins. So they sliced off the fins, and threw the still living, rudderless sharks to die in the open ocean. So began the gruesome practice known as "shark finning." Shark populations have been unable to withstand the demand for their fins, and dozens of species are now threatened or endangered. From enhancing legislation to control the shark fin market to building sustainable fisheries to promoting synthetic shark fin soup - efforts to address the issue of shark depletion are seemingly endless. And yet despite these efforts, both the market for shark fins and global catch rates have continued unabated. If the demand for fins and the practice of shark finning continue at the current rate, human interference may forever change the nature of our oceans.
by Alexandra H. Morris.
S.M. in Science Writing
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De, la Puente Jeri Santiago. "Characterizing the knowledge and attitudes towards sharks and the domestic use of shark meat and fins in Peru." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63144.
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Shark populations show evidence of declines at a global scale. Knowledge of the socio-economic consequences of changes in their abundance is limited. Furthermore, research on the status of peoples’ knowledge and attitudes towards sharks and how these affect their values, behaviours and actions is lagging behind the pursuit of biological and ecological concerns.
Framed within Peru’s National Plan of Action for the Conservation and Management of Sharks, Rays and Chimeras, the present study sought to: (1) characterize coastal Peruvian’s general knowledge and attitudes towards sharks and shark meat consumption; (2) describe the domestic market and trade flows of shark commodities; (3) estimate the apparent consumption of shark meat and fins in Peru; and (4) reconstruct the catches required to maintain the estimated local levels of shark consumption.
Using data from over 2000 surveys provided by OCEANA Peru, I determined that a limited proportion of the Peruvian coastal population was aware of sharks’ presence in the country’s waters, and of these, only a minor subset was capable of naming shark species found locally. Furthermore, Peruvians have very negative attitudes towards sharks, driven by fear and prevalent misconceptions regarding their feeding habits and behaviour, which are reinforced by mass media.
Using public data, provided by various organizations within the Peruvian government, I determined that shark meat consumption in Peru is high and growing, although its contribution to national food security remains low. Nonetheless, most shark meat consumers are not aware that they are eating sharks due to deceptive advertising.
Improvements on seafood traceability have only been observed on exports, as data associated with landings, local markets and imports remains highly aggregated. Moreover, official statistics severely underestimate the catches required to maintain the Peruvian supply (by 39%) and demand (by 85%) of shark products.
These findings can be used to inform the design of communications campaigns and government policies seeking to: (i) improve people’s knowledge and attitudes towards sharks in Peru, (ii) increase seafood traceability, (iii) protect seafood consumers, and (iv) advance towards the incorporation of these dimensions in the quantitative evaluation of policy outcomes for achieving sustainable shark fisheries.Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate
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Filmalter, John David. "The associative behaviour of silky sharks, Carcharhinus falciformis, with floating objects in the open ocean." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1018177.
Full textAbstract:
The silky shark Carcharhinus falciformis forms the primary elasmobranch bycatch in tuna purse seine fisheries using fish aggregating devices (FADs) in all of the world’s tropical oceans. Its life-history traits of slow growth, late maturation and low fecundity make it vulnerable to over exploitation, as is apparent from historical bycatch trends. Very little is known about the associative behaviour of this species with floating objects, information which is essential in formulating effective mitigation and management measures. This study aims to address this knowledge gap through the use of various electronic tagging techniques in conjunction with dietary analysis. Dietary data were collected from 323 silky sharks incidentally caught at FADs. Approximately 40 percent of the diet consisted of prey associated with FADs while the remaining 60 percent were non-associated species of crustaceans, cephalopods and fishes. These results suggest that the associative behaviour is not primarily driven by trophic enhancement, but is likely a combination of predator avoidance, social interactions and feeding. Fine-scale behavioural data from silky sharks associated with drifting FADs were collected through the use of acoustic telemetry techniques. Acoustic tags were implanted into 38 silky sharks (69- 116 cm TL) at eight FADs. FADs were equipped with satellite linked acoustic receivers and abandoned to drift freely. Presence/absence and swimming depth data were telemetered via the Iridium satellite system. A total of 300 d of behavioural data were collected from 20 tagged individuals. Individuals remain associated with the same FAD for extended periods (min = 2.84 d, max = 30.60 d, mean = 15.69 d). Strong diel patterns were observed in both association and swimming depth. Typically individuals moved away from FADs after sunset and return later during the night, then remain closely associated until the following evening. Vertical behaviour also changed around sunset with sharks using fairly constant depths, within the upper 25 m, during the day and switching to rapid vertical movements during the night, with dives in excess of 250 m recoded. Broader scale movement behaviour was investigated using pop-up archival satellite tags (PSATs). Tags were deployed on 46 silky sharks (86-224.5 cm TL) for a total of 1495 d. Light data were used to calculate geolocation estimates and reconstruct the sharks’ trajectories. Movement patterns differed between animals and according to deployment duration. Several extensive horizontal movements were observed, with an average track length of 3240 km during an average tag deployment of 44.02 d. Horizontal movement patterns were found to correlate very closely with drift patterns of FADs. Consequently, it appears that the movement behaviour of juvenile silky sharks is strongly influenced by the movement of drifting FADs in this region. Ghost fishing of silky sharks through entanglement in FADs was also investigated using data derived from PSATs as well as underwater visual censuses. Thirteen per cent of the tagged sharks became entangled in FADs and entangled sharks were observed in 35 percent of the 51 FADs surveyed. Using this information in conjunction with estimated time that sharks remained entangled in the FAD (from depth data from PSATs), and scaling up according to estimates of FAD numbers, it was found that between 480 000 and 960 000 silky sharks are killed annually in this manner in the Indian Ocean. Subsequent management measures in this region prevent the deployment of FADs with netting that could lead to entanglement. Overall, floating objects appear to play a significant role in the juvenile life stages of silky sharks in this region. While their association with floating objects is clearly advantageous in an evolutionary sense, under current tuna fishery trends, this behaviour is certainly detrimental for the population.
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Jaiteh, Vanessa. ""Sharks are important, but so is rice": Opportunities and challenges for shark fisheries management and livelihoods in eastern Indonesia." Thesis, Jaiteh, Vanessa (2017) "Sharks are important, but so is rice": Opportunities and challenges for shark fisheries management and livelihoods in eastern Indonesia. PhD thesis, Murdoch University, 2017. https://researchrepository.murdoch.edu.au/id/eprint/38470/.
Full textAbstract:
Targeted fisheries for shark fin are one of the main causes driving the unprecedented decline of shark populations. Despite widespread concern for sharks and calls for their conservation, a lack of data often delays regulatory action for shark fisheries. For over two decades, Indonesia has reported higher average shark landings than any other nation, but information on its shark fisheries is extremely limited. The eastern Indonesian shark fishery, here defined to extend from East Nusa Tenggara to Papua, is virtually data-less and beyond the focus of central fisheries agencies. The lack of essential information, including the location of fishing grounds, catch composition and fishing effort, as well as biological and socio-economic characteristics of harvested species and the livelihoods they support, impedes the development of effective fisheries management in this region. This thesis uses a transdisciplinary approach to address these knowledge gaps.
My findings are based on extensive field studies in three remote coastal communities with fishing grounds in the Seram, Halmahera, Aru-Arafura and Timor Seas. During my stay in each community, I involved fishers in collecting and interpreting fishery data, studied local fishing practices and patron-fisher relationships, and conducted in-depth interviews with fishers, shark fin bosses and other community members. This allowed me to portray the fishery from biological, economic and sociological perspectives (Chapter 2), and to investigate the reliability and accuracy of fisher data. The description of a range extension for the vulnerable fossil shark Hemipristis elongata demonstrates that fisher’s species identifications are not only reliable, but can lead to serendipitous findings on species occurrences (Chapter 3).
Expanding on the application of fisher data, I then use diverse data sources to provide the first sustainability assessment of the eastern Indonesian shark fishery (Chapter 4). The fishery targets over 40 species, many of which exhibit declining catch rates over the last two decades and are unable to sustain continued fishing pressure due to their low rebound potential and high fishing mortality. Finding that the fishery is most likely unsustainable, I move on to combine fishery and interview data from my case study sites with fishery-independent methods to examine key factors for successful shark conservation in one of the first studies to investigate the effectiveness of explicitly shark-specific spatial closures and their impact on shark fishers (Chapter viii 5). The results of this study clearly show that effective governance of spatial closures can result in higher abundances of sharks by allowing them to recover, and providing a refuge, from heavy fishing pressure. However, it also becomes evident that exclusion from fishing grounds can have profound effects on fishers’ behaviour, evidenced by a shift of fishing effort to unprotected, less productive areas and the pursuit of alternative livelihoods, including, in some cases, illegal activities. The theme of livelihood diversification and alternatives is explored further in Chapter 6, where I deconstruct a series of recent developments that have cumulatively reduced the appeal and stability of shark fishing, a once prosperous livelihood. These developments involve multiple levels of governance from local to regional, bilateral and international scales, and include declining catches in all fishing grounds, a reduction in the demand for, and trade of shark fin, the loss of access to fishing grounds, transboundary fishing, restrictive debt with shark fin bosses, and limited options for livelihood alternatives. Indebted fishers find themselves trapped in an increasingly unprofitable livelihood but are unable to leave the fishery even when willing to do so, due to financial, technical or other constraints. Nevertheless, examples of livelihood diversification are evident in all case study communities, with varying success and without the impetus or support of outside fisheries management or community development interventions.
In Chapter 7, I contend that the eastern Indonesian shark fishery is characterised by levels of uncertainty and complexity that conventional methods of fisheries assessment and management were not designed to deal with. Instead, data-poor fisheries management based on precautionary principles, and actively involving fishers in knowledge generation, are needed to mitigate against continued fishery-driven declines of shark populations. The thesis concludes with twelve recommendations for proactive management, based on challenges and opportunities identified during my research. I propose that the most promising strategy for protecting shark populations in eastern Indonesia is a composite, data-poor management approach that features a combination of spatial protection, consistent implementation and enforcement of trade regulations, researchbased fisheries regulations, and support for fishers’ livelihood diversification.
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Christensen, Joseph. "Shark Bay 1616-1991 : the spread of science and the emergence of ecology in a World Heritage area." University of Western Australia. School of Humanities, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0029.
Full textAbstract:
Shark Bay is an extensive marine embayment located on the central coast of Western Australia that is recognised as a World Heritage Property on the basis of the Outstanding Universal Value of the natural environment of the region. This thesis examines the history of science at Shark Bay between the arrival of the first European explorers in the seventeenth century through to the official recognition of Shark Bay as a World Heritage Area in 1991. Each of the seven chapters is devoted to a different period in the development of scientific investigations, beginning with Dutch and English mariners and naturalists, passing on to French scientific explorers and British surveyors naturalists, and explorers, continuing through a variety of investigations in marine science and research in biogeography and evolution carried out by foreign expeditions and Australian field-workers, and culminating in the transformation of scientific investigations as a result of the rise and development of modern ecological science in the second half of the twentieth century. This development of science at Shark Bay is considered in light of existing frameworks for the development or spread of science in Australia, and in relation to current literature concerning the development or emergence of ecology in Australia. After evaluating the history of science at Shark Bay relative to existing knowledge of the spread of science and the emergence of ecology, the thesis concludes by proposing a new framework for the development of science and the emergence of ecology based on the experience at Shark Bay and with wider application to the history of science in Western Australia.
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Morris, Jackson Alexander. "Application of Shark Skin Flow Control Techniques to Airflow." Thesis, The University of Alabama, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10638677.
Full textAbstract:
Due to millions of years of evolution, sharks have evolved to become quick and efficient ocean apex predators. Shark skin is made up of millions of microscopic scales, or denticles, that are approximately 0.2 mm in size. Scales located on the shark’s body where separation control is paramount (such as behind the gills or the trailing edge of the pectoral fin) are capable of bristling. These scales are hypothesized to act as a flow control mechanism capable of being passively actuated by reversed flow. It is believed that shark scales are strategically sized to interact with the lower 5% of a boundary layer, where reversed flow occurs at the onset of boundary layer separation. Previous research has shown shark skin to be capable of controlling separation in water. This thesis aims to investigate the same passive flow control techniques in air.
To investigate this phenomenon, several sets of microflaps were designed and manufactured with a 3D printer. The microflaps were designed in both 2D (rectangular) and 3D (mirroring shark scale geometry) variants. These microflaps were placed in a low-speed wind tunnel in the lower 5% of the boundary layer. Solid fences and a flat plate diffuser with suction were placed in the tunnel to create different separated flow regions. A hot film probe was used to measure velocity magnitude in the streamwise plane of the separated regions. The results showed that low-speed airflow is capable of bristling objects in the boundary layer. When placed in a region of reverse flow, the microflaps were passively actuated. Microflaps fluctuated between bristled and flat states in reverse flow regions located close to the reattachment zone.
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Aguiar, Ana Raquel Batista. "Trends in deep-water shark fisheries in the Azores." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15485.
Full textAbstract:
Mestrado em Biologia MarinhaDeep-sea resources have been increasingly exploited, and due to that, several ecosystems and species have been considerably affected. Deep-water sharks populations have been of the most disturbed by practices of unselected fisheries, bycatch and discard, mainly due to their low commercial value. Those practices make deep-water sharks very vulnerable to overfishing given their life-history traits, increasing their extinction risk. With the prohibition of the direct fishery, and implementation of quotas and TACs (Total Allowable Catches) regarding the deep-sea shark landings, the official landings have dramatically decreased after the 1990s. However, the IUU (Illegal, unreported and unregulated) catch has exponentially increased. With the analysis of catch per unit effort (CPUE), the depths, and the mean weight of the individuals over the years for each one of the nine most caught species in the Azores, we produced a descriptive analysis of the effect of fisheries in those species. The results show that some of these species have been suffering from a great fishing pressure, and their populations will be greatly affected in the near future if drastic measures are not taken when it comes to managing their long term sustainability.
Os recursos do mar profundo têm sido cada vez mais explorados, e devido a isso, vários ecossistemas e espécies têm sido gravemente afectados. As populações de tubarões de profundidade são das mais perturbadas, especialmente pelas práticas de pesca não seletivas, capturas acessórias e descarte, principalmente devido ao seu baixo valor comercial. Estas práticas tornam os tubarões de profundidade muito vulneráveis à sobrepesca dadas as suas características de história de vida, aumentando assim o seu risco de extinção . Com a proibição da pesca direta, e a implementação de quotas e TACs (Capturas Totais Admissíveis) na pesca de tubarões de profundidade, as capturas oficiais têm vindo a decrescer. No entanto, as capturas não reportadas têm vindo a aumentar exponencialmente. Com a análise da captura por unidade de esforço (CPUE), da profundidade, e do peso médio dos indivíduos ao longo dos anos de cada umas das 9 espécies de tubarões mais pescadas nos Açores, conseguimos fazer uma análise descritiva do efeito das pescas nestas espécies. Os resultados mostram que algumas destas espécies têm vindo a sofrer uma grande pressão por parte da pesca, e que as suas populações serão gravemente afetadas num futuro próximo se não forem tomadas medidas drásticas no que toca à gestão da sua sustentabilidade a longo prazo.
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Francis, Beryl. "Before and after Jaws: Changing representations of shark attacks." Thesis, Francis, Beryl (2011) Before and after Jaws: Changing representations of shark attacks. Honours thesis, Murdoch University, 2011. https://researchrepository.murdoch.edu.au/id/eprint/9471/.
Full textAbstract:
When the film Jaws (1975), about a rogue shark that terrorised a small seaside island community was released, it had an unprecedented paranoia effect on its audience that became entrenched into the psyche of bathers around the world; a fear that media hyperbole exploited. At the same time, the film was also responsible for a surge in scientific interest in sharks and the media responded by giving more attention to the important role of sharks in the marine ecology. In the long term, social perceptions of sharks, changed from fear to conservation, influencing local, national and international government conservation and management policies. Nevertheless, there persists the initial media frenzy after any shark attack and Jaws remains the touchstone for media reporting.
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Doherty, Philip David. "Basking shark movement ecology in the north-east Atlantic." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/27996.
Full textAbstract:
Large marine vertebrate species can exhibit vast movements, both horizontally and vertically, which challenges our ability to observe their behaviours at extended time-scales. There is a growing need to understand the intra- and inter-annual movements of mobile marine species of conservation concern in order to develop effective management strategies. The basking shark (Cetorhinus maximus) is the world's second largest fish species, however, a comprehensive understanding of this species’ ecology, biology and spatial behaviour in the north-east Atlantic is currently lacking. This thesis seeks to investigate the movement ecology of basking sharks using a suite of technologies to integrate biologging, biotelemetry, remotely sensed data, and ecological modelling techniques. I use satellite telemetry data from basking sharks tracked in 2012, 2013 and 2014 to quantify movements in coastal waters off the west coast of Scotland within the Sea of the Hebrides proposed MPA. Sharks exhibited seasonal residency to the proposed MPA, with three long-term tracked basking sharks demonstrating inter-annual site fidelity, returning to the same coastal waters in the year following tag deployment (Chapter 2). I reveal that sharks tracked into winter months exhibit one of three migration strategies spanning nine geo-political zones and the High Seas, demonstrating the need for multi-national cooperation in the management of this species across its range (Chapter 3). I examine the vertical space-use of basking sharks to improve an understanding of the processes that influence movements in all dimensions. Basking sharks exhibit seasonality in depth-use, conduct deep dives to over 1000 m, and alter their depth-use behaviour in order to remain within thermal niche of between 8 and 16 oC (Chapter 4). Finally, I combine contemporaneous data recorded by deployed satellite tags with remotely sensed environmental data to employ novel ecological modelling techniques to predict suitable habitat for basking sharks throughout the Atlantic Ocean (Chapter 5).
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Mowle, Adrien Kathleen. "Characterization of Vitellogenesis in the Bonnethead Shark Sphyrna tiburo." UNF Digital Commons, 2018. https://digitalcommons.unf.edu/etd/819.
Full textAbstract:
Vitellogenin (Vtg) is a precursor to yolk-proteins produced in the liver of many invertebrates and non-mammalian vertebrates; its synthesis is stimulated by the hormone estradiol (E2). This study is the first to characterize vitellogenin synthesis in a placental viviparous elasmobranch, the yolk-sac placental bonnethead shark, Sphyrna tiburo. This study focused on determining where and when Vtg is produced, as well as what hormonal factors regulate Vtg production. The liver was confirmed as the site of Vtg production via immunohistochemistry. Immunoreactivity was also observed within granulosa cells of ovarian follicles; further experimentation is needed to determine if this is indicative of Vtg production by these cells. Using immunoblotting, the highest proportions of Vtg positive females were found in March, with Vtg production continuing into April and May. Putative Vtg production was found to begin in August for some individuals, with production continuing throughout the fall and winter months. In regards to hormonal regulation, immunohistochemical analysis identified receptors for E2 and progesterone (P4) within the liver. Comparison of the monthly E2 and Vtg cycles provides evidence that E2 stimulates Vtg production in S. tiburo, as high or increasing concentrations of E2 correlated with Vtg presence in the plasma. Preliminary results also suggest in vitro production of Vtg by liver tissue when exposed to E2. Comparison of the monthly P4 and Vtg cycles suggests P4 may inhibit Vtg synthesis, with higher levels of P4 found in the months when Vtg production declines. Additionally, the methods developed for this study were able to identify Vtg in the plasma of other elasmobranch species. Vtg detection in plasma may thus be an ideal new, nonlethal method for characterizing elasmobranch reproductive periodicity, which will aid in assessing population growth and allow for managers to possess more accurate information to make appropriate decisions for the populations.
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Holley, David K. "Movement patterns and habitat usage of Shark Bay dugongs." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2006. https://ro.ecu.edu.au/theses/70.
Full textAbstract:
In order to define small and large scale spatial and temporal individual movement patterns of dugongs (Dugong dugon) within the Shark Bay World Heritage Property (SBWHP) a total of 19 dugongs were fitted with remote location recording and transmitting devices. Combined locations from all units totalled over 10,000 locations. This spatial and temporal data was used to define movement patterns of dugongs within Shark Bay as well as areas of high use deemed to be indicative of foraging activity. Platform Transmitting Terminals (PTT?s) using the ARGOS location collection system tracked animals over large temporal scales with 4 animals tracked up to periods of 11 months. Using these instruments it was possible accurately define a previously identified large-scale seasonal movement pattern within the confines of Shark Bay. These four animals showed distinct seasonal home ranges defined by changes in Sea Surface Temperature.