Thesis (Ph. D.)--Simon Fraser University, 2001. / Includes bibliographical references.

Thesis (Ph.D. (Ichthyology and Fisheries Science))--Rhodes University, 2006.

Shark tagging is used as a source of data for shark migration and behaviors. Different tags can collect temperature, salinity, or depth data points while the shark is in motion. There are a variety of shark tagging methods used to monitor sharks. Of these methods, shark bolting has caused some concern. Shark bolting is the method of drilling holes into the first dorsal fin of pelagic sharks and placing steel screws into the fin to secure a satellite (SAT) tag. Bolted SAT tags cause concern due to the limited ways of removal, high probability of excessive biofouling, infections, and increased drag while swimming in many species of sharks. The objective of this study is to assess if bolting is a non-impact shark tagging method in terms of resulting shark health and behavior and, further, whether it should be considered a humane or inhumane practice by examining the present knowledge of dorsal fin anatomy and functionality.

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.

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

The submitted thesis deals with the analysis of selected fish coprolites found in the Loučka site (Moravia; Menilite Fm.). Eleven specimens was selected (provisionally numbered I-XI) of which two were macerated (specimens I and II). The remaining nine specimens were examined at the surface of the sedimentary layers. Recognizable elements were classified to the following taxa: Keasius parvus, Alopias exigua, Squalus cf. alsaticus, Sardinella sardinites, Anenchelum glarisianum, Palimphyes sp., Palaeogadus sp., Gonostomatidae (gen. et. sp. indet.), Perciformes (gen. et sp. indet.), and Teleostei (gen. et sp. indet.). Composition of the studied coprolites I, II and IV suggest that these were produced by shark species Alopias exigua and Squalus cf. alsaticus. Studied coprolites V, VIII, X and XI were produced by some type of undetermined predatory fish (probably piscivore predator). For coprolites III, VI, VII and IX producer can not be determined.

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.

Sharks comprise a large portion of bycatch in pelagic longline fisheries worldwide. Lanthanide metals have been proposed as shark repellents. This study quantified the normalized voltage of lanthanide metals in seawater and found that there was no difference in normalized voltage among the six tested metals. Temperature and salinity had a significant effect on lanthanide normalized voltage. The output at 18ºC was significantly greater than at both 12 and 24ºC. The normalized voltage was significantly greater in freshwater than brackish or seawater. The dissolution rate for the lanthanides varied from -1.6 to -0.2g/h. As the metals dissolved the voltage remained constant. In a behavioral assay, neodymium was ineffective at repelling bonnethead sharks (Sphyrna tiburo) tested individually and in groups, and lemon sharks (Negaprion brevirostris) in groups. Due to high cost, fast dissolution rates, and lack of deterrent effects, lanthanide metals are not recommended for use in mitigating shark bycatch. / by Sara M. McCutcheon. / Thesis (M.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

Orientador: Fausto Foresti / Coorientador: Fernando F. Mendonça / Banca: Diego Teruo Hashimoto / Banca: Paulino Martinez Portella / Resumo: Até poucas décadas atrás, a pesca de tubarões era incidental e sem efeitos significativos para as suas populações. No entanto, devido ao grande aumento no valor de suas nadadeiras na Ásia e ao declínio das populações de peixes mais tradicionais para o consumo humano, os tubarões passaram a ser alvo de pescarias em quase todo o mundo, promovendo a inclusão de diversas espécies na lista de espécies ameaçadas de extinção. Entre os tubarões mais explorados, as espécies pelágicas apresentam uma maior complexidade na avaliação e monitoramento de suas populações devido à sua distribuição em vastas áreas geográficas. Destas, o tubarão mako, Isurus oxyrinchus, com ocorrência circunglobal, está entre as principais espécies que apresentam sinais de vulnerabilidade, com tendência ao esgotamento populacional e, no entanto, avaliações que viabilizem o manejo adequado da pesca ainda são inconsistentes. Estudos relacionados à estruturação genética populacional de peixes têm contribuído substancialmente para a elucidação de questões como a variabilidade genética, distribuição geográfica, padrões de migração, estoques reprodutivos, taxonomia, sistemática e eventos históricos. Tais aspectos são especialmente relevantes para o setor pesqueiro, fornecendo subsídios para o manejo e conservação dos estoques. Considerando a urgente necessidade de controle sustentável da pesca, dificultada principalmente pela falta de informações, este estudo buscou caracterizar a estrutura genética populacional da espécie I. oxyrinchus no Oceano Atlântico, utilizando sequências da região controladora do DNA mitocondrial (D-loop). Foram analisados 144 indivíduos e a análise de 729 pares de bases nucleotídicas desta região genômica permitiu a caracterização de 27 haplótipos, sendo que 18 destes haplótipos (67%) estão compartilhados por todas as regiões amostradas. Os resultados indicam a ... / Abstract: Until a few decades ago, shark fishing was only incidental and had no significant effects on their populations. However, due to the large increase in the value of shark's fins in Asia and the decline of more traditional fish populations for human consumption, sharks became target fishing around the world, promoting the inclusion of several species in the list of endangered species. Among the most exploited sharks, the pelagic species exhibit greater complexity in the assessment and monitoring of their populations due to their distribution in broad geographical areas. From these species, the mako shark, Isurus oxyrinchus, of global occurrence, is among the main species that show vulnerability signs, with a trend to deplete population, and however, evaluations that facilitate appropriate management of fisheries are still inconsistent. Studies related to genetic structure of fish populations have contributed substantially to the elucidation of issues such as genetic variability, geographical distribution, migration patterns, reproductive stocks, taxonomy, systematics, and historical events. These aspects are especially relevant to fisheries sector, providing subsidies for the management and conservation of fish stocks. Considering the urgent need for a sustainable control of fisheries, hampered mainly by the lack of information, this study aimed to characterize the population genetic structure of the shark I. oxyrinchus in the Atlantic Ocean, using sequences of mitochondrial DNA control region (D-loop). We analyzed 144 individuals and analysis of 729 nucleotide base pairs of this genomic region allowed the characterization of 27 haplotypes, with 18 of these haplotypes (67%) being shared by all regions sampled. The results indicate the occurrence of a moderate genetic variability (π = 0.004 and h = 0.791 ± 0.029), with high population structure between the northern and southern hemispheres (FST values: ... / Mestre

The goal of this project was to examine the visual system of the bonnethead shark (Sphyrna tiburo). The eyes of this shark are located at the extreme lateral ends of a broad, elongated cephalofoil. Better understanding of their visual system may aid in determining the adaptive benefits of their usual head shape. The proposed project examined one specific aspect of their visual system: the organization of retinal ganglion cells and identification of areas of increased resolution. Two experiments were conducted to realize these aims: (1) staining of retinal ganglion cells, to examine their distributional pattern, and (2) retrograde staining of retinal ganglion cells to determine morphology.