Bibliography: leaves 202-238. / 238 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Gives an overall understanding of embryonic development of Heterodontus portusjacksoni. / Thesis (Ph.D.)--University of Adelaide, Dept. of Environmental Biology, 2001

Thesis (Ph.D.) -- University of Rhode Island, 2008. / Typescript. Includes bibliographical references (leaves 170-184).

Fresh and prepared museum specimens of the white shark Carcharodon carcharias, bull shark Carcharhinus leucas, and salmon shark Lamna ditropis were measured and compared with respect to tooth position and anterior buccal cavity dimensions. Coordinates of functional tooth position were defined by 1) deviation from the midline and 2) degree of erection. Tooth positions were not unique in any region of the mouth/ but demonstrated less variablity within 30° of the midline, particularly for male specimens of all three species (71.48° +- 10° erect) and all Carcharhinus leucas specimens (46.58° +-.96° erect). Analysis of high-speed videotape of white shark feeding indicated a 15.7° reduction in tooth cutting angle with jaw adduction following upper jaw protraction. It is suggested that such changes in tooth cutting angles during feeding are principally the result of jaw flexure, and may make the teeth more effective by angling them inward towards the gullet. Values for tooth removal from fresh-frozen white shark material using a tensile testing apparatus ranged from 12 kg (for a 110° erect tooth) to 70 kg (for a 59° erect tooth). Removal load was applied directly outward from the mouth to simulate a resistant prey item, and was not significantly different for degree of erection or tooth position on the jaw margin. Tooth position is seen to change with jaw protraction, however this change does not enhance tooth functionality by increasing the load required to remove the tooth. / Science, Faculty of / Zoology, Department of / Graduate

Our goal was to assess regional differences in denticle density and skin tensile properties in four coastal species of shark. We hypothesized that the denticle density, tensile strength (MPa), stiffness (MPa), and toughness of skin (MJ·m^-3) would vary regionally along the body of an individual and among species. An hourglass-shaped punch was used to extract the skin samples at 10 anatomical landmarks and denticle density was quantified. Denticle density varied significantly among both regions and species, and showed a significant species by region interaction. Skin samples were tested in tension at a strain rate of 2 mm-s until failure. We found significant species and region effects for all tensile and denticle density properties. Also, denticle density increases with skin stiffness but decreases with toughness. Shark skin toughness is similar to that of mammalian tendons. These data show shark skin functions as an exotendon, able to conserve energy during swimming. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

The goal of this study was to determine the energetic requirements of juvenile scalloped hammerhead sharks (Sphyrna lewini) in Kaneohe Bay, Oahu, Hawaii using a multidisciplinary approach. A large flume/respirometer (635 1) was constructed to determine the critical swimming speeds (Ucrit )' swimming kinematics (tailbeat frequency, tailbeat amplitude, and stride length), and oxygen consumption rates (V02 ) of juvenile sharks over a range of swimming speeds (U). Swimming kinematics were also compared with unconstrained sharks in a seawater pond. These experiments indicated that tailbeat frequency (TBF) and water temperature could be used as a predictor of U and V02 for free-swimming sharks in the field; however, the flume affected the sharks' swimming kinematics at slow speeds. The flume and pond kinematic comparisons were used to correct for flume effects on sharks' V02. An acoustic tailbeat-sensing transmitter was designed and constructed to quantify activity and energy consumption of free-swimming hammerhead shark pups in Kaneohe Bay. Sharks with transmitters behaved similarly to uninstrumented sharks, but incurred a 28% increase in cost of transport due to increased drag from the transmitters. These data were used to correct for the effects of the transmitter on freeswimming sharks in the field. Sharks tracked in Kaneohe Bay with tailbeat transmitters exhibited increased U during dawn and dusk, while sharks tracked in the warmer summer months had higher activity rates and metabolic rates (MR) than a shark tracked during the winter. Sharks tracked in this study had higher MR than those measured for other species of tropical sharks and, as a result, require higher daily rations. Low and negative growth rates determined from sharks in the Bay and declining catch rates over the season suggest that a large percentage of the pups in Kaneohe Bay may starve as the result of their high metabolic requirements. Although prey do not appear to be li~itingi lack of foraging experience compounded by a high daily metabolic demand may explain why sharks lose weight during summer months. Those pups that survive the winter experience lower MR due to seasonal temperature decline and less competition as the result of high neonatal mortality. / x, 130 leaves, bound : ill. (some col.) ; 29 cm. / Missing page 74.

Research Doctorate - Doctor of Philosophy (PhD) / World shark populations are declining rapidly from the increased demand for shark meat and fins and from their capture as by-catch. Techniques to accurately and reliably estimate the age of elasmobranchs are required to understand life history and develop management strategies. Although some biological information exists for the harvested species, few of the many shark species caught as by-catch have been investigated. In the waters of New South Wales, Australia, the Port Jackson shark (Heterodontus portusjacksoni) is a non-targeted species, however it is a major contributor to the elasmobranch by-catch in the bottom trawl and prawn fisheries. Although some biological and ecological information exists on Port Jackson sharks from New South Wales, there is no understanding of suitable techniques to age this species and of the age structure of the New South Wales’ population. Hence, the main purpose for the present study was to determine a suitable technique to age Port Jackson sharks and thereby provide essential age and growth data for its future management, sustainable use and conservation. This study consisted of research into: (1) the macroscopic anatomy of the vertebral centra and dorsal spines from 652 H. portusjacksoni to explore their suitability as ageing structures; (2) a comparison of whole and sectioned vertebral centra and of whole and sectioned dorsal spines for ageing; (3) validation of the annual formation of growth bands; (4) a comparison of the effect of prior experience on readers’ ability to count annual growth bands in vertebral centra; and (5) the development of age-growth models for the New South Wales’ population of H. portusjacksoni. Two types of vertebral centra (trunk and caudal vertebrae) were found in the vertebral column. Both vertebrae consisted of a centrum, 2 ribs, 4 neural arches, basiopophyses and neural foramen and decreased in size from anterior to posterior. A strong linear relationship was identified between vertebral diameter (VD) and fork length (FL). Each dorsal spine was positioned anterior to the dorsal fin and consisted of a stem and the cap. A strong linear relationships were identified between spine base width (SBW) and FL. The existence of alternating opaque and translucent band pairs in both structures further suggested they may be suitable for ageing purposes. Validation (calcein and oxytetracycline injections, marginal increment analysis, and centrum edge analysis) confirmed that translucent band pairs were formed during the winter (September-November) and were annual in both vertebral centra and dorsal spines. Whole and sectioned vertebral centra and dorsal spines were individually examined to determine which method best estimated the age. Although both methods had individual low reading bias and high precision, there was a difference between the two methods. The average bias between the two methods using vertebral centra was -0.158 ±0.05 and the coefficient of variance (CV) was 92.32% for females and -0.157 ±0.03 and CV was 56.95% for males. This indicated that sectioned vertebral centra returned higher ages than whole vertebral centra. When comparing whole dorsal spine age estimates to sectioned dorsal spines, there was an average bias between methods of -0.22 ±0.026 and a low precision 73.09%. Again indicating that sectioned dorsal spines returned higher ages than whole dorsal spines. A comparison of ages estimated from sectioned vertebral centra and sectioned dorsal spines showed that vertebral centra aged older than dorsal spines. Although the two structures each had low reading bias and high reading precision, there were differences between the two structures. The average bias between the two structures was -0.4 ±0.03 and the CV was low (74.7%), indicating that there was a significant difference in age derived from the two structures. Therefore, great caution should be taken when choosing which structure to use for age estimation. Ages of sharks estimated from the recommended sectioned vertebral centra ranged from 0.2 to 32.5 years for females and 0.2 to 23.8 years for males. Four different growth models were compared using both sectioned vertebral centra and sectioned dorsal spines to estimate the best suitable growth curve. Out of the 4 growth models the Gompertz Growth Function (GGF) best described the growth of H. portusjacksoni. von Bertalanffy growth parameters estimated from ageing data using the GGF for females were t0 = 2.584 yr, k = 0.111, L∞ = 1134.1 mm FL, and for males t0 = 1.629 yr, k = 0.131, L∞ = 1012.9 mm FL. This indicates that H. portusjacksoni has a slow growth rate and a longer life span than most other elasmobranch species. The effect of reader’s experience on the bias and precision of age estimates of sectioned vertebral centra was determined in an experiment that compared the author (an experienced vertebral centra reader) with an experienced fish otolith reader, two readers recently trained in reading vertebral centra (but lacking experience), and two untrained and inexperienced readers. Bias and precision were determined for each reader from two ageing trials with the same structure three months apart. Between-trials bias for each reader (except the author)ranged from 0.033 to 0.13 and precision ranged from 8.2 to 19.5%, while the author had low bias 0.006 and high precision 1.1%. When comparing all the readers with the author, bias ranged from 0.033 to 0.13 with an 8.2 to 19.5% precision for trial one, and 0.017 to 0.5 with precision between 2.5 to 5.4% in trial two. The age-bias plots comparing the two trials all indicated that only the author was consistent. And the age-bias plots between the author and the other readers all indicated that neither experience in ageing teleost otoliths or limited training in ageing enhanced the bias or precision compared to inexperienced elasmobranch agers.

Research Doctorate - Doctor of Philosophy (PhD) / World shark populations are declining rapidly from the increased demand for shark meat and fins and from their capture as by-catch. Techniques to accurately and reliably estimate the age of elasmobranchs are required to understand life history and develop management strategies. Although some biological information exists for the harvested species, few of the many shark species caught as by-catch have been investigated. In the waters of New South Wales, Australia, the Port Jackson shark (Heterodontus portusjacksoni) is a non-targeted species, however it is a major contributor to the elasmobranch by-catch in the bottom trawl and prawn fisheries. Although some biological and ecological information exists on Port Jackson sharks from New South Wales, there is no understanding of suitable techniques to age this species and of the age structure of the New South Wales’ population. Hence, the main purpose for the present study was to determine a suitable technique to age Port Jackson sharks and thereby provide essential age and growth data for its future management, sustainable use and conservation. This study consisted of research into: (1) the macroscopic anatomy of the vertebral centra and dorsal spines from 652 H. portusjacksoni to explore their suitability as ageing structures; (2) a comparison of whole and sectioned vertebral centra and of whole and sectioned dorsal spines for ageing; (3) validation of the annual formation of growth bands; (4) a comparison of the effect of prior experience on readers’ ability to count annual growth bands in vertebral centra; and (5) the development of age-growth models for the New South Wales’ population of H. portusjacksoni. Two types of vertebral centra (trunk and caudal vertebrae) were found in the vertebral column. Both vertebrae consisted of a centrum, 2 ribs, 4 neural arches, basiopophyses and neural foramen and decreased in size from anterior to posterior. A strong linear relationship was identified between vertebral diameter (VD) and fork length (FL). Each dorsal spine was positioned anterior to the dorsal fin and consisted of a stem and the cap. A strong linear relationships were identified between spine base width (SBW) and FL. The existence of alternating opaque and translucent band pairs in both structures further suggested they may be suitable for ageing purposes. Validation (calcein and oxytetracycline injections, marginal increment analysis, and centrum edge analysis) confirmed that translucent band pairs were formed during the winter (September-November) and were annual in both vertebral centra and dorsal spines. Whole and sectioned vertebral centra and dorsal spines were individually examined to determine which method best estimated the age. Although both methods had individual low reading bias and high precision, there was a difference between the two methods. The average bias between the two methods using vertebral centra was -0.158 ±0.05 and the coefficient of variance (CV) was 92.32% for females and -0.157 ±0.03 and CV was 56.95% for males. This indicated that sectioned vertebral centra returned higher ages than whole vertebral centra. When comparing whole dorsal spine age estimates to sectioned dorsal spines, there was an average bias between methods of -0.22 ±0.026 and a low precision 73.09%. Again indicating that sectioned dorsal spines returned higher ages than whole dorsal spines. A comparison of ages estimated from sectioned vertebral centra and sectioned dorsal spines showed that vertebral centra aged older than dorsal spines. Although the two structures each had low reading bias and high reading precision, there were differences between the two structures. The average bias between the two structures was -0.4 ±0.03 and the CV was low (74.7%), indicating that there was a significant difference in age derived from the two structures. Therefore, great caution should be taken when choosing which structure to use for age estimation. Ages of sharks estimated from the recommended sectioned vertebral centra ranged from 0.2 to 32.5 years for females and 0.2 to 23.8 years for males. Four different growth models were compared using both sectioned vertebral centra and sectioned dorsal spines to estimate the best suitable growth curve. Out of the 4 growth models the Gompertz Growth Function (GGF) best described the growth of H. portusjacksoni. von Bertalanffy growth parameters estimated from ageing data using the GGF for females were t0 = 2.584 yr, k = 0.111, L∞ = 1134.1 mm FL, and for males t0 = 1.629 yr, k = 0.131, L∞ = 1012.9 mm FL. This indicates that H. portusjacksoni has a slow growth rate and a longer life span than most other elasmobranch species. The effect of reader’s experience on the bias and precision of age estimates of sectioned vertebral centra was determined in an experiment that compared the author (an experienced vertebral centra reader) with an experienced fish otolith reader, two readers recently trained in reading vertebral centra (but lacking experience), and two untrained and inexperienced readers. Bias and precision were determined for each reader from two ageing trials with the same structure three months apart. Between-trials bias for each reader (except the author)ranged from 0.033 to 0.13 and precision ranged from 8.2 to 19.5%, while the author had low bias 0.006 and high precision 1.1%. When comparing all the readers with the author, bias ranged from 0.033 to 0.13 with an 8.2 to 19.5% precision for trial one, and 0.017 to 0.5 with precision between 2.5 to 5.4% in trial two. The age-bias plots comparing the two trials all indicated that only the author was consistent. And the age-bias plots between the author and the other readers all indicated that neither experience in ageing teleost otoliths or limited training in ageing enhanced the bias or precision compared to inexperienced elasmobranch agers.

Thesis (M.S.)--Michigan State University. Dept. of Geological Sciences, 2008. / Title from PDF t.p. (viewed on Aug. 5, 2009) Includes bibliographical references (p. 76-78). Also issued in print.

published_or_final_version / Zoology / Master / Master of Science

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.