Submitted by (edna.saturno@ufrpe.br) on 2017-02-20T13:40:05Z No. of bitstreams: 1 Rodrigo Risi Pereira Barreto.pdf: 2720946 bytes, checksum: f60d89c3648bb992cd8d11c36c037cd5 (MD5) / Made available in DSpace on 2017-02-20T13:40:05Z (GMT). No. of bitstreams: 1 Rodrigo Risi Pereira Barreto.pdf: 2720946 bytes, checksum: f60d89c3648bb992cd8d11c36c037cd5 (MD5) Previous issue date: 2009-05-01 / Between 1994 and 2008, 369 blacknose sharks, Carcharhinus acronotus (43,5-146 cm total length, TL) were collected from gill nets and surveys carried out on Pernambuco’s continental shelf, Brazil (07° 15’ 45’’ S and 09° 28’ 18’’ S). Vertebral sections of 109 males (43,5-124 cm TL) and 141 females (46-146 cm TL) were analyzed; the index of average percentage of error (IAPE) ranged from 1:17 to 13:33% (mean 6,13%) in vertebrae displaying between 0 to 15 growth rings (GR). The marginal increment relative analysis (MIR) was not conclusive showing only a tendency of ring deposition between autumn and winter months. Significant differences were not found between the individual length (TL, cm) and the vertebra radius (VR, mm). Growth parameters were derived using von Bertalanffy function (VBGF a), von Bertalanffy modified (VBGF b), Gompertz and Schnute models. The von Bertalanffy growth model was that which best represented growth for the species. Parameters estimated for both sexes were: k = 0.12, t0 = -3.66, L¥= 142.06 cm. Male and female maturity was reached at 105 cm TL, presenting about 5 growth rings (GR's). The largest specimen whose age was observed had 15 growth rings (132 cm TL). Adults were only caught in longlines. Mortality was estimated from the biological information of the species according literarature. Mortality values obtained were: M = 0,275; Z = 0,709 (gillnets), 0,31 (longline); F = 0,43 (gillnets) 0,04 (longline) Z0 = 0,06 and Z' = 0,349. The Exploitation rates calculated for gillnets were 0,61 and 0,130 respectively. Considering a scenario of equilibrium, the population would increase by approximately 8,3% per 8,5 years (R0 = 1,971; G = 8,43; r = 0,080). However, taking into account the current level of exploitation, the population appears to be over-exploited, decreasing 13,6% in 8,3 years (R0 = 0,3; G = 8,3; r = -0,041). / Entre 1994 e 2008, foram capturados 369 indivíduos de Carcharhinus acronotus (43,5-146 cm de comprimento total, CT) oriundos da pesca com redes de emalhar e prospecções na plataforma continental do estado de Pernambuco, Brasil (07° 15’ 45’’ S e 09° 28’ 18’’ S). Secções vertebrais de 109 machos (43,5-124 cm CT) e 141 fêmeas (46-146 cm CT) foram analisadas. O índice do erro médio (IAPE) variou entre 1,17 a 13,33 % (média 6,13 %) entre 0-15 anéis etários. A análise de incremento marginal relativo (MIR) não foi conclusiva embora tenha apresentado uma tendência de formação do anel entre os meses do outono e inverno. Não foram detectadas diferenças significativas entre o comprimento individual (CT, cm) e o raio da vértebra (RV). Os parâmetros de crescimento foram estimados através da utilização dos modelos de von Bertalanffy (VBGF a), von Bertalanffy modificado, (VBGF b) Gompertz e Schnute. O modelo de von Bertalanffy foi o que melhor representou o crescimento para a espécie. Os parâmetros obtidos para os comprimentos observados para os sexos agrupados foram: L = 142,06 cm CT, k = 0,12, t0 = -3,66. Não foram detectadas diferenças significativas entre as curvas de crescimento para os sexos (p > 0,05). Machos e fêmeas maturam em torno dos 105 cm CT quando apresentam 5 anéis etários. O maior espécime cuja idade foi estimada foi uma fêmea que apresentou 15 anéis (132 cm CT). Adultos foram capturados somente no espinhel. As taxas de mortalidades foram determinadas a partir das informações disponíveis na literatura e dos parâmetros de crescimento obtidos. Os valores estimados por esses métodos indiretos foram: M = 0,275; Z = 0,709 (emalhe), 0,310 (espinhel), F = 0, 434 (emalhe) e 0, 044 (espinhel); Z0 = 0, 063 e Z’ = 0, 349. As taxas de exploração calculadas para o emalhe e o espinhel foram 0,61 e 0,130 respectivamente. Em cenário de equilíbrio a população teria condições de aumentar em aproximadamente 8,3 % a cada 8,5 anos (R0 =1, 971 G = 8,43; r = 0, 080). No entanto, considerando o nível de pesca atual, a população se apresenta sobre-explorada, diminuindo em 13,6 % a cada 8,3 anos (R0 =0,3 G = 8,23; r = -0, 041).

Submitted by (edna.saturno@ufrpe.br) on 2017-02-13T12:40:28Z No. of bitstreams: 1 Fernanda de Oliveira Lana.pdf: 2191655 bytes, checksum: 1c0fe338043dce8d998d515ebec30b36 (MD5) / Made available in DSpace on 2017-02-13T12:40:28Z (GMT). No. of bitstreams: 1 Fernanda de Oliveira Lana.pdf: 2191655 bytes, checksum: 1c0fe338043dce8d998d515ebec30b36 (MD5) Previous issue date: 2012-02-13 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The silky shark, Carcharhinus falciformis, is an abundant species in tropical and equatorial waters of the pelagic zone. The present work aimed at studying the ecology of the silky shark, including aspects of its reproduction, relative abundance, distribution, habitat use and migration on the Equatorial Atlantic Ocean. From November 1992 to December 2011, 153 specimens were examined, 72 males and 81 females, resulting in a sex ratio close to 1:1 (0.89:1.00). All specimens were caught by commercial tuna longline boats, in the area located between 08°N to 53°S latitude and 08°E to 48°W longitude. The results suggest a size at first maturity for females around 205- 210 cm and for males between 180- 200 cm TL. Females were found in 5 maturational stages: juvenile (n = 29/ 35.8% from 74 to 204 cm, TL), maturing (n = 10 / 12.3%, from 215 to 295 cm TL), pre- ovulatory (n = 14 / 17.3%, 177 to 280 cm TL), pregnant (n = 24 / 29.6%, 203 to 270 cm TL) and resting (n = 4 / 4.9%, from 223 to 285 cm TL). Males were classified into 4 stages: juvenile (n = 38/ 52.8% from 81 to 220 cm TL and clasper length - CL <12 cm), maturing (n = 16/ 22.2%, from 166 to 208 TL cm, 9.5 to 24.5 cm CL;), adult (n = 17/ 23.6%, from 141 to 272 cm TL, CL> 24.5 cm) and neonate (n = 1/ 1.4%, 82 cm TL, CL 4 cm). Catch and effort data from 16.016 sets made by Brazilian tuna longliners, from 2004 to 2011, were analyzed. The CPUE was calculated and the catch and effort data were grouped in squares of 5° x 5° latitude and longitude. Two silky sharks were tagged with satellite transmitters PSAT (Pop-up Satellite Archival Tag), in the vicinity of Archipelago of Saint Peter and Saint Paul – ASPSP, but from only one it was possible to recover the data. The preferred temperature range of the tagged animal was between 27 and 28°C with a preferred depth between 1 and 10m. / O tubarão lombo-preto, Carcharhinus falciformis, é uma espécie abundante na zona pelágica, com distribuição em águas tropicais e equatoriais de todos os oceanos do mundo. O presente trabalho teve por objetivo estudar a ecologia do tubarão lombo-preto, incluindo aspectos da sua reprodução, abundância relativa, distribuição, uso do habitat e padrões de migração, na margem ocidental do Oceano Atlântico Equatorial. No período de novembro de 1992 a dezembro de 2011, foram examinados 153 exemplares, 72 machos e 81 fêmeas, resultando uma proporção sexual próxima de 1:1 (0,89:1,00). Todos os espécimens foram capturados por barcos da frota comercial atuneira, que realizaram pescarias com espinhel pelágico, na área localizada entre as latitudes de 08°N e 53°S e longitudes de 08°E e 48°W. Os resultados obtidos sugerem um tamanho de primeira maturação sexual para as fêmeas em torno de 205- 210 cm, e para os machos entre 180- 200 cm de comprimento total (CT). As fêmeas se encontravam em 5 estágios maturacionais: juvenil (n= 29; 35,8%; 74 a 204 cm de CT), em maturação (n= 10; 12,3%; 220 a 295 cm CT), pré-ovulatória (n= 14; 17,3%; 177 a 280cm CT), grávida (n= 24; 29,6%; 203 a 270cm CT); e em repouso (n= 4; 4,9%; 223 a 285 cm CT). Os machos foram classificados em 4 estágios: juvenil (n= 38; 52,8%; 81 a 220 cm CT e Comprimento do Clásper CC < 12 cm), em maturação (n= 16; 22,2%; 166 a 208 cm CT, 9,5 a 24,5 cm CC), Adulto (n= 17; 23,6%; 141 a 272 cm CT; CC > 24,5 cm) e neonato (n= 1; 1,4%; 82 cm CT; 4 cm CC). Foram analisados dados de captura e esforço de pesca de 16.016 lançamentos com espinhel pelágico de deriva, realizados pela frota brasileira atuneira, de 2004 a 2011. A CPUE foi calculada e os dados de captura e esforço foram agrupados em quadrados de 5° x 5° de latitude e longitude. Dois tubarões lombo-preto foram marcados com transmissores via satélite do tipo PSAT (Pop-up Satellite Archival Tag), nas imediações do Arquipélago de São Pedro e São Paulo- ASPSP, mas apenas em um deles foi possível a recuperação dos dados. A faixa de temperatura preferencial do animal marcado se situou entre 27 e 28°C, com uma profundidade preferencial entre 1 e 10m.

The oceanic whitetip shark, Carcharhinus longimanus, is a circumtropical pelagic shark of high conservation concern (IUCN Red List: “Critically Endangered” in the Western North and Western Central Atlantic and “Vulnerable” globally). I present the first, population genetic assessment of the oceanic whitetip shark on a global scale, based on analysis of two mitochondrial genome regions (entire 1066-1067 bp control region and 784 bp partial ND4 gene), and nine nuclear microsatellite loci. No population structure was detected within the Western Atlantic. However, highly significant population structure was detected between Western Atlantic and Indo-Pacific Ocean sharks across all markers. Additionally, a nominally significant signal of matrilineal structure between the Indian and Pacific Ocean sharks was detected by AMOVA and pairwise tests of the ND4 gene only (pairwise ΦST = 0.051, P = 0.046; pairwise Jost’s D = 0.311, 95% CI = 0.020, 0.0614). Although significant inter-basin population structure was evident, it was associated with deep phylogeographic mixing of mitochondrial haplotypes and evidence of contemporary migration between the Western Atlantic and Indo-Pacific Oceans. I theorize that semi-permeable thermal barriers are responsible for the differentiation between the Western Atlantic and Indo-Pacific set in a framework of global phylogeographic mixing. Relatively low mtDNA genetic diversity (concatenated mtCR-ND4 nucleotide diversity π = 0.32% ± 0.17%) compared to other circumtropical elasmobranch species raises potential concern for the future genetic health of this species. Overall, significant population structure exists, at a minimum, between the Western Atlantic and Indo-Pacific Ocean, and effective management strategies must take this into consideration.

Neuroethology and ecomorphology seek to understand ecology and behaviour from the perspective of specialised adaptations of sensory systems, such as vision. Sharks display a large variety of visual specialisations reflecting the diversity of different ecological niches they occupy. Many shark species are long-lived and wide ranging and often select different habitats for reproduction, growth, and feeding. Habitat complexity, ambient lighting conditions and feeding strategies can therefore change throughout a shark’s lifetime or between populations. Few comprehensive investigations of visual function exist for sharks as studies typically focus on a narrow aspect of visual function or a particular life history stage. Consequently, there is limited data on within-species plasticity of visual function in response to acclimation to different visual environments or ontogenetic development. The aim of this thesis is to undertake a functional analysis of the shark visual system. An integrated approach is employed to investigate optical, anatomical and physiological specialisations, linking such specialisations to known habitat and/or behavioural traits, with particular emphasis on ontogenetic, inter-population and inter-specific variability. Fundamental capabilities of the visual system are examined, including optical quality, eye morphology, spectral range, irradiance sensitivity, spatial and temporal resolution, contrast discrimination, and temporal and spatial summation. The main study species is the sandbar shark (<i>Carcharhinis plumbeus</i>; Carcharhinidae), a cosmopolitan species of ecological and economic importance. <i>C. plumbeus</i> occupies a wide range of natural habitats from highly turbid coastal estuaries, to relatively clear waters off the outer continental shelves and near pristine clear waters over the slopes of oceanic islands. This provides an opportunity to explore the relationship between habitat variability and the adaptation of visual specialisations and subsequent behaviour. For inter-specific comparison, the visual systems of two other species of shark with contrasting ecological niches are also assessed: the shortspine spurdog (<i>Squalus mitsukurii</i>; Squalidae) and the tiger shark (<i>Galeocerdo cuvier</i>; Carcharhinidae). The study finds marked differences in visual specialisations of the three species studied. The eyes of <i>S. mitsukurii</i> are adapted to enhance retinal illumination within a dim light environment with a large eye, immobile pupil, reflective tapetum and a relatively high optical sensitivity (2.72 μm² steradians). Visual features include a short wavelength lenticular filter, a high spatial resolving power (7.2 cycles/degree) and a large binocular overlap in the dorsal visual field, suggesting adaptations may facilitate the visualisation of bioluminescent prey. In contrast, the eyes of <i>C. plumbeus</i> are optimised for vision under variable light conditions with a mobile pupil and an occlusible tapetum. The sandbar shark shows an optical sensitivity of 1.11 μm² steradians. Visual resolution is highest in the lateral visual field, reaching a peak spatial resolution of 8.9 cycles/degree. An ERG derived spectral response curve for this species indicates maximal response to blue light between 460-490 nm. Interestingly, the tiger shark is maximally sensitive to a brighter range of light intensities compared to sandbar sharks, implying that tiger sharks occupy a more photopic light environment. However, sandbar sharks have a visual system with higher temporal resolution, as evaluated by the ERG response, (54 Hz) than tiger sharks (38 Hz). These results may reflect a difference in the importance of motion perception between <i>C. plumbeus</i> and <i>G. cuvier</i>. Phenotypic variability in visual function is shown between different populations of <i>C. plumbeus</i> occupying habitats with different ambient light conditions. This study provides new evidence of plasticity of visual function in response to acclimation to different visual environments within the same species. Sandbar sharks show an adaptive plasticity in visual sensitivity and temporal resolution, which appears to enable both temporal and population-specific adaptations to local light environments. In addition, the eyes of <i>C. plumbeus</i> and <i>S. mitsukurii</i> continue to grow even in adulthood. Visual performance, with respect to spatial resolving power and optical sensitivity, improve with eye growth. For example, peak spatial resolution increases with eye growth from 4.3 to 8.9 cycles/degree in <i>C. plumbeus</i> and from 5.7 to 7.2 cycles/degree in <i>S. mitsukurii</i>. These studies suggest that the light environment strongly influences visual function in this ancient class of vertebrates. Anthropogenically induced changes in water clarity may, therefore, impact on visually-mediated behaviours such as prey detection, agonistic signals or vertical migration. Anatomical and physiological parameters obtained from these studies provide a platform from which to model visual behaviours such as 1). Prey detection capabilities, 2). The impacts of water clarity on the limits of visually-mediated behaviour, and 3). The visual strategies that would allow sharks to maximise visual function, such as spatial and temporal summation under low light conditions. In conclusion, neuroethological studies can be a useful means to enrich information obtained from life-history and tagging studies and, together, can inform us of the functional role of sharks in marine ecosystems.

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.