Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-31Bitstream added on 2014-06-13T19:46:41Z : No. of bitstreams: 1 motta_fs_dr_rcla.pdf: 2587305 bytes, checksum: 0ff789362fdf8eb0461ea7ed5c963eeb (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / No âmbito de um estudo sobre a ecologia e a pesca de tubarões costeiros no litoral centro-sul de São Paulo, foram feitas amostragens semanais junto aos desembarques da frota artesanal sediada na Praia dos Pescadores, no município de Itanhaém. Os barcos operam a uma distância de 2 a 12 milhas náuticas (20 km) da costa, em profundidades de 5 a 30 m, utilizando redes de emalhe. Entre julho de 1996 e dezembro de 2003, foram examinados 14730 exemplares, compreendendo sete famílias, nove gêneros e 18 espécies. A acumulação de espécies em função do número de amostragens apresentou tendência de estabilização a partir de 90 amostragens. Em geral, a diversidade foi menor no outono-inverno e maior na primavera-verão. A captura por unidade de esforço (CPUE) dos tubarões apresentou picos nos meses de início (janeiro e fevereiro), meio (julho e agosto) e final de ano (novembro e dezembro). Essas flutuações estiveram associadas aos padrões de recrutamento, distribuição e ocorrência das espécies mais abundantes. Cinco espécies de Carcharhiniformes utilizam o litoral centro-sul de São Paulo como área de berçário entre o inverno e verão. O tempo de permanência dos neonatos e jovens na área de estudo esteve inversamente relacionado com o tamanho de nascimento das espécies, indicando maior dependência dos filhotes menores por águas mais rasas e, supostamente mais protegidas de predadores. Foi observada uma assincronia seqüencial na atividade de parto das espécies, sugerindo que o estabelecimento de berçários coletivos aumenta as chances de competição e predação entre os filhotes. Pressões seletivas neste sentido parecem levar ao desenvolvimento de táticas reprodutivas que amenizam esses efeitos, reduzindo a mortalidade natural dos filhotes durante os primeiros meses de vida. / Ecological aspects of the coastal sharks caught by artisanal fisheries from southeastern Brazil were studied between July 1996 and December 2003. The fishing fleet comprised 12 small motorized boats (4 - 10 m long), using monofilament gill nets with 1500 m length and stretched mesh sizes of 7, 12 and 14 cm on average. The nets are set within an area of 2 - 12 nautical miles from the shore, in waters between 5 and 30 m deep. During the study period, 14730 sharks of seven families, nine genera and 18 species were examined. In general, diversity was highest in spring-summer and lowest in autumn-winter. Catch per unit of effort (CPUE) showed peak in outset (Jan-Feb), middle (Jul- Aug) and, end (Nov-Dec) of the years. Both diversity and CPUE fluctuations were associated with recruitment, distribution and occurrence of the five most abundant species (Rhizoprionodon lalandii, R. porosus, Sphyrna lewini, Carcharhinus brevipinna and C. limbatus), that represented 96% of the total catch. These species use the study area as nursery between winter and summer with a sequence of parturition progressing from the smallest (R. lalandii, 35 cm birth size) to the largest species (C. limbatus, 70 cm birth size). Such pattern was associated with reproductive tactics that may minimize both inter-specific predation and competition among newborns, thereby reducing natural mortality during their first few months of life.

Made available in DSpace on 2014-06-11T19:35:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-01-06Bitstream added on 2014-06-13T19:05:57Z : No. of bitstreams: 1 garla_rc_dr_rcla.pdf: 1566045 bytes, checksum: 33a6e91849d61d578c9d020171e589af (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O presente trabalho visa gerar informações básicas sobre a ecologia e a situação populacional do tubarão-cabeça-de-cesto Carcharhinus perezi, lambarú Ginglymostoma cirratum e tubarão-limão Negaprion brevirostris no Arquipélago de Fernando de Noronha, com ênfase na primeira, por ser numericamente dominante. Utilizou-se a combinação de técnicas de marcação e recaptura e de telemetria ultra-sônica para fornecer informações sobre: estrutura populacional, distribuição espacial dos tubarões e de suas áreas de berçário, época de parto, padrões de movimentação e de utilização do hábitat. Amostras de sangue foram analisadas para caracterização sorológica das espécies. Foi implantado um programa de conscientização e educação sobre a necessidade de conservação dos tubarões, e realizou-se um curso de capacitação em Educação Ambiental para os professores do ensino médio e fundamental. A plataforma insular do arquipélago é utilizada como área de parto e de crescimento de jovens pelas três espécies de tubarões. Carcharhinus perezi apresenta maior segregação espacial por tamanho. Não ocorre segregação espacial em Ginglymostoma cirratum e Negaprion brevirostris pois foram observados indivíduos neonatos, jovens e adultos freqüentando a região próxima à linha costeira do arquipélago. Os tubarões utilizam com menor freqüência o trecho da Área de Proteção Ambiental (APA) do arquipélago, o que possivelmente está relacionado à intensificação da utilização humana e a indícios de empobrecimento biológico da região nos últimos anos. O monitoramento por telemetria mostra que: os tubarões jovens são residentes em trechos específicos do arquipélago; eles podem ser ativos a qualquer horário do dia, mas os maiores espaços de atividade e deslocamentos ocorrem à noite; aparentemente não existem variações sazonais... / The aim of the present study is to provide basic data on the ecology and population status of the reef-shark Carcharhinus perezi, nurse-shark Ginglymostoma cirratum and lemon-shark Negaprion brevirostris at Fernando de Noronha archipelago, with special reference to Carcharhinus perezi, due to its numerical dominance. A combination of mark and recapture and ultrasonic telemetry methods were used to gather data on: the population structure, spatial distribution of the sharks, location of the nursery grounds, parturition time, patterns of movement and habitat use. Blood samples were analyzed for a serological characterization of the species. An educational program was established to increase the community awareness about shark conservation, and a capacitating course on Environmental Education was offered to teachers of the local school. The archipelago s insular shelf is used as a parturition and growing ground for young sharks of the three species. Carcharhinus perezi shows size segregation. Size segregation was not observed in Ginglymostoma cirratum and Negaprion brevirostris, and neonate, young and adult sharks of these species were observed to frequent shallow waters of the archipelago. Sharks rarely frequent the archipelago s Environmental Protection Area (EPA), which is probably related to an intensification of human use and evidences of biological impoverishment of this site in recent years. The telemetry monitoring shows that: the young sharks are resident and present site fidelity to specific portions of the archipelago; they may be active at any time of the day, but the larger activity spaces and excursions occur at night; apparently there is no seasonal variation in activity spaces and habitat use; and larger sharks have more extensive activity spaces. The main problems for the management and conservation of the sharks are:... (Complete abstract click electronic access below)

The southeastern coast of South Africa is deemed unpolluted and with the exception of a few localized areas, is believed to be pristine. This study aimed to (1) assess the concentration of metals in the water and sharks (Squalus megalops, Mustelus mustelus) from different sites along the southeastern coast, (2) determine the effects that metals have on each other and investigate the accumulation and storage of metals in different shark tissues, (3) determine the effects of length and sex on metal concentration and the presence of metallothioneins in the liver. Metal concentrations in water from seven sites along the southeastern coast revealed concentrations below the detection limit of the extraction method, except for iron at St. Francis Bay which was below the recommended levels as supplied by DWAF. Met al concentrations in S. megalops from the seven sites revealed significantly elevated levels in individuals from Algoa and St. Francis Bay when compared to the other 5 sites. This was observed for all metals except manganese, which had a higher concentration at Cape Agulhas. After comparing the metal levels in muscle tissue (S. megalops) with data from the Department of Health it was concluded that the sharks caught at Algoa and St. Francis Bay were unsuited for human consumption. Liver and vertebral tissues from both S. megalops and M. mustelus were deemed unsuited for human consumption but further research should be conducted especially on vertebral metal concentrations. Comparing the metal concentration in different tissue types of S. megalops and M. mustelus significant difference were observed and attributed to differences in the maturity (thus age) of the two species. Significant differences in the metal concentration of males and females for both the species were observed. A higher number of differences were however observed in M. mustelus than in S. megalops, most probably due to the differences in maturity. Length and weight vs. metal concentration regressions in the males and females of both species revealed more negative than positive trends. This was found to be in accordance with other studies from around the world. Using the life stages of S. megalops, significant differences in the average concentration of metals were observed between the life stages, with embryos usually having the highest concentration. The metal concentration series determined for S. megalops were similar to that which have been reported in the literature in that iron and zinc occupied the highest concentration positions while cadmium, copper and manganese occupied the last three. The spleen usually had the highest metal concentration except for aluminium in skin and arsenic in muscle tissue. Pearson correlation revealed significant negative correlations between cadmium and the mentioned metals suggesting that cadmium replaces essential metals such as manganese, iron and copper as. Negative correlations between essential metals were observed most probably due to the competition for binding positions on ligands. Positive correlations were observed between metals in sp ecific tissue types and may be indicative of synergistic effects, e.g. aluminium may result in the accumulation of other metals such as cadmium. Positive and negative correlations between a specific metal and different tissue types have also been observed and it appears that there are movement of metals between tissue types. Positive correlation for essential metals between yolk and other tissue have been observed, although no correlations for non-essential metals were observed. This could potentially indicate a mechanism that prevents the accumulation of nonessential metals in embryos. Though no metallothioneins were isolated form the liver, the presence of cadmium in other proteins indicate that that cadmium is substituted for essential metals, and as this may result in deleterious physiological effects, further studies should be conducted. In conclusion it can be said that although some of the results were expected there are still quite a few unanswered question and further studies should be conducted.

The southeastern coast of South Africa is deemed unpolluted and with the exception of a few localized areas, is believed to be pristine. This study aimed to (1) assess the concentration of metals in the water and sharks (Squalus megalops, Mustelus mustelus) from different sites along the southeastern coast, (2) determine the effects that metals have on each other and investigate the accumulation and storage of metals in different shark tissues, (3) determine the effects of length and sex on metal concentration and the presence of metallothioneins in the liver. Metal concentrations in water from seven sites along the southeastern coast revealed concentrations below the detection limit of the extraction method, except for iron at St. Francis Bay which was below the recommended levels as supplied by DWAF. Met al concentrations in S. megalops from the seven sites revealed significantly elevated levels in individuals from Algoa and St. Francis Bay when compared to the other 5 sites. This was observed for all metals except manganese, which had a higher concentration at Cape Agulhas. After comparing the metal levels in muscle tissue (S. megalops) with data from the Department of Health it was concluded that the sharks caught at Algoa and St. Francis Bay were unsuited for human consumption. Liver and vertebral tissues from both S. megalops and M. mustelus were deemed unsuited for human consumption but further research should be conducted especially on vertebral metal concentrations. Comparing the metal concentration in different tissue types of S. megalops and M. mustelus significant difference were observed and attributed to differences in the maturity (thus age) of the two species. Significant differences in the metal concentration of males and females for both the species were observed. A higher number of differences were however observed in M. mustelus than in S. megalops, most probably due to the differences in maturity. Length and weight vs. metal concentration regressions in the males and females of both species revealed more negative than positive trends. This was found to be in accordance with other studies from around the world. Using the life stages of S. megalops, significant differences in the average concentration of metals were observed between the life stages, with embryos usually having the highest concentration. The metal concentration series determined for S. megalops were similar to that which have been reported in the literature in that iron and zinc occupied the highest concentration positions while cadmium, copper and manganese occupied the last three. The spleen usually had the highest metal concentration except for aluminium in skin and arsenic in muscle tissue. Pearson correlation revealed significant negative correlations between cadmium and the mentioned metals suggesting that cadmium replaces essential metals such as manganese, iron and copper as. Negative correlations between essential metals were observed most probably due to the competition for binding positions on ligands. Positive correlations were observed between metals in sp ecific tissue types and may be indicative of synergistic effects, e.g. aluminium may result in the accumulation of other metals such as cadmium. Positive and negative correlations between a specific metal and different tissue types have also been observed and it appears that there are movement of metals between tissue types. Positive correlation for essential metals between yolk and other tissue have been observed, although no correlations for non-essential metals were observed. This could potentially indicate a mechanism that prevents the accumulation of nonessential metals in embryos. Though no metallothioneins were isolated form the liver, the presence of cadmium in other proteins indicate that that cadmium is substituted for essential metals, and as this may result in deleterious physiological effects, further studies should be conducted. In conclusion it can be said that although some of the results were expected there are still quite a few unanswered question and further studies should be conducted.

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.

Recent research confirmed white shark (Carcharodon carcharias) nursery habitat off Long Island, New York; however, additional research is required to determine the habitat use and fine-scale movements of young-of-the-year and juvenile white sharks within this nursery. Between 2016 and 2019, twenty-five white sharks were fitted with satellite and acoustic tags to better define habitat use. Individuals exhibited horizontal movements parallel to Long Island’s southern shoreline and coastal New Jersey. Log-likelihood chi-square analyses determined preference for water column depth, SSTs, sea surface salinities, and chlorophyll a concentration. Vertical analysis of diving behavior revealed swimming behavior primarily in the upper 20 m of the water column, in temperatures between 18°C and 20°C. Generalized additive mixed modeling suggested SSTs above 20.5°C affected dive depth. These results can help improve characterization of essential fish habitat for young white sharks and provide data to determine the species’ susceptibility to anthropogenic activities. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Cleaning symbioses are a well-studied mutualism among marine species. However, the interactions occurring between cleaner fish and sharks are lacking in research, which makes it a target for further investigation. With this study, intentions were to analyse the behaviour of two kinds of cleaner species, bluestreak cleaner wrasse (Labroides dimidiatus) and moon wrasse (Thalassoma lunare), to be able to distinguish differences in cleaning behaviour on pelagic thresher sharks (Alopias pelagicus). A total of 68,4 hours of video was recorded on the edge of a seamount outside of Malapascua, called Monad Shoal, during 18 days in January 2018. The number of interactions were divided into two categories, where the behaviour was classified as an inspection or a bite and could occur on different patches of the sharks’ body (head, gills, body, dorsal, pectoral, pelvic or caudal fin). In total 118 events occurred which comprised in total 4079 interactions from the two cleaner species. Of these interactions 3626 were considered inspections and 453 were bites. Bluestreak cleaner wrasse conducted 3598 of the inspections and 28 of the inspections were conducted by the moon wrasse. All bites were conducted by bluestreak cleaner wrasses. The results indicated a preference in patches of the body to inspect, where the pelvis got the most inspections on 34,1 %, followed by the pectoral fins on 22,8 %. The dorsal fin and the gills accounted for the least number of bites, with 1,3 % on the dorsal and 1,4 % on the gills. Furthermore, a difference in inspected patches between males and females were discovered, where females got significantly more inspections on their head, gills, body, dorsal and pectoral fin. The pelvis and caudal fin did not show any significant differences.

In a recent global study of whale shark population genetics, aggregations were found to belong to either the Indo-Pacific or Atlantic population. This overview included an aggregation found within the Red Sea near Al Lith, Saudi Arabia, however the Mafia Island, Tanzania, aggregation was not part of the study. Both aggregations have unique aspects with the Saudi Arabian individuals showing sexual parity with no segregation, while recent acoustic results have revealed cryptic residency at Mafia Island. Genetic analysis using 11 microsatellite markers was performed on whale sharks from both locations. A combination of primers sourced from previous studies and newly designed primers were used to compare both aggregations and the individuals within. Samples were collected in the Red Sea for 5 seasons spanning 6 years, and for 2 seasons in Tanzania. Analysis with STRUCTURE showed a lack of significant genetic differences between the two aggregations, confirming that whale sharks in Tanzania are part of the Indo-Pacific population. Kinship analysis using COLONY found two potential pairs of full siblings in Tanzania. One pair had a high probability (.993) of being a full sibling dyad while the other had a lower probability (.357). There were no sibling pairs identified from the Red Sea aggregation. Genetic diversity was investigated using allelic richness over the 6 seasons at Al Lith, with values showing no significant change. This is in contrast to results that showed a decline in genetic diversity at Western Australia’s Ningaloo reef. These differences, however, only highlight the need for genetic diversity studies over longer time periods and at other aggregations within the Indo-Pacific.

No description available.