Farmed Southern Bluefin Tuna (SBT) (Thunnus maccoyii) is an important export product for South Australia (SA). It is exported to Japan, China, Korea and the United States for the sushi and sashimi markets. The primary purpose of SBT farming in SA is to fatten wild-caught juvenile fish (2-4 years of age with initial mean weights between 12-20 kg) over a period of approximately five months by feeding a selection of baitfish types. Farmers, farm managers and consumers of SBT all have an interest in managing chemical residues that have the potential to biomagnify in the fatty tissue of the farmed SBT fillets. Of particular interest are chemical residues of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins / dibenzofurans (PCDD/Fs). This research presents the investigations and experimental validation of a predictive model that can be used to address the levels of residues in the fillets of farmed SBT at harvest from feeding (as the source) when applied to SBT aquaculture. An additional industry-focussed aim of this research was to determine if a Longer Term Holding (LTH) farming period, with a duration of an extra 12 months after a typical farming period of approximately five months, could produce SBT with higher condition index (CI) and lipid content, while keeping levels of PCBs and PCDD/Fs low, compared to the typical farming period. The justification for this research is that an adequate quantitative model is essential to help industry achieve targeted concentrations in the final fillet product by making scientific-based decisions on baitfish selection (baitfish strategies for the feeding of SBT), and longer term, to confidently demonstrate to local markets and importing countries that Australia is actively managing levels of PCBs and PCDD/Fs in farmed SBT, to ensure a high quality and safe product is delivered to the consumer. The novelty of this research is underpinned by four integrated stages, and the criteria for an adequate model established. The important criteria included: accurate predictions versus observed data demonstrated through the analysis of residual plots, potential physiological interpretation of model coefficients, parsimony – the model should be as simple as possible (but no simpler) and that the model should be easy to use. Firstly, a logical starting point was the development of a risk framework for residues in SBT. The developed framework was based on conventional principles of microbiological risk assessment highlighted in Codex Alimentarius. The risk framework consists of five governing principles: hazard identification, hazard characterisation, exposure assessment, risk characterisation and model validation. The advantages of the risk framework is that it provides a systematic research approach and permits information to be handled unambiguously, especially important for the niche SBT industry where chemical residue research is carried out for the first time. Secondly, because of a lack of available scientific data in context of this research, commercial-scale experimental field data for levels of PCBs and PCDD/Fs in typical farmed SBT as affected by feeding and growth were collected over 17 months at seven time intervals from Farm Delta Fishing Pty Ltd in 2005/06 (n = 50). Field data from another commercial company, Farm Alpha Fishing Pty Ltd, was collected over the typical farming period specific to this company, spanning 15 weeks at three time intervals in 2006, for validation work (n = 15). The data obtained from Farm Delta Fishing Pty Ltd revealed that whole weight of farmed SBT increased from 18.5 kg to 30.3 kg for a typical farming period, and subsequently to 41.0 kg by the end of the LTH farming period. A maximum mean CI of 24.0 ± 0.5 kg.m⁻³ and a maximum mean lipid content of 17.6 ± 0.5% was achieved at the third time interval of the typical farming period, for the baitfish types and ratios used as feed. There were no significant differences in the CI and lipid between the final harvests of the typical farming and LTH periods, i.e. even after an additional 12 months of farming. PCB and PCDD/F concentrations, however, increased between the final harvests of the typical farming and LTH periods. The data indicated that a typical farming period was sufficient to achieve a maximum CI and lipid content with lower concentrations of PCBs and PCDD/Fs in the fillets relative to the LTH farming period. For the third stage of this research, a quantitative model was synthesised and applied to the PCB and PCDD/F (2,3,7,8-TeCDF) data detected in farmed SBT fillets. Assimilation efficiencies for PCBs and 2,3,7,8-TeCDF in the fillets of SBT were obtained. An assimilation efficiency, or percentage retention (efficiency expressed as a percentage), in the fillet of SBT is a measure of the uptake of a chemical residue from food (baitfish) to the SBT fillet. For the WHO-PCBs, assimilation efficiencies based on SBT fillets ranged between 19.1 – 35.3 % with the exception of PCB 169. The highest assimilation efficiency of 35.3 %, with a range of 30.4 – 40.3 % (at the 95 % confidence level) was attributed to the most toxic PCB congener, PCB 126. An assimilation efficiency of 39.2 % was determined in SBT fillets for the congener 2,3,7,8-TeCDF, which was higher than the assimilation efficiencies determined for the WHO-PCB congeners. A residual plot as predicted value versus observed value indicated that the predictive model was neither under- or over-parameterised. However, when the predictive model was assessed against the data set from Farm Alpha Pty Ltd, the model over-predicted the actual PCB and PCDD/F concentrations. The over-prediction is attributed to possible overfeeding of SBT farmed by Farm Alpha Fishing Pty Ltd. From a food safety point of view, in the absence of ideal predictions because of a lack of ideal validation data sets, an over-prediction instead of under-prediction is preferred. In the fourth stage, the practical application of the predictive model was demonstrated. Because SBT fillets are retailed as tissue group-specific, i.e. akami (low fat), chu-toro (medium fat) and otoro (high fat) fillets, PCB and PCDD/F analyses were carried out on the three tissue groups for selected SBT (n = 7). Dietary modelling on SBT consumption in humans was carried out using findings from the predictive model and tissue-specific data. The baitfish strategy employed for the feeding of farmed SBT consequently affects dietary exposure to SBT consumers. Exposure to PCBs and PCDD/Fs is approximately seven times lower for the consumption of a skin-free, boneless akami fillet than for a comparable otoro fillet of the same size. This dietary exposure assessment accounted only for consumption of SBT tissue-specific fillets. The experimental field study and modelling work on PCB and PCDD/F concentrations in farmed SBT (fillets) outlined in this thesis importantly directs the need to re-evaluate a specific model to better cater for SBT farming practices where SBT fillets are produced for human consumption. Because conditions that normally pertain to commercial farming of wild-caught fish were studied, findings should be of interest to industries where other species of fish (for food) are farmed in sea-cages in the open ocean. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342453 / Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2008

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.

Regional organisations have often played a catalytical role in developing regional ocean regimes that directly pertain to the peculiar needs and circumstances of a given region. As a response to the challenges imposed by the United Nations Convention on the Law of the Sea, the island States of the South Pacific region established the South Pacific Forum Fisheries Agency, with the specific mandate to assist them manage the enormous tuna resource of the region. The thesis seeks to ascertain the extent to which those needs have been satisfied. The thesis begins with the hypothesis that the Forum Fisheries Agency has in fact fulfilled those needs. The analysis is based on inferences which are drawn from the functions and responsibilities of the Forum Fisheries Agency, and certain significant legal developments it has helped spawn. The thesis does not engage in a cost/benefit evaluation of the Forum Fisheries Agency because that is an issue best left to the purview of individual member States to determine. Two conclusions are drawn from the analysis. First, the Forum Fisheries Agency has met the needs of the island States. Secondly, through the Forum Fisheries Agency, the island States are implementing the United Nations Convention on the Law of the Sea. / Law, Peter A. Allard School of / Graduate

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-09-01T13:19:15Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) MTTolotti_EcologyConservationOceanicWhitetipShark_VF_FichaCatalografica.compressed aprovada.pdf: 5871232 bytes, checksum: 4af848c7c53529f3e28ffa5d085443f1 (MD5) / Made available in DSpace on 2016-09-01T13:19:16Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) MTTolotti_EcologyConservationOceanicWhitetipShark_VF_FichaCatalografica.compressed aprovada.pdf: 5871232 bytes, checksum: 4af848c7c53529f3e28ffa5d085443f1 (MD5) Previous issue date: 2016-02-19 / CAPEs / O objetivo principal da presente tese consistiu em agregar informações ao conhecimento sobre o tubarão galha-branca oceânico (Carcharhinus longimanus), principalmente no que se refere à sua distribuição, índices de abundância e preferências de habitat. Apesar de ser uma espécie muito capturada na pesca oceânica de atuns afins, informações acerca destes aspectos ecológicos são escassas e até mesmo ausentes na literatura relacionada à espécie. A tese é apresentada como um conjunto de capítulos autônomos, representando artigos científicos individuais. No primeiro capítulo-artigo foram discutidos os possíveis efeitos de medidas de manejo restritivas, implementadas recentemente por Organizações Regionais da Pesca Atuneira e que incluem algumas espécies de tubarões oceânicos. Medidas restritivas isoladas terão pouco impacto na redução da mortalidade de tubarões oceânicos. Um conjunto de medidas mitigadoras integradas será mais eficaz na conservação e recuperação das populações dessas espécies. No segundo capítulo-artigo foram analisados dados de captura e esforço de 14.835 lançamentos de espinhel pelágico realizados por embarcações arrendadas da frota atuneira brasileira, nos anos de 2004 a 2010. A CPUE nominal exibiu uma tendência de aumento gradual ao longo dos anos, variando de 0,04 em 2004 para 0,15 em 2010. A CPUE foi padronizada através de uma abordagem delta-GLM, entretanto, o índice de abundância padronizado não diferiu significativamente da CPUE nominal. Os modelos indicaram que as capturas de tubarões galha-branca são maiores para a estratégia de pesca espanhola, que se caracteriza pela utilização de anzóis em profundidades mais rasas. No terceiro capítulo-artigo, a interação entre tubarões galha-branca e a pesca de rede de cerco nos Oceanos Atlântico e Índico foi analisada, com o objetivo de investigar o potencial da utilização do banco de dados dessa pescaria para derivar índices de abundância e determinar tendências populacionais para a espécie. Dados de observadores de bordo da frota francesa combinados com dados históricos da União Soviética foram utilizados na análise. A série temporal combinada incluiu os anos entre 1986 e 2014. No Oceano Atlântico não foi possível determinar uma tendência populacional, uma vez que o índice de ocorrência foi muito baixo e não variou significativamente com o tempo. No Oceano Índico foi observada uma mudança bem-marcada no índice de ocorrência, oscilando em torno de 20% entre meados dos anos 80 e 90 e caindo para menos de 10% a partir de 2005. No quarto capítulo-artigo, a vulnerabilidade do tubarão galha-branca à pesca de espinhel pelágico foi avaliada utilizando dados dependentes e independentes da pesca. Os dados dependentes incluíram informações de diários de bordo (1999- 2011) e observadores embarcados (2004 a 2010), num total de 65.277 lançamentos de espinhel. Os dados independentes foram obtidos a partir de 8 tubarões marcados com marcas do tipo “pop-up satellite archival tag” na área onde a frota de espinhel operou. Locais de marcação e desprendimento das marcas foram relativamente próximos uns dos outros. Entretanto, os indivíduos marcados tenderam a viajar longas distâncias antes de retornar para a área de marcação. Foi observado um certo grau de filopatria à área. “Hotspots” de alta utilização dos tubarões marcados correspondeu à área sob forte pressão pesqueira. Todos os tubarões exibiram uma forte preferência por águas quentes e rasas da camada de mistura, gastando, em média, mais de 70% do tempo acima da termoclina e 95% acima de 120 m. Esse resultado justifica a maior capturabilidade da espécie em espinheis mais rasos. No quinto e último capítuloartigo, os movimentos verticais dos tubarões marcados foram analisados em detalhe. Apesar da distribuição vertical restrita, os dados indicaram que o tubarão galha-branca apresenta padrões de movimento complexos, incluindo padrões de migrações circadianas distintos e mergulhos profundos. O padrão circadiano mais frequentemente observado é caracterizado de um deslocamento à superfície durante o nascer do sol e uma tendência a permanecer em profundidades mais baixas durante o dia. Os movimentos verticais também foram influenciados pela temperatura da superfície do mar, o que pode indicar a ocorrência de termoregulação para espécie. A integração dos resultados de cada capítuloartigo proporcionou boas perspectivas para o desenvolvimento de medidas de mitigação. A evidência em relação à preferência do tubarão galha-branca por águas quentes e rasas é sólida, indicando que a remoção dos anzóis rasos do espinhel pode ser proposta para reduzir a captura incidental da espécie. O fato de variações na CPUE já terem sido observadas, sugere que esta pode ser uma medida eficaz. O comportamento filopátrico observado para o OCS também indica que a espécie pode se beneficiar com a criação de áreas marinhas protegidas. / The ultimate goal of this thesis was to generate knowledge regarding the ecology of the oceanic whitetip shark (Carcharhinus longimanus) and contribute for an ecosystem-based fishery management. The work focuses on the interactions between tuna fisheries and the species and its habitat preferences. Despite being frequently caught on high-sea fisheries, there are wide knowledge gaps regarding the ecology of the oceanic whitetip shark. The thesis is presented as a set of selfcontained standalone chapters, constructed as individual research articles. The first article-chapter provides a discussion concerning pelagic sharks and the recent species-specific banning measures implemented by Regional Fishery Management Organizations (RFMOs) in charge of tuna fisheries. It is unlikely that banning measures alone can reduce the high level of fishing mortality and recover pelagic shark’s depleted populations. Managers should be fully aware that the development and implementation of mitigation measures are critical for a more effective conservation strategy. In the second article-chapter, catch and effort data from 14,835 longline sets conducted by foreign tuna longline vessels chartered by Brazil, from 2004 to 2010, were analyzed. The nominal catch per unit of effort (CPUE) exhibited a gradual increase, varying from 0.04 sharks/1000 hooks in 2004 to 0.15 in 2010. A CPUE standardization was performed using a delta-GLM approach, but the standardized index of abundance did not differ significantly from the nominal CPUE. The models indicated that the catches of oceanic whitetip sharks are higher for the Spanish fishing strategy, which is characterized by the deployment of hooks at shallower depths. In the third article-chapter, the interaction between oceanic whitetip sharks and the purse seine fishery in the eastern Atlantic and western Indian oceans was analyzed, in order to investigate the potential of using this fishery’s database to derive abundance indexes and determine population trends for the species. Observer data from the French purse seine fleet combined with a historic database from the Soviet Union were used in the analyses. The combined time series spanned from 1986 to 2014. The occurrence index was very low for Atlantic Ocean and no marked temporal trend was observed. For the Indian Ocean a well-marked change on the occurrence index was observed, fluctuating around 20% from mid 80’s to mid 90’s and dropping to less than 10% as from 2005. In the fourth article-chapter, a combination of fisheries dependent and independent data was used to assess the vulnerability of the oceanic whitetip shark to pelagic longline fisheries. Fisheries dependent data included information from logbooks (from 1999 to 2011) and onboard observers (2004 to 2010), totaling 65,277 pelagic longline sets. Fisheries independent data were obtained from 8 oceanic whitetip sharks tagged with popup satellite archival tags in the area where longline fleet operated. Tagging and pop-up sites were relatively close to each other, although individuals tended to travel long distances before returning to the tagging area. Some degree of philopatry was observed. High utilization hotspots of tagged sharks fell inside the area under strongest fishing pressure. All sharks exhibited a strong preference for the warm and shallow waters of the mixed layer, spending on average more than 70% of the time above the thermocline and 95% above 120 m. This result explains the higher catchability of the species on shallow longline gear. In the fifth and last article-chapter, the vertical movements of tagged oceanic whitetip sharks were analyzed in detail. Despite its restricted vertical distribution, the analyses reveled that oceanic whitetips perform complex movement patterns, including distinct diel patterns and deep diving behavior. A correlation between vertical movements and sea surface temperature was also observed, suggesting the occurrence of thermoregulation for the species. The combined results of each article-chapter have provided good insights towards the development of mitigation measures. The evidence regarding oceanic whitetip shark’s preference for warm and shallow waters is solid and this information suggests that the removal of the shallow hooks from the longline gear could be proposed as a technique to reduce OCS bycatch. The fact that CPUE variations were already observed suggests that this might be an effective measure. The philopatric behavior observed for the OCS also indicates that the species could benefit from time-area closure measures.