Dissertations / Theses on the topic 'Experimental fishing'

The continuing loss of life at sea due to the capsizing of fishing vessels in inclement weather requires the research and design communities to continue their search to find methods for the prevention of further occurances. As part of this investigative process this thesis was prepared. To gain an initial foothold on the dynamics of capsizing the area of transverse seaways was considered for its contribution to capsizing through the impact of breaking waves on the side of the ship. Two model fishing vessels, built without bulwarks or superstructure, were prepared for testing in a 220 foot test basin where, through the use of computer control, a repeatable sea environment could be created. The models were equipped with adjustable displacements and centers of gravity to allow testing of IMO stability guidelines and the simulation of wind induced decreases in general stability. Tests were conducted in still water, regular waves and breaking waves of the plunging jet type. Motions, including roll, pitch, heave, sway and yaw, were measured and stored on media for analysis by computer. Along with the electronic monitoring of the vessel's motions a video tape was made of the tests to allow visual verification of motions at a later date. From the results of the tests it was found that the single chine seiner exhibited greater intact stability in all transverse sea conditions tested than did the west coast trawler. Under no circumstance did the single chine seiner capsize while, in breaking waves, the trawler exhibited repeated capsizing behaviour when at its heaviest displacement and lowest metacentric height. This capsizing illustrates the need for greater stability characterisitics and improved safety criterion for breaking waves survival over that required in regular seas.<br>Applied Science, Faculty of<br>Mechanical Engineering, Department of<br>Graduate

This study on the hydrodynamics of fishing gear focuses on fish nets. A multi-scale concept has been introduced. By decomposing the fish net structure into 4 distinct scales of flow structure interaction (twine, node, mesh and substructure scales) the complexity is reduced with the potential to integrate new knowledge at each scale to form an overall picture of flow-gear interactions. Within the scope and time-frame of the project, experiments were carried out at the twine and mesh scales. Two sets of experiments were designed at twine scale. The first featured synchronous velocity and drag force measurements on various rigid cylinders consisting of circular cylinders and cylinders inspired by twisted twine. The second aimed to study the cylinder near-wakes in greater detail than previously using PIV. At mesh scale, experiments using rigid bi-plane grids were conducted with individual focus on investigating grid turbulence and flow-grid interactions respectively. The twisted cylinders did not affect mean drag, likely due to free-stream turbulence acting on the boundary layers and free shear layers possibly negating the effects of the twisted cylinder geometry. In the near-wake, the twisted cylinders deflected the free stream into the wake and secondary vortices were introduced, shed along the cylinder span, de-correlating the flow field and in one instance, destroying regular vortex shedding. At mesh scale, for low solidities, a limiting value for mesh length was found where the total drag was dominated by individual contribution of bars. The key to altering the turbulence properties of the flow was found to be alteration of the spectral energy in the largest turbulence scales. For turbulence generation, the spectral energy should be increased and for turbulence suppression, spectral energy should be decreased in the largest turbulence scales.

Coastal shell middens, a prominent feature of the Mesolithic (11,500–6000 cal BP) archaeological record of western Scotland, suggest a maritime economy based on fishing and shellfish. Despite evidence for the importance of fish and shellfish to diet, virtually nothing is known as to the methods of procurement. Initially, work focussed on the palaeoenvironments of Scottish West Coast Mesolithic coastal sites, to establish the resources available to Mesolithic coastal dwellers. A range of archaeological/ethnohistorical fishing gear and food procurement strategies is described, together with views of field archaeologists, bushcraft practitioners and experimental archaeologists. These perspectives together with palaeoenvironmental data were considered when producing fishing gear utilising resources and technologies available during the Mesolithic. Fieldwork and experiments were conducted at the Scottish West Coast Mesolithic coastal sites of Ulva Cave, the Oban area, the island of Oronsay, and Sand, together with South Uist and the Urr estuary on the Solway Firth. The fishing gear manufactured reflects current debates as to fishing strategies, as such, several archaeological ‘models’ were tested. The gear also enabled an attempt at targeting the main fish and crab species found in the middens; Pollachius virens, Labridae, Pollachius pollachius, Carcinus maenas, Liocarcinus depurator and Cancer pagurus. In addition to fishing experiments, ecological surveys and forage exercises established the species present and available to a contemporary coastal forager, providing an indication as to the vigour and abundance of shoreline species. This data was compared to data from the middens, providing an insight into potential collection strategies. Exploratory procurement and manufacture experiments were conducted that tested a variety of materials, including their suitability for use, while bait tests assessed bait desirability. The results suggest that for Mesolithic groups to successfully exploit the coastal environments adjacent to the West coast midden sites, knowledge of tides and species together with simple manufacturing skills would have been sufficient.

Motions and stability of a typical B.C. fishing vessel were experimentally and numerically investigated in a longitudinal seaway condition. The experimental model was self-propelled, radio-controlled and equipped with an on-board data acquisition system. Pitch, roll, yaw, surge, and heave responses to regular waves of predetermined frequencies and amplitudes generated along a 220-ft model basin were obtained. Different displacement conditions and GM configurations were tested. The numerical model for the dynamic analysis of the fishing vessel motions has been implemented using strip theory. A computer program was developed to study the nonlinear motions of the vessel. The velocity dependent coupling terms, responsible for a major part of the nonlinear behavior, were included. A time dependent component analysis of the roll damping has been performed. Regular linear and nonlinear waves were used. A parametric study of the fishing vessel stability has been carried out by considering its dynamic response in waves of varying characteristics. Unstable behaviour was found to be closely related to waves of length of similar magnitude to the ship length. The effects of wave amplitude and rudder usage were found to be of capital importance in the capsizing process. Experimental and numerical results showed good agreement.<br>Applied Science, Faculty of<br>Mechanical Engineering, Department of<br>Graduate

En la segona meitat del segle XX, la industrialització dels vaixells pesquers va donar lloc a una sobreexplotació dels recursos marins a les àrees costeres dels estats tradicionalment pesquers. En conseqüència, els països pesquers industrialitzats van començar a explorar les aigües llunyanes, en gran part sense traves legals, per alimentar la creixent demanda de peix i marisc. Amb l'entrada en vigor de la Convenció de les Nacions Unides de 1982 sobre el Dret del Mar (UNCLOS, en anglès), així com l’Acord de Recursos Pesqueres (“Fish stock agreement”) de les Nacions Unides de 1995, es van reestructurar radicalment els drets i les responsabilitats de la pesca de captura marina. No obstant això, aquestes noves legislacions van deixar molt d’espai a l’explotació econòmicament ineficient i ecològicament insostenible dels recursos pesquers. En tres assaigs, aquesta tesi dóna llum a la interacció entre les flotes industrialitzades d'aigües llunyanes i les regions sovint vulnerables on s’hi pesca. El primer assaig revisa críticament el desenvolupament de la pesca en aigües llunyanes en el món tropical durant els darrers 50 anys i ofereix una anàlisi quantitativa de la relació entre les flotes d'aigües llunyanes i els països tropicals d’acollida. Es conclou que hi ha un clar canvi de poder dels països tradicionalment pesquers als nouvinguts, sobretot asiàtics, i que els països petits i econòmicament febles són els més vulnerables a relacions d'explotació amb els estats que pesquen en aigües llunyanes. El segon assaig aborda la qüestió de si, des d'un punt de vista econòmic, els Països Insulars del Pacífic (PICs, en anglès) haurien de continuar concedint accés als estats pesquers d'aigües llunyanes, o si s'hauria d'intentar desenvolupar una indústria pròpia pesquera nacional. Amb aquesta finalitat, un nou model bioeconòmic amb múltiples espècies i actors és analitzat. Els resultats del model mostren que els PICs maximitzarien els seus beneficis mitjançant l'eliminació gradual dels acords d'accés amb els estats pesquers d'aigües llunyanes, substituint-los per un esforç pesquer nacional. L'alternativa és elevar considerablement les tarifes d'accés, tot i que, per descomptat, això pot tenir diferents conseqüències a llarg termini. En el tercer assaig, es descriu un model empíric per inferir el pes viu de la pesca de la tonyina vermella a l’Atlàntic Est i al Mediterrani (EBFT, en anglès) a partir de dades mensuals del comerç entre 2005 i 2011. En base a la captura total estimada, s’arriba a la conclusió que l’EBFT ha estat persistentment sobreexplotada al llarg de tot el període esmentat. En conclusió, aquesta tesi ha contribuït a la literatura tot estudiant l'impacte de la pesca en aigües llunyanes sobre la salut de les poblacions de peixos en alta mar i en les zones econòmiques exclusives en regions tropicals, així com en el benestar dels països en desenvolupament que són abundants en recursos pesquers.<br>In the second half of the 20th century, the industrialization of fishing vessels led to an over-exploitation of marine resources in near-shore areas of traditional fishing nations. As a result, industrialized fishing nations started to explore distant waters, largely unhindered by legal boundaries, to fuel the growing demand of fish and seafood products. While the coming into force of the 1982 United Nations Convention on the Law of the Sea (UNCLOS), and the 1995 United Nations “Fish Stocks Agreement”, dramatically restructured rights and responsibilities of marine capture fisheries, they left much room for economically inefficient and ecologically unsustainable exploitation of fisheries resources. In three essays, this thesis sheds light on the interplay between industrialized distant water fleets and the often vulnerable regions where they fish. The first essay critically reviews the development of distant water fishing in the tropical world over the past 50 years and provides a quantitative analysis of the relationship between distant water fleets and tropical host countries. It concludes that there is a clear shift in powers from traditional fishing countries to mainly Asian newcomers, and that small and economically weak countries are most vulnerable to exploitative relationships with distant water fishing nations. The second essay addresses the question whether, from an economic point of view, Pacific Island Countries (PICs) should continue granting access to distant water fishing nations or whether they should attempt to develop an own domestic fishing industry. To this end, a newly developed multispecies, multiplayer bioeconomic model is analyzed. It provides the insight that PICs would maximize their profits by phasing out access agreements with distant water fishing nations, replacing these by domestic fishing effort. The alternative is to considerably raise access fees, although this does of course may have different long term consequences. In the third essay, an empirical model is constructed to derive life catch weight for Eastern Atlantic and Mediterranean Bluefin tuna (EBFT) from monthly trade data for all major countries involved in its trade between 2005 and 2011. Based on estimated total catch we conclude that EBFT has persistently been overfished, throughout the entire period. In conclusion, this thesis has contributed to the literature on the impact of distant water fishing on fish stock health in the high seas and tropical Exclusive economic zones, and on the welfare of resource-rich developing countries.

La pregunta central que motiva esta tesis es cómo y en qué medida las relaciones sociales, en particular las relaciones de género, dan forma a el conocimiento ambiental local y a las prácticas de subsistencia en las sociedades de pequeña escala. He tratado de comprender las relaciones de género asociadas a la diversidad intracultural de prácticas y conocimiento ambiental en el contexto de cambio ambiental y económico global. Este estudio se realizó desde la perspectiva de la etnoecología, incorporando métodos de análisis de redes sociales y de estudios de género en la gestión de la biodiversidad. He analizado el caso de la sociedad Tsimane’ de recolectores y horticultores de la Amazonía Bolivia, en concreto, estudié los conocimientos Tsimane’ relacionados con pesca, plantas medicinales y huertos. Los objetivos específicos de la tesis son: 1) evaluar diversidad y redundancia de conocimientos de plantas medicinales en el sistema etnomedicinal Tsimane’ con perspectiva de género; 2) explorar el papel de las redes de intercambio en la riqueza de plantas medicinales en los huertos y en la distribución del conocimiento medicinal entre los/las horticultores; 3) describir potenciales vías de transmisión de conocimientos de pesca en relación a la influencia del conocimiento de los pescadores según la percepción de otras personas; y 4) determinar las interrelaciones entre división genérica del trabajo, acceso y uso de técnicas de pesca y zonas de pesca, y la ecología local en el uso de recursos de agua dulce. Los datos fueron recogidos durante 18 meses de trabajo de campo en dos comunidades del Territorio Tsimane’ incluyendo métodos cuantitativos y cualitativos. Los conocimientos y prácticas Tsimane’ acerca de plantas medicinales y pesca están determinadas por el género. Las mujeres Tsimane’ conocen más usos de plantas medicinales, probablemente, porque son las principales cuidadoras y guardianas de la salud en los hogares. Igualmente, mujeres y hombres Tsimane’ pescan diferentes especies influenciados por la división genérica del trabajo y el acceso a las técnicas y zonas de pesca. Independientemente de la ubicación, los hombres tienden a pescar las especies más grandes y culturalmente más valoradas. Otros hallazgos muestran que la posición de una persona en una red social puede proporcionarle tanto posibilidades como limitaciones para el acceso a los recursos. Los horticultores más centrales en las redes de intercambio - típicamente las mujeres - mantienen una mayor riqueza de plantas medicinales en sus huertos, ya que tienen más acceso a material de propagación. Del mismo modo, la posición de un pescador en la red social de pesca se asocia a sus habilidades de pesca. Los hombres Tsimane’ más prominentes en las redes de pesca son los percibidos como mejores pescadores. En general, los resultados de esta tesis sugieren que las relaciones de género Tsimane’ dan forma al acceso, uso y conocimiento de los recursos naturales, y por lo tanto, al conocimiento ambiental local de mujeres y hombres. Esta tesis enfatiza la importancia de abordar las relaciones de género para explicar la diversidad intracultural de conocimientos ambientales. La aportación más relevante de mi enfoque es la manera innovadora de evaluar los conocimientos de género a través de la estructura social en la que las personas están inmersas. Desde esta perspectiva, los conocimientos y prácticas de género son el producto de 1) las relaciones sociales entre mujeres y hombres y hacia el medio ambiente y 2) sus posiciones en las redes sociales. Estos hallazgos son importantes para la comprensión de procesos sociales más amplios en las sociedades indígenas cada vez más integradas en la economía de mercado y en las sociedades nacionales así como los potenciales impactos de estos procesos en su bienestar y soberanía.<br>The central question that motivates this dissertation is how and to what extend do social relations, particularly gender relations, shape local environmental knowledge and subsistence practices of people in small-scale societies. Specifically, I sought to comprehend the gendered relations associated with the intracultural diversity of local environmental knowledge and practices in the context of global environmental and economic change. The study is grounded in the discipline of ethnoecology, but also incorporates insights from social network analysis and gender studies in biodiversity management and conservation. The case of the Tsimane’ forager-horticulturalists from Bolivian Amazonia was empirically analyzed. In particular, I focused on Tsimane’ knowledge and practices related to fishing, medicinal plants, and homegardening. The specific objectives of the thesis are: 1) to assess the diversity and redundancy of medicinal plant knowledge within Tsimane’ ethnomedicinal system through a gender lens; 2) to explore the role of social exchange networks in medicinal plant richness maintained in homegardens and in the medicinal plant knowledge distribution among gardeners; 3) to describe potential patterns of fishing knowledge transmission in relation to the influence of fishers’ knowledge, as perceived by other people and 4) to ascertain the interrelations among gender division of labor, access and use of fishing techniques and grounds, and local ecologies in freshwater resource use. Data were collected during 18 months of fieldwork in two villages of the Tsimane’ Territory integrating both quantitative and qualitative methods. Tsimane’ knowledge and practices regarding medicinal plants and fishing are gendered. Tsimane’ women hold a wider range of knowledge about medicinal plant uses than men, probably as they are the principal caregivers and health custodians at a household and community level. Likewise, Tsimane’ women and men target different fish species influenced by the gendered division of labor and the access to fishing techniques and fishing grounds. Irrespective from the location, men tend to target the larger and culturally regarded fish species. Further findings show that an individuals’ location in a social network can provide both possibilities and constraints for accessing resources and knowledge through other people in the network. Thus, more central gardeners in exchange networks - typically women - maintain higher richness of medicinal plants in their homegardens, as they have more access to medicinal planting material and associated knowledge. Similarly, a fisher’s position in the fishing network is associated to fishing abilities. Tsimane’ men are more prominent in fishing networks and have higher perceived knowledge. Overall, results of this thesis suggest that Tsimane’ gender relations shape the access to, use of, and knowledge about natural resources, and therefore, women’s and men’s local environmental knowledge. Findings from this thesis advance the understanding of how local practices and environmental knowledge diversity arises in a dynamic context with a fresh interdisciplinary perspective that relies on social networks analysis. This thesis emphasizes the importance of addressing gender relations in the quest to explain intracultural knowledge diversity. The more relevant contribution of my approach is the innovative manner of assessing people’s gendered practices and knowledge in the light of the social structure in which they are embedded. Therefore, from the perspective adopted here, gendered knowledge and practices are the product of 1) women’s and men’s social relationships among them and towards the local environment they in which dwell and 2) their positions in the social networks. These findings are important for comprehending the broader social processes that occur in small-scale indigenous societies that are increasingly integrated into the market economy and national societies, and the potential impacts of these processes in their wellbeing and sovereignty.

En general, la falta de oportunidades de ingresos alternativos es un problema que afecta a la pesca en pequeña escala, tanto marina como continental. Debido a esto, los pescadores intensifican el esfuerzo pesquero. Por lo tanto, algunas evidencias han demostrado que las soluciones a este problema pueden encontrarse fuera de la actividad. Por lo general, las comunidades que se dedican a esta actividad están ubicadas en zonas rurales remotas, con muy pocas oportunidades de empleo que tienden a incluir a personas no calificadas, pobres y sin tierra que dependen de los ingresos derivados únicamente de la pesca. De este modo, las pesquerías de acceso abierto se consideran como el último recurso para los hogares de pescadores cuando no se obtiene una fuente diferente de ingresos. El objetivo de esta investigación es explicar que invertir en educación ayuda a evitar el agotamiento de las economías dependientes en recursos naturales. Por tanto, se argumenta que invertir en educación promueve la gestión eficiente de los recursos elimina el efecto negativo causado por su auge, fomenta la mejora tecnológica y aumenta la posibilidad de sustitución entre los factores de producción y las actividades económicas. En consecuencia, al mejorar el conjunto de capacidades como la educación, los pescadores pueden diversificar sus actividades de medios de vida fortaleciendo sus ingresos, asegurando el desarrollo de la comunidad y reduciendo su vulnerabilidad. Bajo esta premisa, esta investigación presenta los resultados de tres estudios de caso de comunidades pesqueras a pequeña escala en Colombia. El objetivo de esta investigación es contribuir a la discusión argumentando que también se pueden encontrar soluciones para el problema con respecto a la presión sobre las pesquerías mejorando el capital humano y proporcionando diferentes oportunidades económicas para cada comunidad pesquera.<br>Generally, the lack of alternative income opportunities is a problem that affects the smallscale fisheries, both marine and inland. Due to this, laborers in the activity intensify the fishing effort. Thereof, some findings have shown that solutions to this problem might be found outside the activity. Usually, communities that depend on this activity are located in remote rural areas, with very few employment opportunities tending to include non-skilled, poor, and landless people who rely their livelihoods only on fishing. Then, open access fisheries are considered as a last resort for fishing households when a failure to obtain a different source of income exists. This research aims to explain that investing in education helps to avoid depletion of resource-based economies. Then, it is argued that investing in education promotes efficient management of resources, eliminates the negative effect caused by a resource boom, encourages technological improvement, and increases the possibility of substitution between production factors and economic activities. Accordingly, by enhancing the set of capabilities such as education, fishermen can diversify their livelihood activities strengthening their income, ensuring the community development and reducing their vulnerability. Under this premise, this research presents findings from three case studies from small-scale fishing communities from Colombia. The objective of this research is to contribute to the discussion by arguing that solutions for the problem regarding the pressure on fisheries can also be found by enhancing human capital and providing different economic opportunities of fishing communities.

O uso de praguicidas vem sendo a principal forma de combater os ectoparasitas dos viveiros de peixes, sendo que os mais utilizados na bacia do rio Mogi-Guaçu são o diflubenzuron (DFB), e os organofosforados paration metílico (PM) e triclorfon (TCF), cujo principal subproduto é o diclorvós (DDVP). O uso indiscriminado destas substâncias nos cultivos de peixes pode ocasionar danos aos ecossistemas aquáticos que recebem os efluentes dos tanques comprometendo a qualidade ambiental, além de representar risco aos consumidores destes pescados. Conhecer o padrão de acumulação destes praguicidas, bem como o efeito em espécies não-alvo são fundamentais para a correta gestão desta atividade. Foram analisadas quanto à presença de DFB (CLAE-DAD), PM e DDVP (CG-NPD), amostras de água, sedimentos e peixes (Oreochromis niloticus) coletadas em três pesqueiros do município de Socorro, SP (junho de 2005) e em 4 tanques experimentais (10.000 L de água, 10 cm de sedimento arenoso, localizados no CRHEA - USP, Itirapina, SP) os quais foram utilizados num experimento de simulação de tratamento contra ectoparasitas de peixes (junho a agosto de 2005). Neste caso, antes e após uma única aplicação das formulações Dimilin (1,0 g/\'M POT.3\' DFB), Folisuper (0,25 g/\'M POT.3\' PM) e Neguvon (0,25 g/\'M POT.3\' TCF), amostras de água sedimentos, peixes e comunidades fitoplanctônica, zooplanctônica e de macroinvertebrados bentônicos foram coletadas nos tempos zero, 5 horas, 1, 2, 5 e 7 dias após as aplicações. Não foram detectados resíduos dos praguicidas em nenhuma das amostras coletadas nos três pesqueiros do município de Socorro, SP. Foram detectados resíduos nos compartimentos e efeitos nos grupos de organismos analisados nos tanques experimentais. O DFB é persistente nos compartimentos água e sedimentos, assim como o PM o qual possui menor persistência. O DDVP não é persistente nestes compartimentos. Houve acúmulo de DFB e PM nos filés de peixes submetidos ao tratamento com Dimilin e Folisuper, respectivamente, em todos os tempos amostrados. Estes valores excederam os limites máximos recomendados para alimentos segundo o Codex Alimentarius. As aplicações dos praguicidas causaram efeitos na composição e densidade das comunidades biológicas os quais variaram em função do produto aplicado e do tempo de exposição. De maneira geral, os macroinvertebrados bentônicos foram mais sensíveis aos organofosforados, enquanto que o zooplâncton foi mais sensível ao DFB. Os cladóceros mostraram alto grau de sensibilidade para todos os praguicidas aplicados. Com relação à comunidade fitoplanctônica, aparentemente os praguicidas causaram efeitos indiretos na composição e densidade deste grupo.<br>The use of pesticides has been the foremost course of action to combat the ectoparasites of farmed fee fishes, in which diflubenzuron (DFB) and the organophosphates methyl parathion (PM) and trichlorfon (TRC) (witch the main sub product is dichlorvos - DDVP) are the most widely used in the Mogi-Guaçu river catchments. The indiscriminate use of such compounds on aquaculture can cause damage to the aquatic ecosystems that receive the pond\'s effluents, hence endangering environmental quality and consumer\'s health. The knowledge of understanding the environmental fate, accumulation rate, as well as their effect upon non-target species, is particularly important for the correct aquaculture management. Samples of water, sediments and fishes (Oreochromis niloticus) from three fee fishing enterprises from Socorro, SP, Brazil (June, 2005), were analyzed to verify residues of DFB (HPLC-DAD), PM and DDVP (GC-NPD). In addition, four experimental ponds (10.000 L, 10 cm of sediment, localized on CRHEA - USP, Itirapina, SP, Brazil) were used to simulate a treatment against fish ectoparasites (June to August, 2005). In this case, before and after a single application of Dimilin (1,0 g/\'M POT.3\' DFB), Folisuper (0,25 g/\'M POT.3\' PM) and Neguvon (0,25 g/\'M POT.3\' TCF), samples of water, sediments, fishes, phytoplankton, zooplankton and benthonic macro invertebrates were collected on zero, 5 hours, 1, 2, 5 and 7 days after contamination. No pesticides residues in the samples of the three fee fishing enterprises from Socorro were detected. Pesticides residues in the compartments and effects in all of the organism groups analyzed were detected on the experimental ponds. The DFB is persistent in water and sediments, as well as the PM, which was comparatively less persistent. However, DDVP is not persistent on those compartments. There was DFB and PM accumulation on fish filets subjected to treatment with Dimilin and Folisuper, respectively, which were detected in all sampled times. These values exceed maximal level limits proposed by the Codex Alimentarius. The pesticides applications caused effects on the biological community composition and density, which varied due to the formulation applied and time exposition. Overall, the benthonic macro invertebrates were more sensitive to organophosphorates, while zooplankton were more sensitive to DFB. The cladocerans indicated high degree of sensitivity to all pesticides applied. With respect to phytoplankton, apparently, pesticides caused only indirect effects upon the composition and density of this group.

Small-scale fishers are often identified as key players in the recovery of overexploited fish and invertebrate stocks supplying food for rural people and contributing to achieving healthy marine ecosystems. Stocks harvested by small-scale fisheries tend to be largely unassessed, but methods based on the data-limited toolbox exist that help provide information on exploitation status for fished stocks that do not have historical time series of catches, as usually occur in small-scale fisheries. Many of the data-limited methods follow length-based assessment approaches, which assume steady state, use at least length structure derived from fishery and knowledge on the life history parameters of the fished species. Accordingly, this thesis aimed at addressing the reliability of data-poor stock assessment methods in providing advice on the status of small-scale fisheries lacking knowledge of catch history. The data-rich bottom trawl fishery for European hake (Merluccius merluccius) in GSA 06 (Northwest Mediterranean Sea) was assumed as data-limited. This case study allowed me to test the performance of the pseudo-cohort Virtual Population Analysis (VPA) when input data are considered well known and unbiased. The same fishery but held in GSA 01 (Southwest Mediterranean Sea) was used as data-limited case study to introduce the uncertainty derived from parameterizing the length-based spawning potential ratio (LB-SPR) model with two contrasting growth hypotheses. Acknowledging challenges faced by stock assessment of small-scale fisheries around the world, I considered high input-data bias and large outputs uncertainty. The effect of biases in fishery data and uncertainty in life-history parameters on the outputs of the pseudo-cohort VPA model was explored by assessing the small-scale Wayuu fisheries for lane snapper (Lutjanus synagris) and white grunt (Haemulon plumierii) in the northern Colombian Caribbean Sea. An extreme, but common, case of uncertainty in small-scale fisheries was explored through assessing the beach fishery of the Peruvian grunt (Anisotremus scapularis) in the central coast of Peru on the Pacific Ocean, holding poor information on life-history parameters and catches. My findings indicate that the pseudo-cohort VPA may offer useful information regarding the exploitation trend but the absolute values of the indicators do not accurately express the fishing mortality and stock size among years for the European hake. The SPR estimates for this species is not specially linked to the growth hypothesis, and estimates of the ratio of fishing mortality to natural mortality (F/M) and the SPR value depend on the sample size and representation of the stock structure. The contribution of the information derived from the participatory monitoring of small-scale fisheries in Colombia, instead of using only official fishery data, largely demonstrated an improving picture of the exploitation of the lane snapper and white grunt. The uncertainty related to estimates of the von Bertalanffy growth parameters and natural mortality of the Peruvian grunt could be addressed but an accurate definition of SPR was not straightforwardly achieved. This thesis highlights that the data-limited methods assuming a steady state might contribute to defining the status of the small-scale fisheries. However, the stock status is importantly affected by bias in the input data, the available knowledge on the assessed fisheries and how fishery fit the model assumptions.<br>Los pescadores artesanales se identifican generalmente como actores claves en la recuperación de poblaciones sobreexplotadas, en el suministro de alimento a poblaciones rurales y en contribuir a alcanzar ecosistemas marinos saludables. Las poblaciones que son extraídas por las pesquerías artesanales (denominadas pesquerías de pequeña escala) tienden a carecer de evaluación. Sin embargo, algunos métodos de evaluación que se incluyen en el grupo “datos limitados” ayudan a suministrar información sobre el estado de estas pesquerías cuando no poseen información histórica de capturas. Muchos de los métodos limitados en datos y basados en estructura de tallas asumen estado de equilibrio. Estos métodos usan al menos como datos de entrada la estructura de tallas que provienen de la pesquería y el conocimiento disponible sobre los parámetros de historia de vida de las especies pescadas. Por todo lo expuesto anteriormente, el propósito de esta tesis es direccionar la fiabilidad de los métodos limitados en datos para proporcionar información sobre el estado de poblaciones que no cuentan con información histórica de capturas. La pesquería de merluza (Merluccius merluccius) de arrastre en GSA 06 (Mar Mediterráneo noroeste) “rica en datos” se asumió limitada en datos. Este caso de estudio me permitió probar el desempeño del Análisis de Población Virtual (VPA por sus siglas en inglés) basado en pseudo cohortes cuando los datos de entrada se asumen bien conocidos y libres de sesgos. Esta misma pesquería pero llevada a cabo en GSA 01 (suroeste del Mar Mediterraneo) también fue usada como un estudio de caso limitado en datos. Esto con el propósito de explorar la incertidumbre producida por el modelo que determina la proporción del potencial reproductor que es basada en tallas (LB-SPR por sus siglas en inglés) cuando son consideradas dos hipótesis de crecimiento contrastantes. Reconociendo los desafíos que enfrenta la evaluación de las pesquerías artesanales alrededor del mundo, yo consideré el análisis de sesgos relevantes en los datos que alimentan el modelo así como una gran incertidumbre en los resultados de evaluación. De esta manera, el efecto de los sesgos en la información proveniente de las pesquerías y la incertidumbre en los parámetros de historia de vida sobre los resultados del VPA basado en pseudo cohortes se exploró a través de la evaluación de las pesquerías Wayuu del pargo rayado (Lutjanus synagris) y la boca colorada (Haemulon plumierii) en el norte del Mar Caribe colombiano. Posteriormente, un extremo pero común caso de incertidumbre en pesquerías artesanales se consideró a través de la evaluación de la pesquería de playa de la chita (Anisotremus scapularis) en la costa central de Perú en el Océano Pacífico. Esta pesquería posee limitada información sobre la historia de vida de la especie y sobre las capturas producidas por la pesquería. Mis hallazgos indican que el VPA basado en pseudo-cohortes puede ofrecer información útil respecto a la tendencia de explotación de la pesquería, pero los valores absolutos no expresan apropiadamente la mortalidad por pesca ni el tamaño de la población entre años para la merluza. El valor de SPR para esta misma especie no se vincula a la hipótesis de crecimiento asumida y las estimaciones de la proporción de mortalidad por pesca respecto a la mortalidad natural (F/M) y el valor de SPR dependen del tamaño de la muestra y de la representación de la estructura de tallas del stock. La contribución de la información derivada del monitoreo participativo de la pesca artesanal en Colombia demuestra mejoramiento de la imagen de explotación del pargo rayado y la boca colorada que no cuando solo se usa información oficial. De otro lado, encontré que la incertidumbre relacionada con los parámetros de crecimiento de von Bertalanffy y la mortalidad natural de la chita puede ser direccionada pero una definición precisa del valor de SPR no se obtiene fácilmente. Esta tesis resalta que lo métodos limitados en datos que asumen estado de equilibrio pueden contribuir a definir el estado de explotación de las pesquerías artesanales. Sin embargo, el estado de la población se encuentra afectado de manera importante por los sesgos de los datos que alimentan el modelo, el conocimiento disponible sobre la pesquería evaluada y el cómo la pesquería se ajusta a los supuestos de los modelos de evaluación.

The results presented in this thesis have shown the strong dependence of Audouin’s gull from the Ebro Delta on fisheries. Foraging movements of breeding birds showed a great association with fishing activities (specially trawling), determining the most of its at-sea distribution on work days. An increase in the use of rice field habitats was also detected in absence of fishing activities (during weekends) due to the opportunistic feeding on the American crayfish. However, a key aspect presented in this thesis was the significant sex-differences in their foraging behaviour in relation to fisheries. Female Audouin’s gull tended to perform longer at-sea foraging trips on weekends compared to males, probably due to the need of feeding on high quality resources after laying instead of the easily available but lower quality American crayfish. This great dependence on fishing activities was also reflected in the resource allocation into the clutch. An isotopic δ15N enrichment in the albumen of eggs synthesized during the weekends was observed, which is attributed to an increase in the consumption of rice field resources as well as to the mobilization of female reserves. However, rice field diets were associated to lower antioxidant capacity in the eggs. Also, rice field diets were related to smaller egg size. Finally, the limiting nature of calcium (in constraining egg synthesis) and antioxidant molecules (decreasing their concentration especially in the latter eggs of the clutch) were also revealed for females.<br>Los resultados presentados en esta tesis han mostrado la gran dependencia de las gaviotas de Audouin del Delta del Ebro sobre las pesquerías. Los movimientos de búsqueda de alimento de las aves durante la reproducción mostraron una gran asociación con las actividades pesqueras (especialmente el arrastre durante el día, aunque también es notable la influencia de la pesca de cerco durante noche), determinando la mayor parte de su distribución en el mar los días laborables. Un incremento en el uso de arrozales fue detectado en ausencia de actividades pesqueras (durante los fines de semana). Sin embargo, un aspecto clave presentado en esta tesis fue las diferencias significativas entre sexos para el comportamiento de alimentación en relación a las actividades pesqueras. Las hembras de gaviota de Audouin tendieron a realizar viajes de alimentación más largos que los machos durante los fines de semana. Esta gran dependencia sobre las actividades pesqueras fue también reflejada en la asignación de recursos sobre la puesta. Un enriquecimiento del δ15N fue detectado en el albumen de los huevos sintetizados durante los fines de semana, lo cual puede ser atribuido a un incremento en el uso de recursos de arrozal así como a la movilización de reservas de la hembra. Sin embargo, un mayor uso de dietas de arrozal se asoció con una menor capacidad antioxidante de los huevos. También, dietas de arrozal estaban relacionadas con tamaños del huevo más pequeños. Finalmente, se puso de manifiesto la naturaleza limitante del calcio (restringiendo la síntesis del huevo) y de las moléculas antioxidantes del huevo (decreciendo su concentración especialmente en los últimos huevos de la puesta).

The overarching goal of this doctoral thesis was to advance the understanding of the interactions between marine fish farming, wild fish populations, the local small-scale fishery and the society. This thesis was designed as a multi-disciplinary study and is divided into three different sections: ecology (chapter 1 and 2), fisheries (chapter 3) and social science (chapter 4). In the ecological part we examined the spatial and temporal extent of the attraction effect of wild fish at an Atlantic bluefin tuna and a Gilthead seabream farm. At both farms wild fish aggregated closely to the cage structure, revealing an abrupt decline of fish abundance rather than a gradient. The intensity of the cage effect varied according to farm, season and depth. At the seabream farm, the cage effect persisted year round, whereas at the tuna farm, the effect was restricted to summer and spring. The variability of wild fish aggregations within the Gilthead seabream farm was analyzed because it can be a distorting factor in estimating the farm attraction effect. Our findings showed that at the surface, fish abundance was significantly higher during feeding compared with non-feeding periods. Moreover, the distance from the feeding vessel significantly influenced fish aggregations in the water column. At the bottom, substrate type was the dominant factor explaining aggregation variability. The effect of fish farming on the small-scale fishery was evaluated in order to determine whether farms act as protection zones or as traps for wild fish populations. The findings revealed a relevant amount of commercial and recreational fishing effort in farm vicinity. However, the results showed no benefit or difference of fishing in close proximity to the farm compared to areas away from the farm (in terms of yield, income, and catch composition). Yet, farm-aggregated fish are vulnerable to hidden fishing practices inside the farm. The analysis of the perception of marine fish farming in Catalonia was performed with five key stakeholder-groups (NGOs, local fishermen, fish farming industry, scientists and regional administration). Four perceptions were identified; two represented divergent views and two intermediate positions. Environmental impacts were not perceived as a high risk by the majority of the participants. The major weaknesses were attributed to economic (e.g. price competition with other producer countries) and social issues (e.g. lack of credible information about farmed products). Overall, this thesis provides new information about the complex dynamics of wild fish aggregations at marine fish farms and investigates how this attraction effect influences the local small-scale fishery. Moreover, an understanding of the different perceptions on marine fish farming can help to secure a social, economic and environmental sustainable activity.<br>Esta tesis persigue avanzar en el conocimiento de las interacciones de la piscicultura marina, de carácter multidisciplinar y estructurada en tres áreas: ecología (capítulos 1 y 2), pesca (capítulo 3) y ciencias sociales (capítulo 4). En el área de ecología, se analizó la extensión espacial y temporal del efecto atractor de peces salvajes sobre dos tipos de granjas: atún rojo (Thunnus thynnus) y dorada (Sparus aurata). En ambas el efecto atractor se restringía al límite de las jaulas, variando estacionalmente y en profundidad. Las diferencias entre granjas, permanente en doradas y estacional en atunes, se deben a diferencias en la composición específica asociadas con la localización y tipo de cultivo. El análisis de la variabilidad interna en la comunidad íctica se analizó ya que podría ser un factor distorsionador en la estimación del efecto atractor. Los resultados mostraron que la abundancia de peces en superficie disminuía significativamente en los períodos de no alimentación y durante la alimentación las concentraciones de peces disminuían en función de la distancia al barco alimentador. Por el contrario, la variabilidad de agregación en el fondo dependía exclusivamente del tipo de sustrato. La interacción con la pesca artesanal se evaluó con el fin de conocer si las granjas actúan como zonas de protección o como trampas para los peces salvajes. Los resultados no mostraron beneficio, detrimento o diferencia de la pesca en las proximidades de la granja respecto a zonas distantes (en términos de producción, ingresos y composición de las capturas). El análisis de la percepción de la acuicultura, indicador del escenario de aceptación y de elementos clave para su desarrollo, se realizó sobre cinco grupos de interés (ONGs, pescadores locales, industria de la piscicultura, científicos y administración regional) en el marco regional de Cataluña. Se identificaron cuatro percepciones; dos claramente divergentes y dos de posturas intermedias. Los impactos ambientales no fueron percibidos como de alto riesgo por la mayoría de los actores. Las principales debilidades fueron atribuidas a aspectos económicos (p. ej. la competencia con otros países productores) y sociales (p. ej. la falta de información acerca de la credibilidad de los productos acuícolas).

The Ebro Delta represents the most important wetland area in Catalonia, the second most important in Spain (after Doñana National Park) and one of the most important estuarine zones in Europe. Although relatively recently colonized by human population, it is considered a highly impacted area. The main objective of this PhD thesis was to assess the effects of two important human induced stressors on the fish fauna from Ebro Delta coastal lagoons: artisanal fisheries and water management. Moreover, this study aimed to describe the state of the art of the fish community composition and structure that remained unstudied for over 3 decades. Three specific objectives under the general one were pursued: (i) Study gillnet selectivity and its applicability as a management tool in combination with maturity studies; (ii) construction of a trophic model in order to evaluate the global impact of artisanal fisheries in the ecosystem and (iii) analyze the water management impact derived from the rice cultivation carried out in the area. The set of results obtained in this thesis pointed out that: (i) the artisanal fisheries management for the endangered Atherina boyeri seemed to be inadequate. The approach of combining gear selectivity and maturity studies was useful for the establishment of better management proposals for this species; (ii) the gradual reduction of the current fishing effort as the best strategy to ensure both artisanal fisheries sustainability and conservation of the Ebro Delta coastal lagoons’ fish community and (iii) the water management carried out in the coastal lagoons has caused the inversion of the hydrological cycle, has increased the presence of freshwater species (mostly introduced species) and has altered the fish community composition.<br>El Delta de l’Ebre representa l’àrea humida més important de Catalunya, la segona àrea més important d’Espanya (després del Parc Nacional de Doñana) i una de les zones estuarines més importants d’Europa. Tot i la seva recent colonització humana, està considerat com una àrea fortament impactada. El principal objectiu de la present tesi doctoral va ser avaluar els efectes de dues de les activitats humanes dutes a terme a les llacunes costaneres del Delta de l’Ebre: les pesqueries artesanals i la gestió de l’aigua. A més a més, aquest estudi ha permès investigar l’actual condició de la comunitat piscícola (tant a nivell de composició com d’estructura), desconeguda durant les últimes dècades. Tres objectius específics sota l’objectiu general van ser assolits: (i) estudiar la selectivitat de malla de les xarxes ganyeres i la seva possible aplicació com a eines de gestió en combinació amb estudis de maduresa sexual; (ii) construcció d’un model tròfic per tal d’avaluar l’impacte global de les pesqueries artesanals en l’ecosistema i (iii) analitzar l’impacte de la gestió de l’aigua derivada del cultiu d’arròs a la zona. El conjunt de resultats obtinguts en aquesta tesi doctoral posen de manifest: (i) la inadequació de l’actual sistema de gestió de les pesqueries artesanals pel que respecta l’espècie vulnerable Atherina boyeri. L’enfocament seguit de combinar els estudis de selectivitat de malla amb els estudis de maduresa sexual varen ser d’utilitat per establir noves mesures de gestió per a l’espècie; (ii) una disminució gradual de l’esforç pesquer com la millor estratègia de gestió, assegurant conjuntament la sostenibilitat de la pesca i la conservació de les llacunes costaneres del Delta de l’Ebre i (iii) l’actual esquema de gestió de l’aigua a les llacunes costaneres ha causat la inversió del cicle hidrològic, ha augmentat la presència d’espècies d’aigua dolça (majoritàriament espècies introduïdes) i ha alterat la composició d’espècies de la comunitat piscícola.

La tortuga babaua (Caretta caretta) és una espècie amenaçada, que ha experimentat una greu reducció de les seves poblacions a nivell mundial. En aquest sentit, s’han identificat molts factors implicats en la mortalitat d’aquesta espècie però, de tots ells, el més significatiu és la pesca. En el cas del mar Mediterrani occidental, tradicionalment, la captura accidental de tortugues marines havia estat relacionada majoritàriament amb el palangre de superfície, i molts estudis han confirmat que és l’art amb més incidència al sud de la Península Ibèrica. Tot i així, s’han anat identificant altres arts de pesca que generen importants captures en determinades regions, com és el cas de les Illes Balears o el mar Adriàtic, on el tresmall de llagosta o l’arrossegament, respectivament, són els arts que generen més captures. En aquest context, la manca d’informació sobre l’impacte causat per la flota de pesca professional catalana va impulsar l’inici d’aquesta tesi, amb la intenció d’estudiar la seva interacció amb la tortuga babaua a Catalunya. D’aquesta manera, l’objectiu principal d’aquesta tesi és estimar la mortalitat generada per la pesca professional al mar Mediterrani occidental, així com avaluar el paper que té aquesta espècie dins el conjunt de l’ecosistema, de manera que es puguin fer paleses les conseqüències que comporta la reducció de les seves poblacions. Els resultats descrits en aquesta tesi, mostren una elevada interacció entre les tortugues marines de l’espècie Caretta caretta o tortuga babaua i la flota de pesca professional de Catalunya. El palangre de superfície i l’arrossegament són els arts més implicats en les captures accidentals de tortugues babaues, i el Delta de l’Ebre s’ha identificat com un punt crític per a la conservació per l’espècie en el litoral català. En concret, el palangre de superfície captura tortugues presents en zones pelàgiques i l’arrossegament tortugues de la plataforma continental, en ambdós casos tortugues babaues d’origen atlàntic i mediterrani, tot i que en proporció diferent segons l’àrea. A més, al Delta de l’Ebre, on trobem la plataforma continental més extensa de tot el litoral mediterrani espanyol, és on les captures per unitat d’esforç de la flota d’arrossegament són més elevades. A partir d’aquí, s’ha mirat de veure com reduir aquest impacte. En el cas de la captura en aigües oceàniques per palangrers de superfície, s’ha mirat d’avaluar la mortalitat dels animals alliberats vius, que en són la gran majoria. En el cas de la captura per barques de bou al Delta de l’Ebre, s’ha estudiat la distribució de les tortugues babaues en l’espai i el temps per mirar d’identificar estratègies que minimitzin la captura. Finalment, s’ha comprovat que la tortuga babaua no és l’únic consumidor de meduses a la Mediterrània ans al contrari, existeix un conjunt variat de depredadors oportunistes de meduses, tots ells espècies d’interès comercial, com la tonyina o el peix espasa. Per tant, també es proposen consells necessaris per a gestionar de forma efectiva les preocupants proliferacions de meduses a la Mediterrània occidental.<br>The loggerhead turtle (Caretta caretta) is an endangered species that has undergone a serious reduction of populations worldwide. In this regard, many factors involved in the mortality of this species have been identified, but from all, the most significant is bycatch due to professional fishing. In the western Mediterranean, where loggerhead is the most common sea turtle species, bycatch of sea turtles has traditionally been associated mostly with drifting longlines. However, several cent studies have identified other gears as significant sources of sea turtle bycatch, at least at certain regions within the Mediterranean. At the beginning of this thesis, nothing was known about the impact caused by the Catalan professional fishing fleet on sea turtles and hence this thesis aimed to estimate the mortality generated by professional fishing in the region, identify the relative importance of different fishing gears in sea turtle bycatch, asses the post-release mortality of bycaught turtles and identify methods to reduce the bycatch levels by bottom trawlers. Furthermore, this thesis aimed to test the hypothesis that a decline in the population of sea turtles because of high levels of incidental bycatch was the reason for recent jellyfish outbreaks.

La mortalitat per captura accidental en les pesqueres de palangre representa una de les principals amenaces per a nombroses espècies d’ocells marins a nivell mundial. En el Mediterrani, aquesta mortalitat esta afectant seriosament a la viabilitat d’algunes poblacions d’ocells, en particular de les baldrigues endèmiques d’aquesta conca. No obstant això, la informació disponible sobre la intensitat i extensió del seu impacte és escassa i fragmentada. Així mateix, encara no s’ha implementat cap tipus de mesura per evitar aquesta mortalitat. La present tesis pretén avaluar i contribuir al coneixement sobre la problemàtica de les captures accidentals d’ocells marins en la pesca de palangre de l’oest del Mediterrani, així com identificar l’estratègia de mitigació més adient per a la flota estudiada. En particular, l’estudi s’ha focalitzat en els palangrers de fons ja que fan servir arts més perillosos per als ocells i, a més, existeix una menor informació disponible. En primer lloc, aquest estudi demostra una elevada mortalitat d’ocells marins als palangres, en particular de les 3 espècies endèmiques de baldrigues: cendrosa (Calonectris diomedea), balear (Puffinus mauretanicus) i mediterrània (P. yelkouan), la qual cosa posa de manifest la necessitat urgent de desenvolupar accions efectives per reduir les captures accidentals d’aquestes espècies. A més, s’ha pogut identificar diversos factors temporals, operacionals, espacials i meteorològics que influeixen en el risc de captura accidental, encara que destaca particularment l’estació de l’any i el moment del dia que es realitza la calada. Altres factors influents són el tipus d’esquer, les condicions de vent, la configuració del palangre, el nombre d’hams calats i la distància a les colònies de cria. En segon lloc, s’ha observat que la falta de disponibilitat dels descarts proveïts per la pesca d’arrossegament incita a que les baldrigues cendroses acudeixin amb major intensitat als palangrers, incrementant així el risc de captura accidental. Consegüentment, la imminent normativa adoptada per la Unió Europea, la qual pretén prohibir els descarts, podria agreujar el problema de les captures accidentals. En tercer lloc, l’examen de les baldrigues capturades accidentalment als palangres demostra l’existència d’una mortalitat desigual a nivell poblacional. Els adults són la classe d’edat més afectada. Així mateix, existeix un biaix cap a un dels sexes que varia entre períodes de cria i espècies. També s’ha trobat que la mortalitat als palangres en l’àrea d’estudi està afectant fonamentalment a les poblacions locals (Illes Balears), encara que també són capturades baldrigues provinents d’altres colònies, especialment durant l’època de migració. Per últim, l’assaig de diversos mètodes de mitigació adaptats als palangrers demersals, demostra que, fins al moment, la calada nocturna seria el mètode més eficaç per reduir les captures accidentals sense afectar les captures objectiu o altres espècies no comercials quan la pesca va dirigida al lluç europeu. Tanmateix, seria necessari confirmar els seus efectes sobre altres espècies objectiu de la flota. A més, una restricció temporal de l’activitat durant els mesos més conflictius podria reduir considerablement aquesta problemàtica, encara que s’hauria d’avaluar els seus efectes sobre el rendiment pesquer. Altres mètodes serien l’increment de la taxa d’enfonsament del palangre o evitar l’ús d’esquers atractius per als ocells. Malgrat tot, la alta diversitat d’estratègies i arts de pesca dificulta la identificació dels mètodes que puguin ser aplicables al conjunt de la flota. Consegüentment, es recomana constituir un joc de diferents mesures de mitigació que puguin ser adaptades a la major part dels mètodes de pesca.<br>Bycatch mortality in longline fisheries is considered the main threat for numerous seabirds worldwide. In the Mediterranean, this mortality is seriously affecting the viability of some populations. However, the information available on the level and extent of its impact is scarce. Likewise, no mitigation strategy has yet been implemented in the fleet. The present thesis aims to asses and contribute to the knowledge about the seabird bycatch in longline fisheries of western Mediterranean, as well as to identify the most appropriate mitigation strategy for the fleet. The study has focused on demersal longliners, since they use the most dangerous gear for seabirds and also because there is little information available. This study shows a high seabird mortality on longlines, in particular of the three endemic shearwaters: Scopoli’s (Calonectris diomedea), Balearic (Puffinus mauretanicus) and Mediterranean (P. yelkouan), calling for urgent actions to reduce their bycatch rates. There are several factors influencing on bycatch risk, but the most important are the season and the setting time. Other influential factors are the bait type, wind conditions, longline configuration, proximity to the colonies and the number of hooks set. Moreover, in Scopoli’s shearwater, the reduction of discards by trawlers led to increased interaction between these seabirds and longliners, thus increasing the bycatch risk. Consequently, the incoming legislation that intends to ban discards will likely aggravate this problem. This study also shows adult- and sex-biased mortality in longline fisheries. In addition, this mortality is more pronounced but not limited to the local colonies. It appears that night setting would be the most effective method to reduce bycatch without compromising target or non-commercial species. However, this should be confirmed in longliners targeting species other than European hake. A temporal closure of the fishery is also a promising strategy, although its effects on fishing activity should be carefully evaluated. Others methods include increasing the longline sink rate and avoiding baits attractive to seabirds. The high diversity of strategies and gears hampers the identification of solutions applicable to the whole fleet. Consequently, it would be necessary to establish a set of different measures that can be adapted to the majority of fishing methods.

Las zonas costeras son uno de los ecosistemas que sufre mayor impacto antrópico a nivel mundial. La sobreexplotación de los recursos marinos es una de las actividades humanas que genera mayor impacto, reduciendo la abundancia y tamaño de las especies objetivo. Una de las medidas para proteger estos ecosistemas consiste en el establecimiento de áreas marinas protegidas. En Chile, el sistema actual de manejo de las pesquerías artesanales de especies bentónicas está basado en áreas parcialmente protegidas, las Áreas de Manejo y Explotación de Recursos Bentónicos (AMERBs), lo que ha supuesto una mejora en la sostenibilidad de una actividad de larga tradición en el país. Estas áreas entregan derechos de usos territoriales, conocidos mundialmente como TURF (sigla en inglés de Territorial Use Right for Fisheries). Sin embargo, actualmente estas áreas se gestionan de forma individualizada, de tal manera que la escala espacial de manejo no está acoplada a la escala de la dinámica de las poblaciones de invertebrados bentónicos. El objetivo de esta tesis es identificar áreas de alto valor para la producción, exportación y llegada de larvas en base a los patrones de historia de vida temprana, considerando variables y/o condicionantes relevantes de la fase adulta bentónica, como (a) la inversión reproductiva, (b) la densidad y talla de los adultos reproductores, variables determinantes de la distribución espacial de la producción de huevos y larvas, así como también variables que intervienen en la fase larval planctónica, como (c) los rasgos biológicos larvales, para acoplarlo con los patrones de circulación costera con el fin de contribuir a un mejor entendimiento de la dispersión y conectividad larval. Para este fin se seleccionaron dos especies relevantes social, comercial y ecológicamente: el erizo rojo (Loxechinus albus) y la lapa (Fissurella latimarginata). En primer lugar, se evaluó mediante muestreos de campo el efecto de la protección (relacionada con el régimen de explotación) y afloramiento costero sobre la inversión reproductiva y la condición individual de los adultos reproductores. Esta información sumada a los datos empíricos de distribución de tallas, densidad de individuos y fecundidad de las hembras reproductoras se utilizó para desarrollar un modelo de producción potencial de huevos en la costa central de Chile. Para el estudio del reclutamiento y dispersión se desarrolló un modelo biofísico de dispersión larvaria que permite evaluar el efecto de la variabilidad oceanográfica y los rasgos biológicos (migración vertical de las larvas y desarrollo dependiente de la temperatura) en la distancia de dispersión, el éxito del reclutamiento, y los patrones de conectividad larval. Los resultados sugieren que, para ambas especies, la protección y el afloramiento costero no tienen un efecto sobre la inversión reproductiva y la condición de los individuos. Sin embargo, la protección sí tuvo un efecto sobre la talla y densidad de individuos generando claros patrones espaciales de producción de gametos. Se observó que la variación geográfica y temporal de los procesos de circulación dominaneltransportey la dispersióndelas larvas enlaregión, independientemente de los rasgos biológicos evaluados. La mayoría del reclutamiento fue alóctono, con niveles bajos de auto-reclutamiento y retención local, incluso para la especie con un tiempo de vida planctónica corto (F. latimarginata). Los patrones geográficos de salida y llegada fueron similares para ambas especies, observándose una mayor importancia relativa de la región norte del dominio de estudio. Estos resultados permiten identificar los principales determinantes de la producción de huevos, el éxito del reclutamiento y la distancia de dispersión para dos especies de gran interés comercial en Chile, información que podría guiar recomendaciones para el manejo y la conservación en una de las regiones costeras más productivas pero también más explotadas del mundo.<br>Coastal zones are one of the ecosystems receiving higher anthropic impact. Fishing is a major source of human impact, reducing density and size of exploited species. Marine protected areas are one of the strategies established to control fishing impacts. The current artisanal fisheries management system in Chile is based on partially protected areas, TURFs (Territorial Use Right for Fisheries). This system enhances sustainability of one of the traditional activity in the country. However, these areas are individually managed so the scale of resource management is not coupled with the scale of exploited population dynamics. The objective of this thesis dissertation is to identify areas of high value for propagule production as well as source and sink areas based on early life history patterns, considering variables relevant for the adult phase such as (a) reproductive output, (b) density and size of reproductive adults as both variables define the spatial distribution of eggs and larvae, as well as variables that affect the larval phase such as (c) larval biological traits, coupling these pieces of information with coastal circulation models to reach a better understanding of dispersal and larval connectivity. Two benthic invertebrates species exploited by artisanal fisheries in Chile, the red sea urchin (Loxechinus albus) and keyhole limpet (Fissurella latimarginata) were used as models. First, I evaluated the effect of protection and coastal upwelling on reproductive output and individual condition of reproductive adults. Based on size distribution, density of individuals and fecundity data I developed an egg production model along the central coast of Chile. Finally, I developed a biophysical larval dispersal model to assess the effect of oceanographic variability and larval biological traits (larval diel vertical migration and temperature-dependent larval development) on dispersal distance, recruitment success and connectivity patterns. These results showed that fishing regime and coastal upwelling did not affect individual reproductive output either individual condition for both species. However, fishing regime had an effect on size and density of individuals. I found that the geographic and temporal variation in circulation processes dominate transport and effective dispersal of larvae in the study region, regardless of larval biological traits. Most recruitment to local population was allochthonous, with low levels of self-recruitment and local retention even for the species with short planktonic larval duration. Similar geographic patterns of source and destination strengths were observed in both species, with the northern region of the studied domain showing relatively higher importance. These findings allow identifying primary determinants of recruitment success and dispersal distance for two important exploited species in Chile, and to provide the bases to advance recommendations for management and conservation in one the most productive, but also exploited, coastal regions in the world.

碩士<br>國立高雄海洋科技大學<br>輪機工程研究所<br>98<br>This thesis adopts three kinds of fishing-boat fuels to test in the real ship with the oil, the test of the new prescription uses the oil in current Fish-Boat-Fuel-A(FBFA) that uses separately in add different proportion viscous agents, they are 0.5% of Pyrolysis-Fuel-Oil (PFO0.5) and 0.5% of Residue Desulfurization System (RDS0.5). This research sails and tests at sea actually with the diesel engines of three real ships, as to this three kinds of tests carry on actual quantity to examine with the oil , observe its engine and operate the situation separately, the state and speed of sailing that and note down oil consumption , horsepower output. In addition, the discharge thing sampling in the flue, the difference of the particle that analyse it of comparing to diesel engine performance of fishing boat and exhaust. The testing three kinds of new prescription in real ship trial shows with the result of the oil , operate performance in the engine, have not unusually found shaking and noise , the horsepower state is close that exert oneself, and the oil consumption rate of the new prescription is similar to FBFA for same ship. Analyse from the pollutant that the content of PM (the granular thing) shows, the content of RDS0.5 is lower than FBFA, can study and judge the wearing and tearing that RDS0.5 will not cause engines more. Another learnt , regard RDS0.5 as the engine of the fuel oil by the analysis result of the pollutant , in pollutant CO, in CO2 , NOx , PM , PAHs, only CO is higher than FBFA slightly, but its CO discharging value has not exceeded the American Environmental Protection Agency (EPA) exhaust emission standard value permits the range.

Lee Yee Chak Raymond.<br>"Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 1996-97, design report."<br>Includes bibliographical references.<br>Chapter 1. --- Introduction<br>Chapter 1.1 --- Design Objectives<br>Chapter 1.2 --- Problem Defined<br>Chapter 1.3 --- Description of Client & Users<br>Chapter 1.4 --- Mission and Goals<br>Chapter 2. --- Project Analysis<br>Chapter 2.1 --- Site / Context Analysis<br>Chapter 2.1.1 --- Location<br>Chapter 2.1.2 --- Climate<br>Chapter 2.1.3 --- Special Studies: Natural Ventilation<br>Chapter 2.1.4 --- History -- Sequence of the Settlement<br>Chapter 2.1.5 --- Development of Tai O<br>Chapter 2.1.6 --- Site Analysis Diagram<br>Chapter 2.2 --- Client / Users Analysis<br>Chapter 2.2.1 --- Functional Relationship<br>Chapter 2.2.2 --- Activities<br>Chapter 2.2.3 --- Social Pattern<br>Chapter 2.2.4 --- Organizational Hierarchies in Stilt Homes<br>Chapter 2.2.5 --- Schedule of Accommodation<br>Chapter 2.3 --- Subject Analysis<br>Chapter 2.3.1 --- Architectural Language<br>Chapter 2.3.2 --- Precedents<br>Chapter 3. --- Process<br>Chapter 3.1 --- Organization & Zoning Period<br>Chapter 3.2 --- Conceptual Stage<br>Chapter 3.3 --- Schematic Design<br>Chapter 3.4 --- Design Development<br>Chapter 3.5 --- Design Deveopment I<br>Chapter 3.6 --- Design Development II<br>Chapter 4. --- Final Project<br>Chapter 4.1 --- Settlement Design in 4 Level<br>Chapter 4.2 --- Site Planning<br>Chapter 4.3 --- Methodology: Diagram of Dwelling Units Formation<br>Chapter 4.3.1 --- Resident's Requirement<br>Chapter 4.3.2 --- One Man in Tai O<br>Chapter 4.4 --- Cluster Level<br>Chapter 4.4.1 --- Cluster<br>Chapter 4.4.2 --- Activites in the Cluster<br>Chapter 4.4.3 --- Cluster Level<br>Chapter 4.5 --- Open Space Level<br>Chapter 4.6 --- Details & Construction<br>Chapter 4.7 --- Special Studies: Material<br>Appendix<br>Programming report<br>Schedule of Work<br>Bibliography

碩士<br>國立高雄海洋科技大學<br>輪機工程研究所<br>106<br>In this paper, a vertical single cylinder four-stroke diesel engine unit is used as the experimental machine, and the current domestic common oil for fishing boats is used as fuel. the oil for fishing boats a is combusted and the oil for fishing boats a is mixed with nano-sized scientific and technological fuel additives in proportion ( 0.5 %, 1 %, 1.5 %, 2 % ). Physical properties such as exhaust gas temperature and residual oxygen content of diesel prime Mover combustion exhaust gas are measured under four different horsepower loads. The test results can understand the exhaust gas emission situation under four different load conditions when different proportions of combustion exhaust gas are added. Aiming at the physical and chemical conditions caused by burning a fishing vessel oil and adding different proportions of liquid nano-technology fuel additives to the diesel prime Mover. The measurement results show that the content of carbon monoxide, carbon dioxide and nitrogen oxides in the exhaust of diesel prime Mover and the external characteristics will not produce better results due to the increase in the amount of liquid nano-technology fuel additives contained in the first kind of fishing oil. Through experimental observation and analysis, it is known that the exhaust emission from the combustion of liquid nano-technology fuel additives after being added to diesel oil can have a specific improvement effect on air pollution, depending on the correct proportion of additives used in an appropriate load range, so as to produce a certain degree of reduction effect on the above three exhaust combustion products harmful to the earth, which can be used as a reference for the selection of additives in the future.

This dissertation consists of analyses of a series of common pool resource experiments that I designed and conducted in three regions of Colombia with individuals who face similar dilemmas in their everyday lives as those faced in the experiment. The objectives are to develop an empirical characterization of how individual behavior deviates from purely self-interested Nash behavior, and to further our understanding of the effects of alternative institutions to promote more conservative choices in common pool experiments. The results of this dissertation are organized in three essays. The first essay, What Motivates Common Pool Resource Users?, develops and tests several models of pure Nash strategies of individuals who extract from a common pool resource when they are motivated by combinations of self-interest, altruism, reciprocity, inequity aversion and conformity. The experimental data suggest that a model that balances self-interest with a strong preference for conformity best describes average strategies. The data are inconsistent with a model of pure self-interest, as well as models that combine self-interest with individual preferences for altruism, reciprocity and inequity aversion. The second essay, Communication and Regulation to Conserve Common Pool Resources, tests for complementarities between formal regulations imposed on a community to conserve a local natural resource and non-binding verbal agreements to do the same. The experiments suggest that formal regulations and informal communication are complementary in some instances, but this result is not robust across regions or regulations. Therefore, the hypothesis of a complementary relationship of formal and informal control of local natural resources cannot be supported in general; instead the effects are likely to be community-specific. The third and final essay, Within and Between Group Variation in Individual Strategies in Common Pools, analyzes the relative effects of groups and individuals within groups in explaining variation in individual harvest decisions for particular institutions, and examines how these sources of variation may vary across institutions. Communication serves to effectively coordinate individual strategies within groups, but these coordinated strategies vary considerably among groups. In contrast, regulatory schemes (as well as unregulated open access) produce significant variation in the individual strategies within groups, but these strategies are roughly replicated across groups so that there is little between-group variation.

碩士<br>國立臺灣海洋大學<br>海洋生物研究所<br>100<br>The present study used the catches of mega-crustaceans from the commercial fishing boats in the deep-sea fishing port Dasi to investigate the appropriate experimental design needed to understand the community structure of a high deep-sea biodiversity area. Extensive collections were conducted in three time periods with hot and cold seasons. Altogether 100 collecting events were conducted, with each collecting event last from 1:30pm to 4:00 pm and not interrupted for more than three working days of the fishing boats there. A total of 55 families, 150 genera and 285 species mega-crustaceans have been collected. Representative sampling was only achieved after 40 times of collecting events in hot season and 26 times was needed in cold season. Moreover, there are significant differences in the species compositions between the cold and hot seasons. Comparison with the data from previous studies in the catches of Dasi fishing boats backed to 1981 showed that altogether 74 families, 216 genera and 443 species of mega-crustaceans are known from there. Furthermore, catches during summer are most important in understanding the species composition there. ANOSIM, CLUSTER and nMDS analyses all suggested that the community structure can be divided into two main groups by the year 2000. Trajectory graph revealed that the mega-crustacean community structure is changing with fishing pressure, and marked difference in dominant species were observed before and after the year 2000 from SIMPER analysis. Analysis of taxonomic distinctness showed that the number of species increased with time but with the complexity in community structure becoming more simple. The present results demonstrated again that rare species play a key factor in the understanding of the community structure in areas with high biodiversity.

The objective of this was study was to determine if species specific fishing could produce "cultivation-depensation effects" in an aquatic ecosystem with two predatory, competing fish species. I identified a unique stock of northern pikeminnow living in series of connected lakes that has obligatory rearing in specific nursery lakes; developed two novel likelihoods to measure the growth, movement and mortality responses; developed an ecosystem model to predict how the system would respond to fishing, and finally, compared the ecosystem modeling predictions to observed responses. My research showed northern pikeminnow in South Central B.C. have obligatory rearing in specific nursery lakes then disperse to other lakes as adults. I argue that this large scale spatial ontogeny can be solely explained by temperature cues to spawn and that the distribution of adults is determined by density-dependent dispersal that equalize very large productivity and effective density differences between lakes. I showed that in spite of being included in many stock assessments, and being used as proxies for natural mortality estimates and for exploitation rate targets, von Bertalanffy growth parameters are not generally estimated correctly. The data used to do so are virtually always biased due to: size-selective gears, populations subjected to fishing and natural mortality and in some cases, size-dependent movement. I developed two new likelihoods to simultaneously estimate growth and mortality parameters: one for length-age data, and another for mark-recapture data. The first performs well across a range of recruitment anomalies and steady state fishing mortalities but fails when fishing rates have been variable (especially increasing) and when gear selectivity is dome-shaped. The second likelihood works well with simulated data but is not robust to assumptions of constant recruitment and measurement error being violated. I combined length-age and mark-recapture data to show using simulated sampling that it is possible to simultaneously estimate growth, mortality, and movement parameters where sufficient numbers of fish are observed moving. The assumptions required for these models to perform well are very restrictive. I used a simple ecosystem model and compared the predictions to observed responses following depletion fishing in two-fish lake systems with rainbow trout and northern pikeminnow. Consistent with model predictions, growth was slower and mortality of juvenile rainbow trout higher relative to the control in lakes where northern pikeminnow were removed, while adult rainbow trout survival remained unchanged. Visual survey indices of northern pikeminnow fry indicated survival of 1+ fish worsened and 2+ improved following fishing. Consistent with model predictions, no obvious mortality or growth responses were observed in adult fish in either rainbow trout or northern pikeminnow removals. While the agreement between the model and observations was encouraging, field testing such complex predictions was fraught with difficulty. The probability distributions of the parameters of interest were very broad. Also, the model predicts that survival and behavioral dynamics producing the greatest differences in direction and magnitude of ecosystem response occur in size classes of fish and groups of zooplankton that are difficult to observe. It was not possible to conclude whether an alternate state was produced through cultivation-depensation effects. To do so would require longer term data on recruitment responses, vulnerability exchange processes and survival data of young age classes of fish. This study identifies several shortcomings in our ability to predict and detect how ecosystems will respond to fishing. First, our ability to measure even simple response variables such as growth and mortality is not good. Secondly, even if we could, the direction and magnitude of these responses can be highly counter-intuitive. Finally, those processes with the most violent effects on our predictions are those for which we have very little information, namely dynamics determining the spatial distribution of the stock, the dynamics of young fish and behaviorally mediated predation rates.<br>Science, Faculty of<br>Zoology, Department of<br>Graduate

碩士<br>國立交通大學<br>土木工程系所<br>94<br>The paper develops a non-invasive image system to measure the cover rate of marine algae on bricks with wavy or coarse surface under different light illumination. The tidal pool beside the Lin-Shan-Bi fishery harbor is chosen as a research base to study the environmental factors affecting algae growth. Habitat suitability index (HSI) is figured out for the environmental factors and is used to establish a habitat suitability model. The proposed model can be applied to estimate the growth of marine algae in the northern Taiwan waters. The properties of seawater are slightly different from four seasons and all observed positions. High relationship between the cover rate 25% of marine algae and temperature, salinity, and soak time of a brick is connected to establish a habitat suitability model. The cover rate predicted by the proposed HSI model shows accurately agreement with real one by a high correlation coefficient of 0.74. It is assumed that the water quality conditions in all pools are controlled to be almost invariable by air condition and a circulated system in the indoor experiment. The initial growth of marine algae during the first 1-40 days highly depends on the relative light strength. Therefore, mean leaf length of marine algae can be expressed by the exponential function that can give a high prediction to mean leaf length by a relative correlation coefficient over 0.94. The increase rate of growth of marine algae exponentially decays with time. The empirical expression in form of negatively exponential function has a good prediction to the increasing rate by a relation coefficient more than 0.92. A linear relationship between mean growth rate of marine algae and relative light strength was obtained to have a correlation coefficient of 0.96. Considering both the light strength and natural growth of marine algae the resulting empirical formula can provide a good calculation on mean leaf length by a correlation coefficient over 0.95.

碩士<br>國立高雄海洋科技大學<br>輪機工程研究所<br>104<br>This experiment by vertical single cylinder four stroke diesel generator set as the experimental machine, and use the current domestic general type of fishing boats as diesel engine fuel. Oil type by burning oil for fishing vessels and fishing boats oil mixed pure ethyl ether, according to the proportion (0.5%, 1%, 1.5%, 2%) mixed way. In the four kinds of resistive loads measuring the physical properties of exhaust gas temperature and burning diesel engine exhaust product quantity and remaining oxygen content. Test results can understand the four different load conditions, different ether added, four type combustion boat pure ether of diesel oil and adding different ratios of prime mover caused by physical and chemical conditions. Explore ether added to diesel oil to the improving effect of air pollution, and the choice of additives for the future reference.

碩士<br>國立東華大學<br>海洋生物多樣性及演化研究所<br>101<br>The biodiversity of crustacean and appropriate experimental design were investigated by using the catches of mega-crustaceans from the commercial fishing boats in Donggang fishing port from Oct. 2011 to Oct. 2012. After examined the specimens, there are 281 species belong to 127 genera and 52 families , including 115 species in macrura, 102 species in brachyuran, 37 species in anomura and 27 species in stomatopod. Representative sampling in family level for whole data was achieved after 46 times of collecting events but need more in species level. In winter season, 19 times of collecting events was achieved for family and genus level and 20 times was needed for family level in summer season. More than 28 times may be achieved representatively for species level in both seasons. The data set of Donggang collection was analyzed with combination of the data from Dasi, Kueishan Island, Tosa bay, Suruga bay and Sagami bay. The nMDS and Cluster analysis shows that fishing port in southern and northern Taiwan was belong to different group and Tosa bay, Suruga bay and Sagami bay were in the same group. TAXDTEST analysis shows that the biodiversity in winter season is higher than summer season but summer season has higher biomass. ANOSIM analysis shows that the structure of crustacean composition was significant different between Taiwan and Japan (ANOSIM, global R=0.899).