Aquaculture facilities have been demonstrated to emit massive quantities of waste that incorporates in to the surrounding water column, effectively altering patterns and processes of nearby marine communities. Given that products from aquaculture is heavily relied upon to meet global fisheries demands, understanding its effects is essential to inventing less harmful practices. This research examines one such facility located in Kyuquot, British Columbia. The purpose of this thesis is to spatially and temporally measure the degree and magnitude of integrated multi-trophic aquaculture (IMTA)-derived organic waste as a potential subsidy to adjacent marine communities. Stable carbon and nitrogen isotopes analysis was applied to intended extractive organisms (sablefish Anoplopoma fimbria, Pacific scallops Patinopectin caurinus, blue mussels Mytilus edulis, sea urchin Strongylocentrotus franciscanus, sea cucumber Parastichopus californicus, kelp Saccharina latissima), epibiont biofouling species (brooding transparent tunicates Corella inflata, hairy tunicate Boltenia villosa, broadbase tunicates Cnemidocarpa finmarkiensis) as well as fish feed and sablefish faeces. Stable isotopes of blue mussels and brooding transparent tunicates sampled from both the IMTA and a reference site were compared in order to examine spatial influence of IMTA-derived waste. IMTA site sampled mussels exhibited the most enriched and least variable values among all four sample groups. Brooding transparent tunicates exhibited the most isotopic variability which demonstrates that IMTA-derived waste is not among the most important food source available. This is corroborated by the three-source mixing model results. Only sablefish isotopic signatures were measured to be more enriched than those of fish feed and fish faeces. Isotopic mixing models were employed to all IMTA samples and found that IMTA effluent signatures were proportionately higher in their diets than averaged marine particulate organic matter (POM) signatures taken from the literature. Mixing model results also showed IMTA effluent to be proportionately less than marine POM. Circular statistical results did not demonstrate particular directional change for all IMTA sampled isotopic signatures which could be due to the consistent nature of available fish feed throughout the year and/or perhaps feeding choice changes constantly. Further examination into the monthly physical properties of this region (eg. rainfall, irradiance) as well as measurements of marine POM signatures would greatly compliment these results and are recommended for future study. / Graduate

The breakdown of reproductive isolation leading to inter-specific hybridization is a widespread phenomenon amongst cyprinid fishes. There are seventeen cyprinid species occcurring in the British Isles, within five sub-families, giving rise to some ten different types of hybrid. Most of these belong to the sub-family Leuciscinae. The most commonly occurring hybrids are probably those between roach, Rutilus rutilus (L.), and common bream, Abramis brama (L.). In this study the phenomenon of hybridization amongst species of the Cyprinidae was investigated through: an experimental breeding programme to investigate the nature of inter-species and hybrid gamete compatibilities; the identification of species and hybrids from the experimental breeding programme through the analysis of morphometric, meristic and genetic characters (genetic characters were analysed using enzyme electrophoresis); the comparison of morphmetric, meristic and genetic information of natural fish with similar features of fish from the experimental breeding programme to identify the occurrence of post Fl hybridization in natural populations; the use of restriction enzyme analysis of mitochondrial DNA to elucidate the importance of maternal ancestry in a natural hybrid population. The breeding programme found, for the species in this study, that there was no success in cross-fertilization of taxa between different sub-families. Interspecific gamete compatibility was only found within the leuciscine sub-family. In cases where a hybrid cross produced progeny it was also noted that the reciprocal cross was successful. This suggests that there is not a genetic barrier to gamete compatibility resulting from the sexual directionality of a hybrid cross. Female roach/common bream hybrids also produced progeny when crossed with males of leuciscine species. Identification of the progeny of the experimental breeding programme showed that the genetic techniques of enzyme electrophoresis was more reliable than the statistical analysis of meristic and morphometric traits in the identification of species and their Fl hybrids. However, genetic information alone cannot establish precisely the nature of post Fl hybrids and in the identification of backcrossed roach/common bream hybrids it was noted that meristic information was needed to support genetic data. In the two natural hybrid populations of roach/common bream and rudd/common bream, from the Forty Foot Drain and Essex University Lake respectively, the analysis of morphometric, meristic and genetic characters found no evidence of post Fl hybridization in these waters. It is suggested that absence is due to either the limitations of the sampling methods or biological processes. Possible biological processes include factors such as the inappropriate mating behaviour of Fl hybrids or the inferior fitness of post Fl hybrids. The analysis of mitochondrial DNA did not yield sufficient results to elucidate the importance of maternal ancestry in hybridization. It is suggested that this aspect of hybridization is of such critical importance that it must become the subject of a future research programme. The importance of the causes and consequences of inter-specfic hybridization in fishes are discussed. It is suggested that, because they are rarely investigated in hybrid studies, these become incorporated into research programmes in the future. These areas of investigation will have implications for fisheries management, freshwater ecology, genetic conservation and species integrity.

Overexploitation of many fish stocks underlines the need for more effort directed towards stock management so that the sustainability of resources is assured. To avert the tragic consequences of overfishing in coastal waters, a growing body of theoretical and empirical research provides evidence in support of cooperation among resource users to manage their commons. This study aimed to investigate the factors that contribute to the emergence and evolution of collective action in fishermen's communities to manage their coastal fish resources in South Al-Batinah, Sultanate of Oman. The study emphasises the importance of a collective action approach to fish resource management with examples from three fishing towns.In order to understand why fishermen choose to participate (or not to participate) in local collective action to manage fish resources, the researcher focuses on six main sets of issues that influence fishermen's decisions: economic factors; awareness of resource exploitation problems; institutional rules in use; social identity, group size and heterogeneity among resource users. Social and demographic factors as well as vessel configuration were also considered.Data collection for the study was carried out using three methods: questionnaire, semi-structured interview and observations of fishermen's activities. Statistical reports and other research papers carried out in Oman were also reviewed. The study found that there is a management institution that governs the fishing activities of the fishermen in the study area. Fishermen in the area inherited an indigenous management institution, which was established hundreds of years ago. It was also found that fishermen were very aware of the resource exploitation problems. High awareness of the resource exploitation problems coupled with high interdependence among users might induce them to work collectively to mitigate harm to their long-term welfare.The results of testing a number of hypotheses indicated that among the reasons which may influence collective action, are high economic dependence on the fishery,individuals' social identity as fishermen, awareness of the resources exploitation problems, risk aversion and heterogeneity (differences in objectives and interests).The study findings indicated that individuals using common resources are faced by various "assurance" and "chicken" problems. In both the PD game and the Assurance game, the preferred outcome is mutual cooperation. Whereas the predicted outcome of the former is defection, the latter suggests the possibility that the preferred outcome (i.e., cooperation) will occur, because individuals' decisions in the commons are influenced by a complex set of factors, rather than strictly materialistic self-interest. The analysis presented in this study examined several of those factors for their influence on individual behaviour. The findings of this study strongly suggest that the presence of local management institutions to coordinate the fishermen's activities in the study area is the key factor in avoiding the worst outcome (universal defection). The game structure has been changed from a Prisoner's dilemma to a Privileged game or a game of Chicken where the benefits from cooperation are maximized. It is the role of the institutions to determine how the cost of providing the public goods might be shared among participants.

The dynamics of demersal fish species assemblages and stocks on the continental shelf of Ghana, West Africa were investigated using data from trawl surveys conducted between 1963 and 1990, and in relation to marine environmental and nearshore forcing factors. Time series analysis was used to examine the dynamics of the marine environment. Classification and ordination methods were used to identify fish assemblages and to identify factors that determine assemblage formation and dynamics. The response of the identified assemblages to changes in the Ghanaian shelf ecosystem were assessed. Between 1964 and 1992, three distinct environmental time blocks (ETBs) in the continental shelf ecosystem off Ghana were recognised. In the first ETB (i. e. before 1972) sea surface and bottom temperatures were relatively high and salinity was low. The second ETB (1972 - 1982) was characterised by low temperatures, high but stable salinity, reduced rainfall and freshwater input into the sea. In the third ETB (1982 - 1992), the system bore a resemblance to the first block with rising temperatures and decreasing salinity. Six fish species assemblages were identified, namely the supra-thermocline sciaenid and lutjanid assemblages, two sparid assemblages (shallow and deep elements), the deep shelf assemblage and the upper slope assemblage. During ETB I and ETB3, the assemblages were easier to identify using ordination techniques, than during ETB2. Species diversity also decreased during ETB2 especially in waters between 10 and 50 m deep. This behaviour of the assemblagesis attributed to the increase in abundance of Balistes capriscus, a species that dominated the ecosystem for nearly 20 years from about 1971, and the observed environmental changes. The estimated density of demersal fish was higher in the upwelling season than in the thermocline season and decreased from 50 kg ha-1 in 1963-64 to 32.4 kg ha-1 in 1990. The density reached its lowest value of 22.5 kg ha-1 in the period between 1973 and 1977. The potential yield of the total demersal biomass (excluding triggerfish) is estimated to be 36,000 - 55,000 mt per annum. With landed catches exceeding 60,000 mt in some years, it is apparent that the resource is over-exploited. A number of policy options are discussed and recommendations for the management of the fishery are made.

No description available.

Aspects of oxygen consumption and bioenergetics of the Atlantic halibut (Hippoglossus hippoglossus L. ) were studied under laboratory conditions. Resting oxygen consumption rate was monitored over 36 hour periods in Atlantic halibut while held individually in open system respirometers. Routine oxygen consumption rate was determined in small populations of tank held Atlantic halibut over 24 hour periods, through modification of tank systems as open system respirometers. Values for resting and routine oxygen consumption in this species were quantified and models Produced enabling the prediction of the energetic cost of homeostasis and spontaneousa ctivity for a range of fish size from 53g to 5861g, at temperatures of 6, 10 and 14°C. These results were ftirther used to form the basis of an energy budget equation for this species. PhotoPeriod influences on the periodicity of respiratory rhythm in both resting and routine oxygen consumption trials were determined through analysis of data recorded throughout the 24 hour daily period. The results indicated a cyclic respiratory rhythm, with peak oxygen consumption often observed nocturnally. The relevance of these results to culture of this organism are discussed. Post-prandial oxygen consumption and ammonia excretion were measured in small populations of tank held Atlantic halibut, these results contributing further information to the partitioning of energy within the metabolic and excretory components of the energy budget equation. Values for resting, routine and postprandial oxygen consumption in the Atlantic halibut were found to be low in comparison to roundfish species, but corresponded closely with literature data produced for other species of temperate marine flatfish. Activity patterns in small populations of Atlantic halibut were monitored over 24 hour periods in a specially constructed film unit. The results of this work showed dualistic patterns of activity over the diurnal cycle. Further elucidation of the energy budget was achieved through the determination of the metabolic costs of activity in the tank environment. Atlantic halibut were observed to remain at rest for periods of between 76% and 94% of any 24 hour period, with the time at rest dependent on fish size and stocking density. One 28 day trial was undertaken in which the components of the energy budget were measured simultaneously, and the balance of the budget investigated. Oxygen consumption, ammonia excretion, growth, feed consumption and faecal production were monitored within a purpose built experimental unit, and these values finther applied to the construction of an energy budget model. Finally, the oxygen consumption data of this study was ftirther applied to produce a model quantifying the water requirements of this species in a single-pass tank system, for the intensive culture of this species in the tank environment. Further development of these figures allowed the quantification of the pumping costs in an Atlantic halibut ongrowing tank system, and these figures were incorporated into a simple economic model. The results present some of the first bioenergetic data produced for this species, and this is an important step towards the development of an Atlantic halibut farming industry.

The main aim of this thesis was to study intra- and inter-specific competition among juvenile Atlantic salmon and brown trout. The study concentrated on two critical times for survival: first, the period from shortly after emergence until later in the summer when individuals first establish territories; and second, during the winter, when many salmonid populations experience a bottleneck. In addition, the stability of social hierarchies and the influence these have on growth and survival were studied on older individuals in the summer. Experiments were carried out in a variety of conditions ranging from small arenas and artificial stream channels where behavioural interactions among fish could be observed, to the wild where it was possible to test inferences derived from laboratory observations in an ecological context. Both salmon and trout are known to undergo a behavioural shift in winter, switching from being primarily diurnal during the summer to being predominantly nocturnal in winter. Atlantic salmon and brown trout forage in slow-flowing water at night and shelter in interstitial spaces in the substrate during the day. This thesis shows that salmon and trout compete for both foraging (chapter 2) and sheltering (chapter 3) habitat in winter, illustrating that competition between the two species is not restricted to the summer months. Trout were shown to dominate salmon in competition for foraging habitat, forcing them to move into shallower water or become more diurnal (chapter 2). Intra- and inter-specific competition for shelters was equal in intensity and more dependent on arrival time (prior residency) than species identity (chapter 3). This competition could have short- and long-term survival consequences for over-wintering fish, particularly Atlantic salmon, and have implications for the carrying capacity of streams.

A fifteen-year plan has been developed for cobia (Rachycentron canadum) aquaculture in Brazil. Guidelines are recommended for implementing reachable goals within a reasonable time frame, taking into consideration current status of technology development, environmental parameters, logistics and market. This plan reports potentialities, constraints and outlines the infrastructure and operational needs of a vertically integrated (hatchery and growout) cobia aquaculture industry in Brazil. Fingerlings availability, manpower, feeds among others essential requirements are evaluated and discussed. A pilot-scale operation plan including risk and financial analysis is also presented for the early development stages of the project. Asian countries, especially China, Taiwan and Vietnam, where approximately 50,000 tons are produced per year, currently dominate cobia aquaculture. Although production is expanding rapidly, combined yielding is still incipient. By 2025, an increasing global population is expected to raise seafood demand on 37% (FAO, 2010) and this plan is intended to profit from it. Therefore, the aim is to supply 2.5% of the global aquaculture marine fish demand by 2025, which will be approximately 66,750 tons of cobia per year according to our projections.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1994. / Includes bibliographical references (leaves 198-210). / Microfiche. / xii, 210 leaves, bound ill. 29 cm

No description available.