The decrease in wild fish stocks has led to a search for novel feed sources to supply the aquaculture industry. Polychaetes have recently been identified as suitable feed ingredients due to their favourable nutritional composition, especially their lipid profile which is high in unsaturated fatty acids. As ragworm farms have started to develop, there has been a need to understand and improve rearing techniques, in particular the dietary requirements and nutritional profile of the ragworm. In this thesis, research was focused on the king ragworm. Nereis virens. The protein and energy requirements were identified by increasing inclusion levels of nutrients in the diet as well as manipulating feed rations from starvation to satiation. Weight gain, survival, ingested feed as well as protein and energy retention efficiencies were evaluated. Results demonstrated that N. virens gained a proportional amount of nutrient in relation to the amount ingested up to a critical amount when gain either stagnated or decreased. A pattern of nutrient retention and maintenance requirements for different weight classes were calculated. This data was then used for bioenergetic modelling to calculate nutrient requirements using the equation: Requirement: a x BW (g) + c x growth The energy maintenance requirement was found to be 18 J g-1 worm day-1; for protein, the requirement was 0.19 mg g-1 worm day-1. The predicted weight gain (g) for a worm of any given size (g) was y = 0.015g1.106. The total nutrient requirement is the sum of maintenance and growth, including the constant c which is the cost of nutrient deposition. Alternative feed sources were also investigated to observe the extent at which N. virens can utilize novel sources and their abilities to preserve or convert highly unsaturated fatty acids such as EPA and DHA. Results showed a high adaptability to terrestrial animal or vegetable based feed sources but an inability to convert shorter chain or n-6 fatty acids when fed non-marine based feeds. There may however be potential for N. virens to utilize other feed sources from its natural environment to supplement n-3 HUFA content.

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The development interventions of the past thirty years have relied on microcredit and other microfinancial services as a way to include the poor in the dynamics of the free market, so they may have a better chance of benefiting from economic development. Nowadays, the microfinance industry in Bolivia is highly developed, and the country is usually mentioned next to Bangladesh and India as a success case of microcredit, as a myriad of microfinancial institutions operate combining credit, savings and insurance with education, women empowerment or production efforts. In this setting, the Peces Para la Vida II project was started in Bolivia in early 2015, with the objective of improving food security in Bolivia through the promotion of small-scale aquaculture and fisheries in the Bolivian Amazon. As a part of this promotion strategy, a microcredit component was included in the project with the intention of scaling up the benefits found in the first stage of the project via an individual microcredit component and a group microleasing operation. Using a qualitative application of an analytical framework that combines Amartya Sen’s capability approach and the Department for International Development’s sustainable livelihoods approach, this thesis will argue that unless certain conditions on access to markets that enable savings and wealth creation are met, individual microcredit alone may not be sufficient to lead its users towards capabilities that ultimately improve their access to better endowments of various types of capitals, and that the group leasing operation appears to be more promising in terms of allowing those involved as it tackles productivity and market issues simultaneously, but with an implementation plagued with problems and the short time the operation has been underway, it would be premature to be definitive about these results. / Graduate

The need for developing a dry feed which satisfied the nutrient requirements of Oreochromis mossambicus fry was identified. The spawning and grading techniques which resulted in a higher fecundity and ensured uniformity within and between samples of fry are discussed. Preparation techniques were developed which met the physical requirements of fry feeds. An analysis of the flesh and yolk sac fry for amino acid composition was undertaken. The initial test diet was based on these results, as well as on the natural feeding ecology of the species. Feeding trials were undertaken and growth responses monitored to determine the optimum levels of the various dietary components. A feed was developed which gave superior growth to that obtained with natural food organisms. This feed consisted of Torula yeast (47%), Weider Super Protein (44.39%), Vitamin supplement (0.45% - multivitamin), additional vitamin C supplement (0.16%), Spirulina (5%), and methionine supplement (3%). An optimum particle size range for O. mossambicus fry (between 5 & 25mm) was established at 125-200um. The fry should be fed the following feed ratios depending on age: 30.4% body weight/day up to day 5, 30.6% body weight/day up to day 10 and 25.1% body weight/day up to day 15. An optimum feeding frequency of 8/10hr day was recommended. A feed conversion ratio of 1.24:1 and a protein efficiency ratio of 0.682:1 was obtained. Digestable energy of the feed was determined at 16.1 kj/g feed. The established dry feed is suitable for use in commercial hatcheries, and as a formulation for further research on the intensive rearing of O. mossambicus fry.

This thesis presents research on an alternative spatial-temporal method of fish stock assessment. We develop a simulation model of spatial-temporal stock analysis and compare its assessment with the common VPA/SPA method. In recent years, fisheries biologists have depended mainly on age structured aggregated sequential population analysis (SPA)/virtual population analysis (VPA) for stock assessment purposes. The VPA method is an aggregate model that consolidates all spatial and within-season temporal stock dynamics into a single total stock estimate. The proposed spatial-temporal method produces historical estimates of population size and fishing mortality rate by age and year. In this thesis, the abundance states of age-aggregated stock components are tracked in space over the course of each season using computer simulation. Data about fish stock spatial-temporal migration dynamics are used to estimate stock abundance in space and time over the course of a fishing season. The spatial-temporal assessment method is applied to the herring stock of the Scotia Fundy region of Atlantic Canada. The dynamics of the herring spawning groups are described and the simulation model is developed for a given season. The results suggest that disaggregated spatial-temporal estimates provide more information for in-season management of herring spawning groups than the traditional aggregate VPA approach.

The profitable rearing of the Atlantic salmon (Salmo salar L.) requires artificial diets high in carbohydrates or fats or both in order to avoid the high cost of protein feed; this practice is monitored by growth criteria such as animal length and body weight. The present study investigates the physiological state of hatchery-reared salmon smolts raised under cage culture conditions and fed a commercial pellet food of elevated carbohydrate content. Our results show metabolic disturbances that strongly suggest a diabetogenous situation: hyperglycemia, hypertriacylglycerolemia, some glucosuria and occasional ketonuria. Histopathological examination confirms the initial suggestion: significant reduction of the beta to alpha cell ratio in the islets of Langerhans, frequent alteration of the disposition of insular cells, hydropic changes in the B cells such as degranulation, vacuolization and nucleic pyknosis, evidence of hypertrophy and hyperplasia of B cells and pronounced neoformation of islet tissue. In addition, hyalinization of both the exocrine and the endocrine pancreas was observed as well as fibrosis, lipomatosis and microangiopathy of the exocrine acinar tissue and an increase in intrapancreatic nerve cell number. In conclusion, the smolts fed the pellet diet displayed a syndrome reminiscent of mammalian diabetes; a comparison is drawn between diabetes mellitus and the observed form of salmon diabetes. The study emphasizes the need to involve physiological criteria in the assessment of the suitability of artificial diets especially in the rearing of healthy salmon intended for restocking of natural environments.

The aim of this study, which is mainly osteological, is to clarify the status of the genera Cristivomer and Salvelinus. A morphometric and meristic study in conjunction with osteology was used to assess their phylogenetic relationships with other genera of Salmonidae. About 390 specimens of adult and adolescent fish and 268 eggs and fry were examined. Presently, seven genera are recognized in Salmonidae. The genus Cristivomer is separated from Salvelinus because of the shape of the supraethmoid, supramaxilla, subopercle, vomer, lingual plate, and caudal fin, and also the high number of pyloric caeca, presence of pearl organs, and breeding behaviour of the former. In the genus Salvelinus, S. alpinus (including various forms), S. malma, and S. fontinalis are distinguished. S. alpinus oquassa, previously known as S. marstoni, is considered a subspecies of S. alpinus. The two previously designated species S. oquassa and S. aureolus are synonymized with S. a. oquassa. S. timagamiensis is reduced to a sub-species of S. fontinalis. The genus Salmothymus is maintained. The genus Cristivomer is more generalized than Salvelinus. The species S. malma is intermediate between S. alpinus and S. fontinalis. For the first time a detailed osteological study of C. namaycush and several forms of Salvelinus is undertaken, and their relationships assessed.

The effects of water movement or agitation on the biological performance of planktonic organisms under intensive culture have been rarely studied quantitatively. Stagnation or minimum values are considered important in the problem of scale-up based on optimum conditions. Near stagnation, inadequate water movement brings about undesirable effects, e.g. accumulation of metabolites, uneven distribution of feed and low dissolved oxygen concentration. An important mechanism associated with water movement at these conditions is the oxygenation process which defines the oxygen transfer rate from the gas to the water. Experiments were conducted using potable water to determine the overall oxygen mass transfer coefficient in two types of container geometries; a) cylindri-conical tank and b) oblong-shaped center- partitioned raceway. For each type of container, three geometrically similar sizes were investigated with scale ratio of approximately 1:2:3.5. Agitation was induced by the introduction of air into the system. General correlations for both tank geometries were obtained from experimental data and were expressed in terms of the operating and geometric parameters. The correlations are in the form of dimensionless groups (Froude and Reynolds numbers) making them appropriate for scale-up estimates. The general correlations for the overall oxygen mass transfer coefficient were subsequently used to provide the scaling equations to define the operating parameters in different sizes of containers for the culture of brine shrimp in sea water fed with rice bran. The high correlation coefficient obtained for the relationship between total brine shrimp biomass production and the overall mass transfer coefficient applicable to different sizes of both the cylindri-conical tank and the raceway indicates that the overall oxygen mass transfer coefficient is an effective scale-up criterion in brine shrimp culture. / Graduate and Postdoctoral Studies / Graduate