Thesis (MPhil)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: This paper reviews the status of world aquaculture with a primary focus on Sub-Saharan and Chinese freshwater aquaculture, and proposes a commercial integrated farming model for implementation in rural areas in KwaZulu-Natal. The model combines the paradigms of age-old Chinese integrated pond farming principles with a commercial approach in the socio-economic context of Sub-Saharan Africa. The project's objective is to contribute to the alleviation of poverty through economic development in rural areas using environmentally and economically sustainable farming practices. The project's medium-term goal is to achieve the critical production volume to warrant vertical integration into a hatchery, feed mill and processing facility. Integration would reduce operating costs and afford better standards of basic services. The project's long-term goal is to grow and expand the model to make a contribution to global food security through distributing a fish-based, nutritionally balanced meal to famine relieve efforts in low-income food deficiency countries (LIFDC). The model proposes the development of individual farms each with a production capacity of 40 to 60 tons of fish per annum. The species available include tilapia, catfish, carp, mullet, bass and eels. The farms will each consist of eight grow-out fishponds totalling 4 hectares of water surface area, a basic homestead and 6 hectares for crops and livestock rearing. The farms are designed to utilize the nutrient rich effluent from the fishponds to flood-irrigate crops planted in the fields below. Through application of the principles of the integrated approach to fish-crops-livestock farming as applied by the Chinese over the last 2,000 years, the farms are designed in a way that nothing is wasted. The waste product from one system becomes input for the next system. The integrated approach is extremely cost effective and lends itself to total organic farming adhering to environmentally responsible and sustainable farming principles. Two hundred such farming units would produce a total of 8,000 to 12,000 ton per year that equates to double the current combined freshwater aquaculture production from all the SADC member countries. / AFRIKAANSE OPSOMMING: Die werkstuk bied 'n oorsig van akwakultuur in die wêreld, met 'n primêre fokus op die stand van varswater akwakultuur in Sub-Sahara en China. 'n Ontwikkelingsmodel vir geïntegreerde kommersiële boerdery word voorgestel, in die plattelandse dele van KwaZulu-Natal word woorhou. Die model koppel die konsepte van eeue-oue Chinese beginsels van geïntegreerde visboerdery met kommersiële winsgewendheid, binne die sosio-ekonomiese konsep van sub- Sahara Afrika. Die doel van die model is om 'n beduidende rol te speel in die verligting van armoede deur die ontwikkeling van ekonomiese aktiwiteit in plattelandse gebiede d.m.v. omgewings- en ekonomies volhoubare boerderypraktyke. Die projek se mediumtermyndoelwit is om die kritiese produksievolume te bereik wat vertikale integrasie met 'n visbroeiery, 'n voermeule en 'n prosesseringsfasiliteit sal regverdig. Dit saloperasionele kostes verminder en beter beheer verseker oor hierdie basiese insette. Die langtermyndoelwit is om die model uit te brei ten einde 'n bydrae te maak tot globale voedselvoorsiening deur die verspreiding van 'n voedsame, gebalanseerde maaltyd met vis as basis, as hongersnoodverligting in lae inkomste lande met 'n voedseltekort. Die model stel 'n reeks individuele plase voor, elk met 'n produksiekapasiteit van 40 tot 60 ton vis per jaar. Die beskikbare spesies sluit in tilapia, baber, harder, swartbaars en paling. Elke plaas sal bestaan uit agt uitgroeidamme van 'n halwe hektaar elk, 'n totaal van vier hektaar wateroppervlakte, 'n woonhuis en ses hektaar vir gewasse en veë. Die plase is ontwerp ten eide die voedingsryke uitvloeisel van die visdamme te gebruik vir besproeiing van die laerliggende landerye. Deur gebruik te maak van die beginsel van integrasie van 'n vis-, gewas- en vee-boerdery, aan die hand van die Chinese ontwikkelingsmodel oor die afgelope 2,000 jaar, word gepoog om niks te vermors nie. Die afvalproduk van een stelsel word 'n inset in die volgende. Hierdie benadering is uiters koste-effektief en leen homself tot organiese boerdery praktyke wat voldoen aan bewaringsbewuste en volhoubare boerderymetodes. Tweehonderd plaaseenhede sal 'n gesamentlike bydrae van 8,000 tot 12,000 ton per jaar lewer, wat gelykstaande is aan dubbeld die huidige gekombineerde varswater akwakultuurproduksie van al die SADC-Iedelande.

A problem commonly encountered in stock assessments of tropical marine resources in developing countries is data paucity, which invariably results from the lack of both human and economic capacity within the government to implement and maintain programmes for data collection and analysis. With special reference to the demersal fishery of Brunei Darussalam, this thesis examines approaches for extracting useful information from data-poor fisheries to assess the state of resources and inform fishery management actions. By using official fishery statistics, augmented by local ecological knowledge (LEK) obtained from fishers engaged in either the large-scale (LS) or small-scale (SS) fisheries in Brunei, changes in demersal fishery resources over the years were assessed. The sustainability of Brunei’s demersal capture fishery was evaluated in the face of its ongoing development and climate change. Using trophodynamic indicators such as mean trophic level (MTL), Fishing-in- Balance (FiB), trophic spectra (TS) and community structure analyses, LS fishery catches of Brunei between 2000 and 2009 revealed a deteriorating state of the coastal demersal ecosystem. Closer examination of the abundance of overall demersal finfish stocks, using the Catch-Per-Unit-Effort (CPUE) index – standardised for other factors not related to abundance – indicated a declining trend, even when total catches remained stationary, although trends in abundance of the different demersal fish families varied. This rapid significant change in recent years is further supported by fishers’ LEK on relative abundance of Brunei marine resources. The study on LEK has also revealed the ‘shifting baseline syndrome’ (SBS) among currently active fishers and their exploited populations, a phenomenon not previously reported for Brunei fisheries. Findings from the study are synthesised with other information, where a number of key issues and policy options are discussed, and recommendations for the management of the fishery are made. This thesis demonstrates that researchers in data-poor fisheries can utilise different assessment tools, given the resources at their disposal, to assist in the management of marine resources.

<p> In Arctic Alaska, Dolly Varden <i>Salvelinus malma </i> is highly valued as a subsistence fish; however, little is known about oceanic dispersal or ecology. This study addresses this knowledge gap, by using a fisheries independent method, pop-up satellite archival tags (PSATs). In spring of 2012 and 2013, we attached 52 PSATs to Dolly Varden in a river in northwestern Alaska, which flows into the Arctic Ocean, to examine the marine dispersal, behavior and habitat occupancy of this species. Tagged Dolly Varden demonstrated two types of dispersal, including offshore and nearshore dispersal. The offshore type was the first documented northwesterly dispersal and occupancy of Outer Continental Shelf (OCS) areas of the Russian Chukchi Sea. While occupying this area, tagged Dolly Varden demonstrated affinity for the first 5 m of the water column, diel patterns in depth occupancy, and dive depths of up to 50 m, while experiencing a thermal environment of generally 3&ndash;7&deg;C. During the nearshore dispersal type, Dolly Varden transited in coastal areas of northwest Alaska, likely returning to their natal rivers to spawn. While in nearshore areas, tagged Dolly Varden always occupied shallow waters (&lt; 6 m), and experienced a rapidly changing thermal environment (&plusmn; 15&deg;C), including some waters temperatures cooler than -1&deg;C. This study demonstrates that PSATs offer an alternative and effective platform with which to study several aspects of large adult Dolly Varden dispersal and ecology in areas where it is not practical or feasible to capture these fish, such as in coastal and offshore regions of Arctic Alaska. Additionally, the results of this study have increased our knowledge of the summer marine distribution, behavior and thermal environment of Dolly Varden in Arctic regions of Alaska, and this knowledge is important to several stake holders for the conservation of this important subsistence species.</p>

<p> Arctic Grayling (<i>Thymallus arcticus</i>) are widely distributed on the Arctic Coastal Plain (ACP) of Alaska, and are one of the few upper level consumers in streams, but the trophic pathways and food resources supporting these fish are unknown. Grayling migrate each summer into small beaded streams, which are common across the landscape on the ACP, and appear to be crucial foraging grounds for these and other fishes. I investigated prey resources supporting different size classes of grayling in a beaded stream, Crea Creek, where petroleum development is being planned. The specific objectives were to measure terrestrial prey subsidies entering the stream, quantify prey ingested by Arctic Grayling and Ninespine Stickleback (<i>Pungitius pungitius </i>), determine if riparian plant species affect the quantity of terrestrial invertebrates ingested by grayling, and determine if prey size and type ingested were a function of predator size. Results indicated that small grayling (&lt; 15 cm fork length (FL)) consumed mostly aquatic invertebrates (caddisflies, midges, and blackflies) early in the summer, and increasing quantities of terrestrial invertebrates (wasps, beetles, and spiders) later in summer, while larger fish (> 15 cm FL) foraged most heavily on stickleback. Riparian plant species influenced the quantity of terrestrial invertebrates entering the stream, however these differences were not reflected in fish diets. This study showed that grayling can be both highly insectivorous and piscivorous, depending upon fish size class, and that both aquatic and terrestrial invertebrates, and especially stickleback, are the main prey of grayling. These results highlight the importance of beaded streams as summer foraging habitats for grayling. Understanding prey flow dynamics in these poorly studied aquatic habitats, prior to further petroleum development and simultaneous climate change, establishes essential baseline information to interpret if and how these freshwater ecosystems may respond to a changing Arctic environment. </p>

The fisheries resources of Lake Victoria support the livelihoods to the lakeside rural communities and are vital to the economies of Kenya, Tanzania and Uganda, especially through fish exports. Management decisions to enable long-term sustainable exploitation of these fisheries require appropriate knowledge of the fishing effort and catch statistics, as these are pertinent for evaluating the fish stocks and future prospects of the fishery. Catch assessment programmes in the Ugandan part of the lake, which should provide this type of information, collapsed in the late 1980s. This study evaluated the current status of fishing effort and fish catches and their implications for the management of the fisheries in the Ugandan part of Lake Victoria. Historical trends in fishing effort and fish catches, total fishing effort in 1990 and 2000, and the current status of fish catch-effort, in the Ugandan part of the lake, were examined.

The prevalence of Penaeus monodon baculovirus (MBV) in black tiger prawn (Penaeus monodon Fabricus) was investigated based on 372 diagnostic cases examined from October 1989, to December, 1990. Laboratory transmission of MBV to the different life stages of P. monodon and tolerance of MBV in infected hepatopancreatic tissues to chemicals and extreme environmental conditions were studied. A comparative assessment of the growth performance, survival and food conversion ratio between MBV-infected and non-infected populations of P. monodon was investigated and a new technology called Strategic Egg Prophylaxis (SEP) in the production of MBV-free P. monodon postlarvae was developed and tested. MBV was the most prevalent viral disease of P. monodon accounting for 67.1% of all diseases diagnosed in this species, and was widely distributed in all 12 major shrimp farming provinces in the Philippines throughout the year. The nauplii and zoea larval stages were refractory to MBV infection within 12 days post inoculation, but the mysis larval and the postlarval stages were susceptible to MBV infection within 6 and 2 days post inoculation, respectively. Cumulative mortality was significantly different (α = 0.05) between the MBV-infected and unexposed control groups of mysis larval and postlarval test shrimps. No significant growth rate differences were observed between the MBV-infected and unexposed control groups of larvae and postlarvae. MBV was resistant to 150 ppm iodine, 1:100 dilution of peroxygen/organic acid compounds and 10 ppm calcium hypochlorite at 240, 240 and 480 min of exposure, respectively, and to freshwater and at 37°C for 240 min. Direct exposure to sunlight for 240 min inactivated MBV in the hepatopancreatic tissues. In pond cultured P. monodon populations, the MBV negative stocks grew by as much as 43.4%, 20.8%, 13.7% and 13.7% more than the MBV-infected stocks at densities of 30/m², 20/m², 18/m², and 10/m², respectively over a 126 day growing period. Mortality was significant in MBV positive stocks affected with protozoan and bacterial shell disease. Food conversion ratio (FCR) was not a significant factor among MBV negative and the MBV infected populations. MBV negative P. monodon postlarvae were successfully produced using the Strategic Egg Prophylaxis (SEP) by washing and rinsing P. monodon eggs with iodine, benzalkonium chloride, calcium hypochlorite or ozone-treated seawater. The eggs washed with ozonized and benzalkonium chloride-treated seawater gave higher hatching rates of 72.4% and 60.3%, respectively. Postlarval survival at PL-7 was 67.6% in eggs washed with ozonized seawater and 42.3% in benzalkonium chloride-treated seawater. The unwashed control groups developed MBV infections starting at PL-7 stage.

This research project was designed to test the feasibility of growing catfish (Ictalurus punctatus) in cages at two densities in three types of irrigation waters in Arizona in 1989 and 1990. The types of waters studied were a pre-irrigation flowing water ditch, an irrigation return water sump and a pre-irrigation stationary water reservoir. Cages were designed for each type of water. The duration of the experiment was 76 days in 1989 and 117 days in 1990. Growth of fish was poor at both densities in pre-irrigation flowing water in 1989. Poor growth was probably due to the velocity of water and size variability of fish at stocking (coefficient of variability = 48%). Hand grading and the addition of baffles to cages resulted in increased growth and decreased size variability (25%) in 1990. Poor growth and low food conversion (5.2) were seen at both densities in irrigation return waters in 1989. Reduced growth and poor feed conversion were due in part, to wild fish bumping cages until food was lost. High variability in final weight (48.9%) was due to stocking of ungraded fish. In 1990, wild fish were removed from the pond and catfish were handgraded at stocking. These procedures resulted in higher final weights (660 g), lower conversion ratios (1.3) and lower size variability (31%). In 1989, poor growth and high size variation (55.4%) also occurred at both densities in pre-irrigation standing water. In 1990, grading fish at stocking and lowering stocking densities resulted in increased growth (570.6 g) and a lower coefficient of variability (28.7%). However, the food conversion ratio (2.6) was still high, due to food loss from cages, a disease outbreak and the associated mortality. Growing fish in all three types of irrigation waters appears to be biologically feasible. Fish in irrigation return flow waters had better growth rates than fish in flowing pre-irrigation water or in stationary pre-irrigation water. However, questions concerning the possible addition of contaminants to the system from agriculture effluent and the economics of integrating aquaculture into agriculture requires further study.

The purpose of this study was to determine the status of aquaculture in the State of Arizona, to determine the perceived educational needs of Arizona aquaculturists, to identify their educational and experience backgrounds, and to identify the sources of information that they utilize to meet their needs and to solve problems in aquaculture. An intermediate goal of the study was to compare the differences between private and government aquaculturists. This study was a descriptive survey and utilized a questionnaire as the instrument. Data was collected via telephone interviews. The target population was all active aquaculturists in the State of Arizona. Findings included: (1) The aquaculture industry was expanding, (2) Water quality management and production methods were the top educational needs, (3) Eighty percent of the aquaculturists have had some college, with sixty-eight percent possessing at least a Bachelor degree and, (4) Other aquaculturists and fisheries professionals were identified as the best sources of aquacultural information.

Cholla Lake is a cooling reservoir for the coal-fired Cholla electrical generating plant. The lake provides recreational fishing and water contact recreation. The fish populations are self-sustaining. I collected water, sediment, and whole body fish samples to be analyzed for levels of some possibly toxic inorganic constituents. I also measured dissolved oxygen, pH, Secchi disk transparency. I compared current fish population structure, fish stomach contents, and the frequency of occurrence of benthos, with those same parameters in previous studies. Water temperature and turbidity have increased; catfish and bluegill have increased in their relative abundance; and the density of benthic invertebrates has decreased. Aquatic insects occur most commonly in the stomach contents of bluegill and filamentous algae in the stomachs of catfish. Selenium levels in all matrices exceed national averages and are above levels in a nearby reservoir unaffected by the power station.

In 1995, Squaw and Flash creeks were renovated with Antimycin-A to eradicate non-native fish. After renovation, 129 Apache trout from Flash Creek were introduced into Squaw Creek. Two years later, all size classes were present. Apache trout above a natural barrier on Flash Creek were allowed to repopulate the renovated section. Three years later, 45 Apache trout were found below the natural barrier. In both streams, adults selected deep, slow moving areas. Juveniles selected shallow areas with fast currents. Both size classes selected open areas exposed to sunlight with surface turbulence and other forms of instream cover. Apache and Gila trout were experimentally PIT-tagged in the: (1) pelvic girdle; (2) abdominal cavity; and (3) dorsal musculature to determine the best tagging location. Fish tagged in the dorsal musculature had 0% tag loss and 98% survival. The minimum size Apache and Gila trout could be tagged was 90 mm TL.