The thesis took an interdisciplinary, problem-oriented approach to address the research problem: ’Is farmed fish capable of replacing wild-caught fish in the Malaysian diet?’ The main objectives of the project were to assess current fish consumption habits, evaluate the impacts of these on sustainability of fish stocks and determine whether aquacultured products could be a suitable substitution. A combination of data collection methods was used, namely dietary assessments, systematic literature review, market research interviews and surveys and analysis of electronic and paper-based official records. The review of the Malaysian food balance sheets showed a significant transition in diet over the last three decades, specifically with respect to an increase in animal protein by approximately 60% over this time, with fish as the major source of protein. To further explore the contribution of fish to the diet of Malaysians, and any ethnic and geographical differences in consumption, a food frequency questionnaire (FFQ) was developed to assess habitual dietary intakes within selected coastal, rural and urban populations across different cultural groups in Klang Valley. The FFQ provided a clearer picture of the quantities of fish consumed by Malaysians and enabled the characterisation of Malaysian fish consumers based on the types of fish species consumed for sustainability assessment purpose. The nutritional contribution of wild versus farmed fish was compared and contrasted. Results from this study, combined with detailed studies of perception of wild versus farmed fish by consumers, aquaculturists and wholesalers, provided a greater understanding of the factors that influence consumers’ fish buying and consumption habits. The key findings are discussed with respect to the sustainability of the current situation, potential for expanding the aquaculture sector to replace wild fish in the Malaysian diet and recommendations for future research and issues for policy makers involved in the expansion of the industry.

Most of the scientific knowledge on the pelagic fish (the clupeids Stolothrissa tanganicae and Limnothrissa miodon and the centropomid Lates stappersii) of Lake Tanganyika is from research carried out in localised areas. This makes it difficult to extend the results to the whole lake. Consequently, there is the need to study the pelagic fish resources on a lake-wide basis using the same data collection procedures. Within the framework of an international fishery research project, data from the commercial fisheries targeting the pelagic fish stocks were simultaneously collected at various sampling sites in the riparian countries. Fishery-independent data were also obtained from lake-wide research surveys. The life histories of the three fish species appear to be similar throughout the lake. However, fish distribution across the lake is very uneven. The clupeid S. tanganicae mostly occur in the northern half of the lake and is much reduced in southern areas. This appears to be a recent contraction of the distribution range of this species. Limnothrissa miodon is more evenly distributed than S. tanganicae. The two species have a different inshore-offshore, size-related distribution across the lake. Nursery grounds of the first are close to the shore while those of S. tanganicae are in open, pelagic waters. With increase in size, S. tanganicae tend to move inshore while large L. miodon display the opposite movement. Lates stappersii stock, although relatively common, tends to be at higher concentration in the deep, steep central and southern basins. The feeding ecology of L. stappersii varies depending on the area and prey availability, but is mainly based on S. tanganicae and pelagic shrimps. Local occurrence of S. tanganicae is associated with that of copepod prey. The fish stocks experience different exploitation rates across the lake. While the fishing pressure is not excessive in the most of the lake areas, in others local overfishing is taking place. The biological characteristics of the pelagic fish species are discussed for the management of the lake fisheries. Fisheries management options are formulated on the basis of the assessment of the current exploitation levels.

Philippine aquaculture is a dynamic industry and a fast growing sector of the economy. Tremendous progress in production and technology has been achieved during the past decade. However, the country is experiencing a fish production shortfall which the aquaculture sector is expected to address. Given the proper support and direction, the aquaculture industry in the Philippines has great potential for growth and development. The Philippines has the principal attributes necessary for expansion of aquaculture production (e. g. important aquaculture species, ideal climatic conditions, existing fish farms and large water resources, expertise and manpower, markets, technologies). As part of the present research, several production-oriented studies were conducted for the development of the brackishwater aquaculture sector. The studies have shown that aquaculture technologies are available (e. g. milkfish - semi-intensive culture in ponds and marine cage culture, salt-tolerant tilapia hybrid - pond-based and marine-based cage culture, grouper - pond culture, shrimp - semiintensive culture) which are technically feasible and financially viable under present economic and environmental conditions. However, there are several important aquaculture constraints (e. g. seed supply and quality, feed supply and quality, government policies, marketing and post-harvest, environmental degradation and diseases, aquaculture credits) that must be overcome in order for the country to attain the maximum benefit from the potential of aquaculture. The study also identifies the important socio-economic benefits that can be derived (e. g. contribution to Gross Domestic Product, fish food supply, foreign exchange earnings, employment opportunities, tax revenues) from the development of the aquaculture sector. Finally, the study provides some strategies for the development of the brackishwater aquaculture sector with emphasis on the culture of milkfish, salt-tolerant tilapia hybrid, grouper and shrimp.

The biological characteristics of the adult sea trout stock in the River Tywi were examined between 1988 and 1992 by sampling catches from a temporary main-river trap, and the commercial seine, commercial coracle and recreational rod fisheries. Radio tracking of adults during the spawning season investigated behavioural activities and their possible effects on stock characteristics. Catch effort data from angler log books assessed the annual performance of the rod fishery between 1990 and 1993. The effects of ameliorating the impact of acidification on water quality, benthic macro-invertebrates and juvenile salmonids, through reservoir liming, was studied.

The crabs Cancer pagurus (L) and Necora puber (L) are exported live, in bulk, from the UK to various continental countries. The success of this relatively new trade is marred by the incidence of mortalities and impaired quality of the delivered product. These studies addressed various causes - procedural and biological - of these events.Descriptions are given of detailed examinations of handling and other marketing protocols for both species from point of capture to arrival at continental dealer's premises. Such examinations were made with the help of a number of major dealers in the UK, Spain and France and included studies of handling, packing, holding and transportation methods, physical damage assessments before and after consignment, and chemical and biochemical analyses of seawater and blood samples.Dissolved ammonia levels were found to increase greatly in the fixed volume water of vivier tanks and this was found to be matched by correspondingly high blood ammonia values of the contained animals. The measurement of both free ammonia and ionic ammonia efflux rates of juvenile and adult Cpagurus and Npuber in media with high dissolved ammonia levels was investigated and was found to be related to concentration gradients between the internal and external media. The fluxes could be explained on the basis of diffusion down concentration gradients. When animals were transferred to media with higher ammonia levels than those in blood, a cessation of efflux, or even a net influx of ammonia (NH4+) occurred.During emersion, blood ammonia concentration rose. Such accumulated ammonia was very rapidly off loaded when the animals were re-immersed.The data produced has been discussed in the context of crustacean physiology and of improving the expectations of delivering a live, quality product after journeys of several days.

Of all the corporate tasks facing government agencies and business enterprises, none is more challenging or has received more attention than those involving the management of capital. This is as true for fisheries as any other sector of the economy. However, a fishery is the meeting place of many disciplines and the complex interactions that result from the biological, legal, social, psychological, political, technological and engineering problems within it, intensify the difficulties in the search for ideas and solutions for the rational economic management of capital investment.In spite of the complexities a rational approach is needed involving the location and evaluation of all the opportunities for development across the whole of a fishery now or in the future. Capital investments dictate the entire pattern of production of fish and fish products and decisions taken in this area are usually irreversible. It is therefore, undesirable to allow the situation to develop as a random process.No system of capital budgeting will substitute for the final judgements that have to be made regarding fishery investment decisions. They can provide systematic approaches to reducing available information into patterns that suggest particular decisions'and strategies and an outstanding requirement is to determine in which sectors and to what extent they can assist with these problems.The benefits that can be obtained from the ability to programme capital investments which will secure improvements in the utilisation of capital labour and other resources have not been investigated within a comprehensive framework. A number of theoretical studies have been published and in a few cases have been validated on actual fisheries. Some of them are well developed but have generally considered the problems of sections of the industry in isolation.This thesis is concerned with the development of the methodology; techniques, criteria and data that will assist with management decision-making in this field and, also with an assessment of the relative contributions that result. The particular approach is to consider a completely integrated national fisheries system and investigate the overall problems that develop and then consider the independent sections of fisheries in order to investigate the specific problems that are peculiar to those sections.It is essential for work of this kind, that a theoretical study of the methodology, techniques and criteria should be developed within a realistic environment. For this reason, all the cases examined are based on actual fishery problems.

Tuna fisheries in the coastal states of the West Indian Ocean (WIO) have been at the centre of the social, economic and political development of the region. Their significance in creating employment, providing food, and generating revenue for the people in the region cannot be overemphasized. To be able to derive full benefits from the tuna resources in the WIO, the coastal states will have to devise an efficient management strategy, not individually, but collectively. Currently, there is no such management structure in the region to accomplish this goal. This study is, therefore, an attempt to find some solution to this important issue, and to propose a suitable management framework that would guarantee an efficient and profitable tuna resource management mechanism in the region. To tackle this task, data were collected through documentary statistical sources as well as by the use of questionnaires. Information was received from many fisheries organisations, as well as from other international fishing institutions. The results show that there is an urgent need for a regional organisation to manage tuna resources in the WIO, in order to avoid overfishing and stock depletion which will have adverse consequences on the economic and development prospects of both the coastal states and distant water fishing nations (DWFNs) operating in the region. This study recommended the establishment of a "Regional Organisation for the Management of Tuna in the West Indian Ocean" (ROMTWIO) using a contingency-political model in recognition of the need for a systems organisational structure that reflects the political elements in the region. The organisation should address the issues of joint co-operation in self-determination and self-management of tuna resources in the region within the remit of existing international laws, and in recognition of the significant role other international bodies can play in the realisation of the benefits of a common tuna resources for all.

This study of the fish and fishery of Stocks Reservoir, Lancashire, is the result of contract work undertaken by the researcher for North West Water (NWW). In an attempt to describe the location of the study, relevant information covering the catchment, local geology, reservoir construction and flora and fauna is included.The Authority's remit suggested a study of three facets of the catchment, namely, a study of the native fish populations, a monitoring of the recently opened fishery and an analysis of operational filter plate impingement.In order to minimise disturbance of the sport fishery, native fish population work was necessarily limited to the reservoir's three major afferent streams, the River Hodder, Hasgill Beck and Bottoms Beck.As a preliminary measure of tributary stream status, a simple invertebrate site study was undertaken by the researcher in 1985.Fish population work based on catch per unit effort (CPUE) was pursued in the spring, summer and winter of 1985, 1986 and 1987 at 8 sites, employing D. C. electric fishing equipment, whilst Carle and Strub's (1978) MWL Method was adopted for population estimations. The validity of the electric fishing survey and age determination are discussed in the text.The native species of brown trout, bullhead, stone loach and minnow were encountered, as was the introduced rainbow trout. Species densities and the population structure of the native brown trout were examined in detail for each survey site. The River Hodder was revealed to be the least populous tributary, whilst Hasgill Beck exhibited the greatest fish densities. Spawning migrations of native brown trout were evident, with fry recruitment at its optimum at site 4 on Hasgill Beck and site 8 on Bottoms Beck. The waterfall on Bottoms Beck might well have precluded upstream access to the head waters of this tributary. Observed mean brown trout length for age data were similar to those recorded by authors researching other upland stream locations.The history of Stocks Reservoir as a sport fishery is outlined prior to the present leaseholder's opening of the reservoir as a day ticket fly fishery for the 1985 season. The water was stocked predominantly with rainbow trout, together with some brook trout and brown trout before fishing commenced.The present study covering the seasons 1985 to 1987 was based primarily on data abstracted from catch return forms, which displayed a notably high rate of submission, and stocking consent data provided by NWW. The validity of return form data is discussed.Over the three seasons studied, angler patronage was observed to decline by 16%, whilst the number of fish caught and taken also declined by 34.8% and 20.5% respectively. Angler success was similarly observed to decline in accord with the decrease in patronage and catches. Interestingly, there was an increased reliance on introductions of rainbow trout over the period, including larger fish, and by 1987 a cessation in the stocking of other trout species.From correlations observed between environmental parameters and angler patronage, anglers appeared to prefer fishing in dry, sunny conditions, but decreases in angler success occurred during periods of increased water turbidity. Such declines in success also displayed congruity with decreases in angler patronage.From a comparison undertaken with a cross-section of English and Welsh stillwater trout fisheries, Stocks Reservoir was judged to rate poorly, returning the lowest performance data in the upland stocked category.An examination of the stomach and hind gut contents of 127 rainbow trout, 7 brook trout and 8 brown trout caught by anglers, was undertaken in the 1985 and 1986 seasons, and was compared with the reservoir fauna data of Mills, M. L. (1971).A description of the water treatment plant and its operation is delineated, and a pertinent collection of fish impingement and screening literature is included.Impingement data were collated from lst March 1985 to 31st December 1987 from routine and emergency cleaning of the filter plates. After storage in a freezer, the thawed fish were examined chronologically, identified, measured and weighed. During the examinations a random sample of stomach and hind guts was procured, and scales from brown trout were removed for possible future reference.The total annual impingement was observed to vary considerably, although brown trout habitually exhibited the greatest losses, comprising 71%, 64% and 89% of fish impinged annually. Of the introduced species, rainbow trout and brook trout, brook trout were the more susceptible to impingement, but remarkably few rainbow trout were lost considering the number stocked.Rainbow trout and brook trout of medium (150mm to 300mm) and large (>300mm) length classes were impinged, whereas many smaller (<150mm) brown trout were lost, a phenomenon concurrent with the recruitment of juvenile stream fish to the reservoir population.Brown trout in particular exhibited an annual dissimilarity in rates of impingement, probably suggesting that seasonal migration was not causative of their increased impingement.Impingement of rainbow trout showed limited correlation with environmental parameters. In 1985 and 1986, increased impingement of both brown trout and brook trout was significantly correlated with low reservoir levels, and to some extent might be linked to rising values of water turbidity.The collecting of stomach and hind gut samples from impinged fish was discontinued after 1985 because of problems in collection associated with delays in sampling and probable regurgitation of stomach contents. The problem of eye fluke infestation in impinged fish was noted and enumerated as sampling progressed.A brief discussion of further routes of operational fish loss from the reservoir is included.

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.

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.