In 1971, the European Communities introduced a Common Fisheries Policy (CFP), which was more fully developed in 1983. Its success remains largely questionable because it has failed to conserve fish stocks, has been unable to tackle the problem of vessel overcapacity or to generate rents from the fishery resource. This thesis presents an overview of the main components of the CFP and assesses their impact on different aspects of the fishing industry. The economic and biological knowledge on which the fisheries management is based has been evaluated and a management scheme for reforming the CFP is proposed. The thesis initially surveys the literatures in fisheries economics and in fish population dynamics. These should provide the basis for efficient management, and their role is evaluated. European Community institutions and the procedures which are involved in the policy formation are examined. Particular attention is paid to the evolution of the legislative framework of the Common Fisheries Policy from its establishment to the latest developments. The work evaluates the main constituent parts of the CFP, whose objectives are the rational development of the production factors, a fair standard of living for the producers, a stable market and the availability of supplies for consumers. The main conclusions reached are that the policy has been consistent with a decline in fish stocks, an increase in vessel capacity, a failure to stabilise market prices and a decline in the average fisherman's income. These outcomes can be attributed largely to an inadequate policy framework, which ignores the main conclusions of fisheries economics, and to an inadequate system of information gathering and of policing the regulations.

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This study investigates the population biology of horse mackerel inhabiting the Northeast Atlantic, their spawning grounds and migrations, and the degree of stock separation, with emphasis on the Southern and Western areas of the European shelf. The investigations involved the use of a wide range of methodologies and techniques, including age determination techniques, tagging experiments, the analysis and evaluation of commercial catch data, egg survey data, bottom trawl survey data, biochemical methods, morphometric methods, survey sampling methodology, and associated statistical analysis. Multivariate analysis of morphometric measurements, indicate that the horse mackerel that spawn on the Portuguese shelf (Southern area) are distinct from those that spawn on the Irish shelf (Western area). A distinction can also be made between the Portuguese horse mackerel and those from the Celtic Sea, English Channel and Northern Bay of Biscay. These findings are further supported by a study of otolith first ring distance, which also indicates that the Western and the North Sea horse mackerel are not significantly different from each other. Growth parameters of horse mackerel from the Western and Southern areas were estimated using length and age data and the resulting growth curves for the two areas are different. This result is primarily due to differences in the growth of the younger fish. In the Southern area the fish grow faster than in the Western area. These results provide evidence for the existence of a separate unit stock of horse mackerel off the Portuguese coast, which is reproductively distinct from other populations in the north-east Atlantic. The results froma study of plasma transferrin polymorphisms did not provide any evidence in support of these findings. The population structure and stock separation of horse mackerel in the north-east Atlantic are described and the implications for future management are discussed

The potential of the aquaculture in the Arabian Gulf has been evaluated. The factors t~at affect the selection of a species and system for the culture have been discussed. Among the indigenous species grouper (E. tauvina) and sea bream (M. cuvleri) give the best options. However, larval rearing is still the main problem in their large scale culture. Among the exotic species Tilapia (Sarotherodon) spp. give the best prospects. Open flow pond system seem to be the most acceptable system for use to operate in the Gulf area

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The movements of adult Atlantic salmon (<I>Salmo salar </I>L.) were investigated in relation to hydroelectric schemes in Scotland. Salmon were tagged with radio- and acoustic transmitters and released into the River Tummel, Perthshire, and River Conon, Ross-shire, and their subsequent movements recorded. Thirty-nine salmon were monitored in the vicinity of Pitlochry Dam on the R. Tummel. All fish that approached the dam successfully ascended a fish pass located here. Pass efficiency was estimated at 100%. Movements through the fish pass were related to water temperature and ambient light level. The three-dimensional movements of four salmon were recorded as they moved through a hydroelectric reservoir, Loch Faskally. Fish migrated to the head of the reservoir in under 48hours. Gross swim speeds were in the region 0.4 to 0.8mh^-1. Swimming depths were similar to mean loch depth. Two fish were recorded at shallower mean depths during the night than during the day. A total of 54 salmon were radio-tagged on the River Conon to determine the effects of a series of hydroelectric obstructions on upstream migration. Fish were either unable or unwilling to pass beyond each of the obstructions: only 20.7% of fish migrated beyond six obstacles, thus reaching their spawning grounds. Salmon were recorded moving through a 2.5km long pipeline into a separate tributary of the river. The muscle activity of three salmon were recorded, using electromyogram (EMG) telemetry, as they ascended Conon Falls fish ladder. The results show that fish are required to make use of anaerobic white muscle in order to ascend the structure. The highest mean levels of activity were recorded when fish were delayed in the ladder overnight. This finding is of great significance when designing new fish passes.