Thesis (Ph.D.)--Memorial University of Newfoundland, 2004. / Includes bibliographical references.

Thesis (M.S.)--Rhodes University, 2001. / Title from PDF t.p. (viewed on Apr. 23, 2006). Includes bibliographical references (leaves 100-110).

No description available.

Despite the fact that fishing is an inherently uncertain business, risk has rarely been formally recognized in fisheries science or management. Few fishery management plans include any form of risk assessment and those that do focus on minimizing risk caused by uncertainty associated with markets and environmental conditions. Fishermen's attitudes towards risk, whether they are risk-neutral, risk-averse, or risk-prone, have rarely been considered. Although fishermen's attitudes towards risk have been shown in theory to have an impact on fish populations, none of the previous investigations precisely identified whether fishermen are risk-neutral, risk-averse, or risk-prone. This research attempted to identify fishermen's attitudes towards risk from an analysis of their decisions about where to fish. The research applied risk-sensitive foraging theory to an analysis of data from the Oregon trawl fishery for 1991. The data were provided by the Oregon Department of Fisheries and Wildlife. One file contained tow-by-tow information for each fishing trip on landings by species, time spent fishing, type of gear, and fishing locations. A corresponding file contained trip-by-trip information on landings and price by species. The two data files were screened for inconsistencies and then classified into small homogeneous categories based on port, fishing gear, fishing area, and boat size. Various variance-discounting models were fitted to each category to determine fishermen's attitudes toward risk. The models describe the expected utility of fishing at a given distance from port as a linear function of the mean, variance, and third moment of the dollar value per hour of the retained catch. The unknown parameters were estimated from the data using logistic regression techniques. The results of the analysis indicated that in two of fifteen categories the fishermen were risk-averse, and in four categories they were risk-neutral. However, for the remaining nine categories the results were inconclusive and in some cases the fishermen's choice of fishing locations appeared illogical. Instead of preferring fishing grounds that generated higher profits, it appeared that fishermen actively avoided such grounds. The inconclusive and sometimes illogical results may have been due to inappropriate assumptions about the data and about the factors motivating fishermen's decisions. Additionally, there might have been some factors that could have affected the analysis which this research overlooked. For example, this research only accounted for monetary rewards, but fishermen may have preferences other than revenues and costs that influence their choice of fishing grounds. / Graduation date: 1995

Thesis (M.M.S.)--Memorial University of Newfoundland, 2001. / Bibliography: leaves 75-82.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2001. / Restricted until October 2004. Bibliography: leaves 99-101.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [120]-129).

Thesis (M. Sc.), Memorial University of Newfoundland, 1998. / Bibliography: leaves p. 71-84.

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Made available in DSpace on 2015-01-26T13:21:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-27Bitstream added on 2015-01-26T13:30:32Z : No. of bitstreams: 1 000792978_20150127.pdf: 384795 bytes, checksum: e2d28327453e133ac0c4f145810767c2 (MD5) Bitstreams deleted on 2015-01-30T18:23:36Z: 000792978_20150127.pdf,Bitstream added on 2015-01-30T18:24:05Z : No. of bitstreams: 1 000792978.pdf: 3958190 bytes, checksum: 616d234386031ca87d88755d7374b280 (MD5) / Frente aos impactos causados pela ação antrópica no ambiente marinho, a proposta desse trabalho foi fornecer subsídios para a conservação das espécies, na área adjacente à Baía da Babitonga, estado de Santa Catarina, Brasil. O objetivo foi inventariar as espécies existentes da comunidade de camarões marinhos, detectar e descrever padrões gerais na sua distribuição espaço-temporal e relação às variáveis ambientais que caracterizam seu habitat. Portanto, foram mensurados os índices ecológicos e testados os parâmetros ambientais aos biológicos com análise multivariada. Os camarões foram coletados em julho de 2010 a junho de 2011, junto às variáveis ambientais, como temperatura e salinidade da água e textura e conteúdo de matéria orgânica do sedimento. Utilizou-se um barco camaroneiro equipado com redes double-rig, o qual percorreu cinco pontos paralelos a costeira com profundidades de 5, 8, 11, 14 e 17 m. A riqueza total chegou a doze espécies, pertencendo a três superfamílias, seis famílias e onze gêneros. Dessas, seis espécies de camarões peneídeos são comercializados: Xiphopenaeus kroyeri, Artemesia longinaris, Pleoticus muelleri, Farfantepenaeus brasiliensis, Farfantepenaeus paulensis e Litopenaeus schmitti. As demais espécies de peneídeos, Rimapenaeus constrictus e Sicyonia dorsalis, e carídeos, Exhippolysmata oplophoroides, Alpheus intrinsecus, Nematopalaemon schmitti e Periclimenes paivai, pertencem à fauna acompanhante dos recursos pescados. X. kroyeri foi a espécie dominante (D) espacialmente e temporalmente, apresentando valores discrepantes de abundância relativa 97,7% quando comparada à segunda espécie de maior abundância P. muelleri (1,1%), circunstância que influenciou diretamente nos resultados das análises de agrupamento e nos valores de diversidade (H’) e equitabilidade (J’), que foram altos quando a abundância da espécie foi menor. Esse resultado corroborou aos padrões das ... / Due to the impact caused by anthropic action on marine environment, the purpose of this work was to provide subsidies for species conservation at Babitonga Bay adjecent area in the state of Santa Catarina, Brazil. The aim was to catalogue existing species of marine shrimps communities, to detect and to describe general patterns in its temporal-spatial distribution and the relation to environmental variables that characterize its habitat. Therefore, ecological indexes were measured and environmental to biological parameters were tested with multivariate analysis. A shrimp boat equipped with double-rig nets was used and it travelled five parallel to the coast with a depth of stations 5, 8, 11, 14 e 17 m. The total richness reached twelve species, belonging to three superfamilies, six families and eleven genera. Of these, six species of peneid shrimps are marketed: Xiphopenaeus kroyeri, Artemesia longinaris, Pleoticus muelleri, Farfantepenaeus brasiliensis, Farfantepenaeus paulensis and Litopenaeus schmitti. The other species of peneids Rimapenaeus constrictus and Sicyonia dorsalis, and caridean shrimps Exhippolysmata oplophoroides, Alpheus intrinsecus, Nematopalaemon schmitti and Periclimenes paivai belong to bycatch of fisheries resources. X. kroyeri was a dominant (D) species in space and time, presenting discrepant values of relative abundance 97.7% when compared with the second most abundant species P. muelleri 1.1%, a circumstance that directly influenced the results of cluster analysis, the diversity (H’) and eveness (J’) values, which were high when the abundance of the species was lower. The patterns of the marine shrimp communities investigated in other regions were corroborated by the result of this study. Changes in shrimp communities could be related to variations in measured environmental variables and biological requirements specific to each species. The bottom temperature and sediment grain size were the preponderant ...