Thesis (M.C.M.) -- Lincoln University, 2009. / Also available via the World Wide Web.

Typescript. Includes vita and abstract. Includes bibliographical references (leaves 303-330). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

Thesis--University of Washington. / Vita. Another copy has number: Thesis 27740. Bibliography: leaves [167]-182.

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1969. / Bibliography: leaves [136]-142. / ix, 142 l

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 64-69). Also available on the World Wide Web.

Thesis (Ph.D.) -- University of Rhode Island, 2009. / Typescript. Includes bibliographical references (leaves 280-295).

This thesis evaluates the utility of a sport fishery for yellowfin tuna, Thunnus albacares, in the Pemba Channel, Kenya, in providing ecological information relevant to commercial fishery assessment and management. Age, growth, reproductive status and diet are measured, together with an innovative assessment of the Indian Ocean yellowfin tuna stock. Catch/effort and weight data from the records of the sport fishery from 1963-1995 demonstrate a decline in tuna mean weight since the advent of purse seining in 1984. A periodicity of 5-6 years was detected in the Indian ocean longline fishery catches, and in the sport fishery catch/effort and mean weights. Samples were taken from tuna caught in the sport fishery from 1981-88. Sport-fished samples were more random in size, age and sex (ratio = 1: 1) than catches from any of the three major commercial fisheries. The total mortality rate of cohorts deconvoluted from weight-frequencies in the sport fishery catch over 6 years was used in a Caddy & Csirke analysis. Maximum Sustainable Yield estimates of the Indian Ocean stock were 113,000 tonnes (new method), 110-160,000 tonnes (Walters' method); compared with only 40-52,000 tonnes using the standard equilibrium method. Tuna (1653 over 7 years) were successfully aged using length frequency analysis and by a novel method based on clusters from a Principal Components Analysis of morphometric measures. Juvenile growth was fast, 3.1 cm/month, whereas adults grew at about 2 cm/month. Gonads (>1500) were staged for 5 years and histologically examined for 2 years. Female yellowfin mature earlier than males, but males become ripe earlier in the season. The spawning stock consists of females >120 cm FL. Diet was scored over 4 years and evaluated volumetrically over 2 years. Juvenile tuna eat fish, but adults opportunistically consume fish, cephalopods and crabs, depending on availability. Catchability by gear in both the sport and commercial fisheries is likely influenced by the currently abundant food.

Master's thesis. / Format: PDF. Bibl.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 146-157).

Yellowfin tuna Thunnus albacares is a commercially and economically important fisheries species, which comprises the second largest component of South Africa’s catch of tuna and tuna-like species. Catches of the species off South Africa are treated as two discrete stocks by the two tuna Regional Fisheries Management Organisations (tRFMOs) under whose jurisdictions they fall. Individuals caught off the Western Cape, west of the boundary between the tRFMOs at 20°E, are included in assessment and management of the Atlantic Ocean yellowfin tuna stock by the International Commission for the Conservation of Atlantic Tunas (ICCAT), and those caught east of this boundary are assessed and managed as part of the Indian Ocean stock by the Indian Ocean Tuna Commission (IOTC). The boundary between these stocks is based on the confluence of the two oceans in this region and does not incorporate the population structure of species. For sustainable exploitation of fisheries resources, it is important that the definition of management stocks reflects species’ biological population structure; the fine-scale stock structure of yellowfin tuna off South Africa is therefore a research priority which this study aimed to address by means of population genomics analyses. Yellowfin tuna exhibit shallow genetic differentiation over wide geographic areas, and as such traditional population genetic approaches have limited power in resolving fishery significant population structure in the species. Herein, a population genomic approach was employed, specifically, genome-wide analysis of single nucleotide polymorphisms (SNPs) discovered using a next-generation DNA sequencing approach, to confer (i) increased statistical power to detect neutral structuring reflecting population connectivity patterns and (ii) signatures of local adaptation. The mitochondrial Control Region (mtDNA CR) was also sequenced to compare the resolving power of different approaches and to permit coalescent based analyses of the species evolutionary history in the region. Neutral SNP loci revealed significant structure within the dataset (Fst=0.0043; P<0.0001); partitioning of this differentiation within the dataset indicated significant differentiation between yellowfin tuna from the Western Cape and the Gulf of Guinea in the eastern Atlantic Ocean, with no significant differentiation between individuals from the Western Cape and Western Indian Ocean regions. This indicates two population units wherein there is a separation of the Gulf of Guinea from the remaining samples (Indian Ocean including Western Cape) that are largely derived from a single genetic population. This pattern was also supported by assignment tests. Positive outlier SNPs, exhibiting signatures of diversifying selection, suggest that individuals from these regions may be locally adapted, as well as demographically isolated. The mtDNA CR did not reveal any significant genetic structure among samples (Fst=0.0030; P=0.309), demonstrating the increased resolving power provided by population genomics approaches, but revealed signatures of historical demographic fluctuations associated with glacial cycles. Based on the findings of this study, it is suggested that yellowfin tuna caught off the Western Cape of South Africa are migrants from the Indian Ocean population, exhibiting significant genetic differentiation from the Atlantic Ocean Gulf of Guinea individuals, and should thus be included in the assessment and management of the Indian Ocean stock. It is therefore recommended that the boundary between the Atlantic and Indian Ocean yellowfin tuna stocks, under the mandates of ICCAT and the IOTC respectively, should be shifted to approximately 13.35°E to include all individuals caught in South African waters in the Indian Ocean stock.