Dong Gang are the biggest fresh tuna market in Taiwan. This thesis deals with the social networks in Dong Gang tuna market and how they affect the tuna market in Dong Gang. This thesis finds that although Dong Gang tuna market has public auctions, the transactions and exchange of information are highly shaped by social networks, especially in the Bluefin Tuna season that starts in April and end in June. Actors use social networks to avoid risk, control prices and maintain the quality of purchase. On the other hand, the status of actors, which is highly influenced by the licenses from the state, also has significant impacts. There are two kinds of license in Dong Gang tuna market; one for domestic market and one for export. Actors with higher status buying fish firs. This research recognizes that the market is embedded in social structure of economic sociology, and explains the dual meaning of the market: entity and concept. It also points out how local social networks shape deal of market. On the other hand, the price of Japanese tuna market influences Dong Gang tuna market; in other words, the Dong Gang tuna market is part of global tuna market leading by Japan, and the state uses license to control. That is, the Dong Gang fish market consists of local social networks, but also connects with state and global tuna market.

In this study, based on the basic theory model ¢wGordon-Schaefer model is used to discuss the equilibrium levels for yellowfin tuna in the Western and Central Pacific of open access (OA) and present value maximization (MPV). And then to compare the catches and the stocks on the two model¡¦s equilibrium value, the result shows the management of yellowfin tuna in the Western and Central Pacific tend to MPV model, the regional fisheries organization (RFMO) to detect the implementation of the measures (MCS) is significant; in addition, use sensitivity analysis and then to understand the changes on the stocks and the effort quantities effected by varying different parameters. In OA, if you want to get effectively maintain the sustainability of the stocks, should be considered to reduce the price and the catch coefficient, increase the cost per unit of effort to control; in MPV, we can understand that the catch coefficient and the intrinsic growth rate have a bigger influence in the effort quantities; Finally, by simulating the catches and the stocks, that if it can continue to effectively manage fishery by MCS in the future, the catches and the stocks of yellowfin tuna will tend to balance the value of MPV, and so on, not only resources effective use of maximum profit and maintaining our fleet of ocean-going business interests, but also resources can be sustainable.

In the early years of human society, all natural resources such as agriculture, animals, forestry, and fisheries were considered to be public property and the treasure belonged to all people. One branch of these natural resources threatened by over-development is straddling and highly migratory fish species, like tuna, which cannot be protected by a single government. While discussing fishery management, we review the change in tuna catches of thirteen countries in Western and Central Pacific Fisheries Commission (WCPFC), as it represents the impacts from different policies and events during a specific period of time. We reference the method applied in economics science by testing for the existence of stochastic convergence and addressing these break points, which are the important targets due to external shocks or internal influence. The characteristic of the method is in testing both time series and panel data by following the traditional unit root tests methods and unit root tests while considering structural breaks. We are able to conclude in preliminary estimates that some serious historical fishery events happened at the break point time, and if we take these structural breaks into consideration, then the growth of tuna catches will be stationary. In other words, if shocks to relative tuna catches are temporary, then the series stochastically converges, meaning that the manager does not need to intervene in the development of tuna fishery, because temporary shocks do not affect the stationarity of tuna catches¡¦ levels. Once the structural breaks occurred in the past, it is not necessary for these government and international organizations to change fishery policies in order to respond to the breaks. They should realize the meaning of the stationary panel instead of enacting an over-intervening policy based on temporary shocks.

Japan, South Korea, and Taiwan have similar economic backgrounds, as they have undergone the aftermath of destruction and restructuring from the World Wars, and they are all situated in important locations in the East Asia region. Since there have been abundant research studies about competition in economic growth, international trade, and technology advances, however, there competition might also be competition between these countries in the fishery industry. Resulted of Western and the Central Pacific Ocean (WCPO) has been one of the most valuable fishery areas in the world, we use the tuna capture data from the Western and Central Pacific Fisheries Commission (WCPFC) and utilize a cointegration test and error correction model in a time series analysis to analyze the competitive relationship in the three countries. In our study, we found that if the Japanese captures increase, the Taiwanese captures also increase and the same cases occur in the contrasting cases. But the relationships with South Korea and Japan or with South Korea and Taiwan are negative. It represents that the capture in the three countries impact each other. We also try to find the reasons for impact and long-run and short-run competitive relationships.

Little is known about the population structure and genetic variability of blackfin tuna despite catch increases over the past 25 years. In this thesis, levels of genetic variation contained in 323bp of the mitochondrial DNA (mtDNA) control region-I (CR-I) and in six microsatellite loci were characterized for two regions: the Gulf of Mexico (GoM) and the Northwest Atlantic. Large amounts of mtDNA diversity (h>0.99; =0.047) were observed in both regions. Mismatch distribution analysis of the CR-I sequence data, using a mutation rate of 1.6% Ma-1for scombroid fishes, indicate blackfin tuna underwent population expansion about 1.4 Ma, a timeline concordant with the expansion of other tunas and billfishes. Estimates of female effective population size were very large at 7.8 million and 12.8 million individuals for the NW Atlantic and the GoM, respectively. Both mtDNA and six microsatellite loci were used to determine blackfin tuna population structure. Microsatellite and mtDNA AMOVAs revealed significant differentiation (msat st=0.01, p=0.006 and mtDNA st=0.01, p=0.049) between the GoM and the NW Atlantic samples. Migration estimates using mtDNA data indicate that twice as many females enter the NW Atlantic from the GoM (346 individuals/generation) than the opposite direction (150 individuals/generation). Migration estimates using microsatellite data were substantially smaller, with the Gulf receiving 7 individuals/generation and the NW Atlantic 4 individuals/generation. Finally, low levels of genetic differentiation using microsatellite data have been reported in other highly abundant marine fishes, which have been attributed to homoplasy in allele size. To test this hypothesis, the allele frequency distributions of blackfin and yellowfin tuna at six microsatellite loci were compared. The distances between species were surprisingly small (Da=4.0%, (delta mu)squared=1.08), with a large degree of similarity in frequency distributions at four loci. The comparison of bigeye tuna at two microsatellite loci revealed additional inter-specific similarities. A mutation rate for these loci was estimated by modifying an equation used to estimate time since divergence. Microsatellites in tunas appear to evolve at a rate (4.3x10-7 Ma-1) that is two orders of magnitude slower than other fishes (1x10-5 Ma-1). Accordingly, microsatellite allele size similarities are plesiomorphic and not due to homoplasy.

Abstract Recently fishing industry in Taiwan is under hugely severe business environment. Due to distinctness of diplomatic situation, it is totally different competitive situation Taiwan is facing. Therefore, not only development of ultra-low-temp tuna fishing industry and managerial means and of international or regional incubate organization will be deeply described but also diamond model of Porter will be explored to analyze the competitive advantages of ultra-low-temp tuna fishing industry of Taiwan in the thesis. Definitely, the conclusion will used to develop practical plans for future severe situation. After well understanding literature about development of ultra-low-temp tuna fishing industry in Taiwan, I concluded the followings based on perspective of diamond model: 1. The first is that operations of Taiwan Tuna Association and cluster effects build the competitive advantages other countries are hard to get beyond. 2. Secondly, under relatively stable variation of tuna prices, the fishing boat owners are emphasizing on cost reduction in order to maintain business operations and get above average earnings. The ability of cost control is competitive advantage of fishing industry of Taiwan. Keywords: diamond model ,ultra-low-temp tuna fishing industry ,competitive advantage

The spatial movements of yellowfin tunas around the fish aggregating devices which were anchored below 40 meters water with a VEMCO VR2 receiver were investigated using ultrasonic telemetry tags V9P (VEMCO VP9-2H-S256). The experiment was conducted in the Shiao-Liu-Chiu Island of Taiwan from July to September, 2007. A pair of VEMCO VR2 receivers was separated by 400 meter distances in west of south sea ,Taiwan. A total of 9 tagged fishes with different sizes were monitored for maximum 19 days. Preliminary results showed that juvenile fish stayed longer and closer within FADs than the adult fish. Fish could move vertically to as low as 160 meters at daytime. They avoid the surface water where the temperature reach 30oC. In nighttime, juvenile fish that has fork length smaller than 55cm generally moves to the surface mixed layer. On the horizontal movement, there are three types. A) fish stays at FADs site. B) Fish move in and out FADs sites for a few hours period. C) fish moves away from FADs site for a long times (maybe 2~3 days). Sometimes juvenile fish would have B) or C) moved away from the FAD devices during dawn and dusk, and back at daytime. But this would not occurred with large fish. We estimated the attraction radius of FADs at least 1 km.

In this study, the fundamental model of fish dynamic model- Gordon Schaefer Model is used to discuss the equilibrium levels for the Pacific Bluefin Tuna fishery of open access and dynamic optimization, and then to do the sensitivity analysis. By comparing the historical record of catch data with the equilibrium values of open access and dynamic optimization, we could know that the fish stocks and harvests of Pacific Bluefin Tuna are not in the condition of dynamic optimization. In order to ensure the sustainable development of Pacific Bluefin Tuna fishery, we have to take effective measures to preserve and manage the Pacific Bluefin Tuna resources. Finally, this study simulates and analyses the various management scenarios of the Pacific Bluefin Tuna fishery. The results of simulative analysis reveal that the optimal management of the Pacific Bluefin Tuna fishery would imply significant reallocation of the fishing gear shares. Furthermore, the net present value could increase substantially by reallocating the fishing gear shares.

Tuna-dolphin-bird feeding assemblages are unique to the Eastern Tropical Pacific Ocean (ETP). These multiple species groups are believed to forage together in response to the physical properties of the near surface ocean as these constrain the distribution of prey. In the Galapagos Marine Reserve (GMR), intra-annual and interannual changes affect the properties of the water column, inducing mesoscale and fine scale temporal variability. Four three-week oceanographic surveys took place, in September 2008, April 2009, October 2009, and September 2010, between the coast of Ecuador and the Galapagos Islands and one small boat survey took place in June 2010 within the GMR. Marine mammal surveys were conducted during daylight hours and Conductivity, Temperature, Depth (CTD) sensor casts were taken throughout the survey. Data were analyzed to determine the types of water masses present and the strength and depth of the thermocline layer. These data were compared with the sightings of marine mammals, bird feeding groups, and tuna-dolphin-bird assemblages. Additionally, these data were used to predict where tuna would be likely to associate with dolphin groups. Results show Equatorial Surface Water was the dominant water mass throughout the archipelago, regardless of season or ENSO index. High salinity, cold water west of Isla Isabela indicated topographic upwelling of the Equatorial Undercurrent. Tropical Surface Waters from the Panama Current were detected north of the Equatorial Front to the east of the islands. Obvious changes in the water column properties were observed between El Niño and La Niña events in the GMR. Most mixed groups were sighted west and south of Isla Isabela during the four oceanographic surveys, as well as north and west of Isla San Cristobal in June 2010. Most sightings were in cool, high salinity waters, and high chlorophyll concentrations. There were a greater number of sightings during the April 2009 survey (ENSO-neutral conditions) than during any of the three fall surveys. Additionally, tuna-dolphin-bird groups were more likely to be seen near Isla Isabela, with the majority of them sighted during the April 2009 survey and a few sighted in each of the September 2008 and October 2009 surveys. No tuna-dolphin-bird groups were sighted during the September 2010 surveys. Results show that the presence and location of these multi-species groups may be controlled by the inter-annual cycles, the intra-annual cycles, or a combination of both types of changes seen within the Galapagos.

Typescript. / Bibliography: leaves 239-263. / Microfiche. / xiii, 263 leaves, bound ill. 29 cm