Academic literature on the topic 'Tuna purse-seine fisheries'

Abstract The purse seine is the dominant fishing gear operating at the Tumumpa Fishing Port with a vessel of >90%. The purse seines that have developed are large pelagic targets, with the main catch targets being skipjack, mackerel tuna, and tuna. Tuna, mackerel tuna and skipjack are important commodities for fisheries in Indonesia. This study aims to determine the characteristics of purse seine fishing gear and its catch in the Sulawesi Sea. Data collection was carried out for two years from 2019-2020 at Tumumpa Fishery Port. Indications for the use of fish resources are calculated by comparing the length-at-first-capture (Lc) with the length-at-first-mature (Lm). The results showed that purse seines are very dominant in exploiting large pelagic resources (skipjack, mackerel tuna and tuna) with the proportion reaching 78%, small pelagic (21% scads and 1% other fish). The large pelagic fishing season using the purse seine vessel occurs in May – November, with 2 peak seasons in July and September. While the small pelagic occurs in May – September, with the peak occurring in July. The size when the frigate tuna was first caught was at a fork length of 25.15 cm (Lc) and Lm in a size of 28.52 cm for females and 28.29 cm for males. Meanwhile, the first scads was caught (Lc) at a length of 21.4 cm with the length-at-first-mature (Lm) being 20 cm for the female and 19 cm for the male. Based on this analysis, it was shown that the purse seines is a selective fishing gear for small pelagic fish but not selective for large pelagic fish.

Fisheries productivity plays an important role in national development. The potential of fisheries in Indonesia is quite large so that many coastal communities depend on their lives from fishing activities. East Java province has a fishery area that is quite potential with the availability of considerable human resources, one of them is Lamongan. This research was conducted in Fish Auction Site (Tempat Pelelangan Ikan, TPI) Kranji, Lamongan. The purpose of this study is to find out the productivity value of purse seine fisheries in TPI Kranji based on the size of the ship and the fishing trip. This research was conducted by survey method to know the condition of purse seine fishery in the field directly. Purse seine fishing vessels located in TPI Kranji in 2020 as many as 32 ships that have gross tonnage (GT) of 9 to 24 GT. The dominant catches are Longtail Tuna (Thunnus tonggol), Mackerel Tuna (Euthynnus affinis), Fringescale Sardinella (Sardinella fimbriata), Short Mackerel (Rastrelliger brachysoma) and Goldstripe Sardinella (Sardinella gibbosa). There are two seasons in the fishing process at TPI Kranji, the regular season (Fringescale Sardinella) and the peak season (Tuna). The highest value of productivity per trip was obtained 1.59 tons / trip / year which occurred in 2019 with 223 of fishing trips and the amount of catch production of 356.71 tons. The highest value of productivity per GT occurred in 2020, obtained 2.09 tons / GT / year, which currently has 32 purse seine vessels. The productivity per GT from year to year is increasing because the amount of production is also increasing every year.

Tuna fisheries have been identified as one of the major threats to populations of other marine vertebrates, including sea turtles, sharks, seabirds and marine mammals. The development of technical mitigation measures (MM) in fisheries is part of the code of conduct for responsible fisheries. An in-depth analysis of the available literature regarding bycatch mitigation in tuna fisheries with special reference to elasmobranchs was undertaken. Studies highlighting promising MMs were reviewed for four tuna fisheries (longline, purse seine, driftnets and gillnet, and rod and line – including recreational fisheries). The advantages and disadvantages of different MMs are discussed and assessed based on current scientific knowledge. Current management measures for sharks and rays in tuna Regional Fishery Management Organizations (t-RFMOs) are presented. A review of relevant studies examining at-vessel and postrelease mortality of elasmobranch bycatch is provided. This review aims to help fisheries managers identify pragmatic solutions to reduce mortality on pelagic elasmobranchs (and other higher vertebrates) whilst minimizing impacts on catches of target tuna species. Recent research efforts have identified several effective MMs that, if endorsed by t-RFMOs, could reduce elasmobranchs mortality rate in international tropical purse seine tuna fisheries. In the case of longline fisheries, the number of operational effective MMs is very limited. Fisheries deploying driftnets in pelagic ecosystems are suspected to have a high elasmobranchs bycatch and their discard survival is uncertain, but no effective MMs have been field validated for these fisheries. The precautionary bans of such gear by the EU and by some t-RFMOs seem therefore appropriate. Recreational tuna fisheries should be accompanied by science-based support to reduce potential negative impacts on shark populations. Priorities for research and management are identified and discussed.

Abstract Fish Aggregating Devices (FADs) are tools for collecting fish by using various attractors from solid objects that attract fish to gather. Portable FAD uses sound frequency attractors that can be operated in various fishing areas. Portable FAD is not placed permanently in the waters and can be stored until fishing operations are carried out. The purpose of this activity is to calculate the buoyancy and gravity of portable FAD, determine the composition of the catch, and determine the distribution pattern of fish in the morning, afternoon, and evening. For 17 (seventeen) days, this activity was carried out in Yamdena waters, Ambon. The calculation results of the total buoyancy force of portable FAD were 20554.69 gs, total sinking force was 5460.69 gs, and the extra buoyancy value was 73%. The dominant fish caught using purse seiner were skipjack tuna (Katsuwonus pelamis) of 37.41%, yellowfin tuna (Thunnus albacares) of 33.53%, scad fish (Decapterus russeli) of 11.62%, tuna (Euthynnus affinis) by 8.12%, and sunglir fish (Elagatis bipinnulata) by 5.14%. Portable FAD can attract fish from 15 minutes and continue to increase to a peak at 105 minutes with 160 fish approaching. The highest fish approach to portable FAD was recorded in the morning at 105 minutes at a depth of 20-25 m were 89 fish, the lowest was in the afternoon at 15 minutes at a depth of 5-10 m were 7 fish. The best use of portable FAD is in the morning and evening.

In the lack of fishery-independent information, catch per unit of effort (CPUE) is the conventional abundance index. In the case of the tropical tuna purse seine fisheries, a critical difficulty lies in the definition of an effective fishing effort, because fishermen use two different fishing modes (free swimming schools versus schools under fish aggregating devices) alternatively during the same trip. In this study, vessel monitoring system (VMS) data were used in an operational level to study and quantify the spatial dynamic of the tropical tuna purse seine fishing activity. A Bayesian state–space model allowed classifying VMS steps into three activities (fishing, tracking, and cruising), which were characterized by a small set of complementary spatial indicators. The dominant activity (49%) was clearly the tracking of tuna schools within areas of aggregations. A hierarchical spatial organization of the three fishing activities was also evidenced. Fishing strategies described by the triplets of proportions of time devoted to each activity and interpreted as compositional data were modelled by the sum of a vessel effect and a seasonal effect.

This study aims 1) to determine the technical aspects of fishing with a mini purse seine; 2) to analyze the feasibility of a mini purse seine fishery business in the southern part of Ambon Island. This research was carried out from January to December 2018 in several fish landing sites scattered in the southern part of Ambon Island waters, namely Nusaniwe, Hutumuri and Lehari Villages. Sampling was by purposive sampling. Primary and secondary data were taken. Data were analyzed using descriptive analysis and business financial analysis. The dimensions of the mini purse seine vessels are 20-22.5 m long, 2.70-3.85 m wide, and 1.5-1.8 m high, the dimensions of the net are 225- 345 m long, 50-70.5 m high. The composition of the catch consisted of 4 types of fish, namely blue fly (59.8%), tuna (18.4%), skipjack (17.7%), and baby tuna (4.1%). The results showed that the mini purse seine fishery business met the requirements and was still feasible to develop. The results of the calculation of the business feasibility of a positive NPV and greater than zero (NPV> 0) of Rp. 933,471,927, an IRR of 15.8% greater than the interest rate (10.5%), the value of B / C> 1 of 1.18, the criteria for ROI of 20.14%, the value of PI (Profitability Index)> 1.

Abstract Fisheries potentially affect seabirds both directly and indirectly. Well-documented direct effects have resulted in significant losses to seabird populations, but indirect effects are less well known. One way in which tropical seabirds may be indirectly affected is through overexploitation of large subsurface predators. Tropical seabirds must forage over wide areas to attain sufficient prey and have evolved various methods of increasing foraging efficiency. One strategy is their association with surface-feeding tunas. When feeding, these predators drive prey to the surface, making them available to seabirds feeding from above. Losses in predator biomass will reduce prey accessibility (but not necessarily prey abundance) for seabirds, contributing to declines in bird populations. To explore indirect fisheries effects, we compared estimates of the magnitude and spatial distributions of consumption by breeding seabirds with fisheries offtake in the western Indian Ocean (WIO). Data from the literature were compared with Indian Ocean Tuna Commission longline and purse seine landings of selected tuna and billfish species from between 2000 and 2009. Breeding seabird populations (adults and immature birds) were estimated at ∼19 million individuals, assuming 50% breeding success. Based on the literature, these birds will consume between 150 000 and 500 000 metric tonnes (t) of prey; values that are of the same magnitude as mean annual longline (904±632 t) and purse seine (349 861±61 820 t) landings for the region. Spatial overlap between fisheries and seabirds is high, especially around the Seychelles, suggesting that the indirect impacts of fisheries on seabird populations may be great. Sooty Tern (Onychoprion fuscatus) is by far the dominant seabird in the study area, accounting for over 80% of numbers and consumption estimates. Our results highlight the importance of seabirds within WIO marine trophic webs and emphasize the potential indirect effects of industrial tuna fisheries on their populations.

Fishing on floating objects (FOBs) dominates catch in tropical tuna purse seine fisheries. One frequently cited advantage of deploying GPS-monitored FOBs is that the position information can be used for directed fishing to reduce search time for tuna. However, purse seiners also fish on foreign objects for which position information is not available. It is critical to quantify the prevalence of fishing on GPS-monitored versus unmonitored FOBs to understand how they impact fishing effort and catch per unit effort. We analyzed French commercial, observer, and FOB trajectory data in the Atlantic and Indian oceans to determine how often purse seine vessels fish on GPS-monitored FOBs. Only 2.7%–20.4% of French FOB fishing sets over 2007–2013 in both oceans were made on GPS-monitored FOBs. Though increasing over time, the low percentage suggests that French vessels do not primarily use GPS-monitored FOBs to reduce search time for tuna. We hypothesize that fishery-wide FOB deployments have important collective consequences for overall fishing effort and recommend that future effort metrics should be based on fishery-wide FOB activities.

<p>ABSTRACT<br />In general, fisheries in Indonesia is still dominated by small-scale fisheries, one of themis the purse seine fishery based in Tamperan Fishing Port. This study aims to determine aspects of purse seine fishery based on Tamperan Fishing Port such as vessel size and fishing gear, FADs , fishing ground and catches. The study was conducted in 2012 in Tamperan Fishing Port with measurement methods and direct observation and interviews with owners, skippers and crew. The results showed that the vessel of small-scale tuna purse seine fishing based in Tamperan Fishing Port have tonnage between 28-45 GT and made of wood with length 17.21-28 m, width 6-7 m, and depth 2-3 m. Nets is used have length between 250-300 m and width 8-10 m. Fishing ground is FADs at coordinates 10º-12º S and 100º-110º E, 60-100 miles from the Pacitan Bay with distance to the location of FADs about one day. The catch is dominated by skipjack about 57.27%, followed by scad26.31% and juvenile yellowfin 10.05%.</p><p><br />Keywords: Purse seine, small scale tuna fisheries, Tamperan</p><p>-------</p><p>ABSTRAK</p><p>Secara umum, perikanan tangkap di Indonesia masih didominasi oleh usaha perikanan skala kecil, salah satunya adalah nelayan pukat cincin yang berbasis di PPP Tamperan. Penelitian ini bertujuan untuk mengetahui aspek penangkapan perikanan pukat cincin yang berbasis di PPP Tamperan berupa ukuran kapal dan alat tangkap, rumpon, daerah penangkapan dan hasil tangkapan. Penelitian dilakukan pada tahun 2011 di PPP Tamperan Pacitan dengan metode pengukuran dan pengamatan langsung di lapangan serta wawancara dengan nelayan pemilik, nakhoda dan awak kapal. Hasil penelitian menunjukkan bahwa armada pukat cincin perikanan tuna skala kecil yang berbasis di PPP Tamperan memiliki ukuran tonase antara 28-45 GT dan terbuat dari kayu dengan ukuran panjang antara 17,21-28 m, lebar 6-7 m, dan dalam 2-3 m. Jaring yang digunakan memiliki panjang antara 250-300 m dan lebar 8-10 m dengan menggunakan rumpon. Daerah penangkapan berada pada koordinat 10º-12º LS dan 100º-110º BT dan berjarak sekitar 60-100 mil dari Teluk Pacitan dengan lama perjalanan menuju lokasi rumpon sekitar 1 hari. Hasil tangkapan didominasi oleh cakalang sebesar 57,27%, diikuti oleh layang 26,31% dan yuwana madidihang 10,05%.</p><p><br />Kata kunci: Pukat cincin, perikanan tuna skala kecil, Tamperan</p>

Bycatch and mortality in fishing gear poses a conservation threat worldwide to many marine species. Resource managers and conservation scientists face challenges in identifying bycatch mitigation solutions that work for multiple taxa while maintaining acceptable levels of target fish catch. The most successful mitigation measures to address bycatch concerns are those that (1) minimize bycatch with limited or no impact on target species catch, (2) have been proven through at-sea experimental research, (3) are practical, affordable, and easy to use, and (4) do not risk the safety of the fishing vessel crew or the bycaught animals. We conducted a review of mitigation measures in fishing gears that target tuna and tuna-like species and that either prevent capture of non-target species in fishing gear or facilitate alive post-capture release, and evaluated these against 4 defined criteria: effective, proven, practical, and safe. This paper outlines the most effective bycatch mitigation measures, as based upon the best scientific information available, in commercial and artisanal pelagic longline and purse seine fisheries, specifically those that target tuna and tuna-like species. This review includes information on gear and operational changes to fishing practices that reduce bycatch for protected and threatened species across taxonomic groups, with a focus on cetaceans, sea turtles, seabirds, sharks, and istiophorid billfishes. The information provided can guide future research and management efforts in Regional Fisheries Management Organizations that are specific to tuna fishing and that aim to minimize impacts to protected and threatened species while maintaining viable commercial fisheries.

Thousands of floating objects, known as drifting fish aggregating devices (dFADs), are released every year by commercial tropical tuna purse seine vessels in the three equatorial oceans to aggregate tuna and increase catch. The escalation in the number of dFADs deployed over the last three decades has caused changes in fishing effort that are poorly reflected in traditional indices of purse seine effort and catch per unit of effort (CPUE). In addition, concerns have been raised regarding the impacts of such high numbers of dFADs being deployed on both catch and bycatch species. I studied two aspects of dFAD deployments in order to clarify how dFADs are used by purse seiners and how they affect the magnitude of bycatch. My specific goals were to determine how often purse seine vessels fish on the dFADs they deploy and how regional dFAD density affects the magnitude of bycatch and catch. I analyzed commercial data, independent observer data, satellite buoy trajectories, and estimated floating object densities from the French tropical tuna purse seine fisheries in the Atlantic and Indian Oceans to examine these relationships. My results indicate that only 2.7-20.6% of dFAD fishing sets were on the dFADs that French purse seiners deployed over the period 2007-2013. Although this percentage increased over time, such a low percentage suggests that French vessels do not primarily increase CPUE by using the dFADs they deploy for directed fishing. If French purse seiners are not mainly using their own dFADs in this manner, then using a metric of nominal effort based on individual vessel activity is unlikely to produce reliable CPUE estimates for the fishery. While information about how often purse seiners fish on their own dFADs could be incorporated into indices of fishing effort, it may be just as important, if not more so, to quantify the collective component of dFAD releases for overall fishing effort. The results for the second objective showed that average dFAD density had a relatively weak relationship with total bycatch biomass. There was no statistically significant effect on mean total bycatch biomass, but dFAD density was related to heteroscedasticity in bycatch biomass. In particular, there was a significant negative relationship between dFAD density and the upper quantiles of the bycatch biomass distribution, suggesting that dFAD density determines the upper bound for bycatch biomass caught per set. These relationships were not constant across species, however, as the five most prevalent bycatch species (i.e., those caught in the greatest number of sets) showed a mix of positive, negative, or no relationships to dFAD density. The total biomass of catch increased significantly as average dFAD density increased both at the mean and throughout the majority of the distribution, although this effect only explained a small fraction of the total variance in catch biomass. at this time, the low amount of variance explained and the inconsistent impact of average dFAD density on bycatch and target species indicate that it would be ineffective to mitigate bycatch levels in these fisheries by attempting to control regional dFAD densities.

Dans le cadre de l’Approche Ecosystémique des Pêches (AEP), il est nécessaire d’évaluer l’impact de la pêche thonière tropicale à la senne sur les espèces ciblées et sur les espèces accessoires. Parmi ces dernières, les espèces de la mégafaune, telles que des requins, raies, cétacés, tortues, oiseaux marins, sont souvent emblématiques et vulnérables. Les thoniers senneurs tropicaux recherchent activement à la surface de l’eau tout indice de la présence de bancs de thon (e.g. oiseaux, objets flottants, baleines, dauphins ou requins baleines). Dans l’est de l’océan Atlantique et l’ouest de l’océan Indien, les deux modes de pêches principaux sont les captures de thons en bancs libres et celles sur bancs associés à un objet flottant, naturel ou artificiel, rassemblés ici sur sous le terme de dispositif de concentration de poisson (DCP). Les calées associées aux requins baleines et aux cétacés sont toutefois peu étudiées. L’objectif de cette thèse est donc d’analyser les co-occurrences et/ou interactions spatio-temporelles entre requins baleines, cétacés et pêche thonière à la senne, dans une perspective de conservation de l’écosystème. Ce travail, basé sur des données de livres de bord et d’observateurs scientifiques embarqués, a montré que la co-occurrence pêche thonière/ mégafaune se localise dans des strates spatio-temporelles relativement précises: i) du Gabon à l’Angola (avril–septembre), ii) dans le Canal du Mozambique (juin–septembre) et iii) à l’est des Seychelles (avril–septembre). Les baleines et requins baleines étant planctivores, la co-occurrence avec la pêche à la senne est principalement liée à une forte productivité primaire (appréhendée à travers des proxys tels que la concentration en chlorophylle-a). De plus, les calées sur ces deux groupes étaient assez élevées avant 2000 (jusqu’à 20% des calées), et qu’elles sont moins fréquentes aujourd’hui (AC3 et 1,5% des calées associées à des baleines et des requins baleines, respectivement). L’impact de la pêche à la senne sur ces espèces semble relativement faible au regard du taux de mortalité apparente de 1,4% pour les requins baleines et 5,6% pour les cétacés. Des marquages satellites réalisés sur les requins baleines, confirment ces observations sur le plus long terme, mais la taille de l’échantillon limite la formulation de conclusions définitives. Concernant les dauphins, bien que présents sur les zones de pêche, ils interagissent très peu avec celle-ci, soulignant ainsi une différence majeure avec l’océan Pacifique est où ce mode de pêche est majoritaire. La diversité spécifique des espèces cible et accessoire associées aux calées sur mégafaune a également été étudiée. Les requins baleines sont associés aux listaos et à l’albacore (dans une large gamme de tailles), alors que les baleines le sont principalement à de gros albacores. De plus, la capture accessoire associée à ces deux groupes de mégafaune est relativement faible et dominée par le requin soyeux et la diversité spécifique est proche de celle trouvée sous les bancs libres de thons. Enfin les effets de mesures de conservation vis-à-vis de la mégafaune encerclée ou de mesures de gestion de l’effort de pêche, notamment les moratoires sur DCP réelles ou simulées (e.g. moratoires élargis), ont été analysés. Les premières ont eu un effet limité en terme de captures cibles et accessoires, alors que les moratoires impactent peu le nombre de calées associés à la mégafaune, ceci en raison du décalage spatio-temporel des co-occurrences. Cependant des moratoires élargis pourraient être bénéfiques pour les thons juvéniles et certaines espèces associées. Par l’analyse quantitative des interactions entre la pêche thonière à la senne et la mégafaune, cette thèse apporte des connaissances essentielles sur les espèces étudiées dans le cadre de la mise en place d’une AEP, applicable à la pêche thonière tropicale
In the frame of the Ecosystem Approach to Fishery (EAF) management, impact of the tropical tuna purse-seine fishery on targeted and incidentally captured species should be investigated. They may include megafauna species, such as sharks, rays, cetaceans, turtles or sea birds, which often are emblematic and vulnerable species. Tropical tuna purse-seiners actively search, at the surface of the sea, for clues indicating the presence of tuna schools (e.g. birds, floating objects, whales, dolphins or whale sharks). In the eastern Atlantic and western Indian Oceans, the main two fishing modes are sets on free swimming tuna schools and schools associated to natural or artificial floating objects, thereafter called Fish Aggregating Device (FAD). However dedicated studies on fishing sets associated to whale sharks and cetaceans are still lacking. The aim of this thesis is therefore, using logbook and scientific onboard observer data, to investigate the spatio-temporal co-occurrences and/or interactions between whale sharks, cetaceans and the tuna purse-seine fishery within an ecosystem conservation perspective. This work underlines that the megafauna/ fishery co-occurrence occurs in specific spatio-temporal strata: i) Gabon to Angola (April–September), ii) the Mozambique Channel (June–September), and iii) East of Seychelles (April–September). As baleen whales and whale sharks are filter feeders, the co-occurrence with the purse-seine fishery was mostly linked to highly productive environments (i.e. using proxys including chlorophyll-a concentration). In addition fishing sets involving megafauna were relatively high before 2000 (up to 20% of the sets), but are nowadays less frequent (AC3 and 1.5% of the sets associated to baleen whales and whale sharks). The purse-seine fishery appears to have a relatively low impact on megafauna species with mortality rates of 1.4% for whale sharks and 5.6% for cetaceans. Whale shark satellite tagging also confirms these results on the longer term, but the low sample size precludes any final conclusion. While dolphins are present in fishing areas, very few interactions with the fishery was detected, which highlights the striking difference with the eastern Pacific Ocean where half the sets are associated to dolphin herds. In addition, the diversity of targeted and bycatch species captured under whale shark and baleen whale sets was also investigated. Whale sharks are principally associated to skipjack and yellowfin (of various sizes) tunas and baleen whales mostly to large yellowfin tuna. In addition, bycatch species associated to these two megafauna groups was relatively low and dominated by the silky shark, and bycatch diversity was close to the one found for free swimming tuna schools. Finally, real and/or simulated encircled megafauna conservation measures or fishing effort management measures (especially FAD moratoria including larger ones) were investigated. The first ones were found to have limited consequences on tuna catch and bycatch. Conversely FAD moratoria had limited impacts on the number of megafauna associated fishing sets, due to the fact that the main spatio-temporal strata of megafauna and FAD sets differ. However larger and longer moratoria could be beneficial for juvenile tuna and some bycatch species. Overall, this thesis has lead to increase the knowledge on megafauna/ fishery interactions, essential in the general framework of setting up an EAF in the tropical tune purse-seine fishery

碩士
國立臺灣海洋大學
海洋事務與資源管理研究所
102
To be confronted with population growth, fishery resources have been a major source of protein for human. In virtue of some reasons, like nutritive value, tuna species are popular among others. The tuna industry in the Western and Central Pacific Ocean (WCPO) is one of the largest and most valuable fisheries in the world and many countries developed their tuna fisheries there. The tuna fishery in WCPO is complicated with Regional Fisheries Management Organisations (RFMOs), agreements, treaty and scheme. The South Pacific Committee (SPC) established in 1947 as the oldest RFMOs, Forum Fisheries Agency (FFA) in 1979 and Western and Central Pacific Fisheries Commission (WCPFC) in 2004. The fishery cooperations between Pacific island countries (PICs) and distant water fishing nations (DWFNs) by multilateral agreements or bilateral agreements, and manage under the scheme, conservation and management measure (CMMs), which include Vessel Day Scheme (VDS) implemented in 2007. This research aims to study of Taiwan purse seine fishery cooperation with PICs in WCPO and analysis by Game Theory, which include Federated States of Micronesia, Kiribati, Marshall Islands, Nauru, Palau, Papua New Guinea, Solomon Islands and Tuvalu. In order to set the game of WCPO tuna purse seine fisheries by the mechanism design, collected the informations by literature analysis method and case study, then use the semi-standardized in-depth interview with the experts. There are totaol 7 games were setted, include two categories and two scenarios. The categories are “The Taiwan Purse Seiner to PICs Game ” and “The Taiwan Purse Seiner to individual PIC Game”, under two scenarios as the high price and low price of fish by 2009-2012. “The Taiwan Purse Seiner to Individual PIC Game” select Kiribati, Papua New Guinea, Marshall Islands as Players by total fishing days and by area. “The Taiwan Purse Seiner to PICs Game” and “The Taiwan Purse Seiner to individual PIC Game”, show the Nash equilibrium, the dominant strategy of PICs is “continue implement the VDS” and for Taiwan is “co-management the purse seine fishery”. The Game of Taiwan-Papua New Guinea and Taiwan-Kiribati show the situation of Taiwan purse seine vessel could be well-manage under the scenario of high price of fish. In the case of Taiwan-Marshall Game, Marshall Islands need work opportunities than access fee, therefor co-management is the dominant strategy remarkably for Taiwan when build fishery cooperation with Marshall Islands.

The processes driving distribution and abundance patterns of highly migratory marine species, such as filter-feeding sharks, remain largely unexplained. The whale shark (Rhincodon typus Smith 1828) is a filter-feeding chondrichthyan that can reach > 18 m in total length, making it the largest extant fish species. Its geographic range has been defined within all tropical and warm temperate waters around the globe. However, even though mitochondrial and microsatellite DNA studies have revealed low genetic differentiation among the three major ocean basins, most studies of the species are focussed on the scale of single aggregations. Our understanding of the species’ ecology is therefore based on only a small proportion of its life stages, such that we cannot yet adequately explain its biology and movement patterns (Chapter I). I present a worldwide conceptual model of possible whale shark migration routes, while suggesting a novel perspective for quantifying the species‘ behaviour and ecology. This model can be used to trim the hypotheses related to whale shark movements and aggregation timings, thereby isolating possible mating and breeding areas that are currently unknown (Chapter II). In the next chapter, I quantify the seasonal suitable habitat availability in the Indian Ocean (ocean basin-scale study) by applying generalised linear, spatial mixed-effects and maximum entropy models to produce maps of whale shark habitat suitability (Chapter III). I then assess the inter-annual variation in known whale shark occurrences to unearth temporal trends in a large area of the Indian Ocean. The results from the Indian Ocean suggest both temporal and spatial variability in the whale sharks occurrence (Chapter IV). Therefore, I applied the same analysis to the Atlantic and Pacific Oceans using similar broad-scale datasets. While the results for the Pacific Ocean were inconclusive with respect to temporal trends, in the Atlantic Ocean I found preliminary evidence for a cyclic regularity in whale shark occurrence (Chapter V). In Chapter VI, I build a model to predict global whale shark habitat suitability for the present, as well as within a climate change scenario for 2070. Finally, Chapter VII provides a general discussion of the work developed within this thesis and presents ideas for future research.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2013