In this paper, the presence and amount of mercury and polychlorobiphenyls (PCBs) were determined in 23 bluefin tuna samples collected in the spring of 2012 in Porto Scuso (South West Sardinia, Italy) and Villa Putzu (...In this paper, the presence and amount of mercury and polychlorobiphenyls (PCBs) were determined in 23 bluefin tuna samples collected in the spring of 2012 in Porto Scuso (South West Sardinia, Italy) and Villa Putzu (South East Sardinia, Italy) in order to assess the current levels of these two contaminants in fish muscle and the consequent risk to humans consuming said fish. Values of polychlorobiphenyls in bluefin tuna muscle vary between 0.155 and 1.403 mg/kg f.w.;the average of PCBs in tuna muscle is 0.732 mg/kg f.w. With regard to PCBs the presence of more elevated concentrations is confirmed in larger fish. The results regarding mercury in muscle show an average of 0.660 mg/kg f.w. and mercury values vary between 0.140 f.w. and 2.211 mg/kg f.w.;for mercury as well, the highest concentrations were found in the largest bluefin tuna. Six samples, 26% of total, contained more than 1 mg/kg f.w., which is the maximum level set by the European Commission (EC, Regulation n. 1881/2006) for this species. Mercury, in particular methylmercury, poses a risk to public health, therefore, taking into account the important nutritional contribution that tuna fish makes to the diet, it is advisable that women of childbearing age, pregnant and breastfeeding women as well as young children strictly limit their consumption of tuna from this area of the Mediterranean.展开更多
Pacific bluefin tuna (Thunnus orientalis) is one of the most economically important species in the Percomorpha group of teleost fishes. Their migrations are extensive and depend upon continuous swimming at a high rate...Pacific bluefin tuna (Thunnus orientalis) is one of the most economically important species in the Percomorpha group of teleost fishes. Their migrations are extensive and depend upon continuous swimming at a high rate of speed throughout their life. The draft genome sequence of this species has been reported but remains highly fragmented. We constructed a Pacific bluefin tuna genetic linkage map using microsatellite markers developed on each of the scaffolds from the draft genome sequence to link these genome fragments and understand the genomic structure of species in Percomorpha. Of the 606 polymerase chain reaction microsatellite primer pairs tested, 473 were polymorphic in the mapping populations for the linkage analysis. We constructed sex-specific maps for 24 linkage groups consisting of 470 markers, which allowed us to place scaffolds that cumulatively represented 20.8% (153.8 Mb) of the sequenced genome onto the linkage groups. The distribution of orthologous genes on the chromosomes of tuna and four other teleost fish species suggested that the constitution of tuna chromosomes is closest to that of medaka. Both species have the 24 chromosomes of the ancestral teleost, including several chromosomal inversions. The integrated map developed in this study will be useful to construct a complete physical map to conduct comparative teleost genomics and genetic studies on economically useful traits in Pacific bluefin tuna.展开更多
This study proposes a simulation model that well reproduces the spawning stock biomass of Pacific bluefin tuna. Environmental factors were chosen to estimate the recruitment per spawning stock biomass, and a simulatio...This study proposes a simulation model that well reproduces the spawning stock biomass of Pacific bluefin tuna. Environmental factors were chosen to estimate the recruitment per spawning stock biomass, and a simulation model that well reproduced the spawning stock biomass was developed. Then, effects of various fisheries regulations were evaluated using the simulation study. The results were as follows: 1) arctic oscillations, Pacific decadal oscillations and the recruitment number of the Pacific stock of Japanese sardine were chosen as the environmental factors that determined the recruitment per spawning stock biomass;2) spawning stock biomass could be well reproduced using a model that reproduced the recruitment per spawning stock biomass and the survival process of the population that included the effect of fishing;and 3) the effects of various fisheries regulation could be evaluated using the simulation model mentioned above. The effective regulation in the simulations conducted in this paper was a prohibition of fishing for 0- and 1-year-old fish in terms of recovering the spawning stock biomass. The reduction of fishing mortality coefficients for all age fish to 50% of actual values also showed a good performance. The recent reductions of the recruitment and spawning stock biomass were likely caused by heavy harvesting, especially of immature fish, since 2004.展开更多
This paper addresses a fundamental question in conservation ecology, which is the balance between rebuilding of a species’ population and exploiting them, by examining an appropriate sustainable management regulation...This paper addresses a fundamental question in conservation ecology, which is the balance between rebuilding of a species’ population and exploiting them, by examining an appropriate sustainable management regulation for Pacific Bluefin tuna. The population of Pacific Bluefin tuna has been heavily depleted to just 2.6% of its historic unfished size by many years of overfishing. In order to rebuild the population, an immediate implementation of a moratorium on all commercial fishing was proposed by NGOs such as the Pew Charitable Trusts and Greenpeace. The primary objective of this paper is to examine the necessity of the moratorium as a sustainable stock management regulation. The paper concludes that an additional 10% reduction in catch limit of fish less than 30 kg could be a better alternative management regulation than a total ban on all fishing. This option can increase the probability of the stock recovery, while allowing to catch as many large fishes as under the current management regulation. Through the examination of sustainable stock management for Pacific Bluefin tuna, it can be said that it is important to consider the balance between the recovery of the population and utilization of them. Since millions of people rely on the consumption of the species, it is more realistic to gradually rebuild the population with an intermediate target and an efficient additional catch limit. This consideration can be applied to conservation of other species such as whales and eels.展开更多
In the present study, we investigated the effect of collagen and collagen peptides from bluefin tuna abdominal skin on cancer cells. Collagens were extracted from bluefin tuna (Thunnus orientails) abdominal, mackerel,...In the present study, we investigated the effect of collagen and collagen peptides from bluefin tuna abdominal skin on cancer cells. Collagens were extracted from bluefin tuna (Thunnus orientails) abdominal, mackerel, and carp skin. The calf and salmon collagen were used reagent grade as a standard samples. The main protein band pattern produced by SDS-PAGE of all collagen samples consisted of two chains and one chain. For collagen peptides samples, bluefin tuna ab-dominal skin collagen and salmon skin collagen were hydrolyzed by trypsin. Among samples, salmon, mackerel, carp collagen, and their collagen peptides did not significantly reduce relative cell growth. However, the bluefin tuna abdominal skin collagen dramatically reduced HepG2 and HeLa cell growth by over 50% relative in a concentration-dependent manner when added to cells seeded 96-well plates. This suggests the collagen adding time was mightily important for effect of the collagen.展开更多
This paper is to present a framework to analyse international relations regarding protection and exploitation of an endangered species. The question of how to balance conservation and consumption in order to maintain ...This paper is to present a framework to analyse international relations regarding protection and exploitation of an endangered species. The question of how to balance conservation and consumption in order to maintain the sustainability of resources and nature is not only the central challenge of conservation ecology, but also an international political and economic issue that frequently leads to confrontation between countries. In relation to whales, for example, Japan has long been subjected to criticism by anti-whaling countries such as the United States and Australia, and has faced off against them on the international stage. And, more recently, similar confrontations have begun to appear in relation to tuna and eel. It has been highlighted in recent years that Pacific Bluefin Tuna are becoming endangered, and there is considerable national and international concern with regard to their resource management. This paper first obtains an implication about the course of events that led to the fishing ban. The implication is applied to the case of Pacific Bluefin Tuna. Pacific Bluefin Tuna and the whaling issue reveals points of commonality. The conclusion is that history of the whaling issue implies that Japan will lose the support not only of countries opposed to fishing but also of neutral countries, if Tokyo continues to adopt policies which make light of resource conservation. Even a total ban on the fishing of Pacific Bluefin Tuna may result. This implication from the whaling issue is potentially helpful to predict the development of international relations and conservation regarding other endangered species.展开更多
This study shows that the stock-recruitment relationship (SRR) for Pacific bluefin tuna and the Pacific stock of Japanese sardine can be expressed by the same SRR model. That is, (environmental factors), where Rt and ...This study shows that the stock-recruitment relationship (SRR) for Pacific bluefin tuna and the Pacific stock of Japanese sardine can be expressed by the same SRR model. That is, (environmental factors), where Rt and St-1 denote the recruitment in year t and spawning stock biomass in year t - 1, and f(.) is a function that evaluates the effect of environmental factors in year t. The simulations showed that when the fluctuation in environmental factors cyclically changed, 1) the shape of the apparent SRR assumed clockwise loops for the shorter maturity age of fish, and 2) the apparent SRR comprised scattered anticlockwise loops for the longer maturity age of fish. These features coincided well with those observed. This finding gives us a new paradigm in SRR, which is far different from the concept that has predominated in the field for more than 60 years.展开更多
南方蓝鳍金枪鱼(Thunnus maccoyii)属高度洄游鱼类,主要分布在南半球30°S~50°S水域,是金枪鱼类中经济价值最高的种类之一,南方蓝鳍金枪鱼养护委员会(Commission for the Conservation of Southern Bluefin Tuna,CCSBT)是当前...南方蓝鳍金枪鱼(Thunnus maccoyii)属高度洄游鱼类,主要分布在南半球30°S~50°S水域,是金枪鱼类中经济价值最高的种类之一,南方蓝鳍金枪鱼养护委员会(Commission for the Conservation of Southern Bluefin Tuna,CCSBT)是当前管理该鱼种的唯一区域渔业管理组织。该资源的可持续利用日益受到国际社会的关注,也是CCSBT面临的挑战。结合南方蓝鳍金枪鱼种群分布、资源开发状况以及CCSBT现行养护和管理措施,探讨了南方蓝鳍金枪鱼渔业可持续利用面临的挑战,认为CCSBT通过实施一系列养护和管理措施,比较有效地遏制了南方蓝鳍金枪鱼资源的衰退趋势,而且近几年生物量呈现增加迹象,但仍然面临可能的非法、不报告和不受管制(Illegal,Unreported and Unregulated,IUU)捕捞活动、其他金枪鱼管理组织管辖范围内的兼捕以及渔获统计数据不完善等方面的挑战。就配额分配、提高数据质量、打击IUU捕捞,履行观察员最低覆盖率,以及妥善解决重叠区内南方蓝鳍金枪鱼兼捕问题等方面提出了相应的建议。结果可为研究或希望了解CCSBT渔业的有关企业和渔业管理人员提供参考。展开更多
文摘In this paper, the presence and amount of mercury and polychlorobiphenyls (PCBs) were determined in 23 bluefin tuna samples collected in the spring of 2012 in Porto Scuso (South West Sardinia, Italy) and Villa Putzu (South East Sardinia, Italy) in order to assess the current levels of these two contaminants in fish muscle and the consequent risk to humans consuming said fish. Values of polychlorobiphenyls in bluefin tuna muscle vary between 0.155 and 1.403 mg/kg f.w.;the average of PCBs in tuna muscle is 0.732 mg/kg f.w. With regard to PCBs the presence of more elevated concentrations is confirmed in larger fish. The results regarding mercury in muscle show an average of 0.660 mg/kg f.w. and mercury values vary between 0.140 f.w. and 2.211 mg/kg f.w.;for mercury as well, the highest concentrations were found in the largest bluefin tuna. Six samples, 26% of total, contained more than 1 mg/kg f.w., which is the maximum level set by the European Commission (EC, Regulation n. 1881/2006) for this species. Mercury, in particular methylmercury, poses a risk to public health, therefore, taking into account the important nutritional contribution that tuna fish makes to the diet, it is advisable that women of childbearing age, pregnant and breastfeeding women as well as young children strictly limit their consumption of tuna from this area of the Mediterranean.
文摘Pacific bluefin tuna (Thunnus orientalis) is one of the most economically important species in the Percomorpha group of teleost fishes. Their migrations are extensive and depend upon continuous swimming at a high rate of speed throughout their life. The draft genome sequence of this species has been reported but remains highly fragmented. We constructed a Pacific bluefin tuna genetic linkage map using microsatellite markers developed on each of the scaffolds from the draft genome sequence to link these genome fragments and understand the genomic structure of species in Percomorpha. Of the 606 polymerase chain reaction microsatellite primer pairs tested, 473 were polymorphic in the mapping populations for the linkage analysis. We constructed sex-specific maps for 24 linkage groups consisting of 470 markers, which allowed us to place scaffolds that cumulatively represented 20.8% (153.8 Mb) of the sequenced genome onto the linkage groups. The distribution of orthologous genes on the chromosomes of tuna and four other teleost fish species suggested that the constitution of tuna chromosomes is closest to that of medaka. Both species have the 24 chromosomes of the ancestral teleost, including several chromosomal inversions. The integrated map developed in this study will be useful to construct a complete physical map to conduct comparative teleost genomics and genetic studies on economically useful traits in Pacific bluefin tuna.
文摘This study proposes a simulation model that well reproduces the spawning stock biomass of Pacific bluefin tuna. Environmental factors were chosen to estimate the recruitment per spawning stock biomass, and a simulation model that well reproduced the spawning stock biomass was developed. Then, effects of various fisheries regulations were evaluated using the simulation study. The results were as follows: 1) arctic oscillations, Pacific decadal oscillations and the recruitment number of the Pacific stock of Japanese sardine were chosen as the environmental factors that determined the recruitment per spawning stock biomass;2) spawning stock biomass could be well reproduced using a model that reproduced the recruitment per spawning stock biomass and the survival process of the population that included the effect of fishing;and 3) the effects of various fisheries regulation could be evaluated using the simulation model mentioned above. The effective regulation in the simulations conducted in this paper was a prohibition of fishing for 0- and 1-year-old fish in terms of recovering the spawning stock biomass. The reduction of fishing mortality coefficients for all age fish to 50% of actual values also showed a good performance. The recent reductions of the recruitment and spawning stock biomass were likely caused by heavy harvesting, especially of immature fish, since 2004.
文摘This paper addresses a fundamental question in conservation ecology, which is the balance between rebuilding of a species’ population and exploiting them, by examining an appropriate sustainable management regulation for Pacific Bluefin tuna. The population of Pacific Bluefin tuna has been heavily depleted to just 2.6% of its historic unfished size by many years of overfishing. In order to rebuild the population, an immediate implementation of a moratorium on all commercial fishing was proposed by NGOs such as the Pew Charitable Trusts and Greenpeace. The primary objective of this paper is to examine the necessity of the moratorium as a sustainable stock management regulation. The paper concludes that an additional 10% reduction in catch limit of fish less than 30 kg could be a better alternative management regulation than a total ban on all fishing. This option can increase the probability of the stock recovery, while allowing to catch as many large fishes as under the current management regulation. Through the examination of sustainable stock management for Pacific Bluefin tuna, it can be said that it is important to consider the balance between the recovery of the population and utilization of them. Since millions of people rely on the consumption of the species, it is more realistic to gradually rebuild the population with an intermediate target and an efficient additional catch limit. This consideration can be applied to conservation of other species such as whales and eels.
文摘In the present study, we investigated the effect of collagen and collagen peptides from bluefin tuna abdominal skin on cancer cells. Collagens were extracted from bluefin tuna (Thunnus orientails) abdominal, mackerel, and carp skin. The calf and salmon collagen were used reagent grade as a standard samples. The main protein band pattern produced by SDS-PAGE of all collagen samples consisted of two chains and one chain. For collagen peptides samples, bluefin tuna ab-dominal skin collagen and salmon skin collagen were hydrolyzed by trypsin. Among samples, salmon, mackerel, carp collagen, and their collagen peptides did not significantly reduce relative cell growth. However, the bluefin tuna abdominal skin collagen dramatically reduced HepG2 and HeLa cell growth by over 50% relative in a concentration-dependent manner when added to cells seeded 96-well plates. This suggests the collagen adding time was mightily important for effect of the collagen.
文摘This paper is to present a framework to analyse international relations regarding protection and exploitation of an endangered species. The question of how to balance conservation and consumption in order to maintain the sustainability of resources and nature is not only the central challenge of conservation ecology, but also an international political and economic issue that frequently leads to confrontation between countries. In relation to whales, for example, Japan has long been subjected to criticism by anti-whaling countries such as the United States and Australia, and has faced off against them on the international stage. And, more recently, similar confrontations have begun to appear in relation to tuna and eel. It has been highlighted in recent years that Pacific Bluefin Tuna are becoming endangered, and there is considerable national and international concern with regard to their resource management. This paper first obtains an implication about the course of events that led to the fishing ban. The implication is applied to the case of Pacific Bluefin Tuna. Pacific Bluefin Tuna and the whaling issue reveals points of commonality. The conclusion is that history of the whaling issue implies that Japan will lose the support not only of countries opposed to fishing but also of neutral countries, if Tokyo continues to adopt policies which make light of resource conservation. Even a total ban on the fishing of Pacific Bluefin Tuna may result. This implication from the whaling issue is potentially helpful to predict the development of international relations and conservation regarding other endangered species.
文摘This study shows that the stock-recruitment relationship (SRR) for Pacific bluefin tuna and the Pacific stock of Japanese sardine can be expressed by the same SRR model. That is, (environmental factors), where Rt and St-1 denote the recruitment in year t and spawning stock biomass in year t - 1, and f(.) is a function that evaluates the effect of environmental factors in year t. The simulations showed that when the fluctuation in environmental factors cyclically changed, 1) the shape of the apparent SRR assumed clockwise loops for the shorter maturity age of fish, and 2) the apparent SRR comprised scattered anticlockwise loops for the longer maturity age of fish. These features coincided well with those observed. This finding gives us a new paradigm in SRR, which is far different from the concept that has predominated in the field for more than 60 years.
文摘利用酸溶法和酶溶法分离纯化绿鳍马面鲀(Navodon septentrionalis)鱼皮酸溶性胶原蛋白(ASC)和酶溶性胶原蛋白(PSC),并对所得的ASC和PSC的氨基酸组成、亚基组成、红外光谱(FTIR)、黏度和热变性温度,以及溶解度等性质进行系统分析。研究结果表明:马面鲀鱼皮酸溶性胶原蛋白(ASC)和酶溶性胶原蛋白(PSC)的得率分别为0.87%±0.15%和9.52%±0.41%(按鱼皮干重计算)。ASC和PSC中含有的主要氨基酸为甘氨酸(Gly),含量分别为323.3残基/1000残基和321.7残基/1000残基;二者中所含的亚氨基酸含量分别为191.1/1000残基和183.4/1000残基。氨基酸组成分析、SDS-PAGE和FTIR证实马面鲀鱼皮酸溶性胶原蛋白(ASC)为I型胶原蛋白,且其SDS-PAGE图中的亚基组成(α1-肽链和α2-肽链)、氨基酸序列,以及胶原蛋白构型与PSC明显不同。ASC和PSC的热变性温度(Td)分别为21.5℃和18.9℃,显著低于哺乳动物来源的胶原蛋白。ASC和PSC的最大溶解度出现在p H 2—3时,当Na Cl的浓度低于2%时,二者的溶解度就开始急剧下降。此外,冻干的胶原蛋白显示出疏松多孔的超微结构。综上,相对于哺乳动物类胶原蛋白,马面鲀鱼皮ASC和PSC的亚氨基酸含量和热变性温度较低,结构稳定性差,易于降解,可作为胶原蛋白肽的制备原料进行开发利用。
文摘南方蓝鳍金枪鱼(Thunnus maccoyii)属高度洄游鱼类,主要分布在南半球30°S~50°S水域,是金枪鱼类中经济价值最高的种类之一,南方蓝鳍金枪鱼养护委员会(Commission for the Conservation of Southern Bluefin Tuna,CCSBT)是当前管理该鱼种的唯一区域渔业管理组织。该资源的可持续利用日益受到国际社会的关注,也是CCSBT面临的挑战。结合南方蓝鳍金枪鱼种群分布、资源开发状况以及CCSBT现行养护和管理措施,探讨了南方蓝鳍金枪鱼渔业可持续利用面临的挑战,认为CCSBT通过实施一系列养护和管理措施,比较有效地遏制了南方蓝鳍金枪鱼资源的衰退趋势,而且近几年生物量呈现增加迹象,但仍然面临可能的非法、不报告和不受管制(Illegal,Unreported and Unregulated,IUU)捕捞活动、其他金枪鱼管理组织管辖范围内的兼捕以及渔获统计数据不完善等方面的挑战。就配额分配、提高数据质量、打击IUU捕捞,履行观察员最低覆盖率,以及妥善解决重叠区内南方蓝鳍金枪鱼兼捕问题等方面提出了相应的建议。结果可为研究或希望了解CCSBT渔业的有关企业和渔业管理人员提供参考。
