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鱼病是一种灾害，防治不当不但不能达到药到病除的效果，而且会雪上加霜造成更大的损失。在往年发生的一些爆发性鱼病，比如珠三角和海南的虾病毒病、江苏的鲢鱼脑孢虫病、湖北浙江的蚌瘟病和南方地区的细菌性败血症及罗非鱼链球菌病都给养殖户造成了巨大的损失。其实造成巨大损失的原因，“病”的本身只是其中的一个不足分量的因素，而“治”的不当所引起的不能及的挽救才是真正的祸害源头。经本人对众多来访求医者调查发现20％的鱼病所造成的损失是因为“病”本身的难治，80％是因为“治”的不当而造成的。这是一个值得我们渔业界深思的问题。 相似文献
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对各种微量电泳方法的利用要求实验才对他（她）的特定的问题有适当的研究，这些选择中所涉及到的一些因素多半是微量样品的大小，酶的浓度，特定酶染色剂的灵敏性，在选定的凝交和缓冲液条件下满意的同工酶谱，是否同工酶被显微镜光密度计定量。材料的价值和工作人员在方法上的取舍。利用动物细胞克隆的微量电泳能够进一步地开展许多技术要求得严格的领域的研究工作。 相似文献
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正水色,最通俗的解释就是水面所呈现的色泽。一般来说,水是无色透明的,我们常见的自来水都是清澈明澄的。但水在不同的地方会表现出不同的水色,因此我们所指的水色主要是指水体的颜色。水色的形成是太阳光经水体散射后,可见光与近红外辐射的散射光所呈现的颜色,它会受到各种因素影响,其中包括物理的、化学的,还有生物的。水产养殖的水色是由养殖水体中的溶解 相似文献
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鱼粪洄游速度的研究,无论理论上还是在实践方面都具有趣味,特别是对洄游鲑游泳的生物能量季相的揭露具有很大的意义。对于鱼类游泳效率提高的特性总的综合有:特殊的体型,粘液的覆盖,肌肉的合理分布,组织和气体代谢能量的可能。可见,最好的游泳速度是在能量消耗最低的情况下。这在游泳鱼类远距离的和疲劳的洄游时期内具有特殊的意义。实验证明:无疲劳的鲑科鱼类每秒钟可长时期的维持3—4体长(L)的游泳速度。用 相似文献
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渔业的功能是多元化的,不同的功能在不同的发展阶段上有着不同的发展方向与重点。研究分析渔业功能在不同的发展阶段上的特点与要求,找准其发展的方向与重点,采取相应的对策,促其持续协调发展,发挥功能的最佳效益,实现渔业的可持续发展,则是当前渔业发展上迫切需要解决的一个重 相似文献
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Relationships among yellowfin and skipjack tuna, their prey-fish and plankton in the tropical western Indian Ocean 总被引：2，自引：0，他引：2
CLAUDE ROGER 《Fisheries Oceanography》1994,3(2):133-141
Stomach contents of yellowfin (Thunnus albacares) and skipjack (Katsuwonus pelamis) tuna caught by trolling and purse seining in the tropical western Indian Ocean, together with those of the prey-fish found in their stomachs, have been analysed. Epipelagic fish are the main prey of these tunas, whereas no vertically migrating fish, which inhabit subsurface layers at night, have been found in their stomachs. These tunas are thus considered day-feeders. Purse-seine-caught tunas, which belong to large schools, have a much higher number of prey-fish in their stomachs than tunas caught by trolling on small schools. Similarly, prey-fish from purse-seine tunas have a much higher number of plank-tonic prey in their stomachs than those from troll-caught tunas. Therefore, these tunas adopt a wandering strategy in small schools when food resources are scarce and form large schools when they are abundant. The planktonic organisms found in the stomachs of prey-fish are described by taxa and sizes; they represent the fraction of the planktonic biomass actually supporting the stock of tuna. Size ratios between the three links tuna-prey-fish-plankton are very high, suggesting that these tunas benefit from a short food chain which is probably efficient from the energetic point of view. 相似文献
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Hamish M Aiken Nathan J Bott Ivona Mladineo Francisco E Montero Barbara F Nowak & Craig J Hayward 《Fish and Fisheries》2007,8(3):167-180
Global distribution of platyhelminth parasites and their host specificities are not well known. Our hypothesis was that platyhelminth parasites of large pelagic fishes are common around the world. We analysed molecular variation in three different taxa of platyhelminth parasites infecting four species of tunas: yellowfin tuna (Thunnus albacares, Scombridae) from Western Australia, southern bluefin tuna (Thunnus maccoyii, Scombridae) from South Australia, Pacific bluefin tuna (Thunnus orientalis, Scombridae) from Pacific Mexico and northern bluefin tuna (T. thynnus, Scombridae) from two localities in the Mediterranean (Spain and Croatia). Comparisons of ITS2 and partial 28S rDNA demonstrated two congeneric species of blood flukes (Digenea: Sanguinicolidae) from multiple hosts and localities: Cardicola forsteri from southern bluefin and northern bluefin tunas, and Cardicola sp. from Pacific bluefin and northern bluefin tunas; and a gill fluke, Hexostoma thynni (Polyopisthocotylea: Hexostomatidae), from yellowfin, southern bluefin and northern bluefin tunas. Partial 28S rDNA indicates that a second type of fluke on the gills, Capsala sp. (Monopisthocotylea: Capsalidae), occurs on both southern bluefin and Pacific bluefin tunas. This appears to be the first report of conspecific platyhelminth parasites of teleosts with a wide‐ranging geographical distribution that has been confirmed through molecular approaches. Given the brevity of the free‐living larval stage of both taxa of flukes on the gills (H. thynni and Capsala sp.), we conclude that the only feasible hypothesis for the cosmopolitan distribution of these flatworms is migrations of host tunas. Host migration also seems likely to be responsible for the widespread occurrence of the two species of blood flukes (Cardicola spp.), although it is also possible that these were translocated recently by the spread of infected intermediate hosts. 相似文献
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Anchored and drifting Fish Aggregating Devices (FADs) are intensively used in tropical tuna fisheries. In both small-scale and industrial fisheries, skipjack (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) are the main targets. The increasing development of this fishing practice by industrial purse seiners has raised the question of the impact of FADs on tuna communities, as they might act as an ecological trap. This study investigated the feeding habits of skipjack and yellowfin tuna associated with anchored and drifting FADs in the western Indian Ocean. The diet of 352 tunas was analysed taking into account the type of FAD, ontogenetic variations, and the resources richness of the area. Poor-food and rich-food areas were defined according to the abundance of stomatopod Natosquilla investigatoris, the main prey of tunas, on the fishing sites. Diet composition was expressed through functional groups of prey. Significant dietary differences were found between both FAD types, as well as an effect of individual size. Around anchored FADs tuna preyed on diverse assemblages of coastal fish and crustacean larvae and juveniles, whereas a low diversity of epipelagic prey dominated the tuna diet associated with drifting FAD. Compared to anchored FADs, the frequency of empty stomachs was significantly higher and the stomach content mass significantly lower among skipjack and small yellowfin tunas caught around drifting FADs. This was magnified in poor-food areas, where drifting FADs often evolved, suggesting that these FADs could negatively impact the growth of skipjack and small yellowfin tuna. Larger yellowfin tuna exhibited differences in their dietary habits between anchored and drifting FADs, and between poor-food and rich-food areas. However, drifting FADs did not impact them as strongly as juveniles of yellowfin or skipjack tunas. Our study gives new highlights on possible detrimental effects of FAD on tunas, and this has to be considered in future sustainable management strategies of tuna fisheries. 相似文献
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I. Ferrante R. Ricci E. Aleo S. Passi S. Cataudella 《Aquaculture (Amsterdam, Netherlands)》2008,279(1-4):182-187
Bluefin Tuna (Thunnus thynnus L.) is a fish species of high nutritional and commercial value that is increasingly farmed in the Mediterranean basin. Oxidative stress research in aquaculture is particularly important in the assessment of both the health of farmed fish and seafood quality. Reactive oxygen species (ROS) are able to start the lipid peroxidation process which is potentially dangerous in fish, since they contain a high percentage of n-3 polyunsaturated fatty acids, in particular C20:5 n-3 and C22:6 n-3, which account for most of seafood's nutritional quality. The study of the antioxidant system and how the various components interact to delay post-harvest lipid peroxidation covers both the improvement of quality and the extension of shelf life of the fresh tuna product.In this study, hepatic antioxidant enzymes (catalase—CAT, superoxide dismutase—SOD and glutathione peroxidase—GPx) and lipid peroxidation levels (TBARS) of wild and sea cage-reared tunas were investigated. The aim was to examine the possible oxidative stress state of wild tunas killed by different fishing methods, compared with reared specimens exposed to different periods of confinement but killed by the same method.No significant differences between wild specimens were found in relation to catching techniques. A significant depletion was observed in liver SOD activity in reared tunas (5.00 U/mg protein) in comparison with wild specimens (5.90 U/mg protein). No differences in liver CAT activity between wild and reared tunas were found. In reared specimens we observed an oxidative stress state indicated by an increase in GPx activity (104.70 U/mg protein and 0.83 U/mg protein in reared and wild tunas, respectively). A significantly higher liver lipid content was observed in reared tunas, but no significant differences between wild and reared tunas in terms of TBA reactive substances content were found (2.03 vs 2.02 micromol TBARS/mg lipid). Our results suggest that the increased GPx activity leads to the suppression of lipid peroxidation in liver of reared tunas. This is the first time that antioxidant enzyme activities have been assayed in Bluefin Tuna and the stress state seems to be related to the diet of reared specimens rather than to their confinement, as indicated by the absence of differences in the antioxidant activities related to the period of confinement. 相似文献
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We present a model that simulates the foraging behaviour of tunas in the vicinity of ocean fronts. Stochastic dynamic programming is used to determine optimal habitat choice and swimming speed in relation to environmental variables (water temperature and clarity) and prey characteristics (abundance and energy density). By incorporating submodels for obligate physiological processes (gastric evacuation, standard and active metabolic costs) and sensory systems (visual feeding efficiency), we have integrated into a single fitness-based model many of the factors that might explain the aggregation of tunas at ocean fronts. The modelling technique describes fitness landscapes for all combinations of states, and makes explicit, testable predictions about time- and state-dependent behaviour. Enhanced levels of searching activity when hungry and towards the end of the day are an important feature of the optimal behaviour predicted. We consider the model to be particularly representative of the behaviour of the warm-water tunas or Neothunnus (e.g. skipjack, Katsuwonus pelamis , and yellowfin, Thunnus albacares ) and for surface-dwelling temperate tunas (e.g. young albacore, Thunnus alalunga ), which are often observed to aggregate near fronts. For the bluefin group (i.e. older albacore; northern and southern bluefin, Thunnus thynnus and Thunnus maccoyii ), for which extended vertical migrations are a significant and as yet unexplained component of behaviour, the model is able to reproduce observed behaviour by adopting the lower optimal temperature and standard metabolic rate of albacore. The model cannot explain why physiological differences exist between and within the different tuna species, but it does show how differences in susceptibility to thermal stress will permit different behaviour. 相似文献
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A review of temperature and oxygen tolerance studies of tunas pertinent to fisheries oceanography, movement models and stock assessments 总被引：14，自引：0，他引：14
RICHARD W. BRILL 《Fisheries Oceanography》1994,3(3):204-216
Detailed data on the physiological abilities and habitat requirements of some tuna species have now been collected. Laboratory and field studies show tunas are not strictly prisoners of their own thermoconserving mechanisms, but have rapid and extensive control over the efficacy of their vascular countercurrent heat exchangers. Skipjack tuna (Katsuwonus pelamis) are, therefore, probably not forced out of formerly suitable habitats as they grow because of the potential for overheating, as formerly thought. Because of their thermoregulatory abilities, bigeye tuna (Thunnus obe-sus) apparently can exploit food resources well below the thermocline by minimizing rates of heat loss when in cold water, and then maximizing rates of heat gain from the environment during brief upward excursions into the warmer mixed layer. Widely cited estimates of limiting oxygen levels, based on estimated metabolic rates at minimum hydrostatic equilibrium swimming speeds, are not accurate because tunas have exceptionally high oxygen demands even at slow speeds. High metabolic rates, even at slow swimming speeds, most likely result from the high osmoregulatory costs engendered by tunas' large thin gills and/or their other adaptations for achieving exceptionally high maximum metabolic rates. Recent laboratory research and modelling efforts suggest the capacity of tunas' cardiorespiratory systems to deliver oxygen at extraordinarily high rates was evolved to allow rapid recovery from strenuous exercise, rapid digestion, and high rates of gonadal and somatic growth, not high sustained cruising speeds. The rate at which reduced ambient oxygen levels prolong the time required for tunas to recover from strenuous exercise appears to be a good index of habitat suitability, with respect to oxy-een. 相似文献
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西沙群岛附近海区金枪鱼类仔稚鱼的调查研究报告 总被引：1，自引：0，他引：1
本文是根据,1975年1月至1976年5月，在西沙群岛附近海区采集到的金枪鱼类仔稚鱼标本，进行研究鉴定的结果。共鉴定了双棱线鲅、鲣、鲔、扁舵鲣、金枪鱼、黄鳍金枪鱼和副金枪鱼等7种，作了形态描述，并对它们的分布和产卵期等作了初步探索。 相似文献
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Evaluating the physiological and physical consequences of capture on post-release survivorship in large pelagic fishes 总被引：3，自引：1，他引：3
G. B. SKOMAL 《Fisheries Management and Ecology》2007,14(2):81-89
Abstract Sharks, tunas and billfishes are fished extensively throughout the world. Domestic and international management measures (quotas, minimum sizes, bag limits) mandate release of a large, yet poorly quantified, number of these fishes annually. Post-release survivorship is difficult to evaluate, because standard methods are not applicable to large oceanic fishes. This paper presents information on the current approaches to characterising capture stress and survivorship in sharks, tunas and marlins. To assess mortality associated with capture stress, researchers must examine the cumulative impacts of physical trauma and physiological stress. Physical trauma, manifested as external and internal tissue and organ damage, is caused by fishing gear and handling. Gross examination and histopathological sampling have been used to assess physical trauma and to infer post-release survivorship. Exhaustive anaerobic muscular activity and time out of water cause physiological stress, which has been quantified in these fishes through the analyses of blood chemistry. Conventional, acoustic and archival tagging have been used to assess post-release survivorship in these species. Future studies relating capture stress and post-release survivorship could yield information that helps fishermen increase survivorship when practicing catch and release. 相似文献