Physiology and Behavior Studies on the Stress and Survival of Fish after Escaping from Fishing Gear

从全球环境保护意识的角度来看，21世纪世界人口的增长将要求海洋渔业进一步可持续发展。捕鱼技术目前面临的重大目标是如何树立新的研究和开发理念，不仅要以增加捕捞量为传统目标，而且要改进捕捞过程，以尽量减少捕捞对环境和生物多样性的影响。在发展可持续渔业的综合办法下，完成了下列研究活动，包括比较捕捞和实验室试验。渔具的选择性：拖网、刺网、锅和陷阱是对鱼种和大小的选择性研究的主要对象，网目形状和尺寸的改变、排气孔和其他一些bed / brd装置，如下所述。目前迫切需要一种更符合资源管理实际目标的选择性性能评价方法。养护技术：以拖网渔具为例，副渔获物/弃物问题是最迫切需要解决的问题。对于沿海拖网来说，一些内部分拣网或网口分拣板的brd试验受到了挑战。至于渔网和围网装置，使用放牧/吸引刺激的逃生窗板将是通过与目标渔获物分离来排除非目标物种和大小的下一个目标。水下捕获过程的观察：视频、寻鱼器、声纳和生物遥测等工具现在被广泛用于了解海洋动物的行为，如拖网、套网和围网等。下一步需要采取综合方法，采用几种工具，以便在时间和空间尺度上从数量和质量上查看捕获过程的所有细节。鱼类行为与生理：感觉生理学和肌肉生理学是了解渔具捕获过程中刺激-反应系统的良好工具。与此方法相关的是，心率被用作对声音、光、频闪光等刺激识别的指标。鱼类在逃逸后的应激和生存也是响应持续选择性工作的一个重要目标。这可以成为了解捕鱼对目标物种和渔场生物多样性影响的工具之一。低投资可持续技术：渔业技术领域的研究和发展活动的目标是建立环境友好的捕捞系统。在这一点上，应该清楚地了解在相应渔场的每个渔具上捕鱼的效果。鱼类在逃逸后的应激和生存也是其响应的重要目标。这可以作为了解捕鱼对目标物种和渔场生物多样性影响的工具之一。另一点是渔业技术的成本效益，在各种渔业中寻求低投资的可持续技术。这里将总结一些在捕鱼技术和鱼类行为领域的案例研究。a)捕鱼的影响-以珊瑚礁渔业为例研究充分了解捕捞过程可以了解捕鱼作业如何影响环境和鱼类资源，然后如何通过技术解决方案将这些捕鱼影响降到最低。Craik等人（1990年）主要讨论了拖网渔业的捕鱼影响，或者最近在ICES鱼类行为和捕鱼技术工作组（1999年）和保护生物学会议（1998年）中从拖网渔具的物理影响的角度讨论了捕鱼的影响。首先应清楚地了解影响的广泛范围，并寻求解决办法以尽量减少影响。它们可分为三类：渔场（特别是底栖生物干扰）、生物多样性（包括不需要的物种的副渔获物/弃置物）、过度捕捞和幼鱼副渔获物/弃置物的目标资源。幽灵捕鱼、鱼在逃脱或被丢弃后的压力和生存也可以包括在目标和不需要的捕获物种中。珊瑚礁是公认的全球变暖问题的重要缓冲器，是热带地区多样化生态系统的孕育区，在这里，炸药和毒素等破坏性捕捞行为受到了批评和禁止，在这里，应建议对珊瑚礁地区采用环保捕捞技术，改变传统的破坏性捕捞方式。b)鱼类脱网后的压力和生存鱼类脱网后的生存和压力，以及渔具尺寸/种类选择性的技术改进，可以作为建立可持续捕捞技术的线索。如果由于齿轮的选择性作用而使未计算的死亡率增加，则越高的选择性反而可能导致越高的逃逸者死亡率。本文将总结清扫网的案例研究。扫网围网是一种围捕日本白鲑沙渔场的带扫程序的缠结装置。通过网格选择性研究，研究捕获鱼的生存和压力，以确定捕获过程中由于渔具冲击而逃脱的命运，采用以下方案；1)通过观察饲养池中随时间流逝的死亡率进行生存实验；2)根据死亡/恢复所经过的时间，通过血浆皮质醇水平进行应激测量。少

The world population expansion in the 21^<st> Century will require the further sustainable development of marine fisheries industry from the view point of the global awareness of environmental conservation. The fishing technology has now the great target how to establish the new concepts for the research and development activities, not only for increasing the catch as the traditional goal, but also for improving the capture process to minimize the fishing impact to the environment and bio-diversity.The comprehensive approach for developing the sustainable fisheries, the following research activities were completed, both with the comparative fishing and laboratory experiments.Fishing gear selectivity : Trawl net, gill net, pot and trap are the main target of the selectivity studies for species and sizes with mesh shape and size modifications, escape vent and some other devices of BEDs/BRDs, mentioned below. The evaluation method for the selectivity performance is urgently required in ac … More oordance with the practical goals of resource management.Conservation technology : In case of the trawl gear, the by-catch/discards issue is the most urgent target to be solved. For the coastal trawl, some trials with the BRDs of inside sorting grid or the sorting panel at the net mouth have been challenged. Concerning set-net and purse seine gears, the escape window panel with the use of herding/attracting stimuli will be the next target for excluding non-target species and sizes by separating from the target catch.Underwater observations of the capture process : The tools such as the video, fish finder, sonar and bio-telemetry are now in popular use for understanding animal behavior at sea, for the trawl, set-net and purse seine etc. A comprehensive approach to employ several tools will be required as the next step to see all details of the capture process in quantity and quality in both time and space scales.Fish Behavior and Physiology : Sensory physiology and muscle physiology can be good tools to understand the stimuli-response system in the capture process of the fishing gears. In relation to this approach, the heart beat rate is employed as the index of stimuli recognition towards sound, light, strobe light etc. The stress and survival of fish after escape is also a big target in response with the on-going selectivity works. This can be one of the tools to understand the fishing impact on the target species and bio-diversity in the fishing ground.Low investment sustainable technology : The goal of the research and development activities in the field of fishing technology is to establish the environmentally friendly harvesting systems. In this point, the effect of fishing should be clearly understood in each fishing gear in corresponding fishing ground. The stress and survival of fish after escape is also the big target in response with the on-going selectivity works. This can be one of the tool to understand the effect of fishing to the target species and bio-diversity in the fishing ground. Another point is the cost efficiency in fishing technology to seek the low-investment sustainable technology in various fisheries. Some case studies in the field of fishing technology and fish behavior will be summarized here.a) Effect of Fishing-case study in coral reef fisheriesThe full understanding of the capture process can give the idea how the fishing operation affect the environment and fish resources, and then how to minimize these fishing impacts through the technological solutions. The effects of fishing have been discussed mainly for the trawl fisheries, by Craik et al (1990), or very recently from the view points of the physical impact of the towed gears in ICES Working Group on Fish Behavior and Fishing Technology (1999) andConservation Biology meeting (1998). The wide range of impacts should be clearly understood at first, and challenged towards the solution to minimize them. They can be classified into 3 categories as the fishing ground especially for the benthic disturbance, bio-diversity including the by-catch/discards of unwanted species, and target resources for the over-fishing and juvenile by-catch/discards. The ghost fishing, stress and survival of fish after escape or being discarded can be also included for both the target and unwanted catch species. Coral reefs are well recognized as the important buffer for global warming issues, and as the nursery area for the diversified ecosystem in the tropical zone, where the destructive fishing practices such as the explosives and toxins have been criticized and prohibited Here, the environmentally friendly fishing technology for the coral reef area should be suggested to alter the conventional destructive practices.b) Stress and survival of fish after escapeSurvival and stress of fish after escaping the gear can be the cue to establish the sustainable fishing technology, together with the technological improvement of size/species selectivity of the fishing gear. In case of the increase of the unaccounted mortality due to the selectivity function of the gear, the higher selectivity may just result into the higher mortality for escapees. Case study for the sweeping trammel net will be summarized here. The sweeping trammel net is a type of entangling gear with the sweeping procedure for encircling the sandy fishing ground targeting the Japanese whiting Sillago japonica. Though the mesh selectivity studies, the survival and stress of captured fish were investigated for identifying the escapees fate due to the gear impact during the capture process, by the following protocol ;1) Survival experiment by observing the mortality rate with time elapsed in the keeping tank, and2) Stress measurement by means of Plasma Cortisol level according to the time elapsed toward the death/recovery. Less