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出发，21世纪世界人口的增长将要求海洋渔业的进一步可持续发展。渔业技术现在的大目标是如何为研究和开发活动建立新的概念，不仅是为了增加捕获量作为传统目标，而且是为了改进捕捞过程，以最大限度地减少捕捞对环境和生物多样性的影响。为了发展可持续渔业，通过比较捕捞和实验室实验，完成了以下研究活动。渔具选择性：拖网、刺网、网具和诱捕器是物种和大小的选择性研究的主要目标，通过改变网目形状和大小、泄漏口和一些其他装置的床/BRD，如下所述。交流…迫切需要一种选择性性能的评价方法。养护技术：在拖网渔具的情况下，副渔获物/丢弃问题是最迫切需要解决的目标。对于沿海拖网，一些使用内部分拣栅格或网口分拣面板的BRD试验受到了挑战。关于固定网和围网渔具，使用群聚/吸引刺激的逃生窗板将成为下一个目标，通过与目标渔获物分开来排除非目标物种和大小。捕获过程的水下观察：视频、发鱼器、声纳和生物遥测等工具现在广泛用于了解海洋动物的行为，用于拖网，下一步需要使用多种工具的综合方法，以便在时间和空间尺度上看到捕获过程的数量和质量的所有细节。鱼的行为和生理：感觉生理学和肌肉生理学可以成为理解渔具捕获过程中刺激反应系统的很好工具。在这种方法中，心率被用来作为对声音、光、频闪光等刺激识别的指标。鱼类逃逸后的应激和存活也是正在进行的选择性工作的一大目标。这可能是了解捕捞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开发活动的目标是建立环境友好型捕捞系统。在这一点上，捕鱼的效果应该清楚地了解在相应的渔场的每个渔具。鱼类逃逸后的应激和生存也是正在进行的选择性工作应对的大目标。这可以作为了解捕捞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，以寻求在各种渔业中低投资的可持续技术。这里将概述捕捞技术和鱼类行为领域的一些案例研究。a)捕捞的影响--珊瑚礁渔业的案例研究对捕捞过程的充分了解可以使人们了解捕捞作业如何影响环境和鱼类资源，以及如何通过技术解决方案将这些捕捞影响降至最低。捕捞的影响主要是由Craik等人(1990年)讨论的，或者最近在ICES鱼类行为和捕捞技术工作组(1999年)和养护生物学会议(1998年)中从拖网的物理影响的角度讨论的。首先应该清楚地了解影响的广泛范围，并针对将其降至最低的解决方案提出挑战。它们可分为3类：特别是底栖生物干扰的渔场，生物多样性，包括不需要的物种的副渔获物/丢弃，以及过度捕捞和幼鱼副渔获物/丢弃的目标资源。对于目标和不想要的捕获物，也可以包括幽灵捕鱼、逃脱或被丢弃后鱼类的压力和生存。珊瑚礁被公认为全球变暖问题的重要缓冲，作为热带多样化生态系统的保育区，诸如炸药和毒素等破坏性捕捞做法在这里受到批评和禁止，应建议珊瑚礁区的环境友好型捕捞技术以改变传统的破坏性做法。b)鱼类逃逸后的压力和生存可以作为建立可持续捕捞技术的线索，以及渔具尺寸/物种选择性的技术改进。在齿轮的选择性功能导致不明死亡率增加的情况下，较高的选择性可能只会导致逃生者的较高死亡率。这里将总结横扫索道网的案例研究。拖网是以日本白鲸为目标，在沙地渔场进行扫网作业的一种缠绕渔具。通过网目选择性研究，调查了捕获鱼的存活和应力，以确定捕获过程中由于渔具撞击而逃脱的鱼的命运，采用以下方案：1)通过观察在养殖箱中经过的时间的死亡率进行存活实验，以及2)通过血浆皮质醇水平根据死亡/恢复所经过的时间来测量应力。较少

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