Research on the process of by-catch of discards in coastal fisheries ; development of environmentally-friendly fishing technology

1.沿海渔业副渔获物丢弃情况调查：对Gochi-ami(非拖曳小船围网)渔业的遗弃物进行了船上调查和多变量分析。不同次级部门的物种组成有很大差异，或者是专门发生的丢弃。不同子行业的报废率也不同。大量的蓄积型高商业树种被丢弃。这是在大规模丢弃估计的方法学研究中发展起来的。丢弃估计的最佳因素是总和丢弃率，由于丢弃和保留量之间的相关性较差，因此特定丢弃率没有统计学基础。生物对渔具的行为：通过红外线水下视频观察了深水对虾对围网的行为，发现对虾按概率向后弹跳渔网并穿过网眼的独特行为。对对虾的排斥过程进行了建模，模拟了对虾被排斥的概率。On-Boa…副渔获物捕获过程的进一步研究：根据网板和网尾上有口袋网和盖网的实验网捕获的样本，研究了围网对对虾和副渔获鱼的选择性。对虾被排除在渔具上，而鱼类，主要是通过网囊。作为一个整体，网囊和网囊的选择特性有很大的不同。对不同网目渔具的尺寸选择进行了理论计算，建立了网目选择尺寸管理图，为渔具管理提供了建议。研究现状和未来展望：对虾通过网眼排除的精确过程正在分析中。结合行为的现场观察和上述分析，对诱导选择性的过程进行了模拟。为了验证理论评估的模型和开发实用的选择性渔具，正在准备一系列新的现场试验，以开发选择性围网。较少

1. Survey of by-catch discards in coastal fisheries : Discards in gochi-ami (non-dragged small boat seine) fishery was surveyed onboard and multi-variable-analyzed. Species compositions were largely different among sub-sectors, or discards occur specifically. Discard ratios also differed among sub-sectors. A large amount of stock-enhanced highly-commercial species were discardedThis was developed in methodological study on large-scale discard estimation. The best factor for discard estimation is a summed discard ratio and a specific discard ratio has no statistical basis because of poor correlation between discards and retentions.2. Behavior of organisms against fishing gear : Behavior of deep-water prawn against boat seine was observed by infra-red underwater video and unique behavior of prawn to bounce net webbing backwards and pass through a mesh by probability was found. The exclusion process for prawn was modelled and probabilities for prawns for exclusion were simulated.3. On-boa … More rd study on by-catch capture process : Selectivity of boat seine for prawns and by-catch finfishes were studied on the basis of samples captured by an experimental net with pocket and cover nets over the net panels and codend. Prawns are excluded over the gear, while, finfishes, mainly through the codend. Selective characters were quite different between the codend and the net as a whole. Size-selectivty of the gear with different meshes were theoretically calculated and 'mesh-selective size management diagram' was established for recommendation for fishing gear management.4. Present studies and future prospects : The precise process of exclusion for prawn though a mesh is being analyzed. Together with the field observation of behavior and the above analysis, the process to induce the selectivity is to be modelled. A new series of field experiments to develop selective boat seine is being prepared in order to verify the theoretically evaluated models and to develop practically selective fishing gear. Less