This keynote paper describes twelve important worldwide applications of artificial reef technology. Situations range from emphasis on artisanal and labor-intensive practices using natural materials, to use of man-made materials involving more elaborate engineering practices to achieve recreational fishing and diving objectives, conservation of habitats and biodiversity, and commercial seafood production. Common to all reef technologies is the need to evaluate performance. This paper establishes and “assessment concept” and “success criteria” to determine if and when reefs meet the objectives for which they were created. It identifies reasons for engineering/physical, socio-economic and ecological analysis of reef performance. To make full use of artificial reef technology, it is essential to develop common, consistent and comparade assessment practices and apply them globally. Emerging issues in the field include developing project specific designs, testing the application of reefs in marine reserves, employing reefs as part of sustainable fishery management, developing information transfer among scientists and the public, and further refinement of evaluation procedures.

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In order to enhance the survival rate and retention rate of released grouper, Epinephelus akaara seedlings, the artificial reefs and acoustic-sound feeding method were used. Total of 10, 198 marked grouper seedlings (8-14cm TL) were released on the artificial reefs in the Seto Inland Sea from 1996 to 1999. By underwater observations, 43.7% of the one-year-old seedlings remained for one year on the artificial reefs where they were released. The groupers caught by gill nets around the artificial reefs fed mainly on arthropod (macrurans, anomurans, and brachyurans), fish, and artificial diet that was provided by an acoustic-sound feeding buoy system. These natural food items, which colonized on the artificial reef, may be the most important food for the groupers. Artificial reefs were very effective in supplying nursery grounds and food organisms for the released groupers. The acoustic-sound feeding method promoted the colonization of the grouper seedlings.

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Secondary production on two types of artificial reefs are compared from the aspects of the roles of sedentary epifauna to increase spatial heterogeneity. Food organisms for reef fish were more abundant on a steel reef made of reinforcing rods than on a concrete reef with flat surfaces. On the steel reef, deposit feeding Polychaeta increased as Ascidiacea and Bryozoa densities increased. Maxillpoda and Demospongeae were abundant on the concrete reef while they could not grow on the iron rods of the steel reef. Although their role to offer habitats for small mobile epifauna is important on the concrete reef with flat surface, they kept the faunal community on the concrete reef in an early stage of succession and thus made the secondary production lower than the steel reef. Artificial reef design should consider the attachment of primary inhabitants in terms of community maturing process, too.

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To recycle old fishing vessel as an artificial habitat, design technology is established through physical experiment and numerical simulation. Numerical simulation based on finite volume method with standard κ-ε model and hydraulic experiment using flow visualization scheme are applied to determine sheltered area and reasonable interval between vessel habitats. Reattachment length, as an index of the area, is ranged from 5 to 10 times of vessel height according to Reynolds number. It is necessary of the interval more than 4 times of the length to maximize total area. As results of hydrodynamic experiment, drag coefficient from 1.5 to 2.0 and lift coefficient from 0.3 to 0.8 according to Reynolds number in current field, inertia coefficient of 0.5 in wave field can be applied to estimate demanded weight. Additional measures to enhance fish aggregation are discussed on opening holes with regard to ecological habit of target fish as well as attaching membranes on the hull.

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We have to think environmental conditions in waters for a decision of settled site of artificial reefs. Commonly their settled sites have been decided based on fishermen's experience and there is no scientific evidence to design their settled site. We researched an physical environment of fishing grounds of benthic and pelagic fishes in two waters. In case of benthic fishes, we applied an environmental analysis method extracting some restrict factors for object species to a natural reef named “Kakino-se” off Yamaguti Pref. It could make clear for juveniles of Yellow Sea bream that the interval between reefs, water temperature, and silt concentration in the sea bottom became these factors as the fishig ground. In case of pelagic fishes, internal waves as physical environment concims with an ecosystem. We observed an water mass behavior around the natural reef named Hutashima-guri off Yamaguti Pref. An artificial high-rise reef had been settled close to this natural reef and is aggregating many zooplanktons and horse mackerels. This aggregation was suggested for a internal vertical mixing caused by this shoal hydraulically.

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Snow crab stocks in the westem Sea of Japan have been overfished by the Danish seiners. Six preserved areas were established off Kyoto Prefecture from 1983 to 1999, where artificial reefs made of concrete blocks were provided and all the crab fisheries were closed. As a result, functionally matured males and fully matured females aggregated to the first preserved area. CPUE and survival rates of both adult males and females were higher in the preserved area than that in the outside. The average annual catch from 1995 to 1999 expanded about 75% compared with ones from 1978 to 1982. Our survey suggested that a preserved area with artificial reefs provide protection from over-exploitation by Danish seiners for matured crabs as well as providing suitable habitat for recruiting juveniles.

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Internal waves are inferred to affect the physical environment near bottom and a formation of fishing ground. It is important to make clear the transformation of these internal waves by coastal topography. In this study, we propose the simple practical model in which inserted a continuous layer in an interface of two layers, and added the Coriolis force and investigated an effect of its force. The shallow water transformation and refraction follow the Snell's theorem when the internal waves progress in the shallow area. Then, the Coriolis force acts to mass transport generated by the shallow water transformation, and makes the wave direction change. The height and the breaking condition of internal waves are also estimated. These theories inspected using hydraulic experiments with rotary channel. These theories were applied to two coastal waters. The results suggested as follows. 1) Orientation of internal waves were related with red sea breams behavior in the waters of Oki islands, Shimane Prefecture, 2) The distribution of Juvenile food concentration of red flounder (flathead flounder) was influenced by the location of bottom water's edge of internal waves in Wakasa Bay.

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Freshwater environments in Hokkaido have been significantly altered by human activities. Restoration work in a channelized reach of the Shakotan River was carried out in 1996. Habitat complexity was increased by the addition of structures to the restored section which replaced a simple stream structure with pools, riffles and runs. More spawners and juveniles were found in the restored reach than in the unimproved control reach. Restoration with log dams and deflectors improved habitat for masu salmon, and is a useful habitat enhancement technique in natural streams. We encourage more programs such as ours where biologists and engineers work together to improve habitat conditions in streams to benefit salmon.

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This paper reviews the current situation of the fishing industry, including in the first instance aquacultures in the world as well as examining the studies related to the development of nature-friendly fishing ports. In addition, the integrated preparation strategies of the fishing port consistent from the increase in aquatic resources to processing and distribution will be discussed later, aiming at the sound development of the fishing industry and the security of sea food supply. Consequently, in the 21 st century a variety of environmentally-friendly fishing ports would appear in order to pursue a sustainable development and utilization of aquatic resources.

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The development of fishing ports and coastal fishing grounds is one of the most important policies of Japan. Currently there are quantitatively sufficient fishing ports. At the same time, the “Build and Nurture Fisheries” policy is being used to develop coastal fishing grounds and promote fisheries in coastal areas and make efficient use of resources. Presently, the Japanese fishing industry is under severe pressure, both within and outside Japan. Given the demands of the age for protecting the global and marine environments and ecosystems, more efficient and effective linkages are being required for development projects. This paper will give an overview of the Japanese fisheries infrastructure and examine the development of associated policies in order to promote the integrated development of fishing ports, coastal fishing grounds and fishing villages.

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Red sea bream, Pagrus major, is one of the most popular species for fish stock enhancement in Japan. In order to increase the stocking effectiveness, we examined an extensive intermediate breeding method using fishing ports in Hyogo Prefecture as well as an intensive method from 1997 to 1999. In the intensive intermediate breeding method, juveniles were bred under high density in a small divided net (Kowari-ami), which was not contacted with sea bottom. They became a physical constitution of high basal metabolism. Besides they could not learn how to protect themselves against predators and catch prey animals. As a result they were easily into danger of starvation and predation just after release. On the other hand, in the extensive method, juveniles were bred under low density in an impounding net (Kakoi-ami) and wall net (Shikiri-ami), which was contacted with sea bottom, so that they could naturally shift to bottom life. As they shifted to bottom life, they acquired similar characteristics to natural fish physiologically and ecologically. They could take the adaptive behavior in the field just after release. We found this extensive intermediate breeding using a fishing port is one of effective methods for fish stock enhancement.

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Hydraulic experiments and some field surveys were conducted. Three types were developed by hydraulic experiments. They were found to have enough performance. But their performance was sensitive to tidal change because their principle was converting wave momentum near water surface into inflow. To maintain their performance well against large tidal range, the simple way was developed. Dissolved oxygen of generated inflow was found to be almost saturated every time because of mixing air and water at this facility. Generated inflow rate could be estimated by the developed numerical model and experimental formula.

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In this study, on the basis of observation data of water temperature and salinity at the center of Uranouchi Bay for about one year, stratification strength and vertical mixing during the stratification period were evaluated in terms of energy amount. Then their energy amounts were examined comparatively with the tidal energy amount of the bay. These results are described as follows:
(1) Stratification strength reaches the maximum of 180 Jm^-3 in August. This is equivalent to the energy amount that the tide works on the bay for about two hours.
(2) The vertical mixing energy is as much as 1/260_??_1/2600 of the mean tidal power of the bay.
(3) The energy amount that increases stratification strength is 1/250 of the mean tidal power of the bay.

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To evaluate the hydraulic resistance behind bodies, a drag stress term included the drag coefficient was introduced into the depth-integrated Reynolds equations. The applicability and problems of the model were discussed through various numerical experiments where the analytical solutions exist. For a single body, the results of numerical solutions were good agreement with those of analytical solutions in all cases. If the drag coefficient and the eddy viscosity are precisely decided, the numerical solutions behind a row of bodies can be efficiently used in the real situations. The model was also applied to a field. The velocity decreased around down-stream area of the facilities, while it increased in the other region. The water elevation decreased during the flood flow while it increased during the ebb flow.

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In recent years, natural seaweed and seagrass beds in Japan have been depleted; at the same time artificial seaweed and seagrass beds have been created in order to restore ecosystem functions of coastal waters. Vigorous efforts are being made to recover and re-establish endangered seaweed and seagrass beds in Japan. Fishermen have been transplanting kelp and seedlings using a spore-bag technique for many years. Regenerated seaweed beds are being developed on artificial structures at both the prefectural and national levels. The seaweed beds so created are sometimes protected from fish and sea urchin grazing. Furthermore, the concept has been extended to include the creation of “marine farms” using sea walls, coastal defenses and structures as breakwaters. The recent construction of artificial islands and underwater “mounds” have also increased seaweed bed productivity and associated fishery resources. Artificial seagrass beds have been created by transplantation to new sand-mud substrata and by seeding in the Seto Inland Sea. However, the creation of new seagrass beds is greatly affected by currents and sand-mud conditions at most of the experimental sites.

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In a number of coastal areas of Japan, many naturally occurring Sargassum beds have been severely damaged or reduced due to land reclamation and water pollution. In order to achieve sustainable coastal development, Sargassum bed restoration has been emphasized as a conservation method. New techniques for restoration include: 1) periodic re-transplanting, supported by artificial production of young plants, is effective to form suitable seascapes in severely polluted and sparsely vegetated areas; 2) transplanting or seeding on artificially provided hard substrata are effective in extending nursery and fishing grounds around existing natural beds; and, 3) restoration of shallow and gently sloping sea bed is effective in creating maintenance-free beds along developed coastlines.

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Relationships between the rate of biomass change and standing biomass of Ecklonia cava are classified into three types: 1) the rate of biomass change is positive under a stable equilibrium that is maximum biomass, 2) the rate of biomass change is negative for all biomasses, and 3) the rate of biomass change is positive between the maximum biomass and an unstable equilibrium that is the minimum biomass required for a persistent E. cava stand. Where the biomass change is positive, E. cava can grow. If the biomass is larger than the minimum biomass required for a persistent E. cava stand, then the bed will persist by overcoming the instability. On the other hand, if the biomass change is negative for all biomasses or the biomass is smaller than the minimum biomass required for a persistent E. cava stand, then the biomass will eventually become zero. The maximum biomass decreased with increasing attenuation coefficient and water depth. The minimum biomass required for a persistent E. cava stand is formed with feeding rate that exceeds threshold. The feeding rate on the threshold is affected by water depth and the attenuation coefficient that characterizes the amount of light at the seafloor. Value of the minimum biomass required for a persistent E. cava stand is increased with increasing feeding rate and water depth. Vertical distribution of E. cava was affected not only by the amount of light but also by grazing intensity.

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The barren grounds, so-called “Isoyake” in Japanese, exist along the southwest coasts of Hokkaido, Japan. In the lsoyake area, the sea urchin, Strongylocentrotus nudus, dominates the rock bed, and results in disappearance of the kelp, Laminana religiosa, in all except shallow water refuge. In order to develop the technology of kelp afforestation in the Isoyake area, seasonal changes of selected environmental factors, e.g. water movement, temperature, vegetation and grazers were observed continuously during 1998-1999 in Oshoro Bay. The environments for establishment of kelp forest were summarized; sea urchins were removed to deeper zones by strong water movement and kelp buds were protected from overgrazing during winter. Destructive pressure of the sea urchins occurred on kelp beds with little strong water movement and rock bed for kelp (annual algae) was protected from being occupied by perennial algae during summer. The authors propose two methods to increase kelp forest in lsoyake areas: 1) seasonal control of excess grazing pressure using fences and, 2) adjustment of the sea bed depth with concrete blocks and stone which increased wave velocity and therefore reduced urchin grazing pressure.

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Artificial reefs for the development of valuable fishery resources were placed on the sandy bottom at 8, 10 and 13m depths in Muronohana, Ikata, Japan. They were observed mon thly or bimonthly from February 1999 to June 2001. Enteromorpha intestinalis and Colpomenia si nuosa dominated the reef in spring, and several species of Melobesioideae dominated during su mmer and autumn. E. intestinalis and C. sinuosa were found to be typical primary colonist. The number of seaweed species at all the sites gradually increased in winter. In total, 38 seaweed s pecies were found from all the reefs, over the study period. Each reef was dominated by Sarga ssum spp., Ecklonia kurome and Padina arborescens within 18 months of the placement. The se ttlement of kelp, such as E. kurome, was promoted by reduced sand cover as a result of turbul ence. These results indicate that large-scale surface roughness, and/or kelp knobs, could be imp ortant in maintaining the communities after initial establishment.

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Seagrasses are valuable coastal marine habitats that support fisheries, contribute to ocean food webs, and filter estuanne waters. As seagrasses are lost due to human impacts to coastal environments, techniques are being developed to effectively mitigate these losses by transplanting. In transplanting seagrasses, both site selection and transplanting method are critical for success at the lowest possible cost. In the northeastern U. S., we have developed a model to choose sites most likely to sustain eelgrass, Zostera marina L., transplants. The high cost of restoring eelgrass beds in subtidal environments, and the difficulty in protecting transplants from various bioturbating organisms, led us to develop a new method not requiring SCUBA. “Transplanting Eelgrass Remotely with Frame Systems” (TERFS^TM) is a modification of bare-root transplanting methods. Eelgrass shoots are attached with biodegradable ties to weighted wire frames that provide mechanical protection from uprooting and bioturbation. The TERFS^TM are then deployed from any small boat. After three to five weeks, the frames are retrieved for reuse, leaving behind dense patches of eelgrass. We tested TERFS^TM first in the Great Bay Estuary, NH (USA) and again in New Bedford Harbor, Massachusetts (USA); in both cases the TERFS^TM method was successful. The ease and success of this technique provides an approach to restoration that can involve citizen volunteers. More importantly, it significantly reduces the cost of eelgrass restoration.

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Much of inhabited coastal zones of the Philippines are threatened by overexploitation of resources, pollution and reclamation of shallow habitats. The absence of good management practices inadvertently destroys most of shallow water habitats including seagrass and seaweed beds in this more than 7, 100-island archipelago. World Resources Institute reported in 1998 that practically all of Philippine coral reefs, where seaweed and seagrass beds are part of the complex, are classified as highly threatened. While the country has one of the most diverse seagrass (about 16 species) and seaweed flora than anywhere else in the world, there are indications that anthropogenic pressures have contributed to their gradual destruction, hence to the depletion of marine resources associated with them either directly or indirectly.
Seaweed bed construction is a new idea in the Philippines with only pilot studies, so far, recently being undertaken. On the other hand, seagrass transplantation has been implemented, especially in perturbed areas, for more than two decades now. However a national program using these activities as a bioremediation measure is yet to develop. The complementary contribution of seaweed and seagrass beds, established or otherwise, are expected to increase marine coastal productivity in the Philippines.

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Enhalus acoroides is a large and common species in tropical segrass beds and contributes significantly to total seagrass biomass. Fertile plants with male and female flowers or fruits are found throughout the year. Positive relationships were observed in the species number and total coverage of seagrsses, but negative relationships were observed in the species, number and coverage of E. acoroides. In terms of depth distribution, pattern in relation to tidal level was shown especially with respect the peduncle length of female flowers. There is a meristematic zone at the basal part of the leaf, and the meristematic potential decreased with age. The growth rate of young leaves ranged from 8-19mm day^-1 at the basal part, and about 5-7 weeks were required before attaining maximum length. On the fate of production in E. acoroides, the leaves contributed 85.7% of the total defoliation and 14.3% came from floating leaves. Conditions of the sediments were as follows: COD values ranged from 4-10 mgO•g^-1 DM and the ratio of mud contents (<33 μm grain size) ranged from 2.9-11.3%. These results suggest that individuals E. acoroides can survive in severe environmental conditions.

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Some fisheries science research institutes began to study eelgrass bed restoration in the 1970 s. In the 1980s, the Central Research Institute of Electric Power Industry investigated the environmental factors affecting eelgrass bed formation in Odawa Bay and published guidelines for eelgrass bed creation. In the 1990 s, the city of Hiroshima, Hiroshima Prefecture, Kumamoto Prefecture and the Ministry of the Environment in Japan started restoration of eelgrass beds using both transplantation and seeding. The city of Hiroshima transplanted 60, 000 vegetative shoots in an area of 5, 000m² in order to increase fisheries resources. The eelgrass bed area was enlarged to over 12, 000m². Marino-Forum 21 elucidated the relationships between the upper depth limit on sandy substratum and wave conditions (1/3 significant wave height with a return period of 5 years: 0.5m, orbital velocity: 0.6m/sec., critical shields number. 0.22), and also between the lower depth limit and net photosynthetic rate (monthly net photosynthetic rate=0 or greater).

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Satellite images delineate several meso-scale features, such as warm-core ring, warm and cold streamer. Warm-core ring is very important factor for finding fishing ground. Warm streamer is selectively utilized by fish schools as their migration routes from the Kuroshio Extension to the warm-core rings in the north and from the warm-core rings to the coastal waters. These migration routes were investigated using research vessels, satellite images, aerial observations, and commercial catch data. Fish schools were distributed in the warm streamer, especially at their heads, where phytoplankton and zooplankton were most heavily concentrated.
Sometimes these warm streamers grazed coastal area with pelagic fish schools and supplied many fishes into the set-net. Tip of warm streamer always have some slick-phenomena, which were found in the coastal area from the land. These slick-phenomena become to put mark on approach of warm streamer with many fish schools.
These observing methods had better be utilized at the same time for research of the warm streamer in detail. It is very important for total observing system, which was spatial and simultaneous system, to make clear about fisheries oceanographic phenomena.

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A time series of DMSP-OLS (Defense Meteorological Satellite Program - Operational Linescan System) satellite image in autumn from 1994 to 1998 and SeaWiFS (Sea-viewing Wide Field-of-view Sensor)- Ocean Color Image data of 1997 and 1998 were observed to study distribution and movement of Pacific saury Cololabis saira off Sanriku, Northwestern North Pacific. Daily, 10-days and annual OLS visible-near infrared images were analyzed to determine fishing locations of Pacific saury fisheries. This study provides comprehensive examination of distribution and movement of Pacific saury in relation to satellite image of DMSP-OLS derived fishing fleet light. Pacific saury fishing locations distribute and move according to remarkable changes of environmental conditions especially in the waters of northwestern north Pacific. Our analysis suggests that most of the fishing location of Pacific saury distributed In the colder side of Oyashlo fronts and cold streamers where SST (sea surface temperature) ranged from 4.5°C to 18°C. Two ranges chlorophyll concentration, from 0.1mg m^-3 to 0.5mg m^-3 and from 7.0mg m^-3 to 7.5mg m^-3, mostly observed in the locations of fishing fleet lights.

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This article reviews the historical microstructure measurements and our own recent development in a microstructure measurement profiler (TurboMAP). We show new data obtained from highly turbulent area in the wake of the Kuroshio behind Aoga-shima. We also mention how turbulent measurement data are applied to global circulation ocean models.

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Selective Availability (SA) in order to degrade the position accuracy of Global Positioning System (GPS), was turned off in May, 2000. This improved new positioning accuracy of GPS is reported. And, the GPS compass for ship heading sensor and a small drifting buoy's monitoring system by using low earth orbit (LEO) communication satellite are introduced as the recent unique applications of GPS for fisheries. The results of the evaluation test used these GPS application instruments are also discussed.

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The coexistence of marine mammals, seabirds, sea turtles and fish is an important factor for future fishery continuation. However, in the underwater, it is difficult to observe free-ranging behavior of marine organisms in spite of present-day technical progress. Research on the behavior, ecology, and physiology of marine organisms under natural conditions is limited, except for the information acquired from marine organisms by direct observation and direct measurement. Therefore, biotelemetry is useful technique to observe the habits of marine mammals needed for coexistence with the fisheries. The technology of biotelemetry is developed with use of the communication technology using the artificial satellite, the development of a micro-data logger that carried various sensors by ultra miniaturization of electronic products, etc. Thereby, according to the research purpose and the target marine organisms, we can choose the system of various kinds.

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Tracking for fish movements of sea breams (Chrysophrys major) and halibuts (Paralichthys olivaceus) tagging with the pinger were carried out as locating by ultrasonic receiver and positioning by GPS in Tongyoung Coast, Korea. Mean moving speed and directions for an interval of 6min by the sea bream might be related with the tidal current and higher than those by the halibut. However, their variations in unit time were irregular and complex to show a nonlinear phenomenon. Therefore, movement components such as acceleration of speed and angular velocity can be modelled using chaotic equation of Lorenz in relation to light, tidal current, temperature etc.

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For realising sustainable use of fisheries resources, new types of fishing vessel system should be developed because existing system has been implicitly optimised for unlimited amount of fish resources. Several research attempts in this research direction of fishing vessel technology are overviewed.
In techno-economic analyses on fishing vessel operation, the author updated the procedure for dynamically modelling variation of fish biomass as well as technical aspects of fishing vessel and cash-flow. As a result, his numerical results provided both possible scenarios towards overfishing and sustainable utilisation.
For safety and environment protection, relationship between new international regulations and recent researches is remarked. Efforts for improving onboard working conditions, including riding comfort and automatic control, and environment prevention, including use of wind energy, are also mentioned.

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The Rankine source method is applied for improving the hull form of a fisheries research vessel. The vessel should be enlarged lengthwise. Furthermore, a bulge and a bulbous bow will be added. Effects due to these modifications on the wave making resistance are highlighted. The bulge decreases hull resistance and the physical reason is discussed. The method of optimizing bulge form is proposed and finally an improved hull form with optimized bulge is offered.

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By introducing the unconventional hull forms, we can expect to improve the hull performance of fishing vessels. In this report, we choose the multi-hulls and the hull form above the L. W. L. (Load Water Line) as unconventional hull forms and present several examples and our studies. Generally, the multi-hulls have advantages of the wide deck area and the large transverse stability. In this type of ships, the wave interaction between the hulls induces a serious influence upon the hull strength. Therefore, the knowledge of wave loads taking account of wave interaction is necessary for ship design. Then, we present the results by a new 2-D pressure calculation method of multi-hulls applied to the strip method. For the fishing vessels, the propulsive performance in the actual seas is very important. For this reason, we should study how to improve the hull form above the L. W. L. in the ocean waves. Because the hull form above the L. W. L. is not restricted by the propulsive performance in the calm water. As a first step, we present here the total wave drug equation taking account of the difference of the hull form above the L. W. L. for a ship sailing in a finite regular head wave.

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Ships are potentially suitable for using wind energy. Almost every ship before the 19 th century had been using only the wind power by classic sails, and supporting the worldwide trades and logistics in those days. In 1980's after the last oil crises, many kind of modern sail-assisted ships were developed. Now, they will be hoped to become one of the best solution against the increasing CO₂ discharge. In this paper, the author tries to review the past sail assisted-ships, and investigate into the prospect of the sail-assisted ships especially focusing to the fishing boat in future.

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Philippine small fishing crafts are dominated by double outrigger crafts ranging from small, one man crewed boats of about 3m length overall up to large boats of 30 meters length overall. Severe conditions resulting from typhoons and monsoon weather have resulted in damage to a considerable number of crafts and casualties every year. An analysis of the nature of incidents recorded and experiments were done to determine measures for increased safety. This effort showed distinct characteristics of double outrigger crafts that make the hull form a popular one for Filipino fishermen. Comparisons with existing standards as well as the usual parameters of other hull types are also included. Some recommendations based on the data gathered include hull form changes, material specifications and operational procedures to ensure safety of life at sea.

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Estimating dynamic roll motion under fishing operation conditions is one of the unresolved problems with respect to the capsize accident of fishing vessels. In addition to potential non-linear response of the roll motion to the wave, unexpected factors occurred by fishing operations make the roll motion complicated. Considering the estimation for the dynamic phenomena generating on the fishing vessels, the numerical simulation based on non-deterministic approaches is one of the effective methods. Among them, it is well-known that a Neural Network model is a practical methodology. Based on the tank tests, the roll response models in fishing operation conditions were constructed. Appropriate estimates for the actual roll motion with a full-scale showed the effectiveness of the Neural Network model. Furthermore, as the model forecasts properly the critical condition occurring for the shipping water, it is suggested that the model is also effective utilizing as the forecasting model to avoid the fishing disaster.

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A new evaluation method of passenger comfort is deduced on the basis of experimental works on the training ship Kagoshima-maru. Ship motions are measured during a voyage and the feelings on the trainees are surveyed by questionnaires. The new evaluation method of passenger comfort is expressed by vertical and lateral accelerations and exposure duration represents the relationship between ship motions and seasickness. It is confirmed that the correlation coefficient between the results of the new method and the questionnaires given to the trainees shows a fairly similar results. Furthermore, the method is applied to evaluate the effect of anti-pitching fins on ship motions. By using the new evaluation method of passenger comfort, the most efficient area of anti-pitching fins can be designed from the viewpoint of passenger comfort.

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It is well established that a ship that is safe in beam seas may capsize in following and quartering seas. The capsizing depends on not only stability of ship itself but also operation practice. Therefore, capsizing model experiments were carried out to distinguish dangerous situations. The models of 135 GT, 80 GT and 39 GT purse seiners were used for these experiments. These models were capsized by broaching-to, pure loss of stability and bow diving.
Broaching-to which was one of the most dangerous situation for purse seiners, was greatly confirmed in those experiments. We developed anti-broaching steering system (ABSS) to prevent broaching-to. It was confirmed by the model experiments that ABSS is effective to prevent the broaching.

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A fishing gear system is generally considered as a physical system in which many mass points are connected with flexible lines, and it is modeled as non-linear differential equations, These systems are solved using numerical integration methods, and the answer provides the behavior of the gear in a steady and transient state. The necessity of automatic control in a fishing gear system is increased in accordance with the trend of complicated fishing methods and expanded fishing grounds. Under these fishing environments, rapid and precise fishing gear control is necessary, which can be realized with the intelligent control system made by the combination of the sensitive judgment of a human and control technology.

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The Kyucho is a sudden stormy current that is observed in t he coastal sea area. The Kyucho causes large-scale damage to set nets in Sagami Bay. This study was initiated in the interest of preventing the large-scale damage to the set nets by the Kyucho. Long-term measurements of current near the set net area were carried out and the characteristics of the Kyucho events were clarified.A model of the set nets was then made on basis of Tauti's model testing rule for fishing gear. Experiments on the dynamic action and forces that affect every part of the set net associated with the Kyucho were performed using a circulating water channel at an experimental station. With this research, the current characteristics (current velocity of the Kyucho is 0.7-0.8m/s and its vertical structure is uniform.) of the Kyucho were clarified. And in terms of damage preventative methods, it was shown that the resistance decreases with improvement of the buoyancy and form of the King Float, use of a larger mesh size, urgent removal of the bag net, and removal of the fouling organisms of net. On the basis of these results, a research report that outlines the protection measures against the Kyucho for the set nets was described.

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The moving performance of commercially used trolling depressor was investigated in a flume tank. The ratio of distance between the snout of trolling depressor and the connecting point of leader was changed 3 to 43%. Flow speeds were varied from 0.75 to 1.05m/s. Three components of tension of leader were measured by three components load cell. Positions of connecting point were expressed in a space co-ordinate system located on attaching equipment of load cell. Moving trace of connecting point was estimated basing on the equilibrium of three components of tension. Moving performance of trolling depressor were recorded and analyzed at various conditions. Mean resultant tension increased in square of flow speed at any connecting points. Trolling depressor glided from side to side and turned at short period in any flow speed and the calculated moving trace of connecting point showed an eight figured shape. Theoretically estimated trace agreed with measured one within connected points less than 35% of ratio. Trolling depressor swung uniquely at 43% of the ratio. These results suggested that the distance between the snout and the connecting point affected moving performance of trolling depressor.

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To reuse the garbage fishing gears effectively to the other fisheries production means is the one of rational measures based on the zero-emission concept. This research has aimed to check the ability of regenerated rope with refused gill-net from amiylane material to kelp cultivation facilities.
By the results of some field tests and stochastic analysis, a large individual kelp grew more abundantly on the regenerated rope of gill-net (GR) than the polyethylene rope (PR), which is widely used for cultivation in Japan. The average force to detach kelp from GR comes up to 6.8kg in comparison with the case of PR by 4.6kg. Through the tensile test in a site, the exfoliation probabilities in typical three portions on a kelp have showed the sticking capacity onto GR surpassed PR. Also, kelp on GR has not been easily broken out from a cultivation rope rather than PR.

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The mesh sides and ropes in net or rope system were modeled by the straight-line elements having only resistance to traction load. Fishing nets and ropes can be regarded as the assemblies of such elements connecting together with a non-frictional hinge. A numerical procedure for analyzing the equilibrium configuration and tension of submerged fishing net and rope system, from given loads and arbitrarily initial shape of such structures, is presented. The algorithm accepts the shape-dependent hydrodynamic loads on ropes and netting. The effect of the initially assumed shape of the system on the global computation convergence is discussed and illustrated by some numerical examples.

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For the numerical calculation, the fishing net is modeled as a group of lumped point masses interconnected with springs without mass. The numerical calculation of the dynamic behavior of a net in steady flow can provide good results when using the formula presented. The magnitude of applied tension force to the mesh bars can be observed as the change in the colors of the mesh bars. To observe the net shape qualitatively, it is sufficient to set the number of calculation points equal to the number of knots of fishing net. However, when the tension forces of the mesh bars are estimated, it is necessary to carefully obtain the appropriate coefficients of fluid dynamic force and also to set point masses over the net.

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In the design and operation of a trawl net, main theoretical problem is mechanical one such as its configuration and tension. Many scientists have made a lot of hard research on this field. In this paper, the author has described a systematic way for solving the mechanical problem of trawl net, and on some given net, made some initial studies about the hydrodynamic properties of wire-warp and plane PE-web and the calculation of the configuration and tension of wire-warp.
Results obtained suggest that the hydrodynamic properties of warp and PE-web made from different materials and forms experimented in tank and their configuration, and tension calculated by solving equilibrium equations.
Up to now, the author has not finished the studies on the head rope, food rope and belly webbing of the trawl net. Research work in this respect should be continued.

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In this study, a mass-spring model is used to dynamically describe and calculate the shape and movement of a midwater trawl system. This mathematical model theorizes that the factors constituting the system are the material points and the external forces such as hydrodynamic load, gravity, and buoyancy act on these material points. In addition, it surmises that these material points are connected to each other by springs, the springs do not have any mass, and the internal force acts on these springs. The non-linear differential equations are implicitly integrated with time for guaranteeing a stable solution.
The dynamic simulation by the mass-spring model shows the status of the gear such as fishing gear depth, distance of otter boards, shape of the gear, and tension of each line. It depends on the parameters such as towing force, warp length, force of a sinker, buoyancy of a float, type of otter board and netting materials. The validity of the model is verified by comparing simulation motions of a trawl system obtained from computed values to those from an actual experiment.

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In 1996, Japanese Fisheries Agency started management of fisheries resource by TAC (Total allowable catch). The management of the fisheries resource is an important issue. In this research, it was tried to elucidate the change of the fish resource by using the satellite data. The study fish is a sardine. Sardine resource around Japan repeats a big increasing and decreasing. Sardines catch volume increased rapidly in 80's, and decreased sharply in 90's. The change trend of an oceanic environment of the Touhoku sea area was presumed according to this multi satellite data at the period. The trend of the water temperature presumed from the satellite rose. On the other hand, the trend of Chlorophyll-a presumed from the satellite was descending. The data of the water temperature and Chlorophyll-a presumed the satellite was compared with the data of the sardine resource. As a result, a positive correlation was confirmed between Chlorophyll-a and the sardine resource of Oyashio water and perturbed water. On the other hand, a negative correlation was confirmed between the water temperature and the sardine resource.

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Study was conducted to investigate the effect of underwater illumination pattern by using different lamp shade material on the total catch of boat bagan. The distribution of underwater light intensity of different lamp shade showed almost an oval shaped which decreased with increased depth. The light of lamp with aluminum shade can penetrate more deeper than plastic material. It can be identified that the aluminum material reflected light more intense than the plastic. The main catch was dominated by anchovy Stolephorus sp. The result shows that the total catch of aluminum material more effective than the plastic.

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