More than 90% fishing boats are smaller than 20tons in Japan. Even significant wave heights less than 2m are dangerous for small fishing boats. This paper reports characteristics of wave spectra less than 2m significant wave heights in Tokyo Bay. The water surface elevation was measured by using wave height meter based on micro Doppler radar that was equipped on research vessel "Hiyodori" of Tokyo University of Marine Science and Technology from 1997 to 2003. More than 50% data was the P-M type wave spectrum. And in case of more than 0.5m significant wave height, 80% data was the P-M type wave spectrum. However, it was difficult to apply the conventional method(ITTC, ISSC) based on the P-M wave spectrum to the shape or the frequency characteristic of the actual wave spectrum. In the actual wave spectrum for the short time series(400sec or 200sec), the variation was hardly found in the view point of bandwidth parameter ε. However, each frequency band of peak power changed during the observation.

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According to the statistics of fisheries in 1998, number of the fishing boats within 20 gross tonnages were 98% of all fishing boats in Japan, and the material which are built up of the hull were mostly FRP. The fishing boat has to perform many functions. The hull performances, such as to negotiate rough seas and economical to navigate, have to consider when make plan the hull design. In other words, lines of hull of the fishing boats are essential to understand and discuss for improving these abilities. The researches of hull form measurements have done by means of procedures, such as a level meter and pantograph. But difficulties are induced in handling these procedures, especially measuring in the shapes around stern and stem included sharp curves. The authors intend hull measuring by using laser telemeter. The purpose of this paper is to examine the accuracy of characteristics of this procedure in applying for hull form measurement.

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The establishment of an eelgrass, Zostera marina, bed was performed using a method of artificial seeding on "Gauze cloth and pebble mats(GP-mats)", off Kushiki, Naruto, Tokushima Prefecture, eastern Seto Inland Sea. Gauze cloth sheets were used to allow the artificial seeding. Pebbles were used to increase the stableness of the sandy sediments around the Z. marina plants. The GP-mats were made of three layered gauze sheets fixed to iron quadrates. Three sizes in diameter of pebbles were mixed respectively on each 1m^2 GP-mat. The experiment was started in January 2000 using 45 GP-mats, which were set adjacent to the sediment stabilizer mats(SS-mats) used previously. Plants of Z. marina on GP-mats grew successfully for two years, even under harsh environmental conditions of high wave heights in the winter. Shoot density on the GP-mats was observed to decrease after reached the maximum number(197 shoots/m^2) in the first summer to 8 shoots/m^2 in the 2^<nd> summer, and disappeared (0 shoots/m^2) after the passage of typhoon No.15, Sept. 2001. The GP-mats were effective and useful in germination of seed, growth of seedlings, and survival of adult plants due to the sand accumulation on the mats under usual environmental conditions. However, the usage of GP-mats may be limited in areas prone to the full effects of high waves caused by typhoons.

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In this paper, manufacturing an oyster raft model with scale ratio 1/10, and by use of the model, investigation was made to improve the durability against waves from the viewpoint of improvement of the mooring. Consequently, the following knowledge was obtained: under conditions without "suikaren", the large improvement is obtained by attaching floats to the mooring wire. The mooring method proposed here is useful for keeping the fatigue strength of the oyster raft in the stage where "suikaren" is seldom growing. Under conditions with "suikaren", however, the improvement can't be obtained. The reason for no improvement is that the bending moment induced by the movement of "suikaren" in waves is dominant and the mooring method proposed does not have an effect in reduction of the moment component. In order to reduce the bending moment acting on the oyster raft, it is necessary to make influence of "suikaren" small.

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Investigating the damage conditions and conducting experiments by use of a model of the oyster raft, it was surmised that the main factor causing damaged to rafts is due to the tension acting on the "suikaren" in the 1st report. In this study, how to reduce this tension is examined. The improvement proposal is very simple and only involves attaching a float in the upper portion of the "suikaren". To investigate the validity of this improvement, "suikaren" and raft prototype models are prepared, and the bending moment acting on the raft portion is measured in regular waves. Consequently, it was confirmed that the bending moment for the improved proposal is reduced by about 30\% as compared to the conventional raft Also the improvement was confirmed by numerical computations based on dynamic simulation model for "suikaren". If this improvement is put into practical use, the culture of oysters can be carried out more efficiently than before.

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There were six excellent examples of eel grass Zostera marina bed restoration projects that have been continuing periodical monitoring and publishing of the results on several scientific papers up to date, along the coast of Seto Inland Sea, Japan. Every example included the both important action at their actual project site, e.g., 1) understanding local limiting factors of eel grass Z. marina, and 2) mitigating condition of the limiting factors. Principal actions in these projects were as follows, 1) raising sandy bottom as artificial tidal flat restoration, 2) raising sandy bottom at deepest limit of vertical distributional range for giving the suitable growing ground to eel grass Z. marina, 3) improvement on natural sandy substrata for enhancing the roots and surviving the plants, and 4) transplantation for accelerate flourishing of eel grass Z. marina.

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A creation of seaweed bed is to select suitable site and species, or to control limiting factors of growth. The important growth limiting factors for seaweeds are light intensity, salinity and water movement. A distribution scheme expresses the horizontal and vertical characteristics of dominant species in a comprehensive manner. The scheme is available for selection of suitable species and depth. Growth criteria showing tolerance levels of death and growth on principal growth limiting factors for each species are determined from the results of published papers and experiments. Validity of the growth criteria is tested in a way to compare present distribution of the species and estimated distribution of favorite growth. Possibility of favorite growth of the candidate species is obtained at each 100 meters square mesh in an area. Using the growth criteria, we can determine the possibility to establish the seaweed bed for nature restoration in relation with the construction of ecologically harmonized fishing port.

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I introduced two cases(the recovery as natural phenomena and the recovery by human work) about the recovery of Ecklonia cava beds from the Isoyake in Shizuoka Prefecture. In the recovery from the Isoyake as natural phenomena, it has been understood that the generation group that survived in year when a certain condition was satisfactory grew up and formed Ecklonia cava beds. In the recovery case by human work, after the situation of the Isoyake had been diagnosed by the implantation test, the alga place creation that combined a large-scale transplant and the capture of herbivorous fishes Siganus fuscescens was done. As a result, the Ecklonia cava beds was made to exist in the Isoyake area, and the next generation came to appear.

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We reviewed the mechanism on outbreak and sustentation of 'Isoyake' and the marine afforestation technologies in coralline flats(curstose coralline red algae-dominated communities) called 'Isoyake areas' in Japan. Coralline flats are enlarged when marine forests, the large perennial brown algae dominated communities are reduced by the combined hydrographycal factors of high water temperature and low nutrients. Subsequently, destructive grazing by dense herbivorous populations sustain the coralline flats. The marine afforestation technologies in coralline flats are composed of 1) reduction of grazing pressures by herbivors, 2) production and supply of algal seeds and seedlings and 3) creation of new substrata for marine algae.

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The purpose for the establishment of kelp beds is to increase kelp biomass, thus, calculation of biomass change is a useful tool for the prediction. A photosynthetic production model is one of the major components used in the calculation of the biomass change. An estimation of grazing is another major component to be included in the calculation of biomass change. In this study, grazing effects on the biomass dynamics of Ecklonia cava are analyzed by using the biomass change model(Honda 2000) that combined the feeding equation of Ivlev(1961) with the photosynthetic production model that was developed by Honda(1999). Relationships between the rate of biomass change and standing biomass of E. cava are classified into three types : Type 1) the rate of biomass change is positive under a stable equilibrium, Type 2) the rate of biomass change is negative for all bioraasses, and Type 3) the rate of biomass change is positive between a stable equilibrium and an unstable equilibrium. The spore-bag and vegetative transplantation techniques are effective in the establishment of kelp beds for Type 1. For type 2, the spore-bag and vegetative transplantation techniques are not effective without the removal of herbivores or seafloor piling by the construction of artificial reefs. For Type 3, the vegetative transplantation can be used to increase the kelp biomass and overcome the instability, but the spore-bag technique is ineffective in overcoming an unstable equilibrium.

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