Sometimes they install permeable embankment, wire netting, membranous structure around the aquacultural basin in order to diminish the energv of outer sea waves which strike the basin. Though such installations are effective to protect the basin from the outer sea waves, its become the disturbances for water exchange between aquacultural basin and open sea. This might bring a change forthe worse in the water quality of the basin. It is necessary to estimate permeant discharge precisely for the design of the works of water quality control at such aquacultural basin. Izbash's formula for permeant discharge estimation is taken into consideration and some head losses are also considered. The results of the estimation are satisfactory coincided with observed data. Estimation techniques are evaluated using the data of Kasaoka Bay Land Reclamation Project.

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Kasumi Fishing Port occasionally suffers from long period oscillations caused by northwest monsoons in winter. The authors settled 2 wave gauges and a current meter inside the port and a wave gauge outside. They analysed the data observed during 84-85 winter and simulated numerically to identify prevailing modes of long period oscillations. Long period oscillations are summarized as follows. 1) Cargo handling is influenced by long period oscillations when slgnificant wave heights (H_1/3) of surface waves exceed 5 to 6m outsidethe port, corresponding to a third to a probability year. 2) Outside the port, long waves are regarded as surfbeatswhen long wave heights (H) rapidly augment with the increase of H_1/3 above 2m. Long wave periods (T) of surf beats center on one minute. In Kasumi Bay, prevail free oscillations with T over 10 minutes, when H_1/3 falls below 2m. 3) Inside the port, develop forced oscillations with T of approximately 4 minutes when H_1/3 >2m. They are replaced by free oscillations with T over 10 minutes when H_1/3 <2m. 4) Prevailing periods of currents are 1 minutes, 4 minutes and over 10 minutes. In the port, cargo handling is influenced by long wave height, current Velocity approaching to 1m/s at the entrance and oscillatory displacement beyond 20m in some area behind the entrance.

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Copepod swarming and mysid schooling were reviewed from previous literatures and the author's recent observations. Aggregations of mysid and copepod occurred near to the sea bottom in accordance with bottom material and configuration ; above and inside eelgrass and algal beds, downstream side ofrocks, above sandy bottom and so forth. Copepod swarms observed in Shijiki Bay, a small inlet southwest of Hirado Is., western Kyushu, Japan, consisted of many copepodite stages sometimes of a single species but also of a mixture of severalspecies. The swarm of copepods was maintained stationary in the spatial position when water current was weak. But when current was strong; swarm was carried away from the initial position. Copepod swarms were able to induce in the lee of black boxes set on the flat sandy bottom. Forming process and adaptive significance of mysid schooling and copepod swarmmg were discussed.

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Drift algae often become valuable foods for commercially important abalone and sea urchin, but they are so easily moved by water movement that most of them are wasted away from fishing grounds. Some acquaculture facilities have been placed as drift alga traps in the northem Pacific coastal areas of Japan. Unfortunately, any of the facilities has not been reported to show effects yet. In this situation, it is required to show how to design the drift alga traps more scientifically and how much effect the traps might have. This paper outlines the basic mechanisms of trapmg drift algae to help planners to design the facilities and to arrange the questions for future investigation.

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