As the investigation to estimate the abundance of seaweed has been done mainly by diver's direct sampling, surveying wide area in short time was very difficult. In this paper, a method of combination of the echo sounding and diver's sampling was considered. Examination of the method and application to the coastal area of Hamochi, Niigata Prefecture are described. Obtained results were as follows, : 1. 10 species in 4 families of seaweed were distributed widely in this coast. 2. The abundance of seaweed is closely relating to the type of sea bed. Order of the abundance is, on the rock, boulder, stone, graval, sand. The abundance of seaweed decreased linearly with the depth. 3. The length of seaweed by echogram was compared with samples brought by a SCUBA diver. Both values agreed fairly well, except When the seaweed is longer than 2m. In this case the seaweed was winding and the record was shorter than the sampled. 4. The abundance of seaweed were estimated from the echogram and the data of sampling by SCUBA diver. The abundance of seaweed longer than 0.5m were estimated about 3, 580 metric tons, in the coastal area from Akaiwa to Hamochi fishing port, 3km. As a result. the new method can be applied to estimate the abundance of large size seaweed.

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The investigation of the type and configuration of steel cage frame of floating cage for mariculture mostly used in middle and westem Japan reveals as follows. Major materials for the cage frames are composed of carbon steel pipes. A greater part of them are so-called 'GSP frame' which is formed by welding the Galvanized Steel Pipes, also is adopted 'all hot-dip galvanized frame' after welding the bare carbon steel pipes into a block. The GSP raft frame includes all-welding type, flange comection type and comer jointing type, and the latter is applicable only to a square cage. A circular cage in particular, the flange connection type is mostly used. The all hot-dip galvanized raft frame consists mainly of a circular cage of a flange comection type is applied in open sea, while a flat type square cage frame is also favorably accepted inside a bay. Further, the bridge frames for maintenance of juvenile fish and automatic feeding are being employed by some square cages.

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A fishing port isthe same as other facilities for promoting industries, required to satisfy the feasibility from economic stand point of view concemed cost benefit problems between 'the construction and management' and 'the benefit of the port constructed'. A major part of the cost of construction is shared by of outer facilities such as breakwaters, jetties, revetments, sand groins etc. Especially, on an open coast not sheltered from isles or promontries, most of the ports need aforementioned outer facilities. In case of fishing port construction, main extemal actions required a big money are waves and sand drift. The degree of influence of these two forces depends on a sea bottom slope of the site. Usually, a gentle sIope of sea bottom needs Iong breakwaters and/or sand groins for intercepting sand invasion into the port, but a steep slope does not require so long but tough breakwaters for protecting heavy attack of strong waves. This report describes a basic idea of fishing port layout on an open coast for reasonable planning from economic point of view.

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