状態空間モデルであるカルマンフィルタの適用で，大型水槽（600 m3）における超音波テレメトリーで計測した魚の3 次元位置を推定した。超音波発信機を装着した3 個体のマダイ（63，75，84 kHz）を4 つのハイドロホンによって同時追跡した。4 つのハイドロホンに到達する送信信号の時間差に基づき計算される双曲面の交点によって標識魚の位置を推定した。この3 次元超音波テレメトリーシステムの性能テストでは，最も結果の良かった63 kHz の超音波発信機で，確度が0.69 m，精度が0.02‒0.04 m で推定できた。確度，精度の結果はともに水平成分よりも鉛直成分が低く，精度に関しては超音波発信機の発振周波数の増加とともに低くなった。これらの結果は，発振周波数に対する十分なサンプリングレートに改善することで精度の向上が見込まれる可能性を示した。双曲面交点より推定された値には誤差が含まれるため，実験個体の推定位置が水槽域外に出ることもあった。そこでカルマンフィルタによる状態空間モデルで推定位置を補正した。その結果，3 個体の遊泳軌跡の水平成分は水槽域内に入った。本研究では，誤差の補正が必要なことの多い超音波テレメトリーによる位置推定に状態空間モデルを適用することで，実際の遊泳軌跡に近似させることが可能であることを示した。

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Oxygen-deficient sensitivity index （OSI）represents the hypoxia environment, which is calculated from the continuous values of dissolved oxygen saturation and water temperature. The macrobenthic community which dies from the development of hypoxia can be forecasted from the change of OSI by defining the initial biomass （Bmax）that has been observed before hypoxia. However, OSI is not a generalpurpose index, because it is necessary to set the four parameters estimated from field observations. In addition, the recovery amount of macrobenthos forecasted from the OSI method tends to be overestimated compared with the observed biomass. Therefore, the influence of hypoxia on each species of sampled macrobenthos is expressed as a new index that improved OSI （iOSI）, which is calculated from the two parameters and the continuous values of dissolved oxygen concentration and water temperature. Additionally, the iOSI method adopts the recruitment estimated from dissolved oxygen concentration and subsequent growth rate. As a result, fluctuations in species biomass forecasted using the iOSI method is strongly correlated with field observations in June-July when hypoxia develops, as well as the OSI method. The recovery amount of macrobenthos in August-November when hypoxic water dissipates is able to be forecasted by the iOSI method more accurately than by the OSI method.

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The purpose of this study is to model how to decide a quality of kelp product. The quality of kelp product is decided by numerical standard （length, weight and breath）and non-numerical standard （color and bentness）. It is difficult to estimate quality of kelp product, because non-numerical standard cannot be evaluated before drying. The quality classification in this study was carried out with 276 pieces of kelp from Fukushima area in Hokkaido which were graded by inspection institute. The authors assumed that the quality of kelp product is determined in two steps: numerical judgment and non-numerical judgment. The transition ratio between two steps was estimated. In this case, the grade of many kelp products went down in the second step. This transition suggests the necessity of reconsidering the management strategy.

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We examined what we should consider for design of purse seine vessel in Japan by comparing the characteristics of “large and medium- scale purse seine fishery”in Japan with “large scale purse seine fishery”in Norway. We concluded that there are three points which we should consider. At first, we should determine the appropriate level of the fishing capacities of the large and medium-scale purse seine fisheries in Japan based on the capacities of processing plants on land. The insufficiency of processing capacities often causes price collapse of the landing. Next, the transport ship is necessary in the operations of large and medium- scale purse seine fishery in Japan, because the use of transport ships largely contributes to the stability of landing price. Finally, the profitability of large and medium- scale purse seine fishery in Japan tends to be less than in Norway, so the design of the purse seine vessels in Japan should be determined based on this low profitability.

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This paper presents principal references and charts that are useful for decision-making for the concept design of Japanese purse seiners. The procedure to make a concept is conducted by comparing with the state-of-the-art Norwegian purse seiners associated with considering fisheries management. First, the relationship between the Norwegian fishing management system and the fishing vessel design is described to recognize the characteristics of Norwegian purse seiners. Individual vessel quotas （IVQ） of purse seiners used in mackerel and herrings are controlled by the allocation of basic quotas, and the relationship between the basic quota and the size of a fishing vessel is argued. Second, the basic dimensions of Norwegian and Japanese vessels are compared to acquire differences in basic design. Finally, the specifications and subjects are arranged using “Morphological chart”which is a type of system engineering method.

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