In the 1990s, a reduction of Japanese chum salmon (Oncorhynchus keta) body size was observed. In order to investigate this body size reduction of Japanese chum salmon in the North Pacific, we developed a bioenergetics model for chum salmon. Our model was based on NEMURO.FISH, using respiration and consumption terms and assumed that SST and prey zooplankton density are the determining factors of the reduction of body size. SST and prey zooplankton density are obtained from the result of NEMURO embedded in 3-D physical model, along the migration route of chum salmon. The period of foraging migration is supposed to be four years and the life stage of Japanese chum salmon is divided into eight stages, i.e. four stages for summer and the other four for winter. The model reproduced the body size of the 1972 and 1991 year classes of chum salmon, respectively. Reproduced body size of the 1972 year class was larger than that of 1991 year class. This result showed a good agreement with the observations in the Bering Sea. Moreover, our model reproduces the trend of observations in l970—2000 well. The prey density, especially in the Eastern North Pacific, had a larger influence on the change of body size than SST did. This suggested that the size reduction of Japanese chum salmon in the 1990s was partly affected by prey zooplankton density.

We studied the trend of long-term fluctuation in the abundance of abalone and top shell catch in Japan and examined the relationship of those long-term fluctuations with global climate change. Trend of fluctuation index (TFI) was derived from time-series of yearly catch in five sea areas around Japan by removing the dependence of amplitude of catch fluctuation on its level and calculating the slope of regression line at each year. Approximately two decadal scale fluctuations were found in TFI of each resource. There were significant positive correlations between TFI of three abalone species (Haliotis discus discus, H. gigantea, H. madaka), which inhabit in four sea areas influenced by the warm currents, and moving means of Aleutian Low Pressure Index (ALPI). In two sea areas along the coast of the Pacific, TFI of these three abalone species was positively correlated also with that of agar, red algae belonging to the Gelidiaceae. In contrast, TFI of H. discus hannai, which inhabits in one sea area influenced by the cold current, was negatively correlated with ALPI or TFI of agar. We could not find any coherent relationship of TFI of top shell, Turbo (Batillus) cornutus, with ALPI or TFI of agar. The results of this study suggest the possibility of the influence of global climate change to the long-term fluctuation in the abundance of rocky shore resources, which have been thought to be “local” stocks, and of the difference of such influences among species.

日本海西部の兵庫県沖海域において，7隻の樽流し立縄漁業標本船操業日誌資料を用いて1999年から2005年のソデイカThysanoteuthis rhombusの漁獲位置や漁獲量の水平分布について調査するとともに，漁場周辺の水温環境との関係について解析した．兵庫県沖の漁場は概して北緯36°15’以南，東経134°10’から135°の範囲に形成されていたが，冷水域（山陰・若狭沖冷水）の接岸が確認された2003年と2005年には，より沿岸部寄りの北緯35°459以南に形成された．好漁場の指標水温は，水深50m，100m深でそれぞれ19°C，14–15℃以上と考えられた．兵庫県沖の観測定点（6箇所）の100m深の平均水温は，漁獲量で重み付けした平均漁獲緯度と相関しており，漁場形成位置の指標になると考えられた．

日本最大のサンゴ礁「石西礁湖」の2定点の3m層水温と石垣島の気温を用い，2001年，2003年に礁湖全域でサンゴの白化が起きたときの状況を解析した．両年は，日平均水温と日平均気温が30℃以上の日が多かった．そこで気温30.0℃を白化差引気温とし，30℃を超えた値の合計を白化気温指数と定義し，過去30年の気温を解析した．その結果，気温30℃以上が30日以上で白化気温指数が10以上の年は，石西礁湖で広域の白化が起きる目安になると判断された．この手法は近隣の島々での白化予測にも利用できる可能性がある．