Physical disturbance of the seafloor induced by bottom trawling is of increasing concern from the viewpoints of ecosystem conservation and sustainable fishery. We developed a method for evaluating the impacts of several kinds of trawl gears on the different seafloor habitats using bathymetry and sediment data and scientific survey data off the Pacific coast of north-eastern Japan. Ten types of habitats were classified by the cluster analysis applied to seafloor bathymetry, topography, and sediment hardness over the study area. Our mapping of these habitats demonstrated that the intensity of bottom fishing activities on the seafloor was different among habitat types and related to the abundance of commercial species living in each habitat. The ecological influences of fishing on these habitats were examined by focusing on the changes in demersal species diversity and biomass detected through scientific surveys. A decline in species diversity was more evident in the habitat types with complex topography and hard sediment in the intensely trawled areas. Comparison of fishing gear suggested that the otter trawl may be the most influential owing to the significant change in the demersal ecosystem.

从生态系统保护和可持续渔业的角度来看，海底拖网引起的海底物理扰动日益引起人们的关注。我们开发了一种方法，可以使用测深仪和泥沙数据以及日本东北太平洋沿岸的科学调查数据来评估几种拖网渔具对不同海底生境的影响。通过聚类分析，将十种类型的栖息地分类为适用于研究区域的海底测深法，地形和沉积物硬度。我们对这些栖息地的绘图表明，海底捕捞活动的强度在不同的栖息地类型之间是不同的，并且与生活在每个栖息地中的大量商业物种有关。重点研究了通过科学调查发现的海底物种多样性和生物量的变化，从而研究了捕鱼对这些生境的生态影响。在地形复杂，被严重拖网的地区沉积物坚硬的生境类型中，物种多样性的下降更为明显。比较渔具表明，由于水下生态系统的重大变化，水獭拖网可能是最有影响力的。