Abstract
The purpose of this study was to evaluate the influence of pollutant from Coho Salmon cultivation on water quality through analyzing the data of weather and water quality for several years, and to estimate the adequate loading amount into the Shizugawa Bay locating at Miyagi Prefecture.
As a result, it was recognized that COD in the bay was improved from 0.94 mg·l-1 to 0.57 mg·l-1, the delta DO in the bay was improved from 0.86 mg·l-1 to 0.55 mg·l-1, maximum COD in the salmon area changed from 1.13 mg·l-1 to 0.68 mg·l-1 and δDO in the salmon area changed from 1.28 mg·l-1 to 0.69 mg·l-1, respectively, at the end of the cultivation time compared with the large cultivation period.
From the results of multiple regression analysis, it was showed that the factors affecting the COD in the salmon area were input loading, temperature and duration of sunshine, whereas the factors affecting δDO in the salmon area were input loading, temperature, duration of sunshine and rainfall, respectively. In particular, it was found that both items were great influenced by the salmon cultivation. In addition, through evaluating the prediction equation for the bottom DO in the salmon area, it was suggested that the annual cultivation amount should be restricted by 4,000 ton·y-1 to prevent the bottom water from the deficient water.
