In order to find out the environmental factors influencing the catch of fyke nets in the coastal waters Yosu, the oceanographic factors, i.e., the waters temperature and the salinity were observed respectively from April to November in 1999, and each of them was compared with the catch of common mullet, Mugil cephalus by fyke net. The results obtained are summerized as follows : 1. The water temperature was ranged from 13.0 to $25^circ$C and water temperature increased from April to August and decreased on September to November. 2. The range salinity in the fishing grounds was from 28.6 to 33.8$ extperthousand$, and salinity was high from April to June. From July, however, the salinity decreased to continue a low value still september. 3. The catches of common mullet caught by funnel net were the highest in may and the smallest in November. The ranges of optimum water temperature for the funnel nets fishing was 15.0 to $16.0^circ$C, the ranges of optimum salinity for fishing varied between from 32.6 to 33.8$ extperthousand$.