In this paper, attention is focused on how physical environmental conditions, such as water temperature and tide affect on the Sepia esculenta catch in the fishing grounds of Ariake Sound. In a project done to collect basic data on variations in S. esculenta catch, the comparative studies were made using catch data obtained in different fishing grounds. The data used in evaluation were the catch by cuttlefish basket traps in 1996 fishing period (15 February-15 May ; off Fukae town, and 5 January-13 May ; off Ariake town). The water temperature in each fishing ground was recorded continuously for 20 min with the aid of a thermistor attached on a basket trap. Daily mean tide range in each area was calculated using tide table. Catches were high at water temperature between 12-14 degree. Daily catches varied periodically due to the change in the lunar cycle, and it became maximum at neap tide, or ebb, and minimum at spring tide. In this region, Water temperature seems to be an important long-term factor affecting the main fishing period, and tidal current seems to be an important short-term factor controlling daily catch. The results suggested that the amount of catch was controlled by both water temperature and tidal current, which is therefore the important factors in the S. esculenta basket trap fishery.
