in the last three decades of the twentieth century, with growing coastal development, industrialization and aquaculture, the number of reported red tides reached a peak of about 300 cases a year in the 1970s, according to environmental researchers. Through intensive study and management, the occurrence of red tides has levelled off, but even today there are between 20 and 50 episodes that cause damage to fisheries on the order of hundreds of millions, sometimes billions, of yen each year. Experts are becoming concerned that a combination of higher runoff and warmer seas from global warming, together with the burgeoning development of and greater traffic with other countries, could trigger another increase.