Sam-geun Lee, Hak-gyoon Kim, Chang -kyu Lee and Chang- sook Kim, Harmful Algal Blooms Research Department, National Fisheries Research, Development Institute, Pusan, 619 - 900, Republic of Korea. E-mail: sglee@nfrdi.re.kr

Abstract

The problem of harmful algal blooms(HABs) in Korea are now deeply concerned with frequency, intensity and scale. The blooms of Cochlodinium polykrikoides that is most harmful species to kill farmed fish in Korea have been persisted in the whole coast of the southern coast of Korea every year from August to October since 1995. National Fisheries Research and Development Institute(NFRDI) is carrying HABs monitoring around Korean coastal waters at 70 stations biweekly or monthly by research vessels, helicopter and satellites from March to November to investigate the status of water quality and HABs since 1981. Monitoring information are given to the fisherman by fax, newspapers, automatic response system, and radio and TV broadcasting to mitigate the fisheries damages. HABs movement and distribution is dependent on the wind direction and tidal current. The notice of precaution and warning are forecasted when the density of C. polykrikoides exceed 300 cells/ml and 1,000cells/ml, respectively. The best way to minimize the fisheries damages is to find out the outbreaks of HABs at the initial stage and take emergent action. HABs alarm facility composed of sensor and alarm apparatus was invented to prevent the inflow of HABs into the fish culture tank in 1997. For mitigation strategies, local government authorities scatter yellow clay on the sea surface affected with HABs. The clay has a capability to scavenge the particles and carry them to bottom sediments. The removal efficiency was up to 90% in 10g/l. No big difference was found between the laboratory and field test. In the field, dissolved inorganic nitrogen, chemical oxygen demand and chlorophyll-a concentration decreased slightly after dispersion. Furthermore, surface water temperature by NOAA and chlorophyll-a concentration by SeaWiFS, MODIS and OCM image are also studied to know subsequent development and horizontal distribution. In addition, If fisheries damages arise due to HABs, the government grants governmental subsidy and relief bank loans for the sufferer.