The large-scale red tide that occurred along the southern coast of South Gyeongsang Province this summer was found to have been caused by a combination of heatwaves, heavy rains, and stagnant seawater. According to the National Institute of Fisheries Science, this red tide has shown unusual patterns compared to the past and has caused significant damage for the first time in six years.
Previously, red tides typically occurred in the offshore areas of Goheung and Yeosu in South Jeolla Province and spread to the southern coast with the currents. This gave neighboring regions like Namhae County and the cities of Geoje and Tongyeong time to prepare measures and respond. However, this year’s red tide was first observed in the inshore areas where fish farms are concentrated, leaving fishermen with no means to prevent the damage.
The unusual onset of the red tide in inshore areas, rather than offshore, is attributed to factors including heatwaves, heavy rain, and wind direction. A strong southwesterly wind from late last month pushed the hot surface water outwards, causing the temperature of the inner seawaters to drop. This maintained the coastal waters at an optimal temperature for red tides to thrive, around the mid-to-late 20 degrees Celsius, acting as a catalyst for a massive red tide.
In addition, heavy rain in August led to a greater inflow of nutrients like nitrogen and phosphorus from sewage and agricultural fertilizers into the sea, creating the ‘optimal conditions’ for red tide organisms to flourish. The complex coastline and numerous islands in Namhae stagnate water flow, causing the densely packed red tide combined with abundant nutrients and high temperatures to exacerbate the damage.
Experts analyze that this unusual red tide is not a mere coincidence but rather a result of climate change. Concerns are growing about the potential occurrence of La Niña, which impacts global temperatures and ocean environments, potentially worsening red tide damage in the future. La Niña results in lower sea surface temperatures in the eastern Pacific Ocean and is known to cause extreme weather phenomena, such as heatwaves and droughts, or heavy rains in Korea. Climate variability can cause abrupt changes in sea temperature and increase the influx of pollutants from land, making conditions for red tide occurrence more unstable.
Park Tae-gyu, a researcher at the National Institute of Fisheries Science, mentioned that increasing variability in marine environments could make red tide occurrences more uncertain and change their patterns. In such unpredictable natural disaster conditions, fishery disaster insurance serves as a crucial safety net for fishermen. However, only about a quarter of the affected fisheries were insured. As of June, the main contract insurance subscription rate for fish farms in South Gyeongsang Province was just 24.8%.
The main reason for low insurance subscription rates is the high premium costs. To receive compensation for red tide damage, fishermen must subscribe to a high-temperature special insurance, which costs three times more than general insurance. Additionally, if multiple species are farmed, separate insurance for each species is required. There are cases where a fish farm in Namhae County estimated an annual insurance premium of 600 million KRW. Furthermore, if a claim is made, the premium increases by 20-40% the following year, discouraging fishermen from renewing their insurance.
Currently, 70% of premiums are subsidized by the national budget, but the remaining costs are split between local governments and fishermen, which presents a significant burden in financially strained regions. An official from Namhae County remarked that fishermen face significant burdens as they need to subscribe to different insurances depending on species or disaster types, such as typhoons or low temperatures. The official called for measures to increase the national subsidy rate and alleviate the burden of the premium increase system.