제주도 넙치양식 산업의 지속적 발전 방안: 습사료와 EP사료

Abstract

Marine fish culture in Korea has relatively short history and its production is no more than 10% of the country’s total mariculture production of 1,382,257 metric tons (MT). Olive flounder, Paralichthys olivaceus is major fish species and the production reached 46,329 MT last year. Due to optimal water temperature ranging from 14 to 25℃ and plentiful subterranean sea water of 17℃, Jeju Island is the top flounder producing region in Korea since 1990 when the practical farming was started. However, flounder feeding is still predominantly carried out using moist pellet (MP) composed of trash fish and mash feed. It is estimated that 119,000 MT of trash fish and 5,350 MT of mash feed were employed to culture the flounder in the island in 2008. Only 5,000 MT of extruded pellet (EP) were used, suggesting that fish farmers are still prepossessed with the idea that feeding EP could result in retarded growth and high mortality due to digestive disorder. However, according to the results from a recent on-farm experiment conducted in Jeju Island, no significant differences were recorded in growth rate, muscle composition, sensory evaluation and production profits between fish groups fed EP and MP. On the other hand, much higher water pollution (1.5 to 10 folds) was observed in MP groups. A tremendous quantitative development, leading to large increase in production, has been achieved in flounder farming industry during last two decades. Now the industry should progress qualitatively to improve the sustainability of the industry. In present study, nutrient loadings from flounder farming in Jeju Island were estimated using the nutrient budget modelling. Loadings of dry matter, protein and phosphorus were calculated to be 32,204 MT, 18,977 MT and 516 MT, respectively, while those were decreased to 29,299 MT, 14,154 MT and 368 MT, respectively, when MP were switched to EP. The use of trash fish should be strictly prohibited in order to protect natural seed stocks as future food for the next generation and at the same time to prevent water pollution as much as possible. For this, a compulsory use of EP should be urgently established.