Influence of intensive net cage farming on hydrodynamic and geochemical environmental conditions and the mass mortality of abalone in South Korea.

The abalone aquaculture industry in South Korea has grown rapidly since the 2000s. In this study, we investigated the sedimentary pollution at four major abalone farms responsible for ~60% of all South Korean abalone produced. We also surveyed the current statuses of cage facilities, abalone mass mortality, and current velocities within and outside farm cages. The concentrations of total organic carbon in the study area were 7.92 ± 2.09 mg g, indicating a mild level of sedimentary pollution. We observed higher mortality rates in rectangular-shaped shelter cages than in triangular shelters. With increases in the number and size of abalone farming facilities, current velocities inside the cages declined by an average of 45% relative to those outside the cages, leading to poor habitat conditions for farmed abalone. Our results provide insights into the current status of the benthic environments and major causes of mass mortality in the abalone farms of South Korea.