Report of Working Group 23 -Chap 3 Country reports - 3.4 Republic of Korea

Abstract

Ongoing euphausiid research is carried out as part of a project at the Korea Institute of Ocean Science and Technology (KIOST, formerly KORDI). The project is entitled ‘The study on the impact of the Yellow Sea Cold Water Mass to the ecosystem (2009？2016)’(KIOST grant PE99165). The Yellow Sea bottom cold water mass (YSBCM: ● 10▲C) persists in the deep central region of the Yellow Sea during the summer when the surface temperature increases to > 25▲C. It may provide an over-summering refuge for cold water organisms (such as Calanus sinicus, and Euphausia pacifica) which enables them tomaintain their populations in the Yellow Sea. Studies of the distribution, physiology, and feeding ecology of E. pacifica are included as part of this program. There are two annual cruises for this project: spring (April) and summer (August). Euphausiids arecollected using either a conical net (mouth diameter: 1.5 m mesh size: 333 or 417 ┢m) or mid-water trawl (square mouth: 2 m2 mesh size: 417 ┢m). Sampling is conducted both day and night. Acoustics data are collected using a 200 kHz split-beam transducer(BioSonics, USA). Samples are collected to determine euphausiid abundance and biomass as well as for analysis of lipid composition. When possible, live euphausiid experiments are conducted during these cruises to measure molting rate and egg production (brood size) of E. pacifica using the protocol developed by the Peterson lab (available onthe PICES website at http://www.pices.int/projects/Euphasiid/euphasiid.aspx).