Zooplankton monitoring using a twin NORPAC net during the 63rd Japanese Antarctic Research Expedition in austral summer 2021-2022

As a part of the monitoring programs of the Japanese Antarctic Research Expedition (JARE), zooplankton sampling using a NORPAC (NORth PACific) standard net has been routinely carried out since JARE-14 (1972/73 season) to estimate the long-term trends of abundance, species composition and their temporal/spatial variation in the uppermost 150 m of the Indian Ocean sector of the Southern Ocean. The icebreaker Shirase has a fixed schedule and route, traveling down longitude 110 degree E each December. Data collected on fixed schedule seems to be ideal for long-term monitoring work, and can be used as time series and/or seasonal analysis. Due to the influence of COVID-19, monitoring program of JARE-62 (2020-2021) was canceled, and JARE-63 (2021-2022) was reduced the sampling plan. Sampling was conducted during the daytime at two stations during JARE-63 (December 2021).