What question did this study set out to answer?

The goal is to monitor zooplankton populations and their variations in the Southern Ocean over time.

April 1, 2026Open Access

Zooplankton monitoring using a twin NORPAC net during the 61st Japanese Antarctic Research Expedition in austral summer 2019–2020

Key Points

The goal is to monitor zooplankton populations and their variations in the Southern Ocean over time.
Conducted zooplankton sampling using a twin NORPAC net during two surveys in the 2019/2020 season.
Gathered data from the icebreaker Shirase along fixed routes each December and March.
Performed additional sampling on the T/V Umitaka-maru along 110ºE longitude in January 2020.
Presented the latest data on zooplankton abundance and species composition from the 2019/2020 voyage.
Data collected supports the establishment of long-term trends and seasonal variations over the last 45 years.

Abstract

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. Two separate monitoring surveys were completed during JARE-61 (December 2019 to March 2020). The icebreaker Shirase has a fixed schedule and route, traveling down longitude 110ºE each December and returning along 150ºE each March. Data collected on these fixed schedule seems to be ideal for long-term monitoring work in this region. We present data from its 2019/2020 voyage. In additions, separate samplings were carried out on board the T/V Umitaka-maru along 110ºE longitude in January 2020. This report provides the latest zooplankton data. These transect data can be used as time series and/or seasonal sets over the last 45 years.

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