Observation on the interaction between Antarctic fur seal and krill fishing operation in Subarea 48.3 during the fishing season in 2020

Observation on the interaction between Antarctic fur seal and krill fishing operation was carried out onboard the Chinese krill fishing vessel Fu Rong Hai in Subarea 48.3 during July and August 2020, following a similar observation in 2019. Three year vertical distribution of krill swarms from 2018 to 2020 were also analyzed using acoustic data collected simultaneously from the same vessel. It showed that Antarctic fur seal exhibited three distinct behavior modes (termed as “Idle”, “attracted” and “aggressive” mode) towards the fishing trawl when the net is retrieved on sea surface; and that both of the behavior of Antarctic fur seal and the vertical distribution of krill swarm varied markedly among observations. It may be inferred that the behavior of Antarctic fur seal towards the fishing net may be closely linked to the recruitment status of Antarctic krill in the fishing ground; when krill recruits is scarce, the fur seal may exhibit aggressive behavior to the fishing trawl thus vulnerable to incidental mortality. Special attention needs be exercised when small sized krill is lacking where krill swarms are mainly found in deeper layers.