Krill CPUE standardisation and comparison with acoustic data based on data collected from Chinese fishing vessels in Subarea 48.1

The usability of CPUE data as Antarctic krill abundance index was a widely discussed issue. Many studies suggested the CPUE data should be standardized before using as abundance/biomass index. We tried to develop general additive models to standardize the CPUE data collected from Chinese fishing vessels during 2009/10 -2013/14 seasons. We also compared the CPUE data and acoustic data collected by Chinese fishing vessel Furonghai in 2015/16 season. The result showed that the CPUE data could be impacted by fishing activity, environmental and spatial and temporal factors. Ten days and monthly could be fine temporal scales for CPUE statistic. Catch per hour data could be more close to the acoustic data than catch per day data. The veridical distribution and movement of krill could be important source of differences between CPUE and acoustic data. The uncertainties and biases of CPUE data implied that CPUE used to indicate the krill stock abundance should be very caution. However, the dynamics of CPUE could indicate the changing trends of the density of krill in the water close to sea surface, which may be concerned by krill feedback management.