An outline of narrowband echosounder survey methods to estimate biomass of Antarctic krill in CCAMLR Division 58.4.1 during 2018/19 season by the Japanese survey vessel, Kaiyo-maru

Japanese multidisciplinary survey with a focus on biomass estimation of Antarctic krill will be conducted in CCAMLR Division 58.4.1 during 2018/19. The biomass estimation will be conducted according to the up-to-date CCAMLR standard protocol. The first standardized survey was conducted by CCAMLR in 2000 as the CCAMLR-2000 survey. Quantitative echosounders has evolved since then and a current model is EK80. Though EK80 can transmit both conventional narrowband continuous wave (CW) and new broadband frequency modulation wave (FM), CW will be used for biomass estimation to follow the CCAMLR standard-method. Three-frequency (38, 120 and 200 kHz) krill identification method which is the current CCAMLR standard will be employed in the analysis but utility of 70 kHz data will also be investigated. Measurements of acoustic impedances (mass density and sound-speed contrasts) of krill will also be conducted during the survey. Currently, the compatibility of the output data between EK60 and EK80 has been discussed at ICES WGFAST and this aspect will also be investigated in this survey.