Estimation of krill target strength was made by ensonifying encaged live krill and using trawl hydroacoustic method. Ensonification of encaged live krill. For aggregations with mean lengths from 45 to 50 mm the mean single-krill target strengths range from -68 to -69 dB at 136 kHz. For aggregations with mean lengths from 43 to 47 mm the mean single-krill target strengths range from -71 to -77 dB at 20 kHz. Trawl hydroacoustic method. For aggregations with mean lengths from 47 to 50 mm the mean target strengths ranged from -71 to -75 dB. At the same frequency for aggregations with mean lengths in the range 41 to 47 mm the mean single-krill target strength is in the range -76 to -81 dB.