Acoustic detection of the Greenland shark (Somniosus microcephalus) using multifrequency split beam echosounder in Svalbard waters

•Greenland shark have been detected and measured acoustically at three echo sounder frequencies.•The swimming speed and direction was determined using split beam target tracking algorithms.•Pairwise swimming was detected on several occasions.•Identification of Greenland shark targets was performed using discriminant analysis.