Quantifying movement behaviour of vessels in the Antarctic krill fishery
Ten years of recent fine-scale haul-by-haul krill data were used to characterise the behaviour of the krill fishery. Analysis of distance between hauls in relation to their catch level revealed a distinct pattern. Mean between-haul distances were generally longer when catch levels fell below 10 tonnes/haul, and the travel distance decreased as the catch level increased; this pattern was most obvious for operations by Japanese fishing vessels. There were differences between statistical areas with longer distances moved between hauls in Subarea 48.1 compared to Subareas 48.2 and 48.3, reflecting the large number of fishing grounds within this area. The same patterns were observed for vessels from other nations, but were less clear. The study suggests the movement trends for Japanese vessels could form the basis for describing a generalised fishery model. Updates for some of the parameters for the krill fishery model suggested in the late 1980s are proposed based on the results from this study. These analyses demonstrate the need for high-quality year-round data on all vessels participating in the krill fishery to assist in interpreting the annual fishing patterns, which can best be collected by scientific observers.