Great white sharks in New Zealand waters may head for Australia each spring to hunt for food. Research by the National Institute of Water and Atmospheric Research (NIWA) suggests some leave the seal feeding grounds around the end of winter for Australia. Niwa scientist Dr Malcolm Francis said new information on great white sharks was emerging from the use of âpop-upâ satellite tags, which detach after a set time, float to the surface and send information on their position to a satellite. It was thought that great whites were cold-water, coastal sharks but it is now known that many make trans-oceanic migrations to tropical waters and are probably related to hunting for food such as newborn humpback whale calves, because all the tags have surfaced in or near known humpback calving sites. Research using satellite tagging started in 2005 in an international collaborative programme.