Rights: National Institute of Water and Atmospheric Research (NIWA) Published 3 December 2007 Size: 45 KB

Fisheries acoustic data collected steaming from Wellington to the Ross Sea. Each ‘pixel’ is 20 km long by 50 m deep. The colours show the average amount of sound coming back from each depth (red = strong, blue = weak). Patterns north of 60º S are caused by daily vertical migration of fish to the surface at night.