False killer whales are being by-caught by tuna fishing boats. They sometimes get injured on the baited hooks underwater . Our initial work shows that false killer whales can 'see' the hooks underwater with their biosonar. We want to find out how far away they can detect the hooks, whether some hooks are 'brighter' than others, whether we can make them brighter, whether the whales can detect bright hooks better and whether we can work with fishers to greatly reduce the deaths of whales.