The topic which most attracts funding is the impact of man-made noise on whales. Sources of noise include Navy sonars, ships, explosives and offshore oil exploration work. Because this topic often requires interpretation of the whales behavior to indicate response and because whales tend to habituate to most man-made noises with time, this is a very complex subject. More recently whales have stranded and died as a result of Naval mid-frequency sonar operations. Necropsy of these animals show "gas and fat embolic syndrome" which apparently result from the whales failure to properly decompress. The species most involved have been beaked whales resulting in a redirection of the focus away from baleen whales and towards these more cryptic species.