why do orcas have collapsed dorsal fins in the wild
Captive killer whales Collapsed or collapsing dorsal fins are rare in most wild populations and usually result from a serious injury to the fin, such as from being shot or colliding with a vessel.[72] After the 1989 Exxon Valdez oil spill, the dorsal fins of two male resident killer whales who had been exposed to the oil collapsed, and the animals subsequently died. In 2002, the dorsal fin of a stranded killer whale showed signs of collapse after three days but regained its natural upright appearance as soon as the orca resumed strong normal swimming upon release.[72]