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]
Vancouver Aquarium For many years, the primary attraction for visitors was the orca show. The Aquarium was the first to capture and display a killer whale, Moby Doll, in a pen at Burrard Drydocks, for 3 months in 1964. Since then, it was home to Skana, Hyak II, Finna, Bjossa, and three of Bjossa's calves. When Finna died and Bjossa was left without other orca companions, the Aquarium attempted to acquire one or more female orcas from other marine parks. However, no suitable companions were found, and Bjossa was moved to SeaWorld, San Diego, in April 2001 where she later died due to a chronic respiratory illness. The Aquarium has since moved to emphasize the educational aspects of the displays rather than the public spectacle of the shows. They have also highlighted their research, rescue and rehabilitation efforts.