Dorsal fin collapse or FFS, Flacid fin syndrome is seen very commonly in the orcas kept in captivity, It is not as common in the wild and if it is seen its more often caused by a boating accident/fight than the environment.
No-one knows for certain why they fall in captivity though it could be due to many reasons that are mentioned in this great scientific paper - [link]
The most common factor however is that at marine parks orca spend a large amount of time at the surface or out of water, whereas in the wild roughly 80% of their time is spent underwater where the water pressure helps to keep their fin up. In captivity gravity is slowly pulling it down.
Another common factor with dorsal fins which differs from captive to wild whales is the way they eat. Captive orcas are given frozen dead fish whereas wild capture and kill their own. Eating frozen fish doesn’t allow collagen to be created properly a vital fat used in keeping the fin upright.
I know this really hasn’t any effect on the whales overall health but if something has been warped so unnaturally compared to in the wild it should be a concern as to what may be happening internally.
Disclaimer- I cannot confirm that the above quote on the image is correct but it does display how much a fin can ‘flop’ (x)
(the orca is kanduke)