#dorsal collapse

[orcinus-ocean]

Port and Starboard

While I am "collecting" wild killer whales with collapsed dorsal fins and photos of them, I had no idea these guys existed.

I was googling pictures of great white sharks with dolphins, and this artwork (by Marc Dando) came up. I thought it was some OC pieces from deviantART, but nope, these are depictions of two real animals and their real... diet.

They are actually two South African bull killer whales who hang out together, and both have completely collapsed dorsal fins, one to the left (Port) and one to the right (Starboard).

Because of their distinctive fins, Port and Starboard are easy to recognise and have been seen at numerous points along the southern tip of Africa, from Walvis Bay in Namibia to Langebaan on South Africa’s West Coast and to Gansbaai in the east – a total distance of more than 1,400 kilometres (870 miles).

In all likelihood, the shark-eating orcas have always existed in offshore waters and Port and Starboard are probably part of a larger pod that we have not seen yet.

I don't know how much is known about the South African killer whales, but it seems they resemble the offshore ecotype in the Northeastern Pacific, which is also a poorly studied ecotype and which also feeds on sharks.

[blackfishsound]

A young boy lamented Ikaika's collapsed dorsal. Things are starting to change.

[orcinus-ocean]

All collapsed dorsal fins I’ve found

Anyone know who these individuals are, what their stories are (injuries, for example?), and if I took the same whale more than once?

I know the first one is from Iceland, and several are from Gibraltar.

And who’s that Icelandic whale that looks like Keiko? (Not here, but he has several black blotches, I think he has a collapsed fin too.)

[emptythetanks]

Why do the orcas' dorsal fins collapse? Stress? Other factors? What happens?

Hi, thanks for your question! Sorry this took so long to reply, I’ve been really busy lately and only recently checked my inbox!!

Okay, so to answer your question: in captivity, orcas spend a lot of time at or near the surface of their tanks, considering the fact that the tanks are so shallow. Dorsal fins are tall (growing up to 6ft in males), so when the orcas are near the surface, their fins stick out of the water. Gravity exerts a force on the fins, weakening the collagen in them and causing them to bend. [x]

Now usually, with wild orcas, the ocean exerts enough water pressure to support the dorsal fin and prevent collapse. Wild killer whales do not spend as much time at the surface as captive ones, so less force is exerted by gravity in the wild. 

Also, in the wild, killer whales tend to travel in straight lines, with even water pressure on both sides of the fin, so the fin remains upright. However, in captivity, killer whales are forced to swim in circles in their tiny enclosures, so the water pressure on each side of the dorsal fin is uneven; another factor contributing to the weakening of dorsal collagen.

Even though captivity is a major cause of Flaccid Fin Syndrome in male orcas, it is not the only cause. A few wild orca also have collapsed dorsal fins; usually due to injuries from boat propellors, or from exposure to oil spills.

However, while 100% of captive males have Flaccid Fin Syndrome, this occurs in less than 1% of wild orca. 

more sources [x], [x], [x], [x], [x]

[orcinus-ocean]

SeaWorld on dorsal collapse.

[orcinus-ocean]

Is it just me, or are dorsals flopping over a lot more in Orlando than San Diego?

In the San Diego pod, Corky and Orkid have really tall dorsals, Nakai's is still looking good, Kasatka's barely leans... while in Orlando, all the young ones (even Makaio?) seem to have a dorsal leaning over already. All to the left, too, while in San Diego, it seems to be more to the right.

Am I just seeing patterns here, or? (And of course, not all got those collapsed fins where they are now - like Katina and Kayla.)

[nomoreorcasforentertainment]

[stumpyx163]

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)