Our first orca with a hump was Humpy (AV105) from Hooky family. When we first met her in Avacha Gulf she was a small juvenile, and her hump was rather small. But with time, as she was growing, her hump was growing as well. When we saw her for the last time in 2007, the hump looked like a large black blister. In 2008 Hooky family came without Humpy - obviously, she died. Probably the reason of her death was her hump.
The second humpy orca was a juvenile that we met near Beringa Island in 2011. His himp is still rather small and closer to the head, than Humpy’s.
The reason of these humps is unclear. Interestingly, an adulf female orca with a similar hump was observed in South Africa south of Cape Town.
source of this photo