Did you know that almost everything we knew about pregnant whale sharks came from one female caught by a commercial fishing boat in 1995 ? And some of the conclusions drawn at the time are now proving to be incorrect.
New Research into detecting if a female whale shark is pregnant involves ultrasound devices and even "jet packs" to swim along them. So far it seems to be in the early stages though, only a handful of female whale sharks were tested so far.
Check out the article at sciencenews.org