Animal Planet

So I saw on animal planet that an ultrasound of a pregnant tiger shark will reveal that a mother can carry as many as twenty baby sharks at once, yet at the time of birth, a litter of only a few (sometimes even one!) emerges. It is survival of the fittest at its best, ladies and gentlemen, for the remaining sharks actually EAT their brothers and sisters. It reminds me of that Office episode where Dwight talks about reabsorbing his twin while in the womb. While Dwight has the strength of a "grown man and a little baby," the sole surviving sharks are born with the strength and might of 19 other baby tiger sharks and the "guilty conscience"(not!) of familial cannibalism. It's Charles Darwin meets the Donner party. What I want to know is how animal experts get close enough to the second largest predatory shark to get an ultrasound in the first place.
It's a shark-eat-shark world out there,
R-