DrDeakos

Hard question to answer, the turtle that landed on my head as I was filming a manta ray or the tiger shark that gave me a kiss were both kind of cool

https://www.facebook.com/video.php?v=843373765704662&set=vb.234522059923172&type=2&theater

https://www.facebook.com/video.php?v=843360572372648&set=vb.234522059923172&type=2&theater

Manta rays only have one pup every 2-3 years on average in some populations and maybe every 5-7 years in other populations. The pups are born live and have a disc width of about 4 feet. Males have claspers (same as sharks), cigar shapped appendages by the genitals and while biting the female's pectoral fin (almost always on the left wing) from above, they bend their body so that they are almost belly to belly to insert one of the claspers into her cloaca. He pumps rapidly a few times and ejaculates, usually lasting less than a minute before they break apart and go their separate ways. https://www.youtube.com/watch?v=KZGT2uH7dho

To do manta ray research at a basic level, you only need a snorkel and mask and a camera. If you can free dive and get a photograph of the manta ray's belly (each manta ray has a unique set of spots on their belly that identifies them), you can keep track of individuals each time you go snorkeling and over time you develop life histories of individuals (who hangs with whom, how often is she pregnant, etc.).

Absolutely, we call these K strategists (slow maturation, small, infrequent litters, long lifespan), which means it takes a long time for a newborn to enter the reproductive pool. And so if you remove even a few individuals from the population, especially mature females, it takes a long time to replace that individual. In areas where they are hunted (e.g. Indonesia), small local populations could be wiped out in a matter of months.

I've spent about 10 years and over 500 dives. Some populations are more used to people than others. They are very curious animals, often investigating divers and boats (they have very large brains even compared to the size of their body). The 10% is only the survivors, I don't know how many are being killed from entanglement other than one in Maui and one in Kona that drowned after entangling in a mooring line, so the 10% is a conservative estimate.