Maldives - best island and season to see whale sharks and mantas

Hello everybody, this is my first post

I am a scuba diver and snorkeler/freediver and I have a very basic question about marine biology

I am planning a trip in the Maldives, in other cases it could be Egypt or Philippines. I need a reliable and let me say "scientific" source of information on marine animals behaviour, in this case whale sharks and mantas. Is there a comprehensive and reliable resource on the marine animals (say sharks, mantas, sardines run, etc.) and the "seasons" in which they are more likely to be seen while diving in the different areas of the world?

For example, mantas and whale sharks are supposed to be common to se around south  Ari atoll in the Maldives, and the time should be July or August unless I am mistaken

But I would like to understand if there is something more reliable than travellers reports and possibly describing the distribution and behaviour of many marine animals in several parts of the world

Thank you