Is Marlin fish rare?

Could you elaborate on the rarity of Marlin fish? Are they considered a scarce species in the marine environment, or are they more commonly found in certain regions? Is there a specific reason behind their potential rarity, such as habitat loss or overfishing? I'm interested in learning more about their conservation status and whether they are protected in any way. Additionally, is there any data available on the global population of Marlin fish, and how their numbers are trending over time?