Do mermaids have magical powers?

The magic of transformation when they're on land.

Hell no.  Magical powers are exclusively reserved for witches, sorcerers, Jedi, conjurers and ordained clergy only.  Definitely not mermaids.

How many people have you met who have been affected by a mermaid spell?  How many people have fallen for the classic mermaid mind-trick?  Can you name even one person who was enchanted by a mermaid's magic trickery?  Exactly.

Mermaids know their limitations.  They lure drunken sailors (and sometimes pirates) to their death, they pose for tattoo artists worldwide, and they charge a modest royalty for Starbuck's to use their image.  That's is, that's all mermaids do.  And sometimes they sing really cool songs, but they do that for free.

Mine do I can't speak for anyone else's...

No they just live the same way as dolphins 

The ones around here like to laze around drinking Rum and Coke and insult all the sailors

Aw, they can have whatever you want them to have sport!