Skates do not have venomous barbs like stingrays although some skates do have pointed thorns. Also stingrays give birth to live young where skates lay eggs. I really dont worry about them at all, i think its pretty cool when they are active and you can see them during your morning surf. I would definately rather "see" them than not see them. Plus, shuffle your feet while you are walking in the water, this will keep you from stepping on a stingray, hence not getting stung.
Just fear the sharks, cannonball jellyfish are harmless.