There's 3 full-time staffed Marine units, Marine 1 (which is 2 boats), Marine 6, and Marine 9.
There's also 3 season small boats that operate only in spring-fall during the day, they are Marines 3,4 and 8. (forget what times exactly they operate but it was something like 0800 to 2300)
I don't know of any "reserve" marine units but there's a variety of small boats, inflatables, etc. including 1 at SOC and the 2 carried by the Tactical Support Units.