actually, its 100yards from a beach, IIRC not a shore. not sure about docks...
http://myfwc.com/fishing/saltwater/recreational/
http://myfwc.com/fishing/saltwater/recreational/spearing/
Spearfishing of marine and freshwater species in freshwater is prohibited. Possession of a spear gun in or on freshwater is also prohibited.
Within 100 yards of a public swimming beach, any commercial or public fishing pier, or any part of a bridge from which public fishing is allowed.
Within 100 feet of any part of a jetty that is above the surface of the sea - except for the last 500 yards of a jetty that extends more than 1,500 yards from the shoreline.
In Collier County and in Monroe County from Long Key north to the Dade County line.
For any fish for which spearing is expressly prohibited by law (listed above).
In any body of water under the jurisdiction of the Environmental Protection, Recreation and Parks. (Possession of spearfishing equipment is prohibited in these areas, unless it is unloaded and properly stored.)
Fishermen who catch and/or sell fish harvested by spearing are subject to the same rules and limitations that other anglers in the state are required to follow.