All, the below is the statute re: seizure by the FWC when under search:
379.334 Search and seizure authorized and limited.—The Fish and Wildlife Conservation Commission and its conservation officers shall have authority when they have reasonable and probable cause to believe that the provisions of this chapter have been violated, to board any vessel, boat, or vehicle or to enter any fishhouse or warehouse or other building, exclusive of residence, in which game, hides, fur-bearing animals, fish, or fish nets are kept and to search for and seize any such game, hides, fur-bearing animals, fish, or fish nets had or held therein in violation of law. Provided, however, that no search without warrant shall be made under any of the provisions of this chapter, unless the officer making such search has such information from a reliable source as would lead a prudent and cautious person to believe that some provision of this chapter is being violated.
For taking other stuff (ie. boats, trucks, etc.), the provisions of Section 379.337, Fla. Stat. apply, which basically requires a conviction before they can go in and take your stuff, and even then they have to give you a hearing, etc. There are other provisions in Ch. 379 regarding seizure of things in specific situations.
To my knowledge, they can't even come close to taking your boat on the spot for having an overslot fish or anything like that.