You go to Slateport and go to the museem and you can find him on the second floor
In Slateport city harbour you will see capt. stern being interviewed with a large crowd talk to capt. stern and you will go into the harbour thing and then go to their hideout in lilycove city.
You have to talk to the scientist guy at the ship place in slateport city
He's in the Slateport museum but you might have to go talk to a guy in the big, brown building (go up from the entrance and he's in front of some blueprints).
He is in Slateport City.
Clampearl doesn't evolve by leveling up. Clampearl can either evolve into Huntail or Gorebyss. To get Huntail, you have to choose to receive the Deepseatooth from Capt. Stern in exchange for the Scanner and then have Clampearl hold it while trading. To get Gorebyss, you have to choose to receive the Deepseascale from Capt. Stern and then have Clampearl hold it while trading. You have to choose one or the other. You cannot choose both.
you go into the aquarium place, and he will be there.
He's in the museum.
Capt. Stern is not in Pokemon Leaf Green. He is only in Pokemon Ruby, Saphire or Emerald.
it depends wich captain? capt stern he is in the museum in slateport Ask bill and then he will tell you something then go to the second floor of the museum you migth want to have good Pokemon against dark, flying and water because you figth against team aqua if in sapphire or emerald i don't know about ruby....
You get it in Slateport City, by Capt. Stern. Hope I helped :)
You can't use it for much, but you can exchange it for either a deepseatooth, or a deepseascale. The deepseatooth raises Clamperl's Sp. Atk, and the deepseascale evolves Clampearl into huntail. To exchange the scanner bring it to Capt. Stern in Slateport at the Slateport Harbor.
Go to the shipyard, and talk to the guy standing by the table with a map on it. He will tell you Captain Stern isn't there. Leave the shipyard, and go into the museum. Go to the backroom, and talk to the scientist. He is Captain Stern. Team Aqua will come inside, and be prepared for two battles. After you beat them, you can give the parts to Capt. Stern. Hope this helps! :)