Sorry !
I don knew what a seiner is
//Jugge

Hi Jugge -a Seine is simply a net weighted at the bottom with floats at the top - formed into a ring around the catch - presumably the bottom is closed as they bring it aboard. The Florida US Shrimpers are one kind of seiner - if you Google them you will see they operate with a boom either side - presumably to keep the mouth of the net open ? Most of them would be purse seiners presumably as the net is closed at the bottom to form a purse.