A gate mechanism (20) is adapted for mounting within the extension (4) of a trawl net (1), the gate mechanism comprising a turbine (47/147/247) for powering rotation of the gate mechanism as it is dragged through the water within the trawl net.

Embodiments of the present invention relate to methods and apparatus for sorting undesired marine species during trawling, provides a pliable grid when the trawl net is pulled from the water and wound tightly on the net reel, and when the trawl is deployed in the water, the apparatus is fixed into place inside the trawl and holding its shape with consistent grid spacing. Marine species sorting apparatus in accordance with embodiments of the present invention includes grid, back straps, and lead ring. Grid includes a plurality of bars surrounded by grid frame. Grid frame is attached to lead ring at an angle using terminal couplers. Lead ring supports grid and secures marine species sorting apparatus in trawl webbing referred to as the extension.

A multipurpose portable or transportable selective fish capture system and no touch transport system is described that comprises an interconverting pontoon platform which can be adapted to include a solar and/or hydro electrical energy collection, conversion, storage and distribution system and to convert between a selective fish capture system and no touch fish transport system and an for emergency response for search and rescue or oil spill response support and oil spill collection and oil transport system.

A multipurpose portable or transportable selective fish capture system and no touch transport system is described that comprises an interconverting pontoon platform which can be adapted to include a solar and/or hydro electrical energy collection, conversion, storage and distribution system and to convert between a selective fish capture system and no touch fish transport system and an for emergency response for search and rescue or oil spill response support and oil spill collection and oil transport system.

A gate mechanism (20) is adapted for mounting within the extension (4) of a trawl net (1), the gate mechanism comprising a turbine (47/147/247) for powering rotation of the gate mechanism as it is dragged through the water within the trawl net.