Abstract: The invention has a curved board. The curved board is formed into a shape that curves in a curving direction corresponding to an expanding direction of a net opening in a towing state, from a front-side end section that is a front side in a towing direction in the towing state towards a rear-side end section that is a rear side in the towing direction in the towing state. At least one of a projecting structure having a projecting surface, a top board, and a bottom board is formed in the curved board.

Abstract: The invention has a curved board. The curved board is formed into a shape that curves in a curving direction corresponding to an expanding direction of a net opening in a towing state, from a front-side end section that is a front side in a towing direction in the towing state towards a rear-side end section that is a rear side in the towing direction in the towing state. At least one of a projecting structure having a projecting surface, a top board, and a bottom board is formed in the curved board.

Abstract: The invention has a curved board. The curved board is formed into a shape that curves in a curving direction corresponding to an expanding direction of a net opening in a towing state, from a front-side end section that is a front side in a towing direction in the towing state towards a rear-side end section that is a rear side in the towing direction in the towing state. At least one of a projecting structure having a projecting surface, a top board, and a bottom board is formed in the curved board.

Abstract: A net-mouth inclined trawl-net apparatus includes a substantially rectangular frame and a trawl net attached to the frame. The trawl net is formed of an upper net, a lower net, and a pair of side nets, and the trawl net has a shape formed of a body part of a quadrangular trapezoid shape. Each of the side nets attached to the frame has a longer side and a shorter side as an upper side and a lower side, and a side of each side net defining a net-mouth edge defines a side-net front edge inclination angle relative to a bottom side of an isosceles trapezoid having the shorter side of the side net as a side of the isosceles trapezoid, so that the frame autonomously maintains an inclination angle relative to the vertical axis due to a flow resistance and a lift acting on the net.

Abstract: A trawl net layer-by-layer collecting device includes a rectangular cylindrical frame configured to draw a plurality of trawl nets that are arranged in an up and down direction. The frame includes an upper edge to which a net mouth edge of an upper net of the uppermost trawl net is anchored, and a lower edge to which a net mouth of a lower net of the lowermost trawl net is anchored. A pair of vertical bars are disposed on opposed sides of the frame. A slider having opposed ends slidably engaged with the vertical bars, the slider anchoring thereto the net mouth edge of the lower net of the upper trawl net and the net mouth edge of the upper net of the lower trawl net. A net-mouth opening and closing unit is configured to lock the sliders on upper ends of the vertical bars, and unlock the locked sliders one by one; and a controller.

Abstract: To provide a lightweight trawl net layer-by-layer collecting device capable of autonomously switching opening and closing of a net mouths of trawl nets.

Abstract: There is provided a trawl-net collecting apparatus of net-mouth inclination maintainable type capable of autonomously maintaining a posture thereof.