Patent ID: 8196334

Claim:
A net-mouth inclined trawl-net apparatus comprising: a substantially rectangular frame; and a trawl net attached to the substantially rectangular frame, the trawl net being formed of an upper net, a lower net, and a pair of side nets, and the trawl net having a shape formed of a body part of a quadrangular trapezoid shape and a cod-end part connected to an end of the quadrangular trapezoidal body part, wherein 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 (γ) 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 (β) relative to the vertical axis due to a flow resistance and a lift acting on the net, wherein the inclination angle (β) and the side-net front edge inclination angle (γ) satisfy the following expression: θ 1 =θ 0 −(β−γ) where θ 1 is an attack angle of the upper net against the water flow, and θ 0 is an inclination angle relative to a center line between the upper side and the lower side of the side net.