Research progress of mechanical property of tuna longline gear

The mechanical property of longline gear affects fishing efficiency and energy consumption directly. The paper summarizes relevant research methods and progress on the mechanical property of tuna longline gear, including the initial measurement at sea, the model test in the flume tank, and the numerical simulation. Results show that: 1) the theoretical analysis of mechanical property of longline gear have developed from static analysis to dynamic analysis; 2) the model test of longline could only be carried out on a small scale in order to verify the accuracy of numerical simulation analysis under specific circumstances; 3) the perpendicular drag coefficient (C_N90) and inertia coefficient (C_m) were determined to be 1.12 and 3, respectively. It is suggested that the future studies on longline gear mechanical property should: 1) foucus on the effects of the stiffness and damping of fishing gear materials on the numerical simulation accuracy; 2) combine the behavioral characteristics of tuna to study the hydrodynamic force after hooking and take it into account in the model, so that the model can match the actual operation state; 3) further numerically simulate the interaction among the fishing gear, current, fishing boat, line hauler and catches.