Net depth response of a depth-controllable (towed) gillnet for fish sampling

Flume-tank experiments were performed to examine the depth response of a ne w type of depth-controlled gillnet. Variations of net depth were investigat ed as the warp was paid out and wound up for different changes of warp leng th, main sinker weights, and winch speeds. In most experiments, when the wa rp finished paying out, the net continued to descend and then ascended slig htly to an equilibrium depth (overshoot phenomenon). The overshoot distance was nearly constant when the warp was wound up and increased linearly with increasing winch speed when the warp was paid out. An increase in winch sp eed reduced net settling time, which converged on a constant value for both paying out and winding up.