Development of a new multiple sampling trawl with autonomous opening/closing net control system for sampling juvenile pelagic fish

► A new multiple layer sampling trawl was developed to sample pelagic juvenile fish quantitatively. ► The trawl system (5 layers, 4 m2 mouth area, 490 kg in air) can be towed at the towing speed of 2 m s−1. ► Net opening/closing is controlled by an autonomous control system with respect to depth, time or flow. ► Control system also records the net depth, temperature and flow rate during net towing.