Abstract: The trawl-net apparatus includes, between the net and the bottom, a closing-opening mechanism provided with a first control device. The mechanism holds the entrance of the bottom closed while leaving the rear of the net open. Under action of its control device, the rear of the net is caused to communicate with the entrance of the bottom. A folding over closing system is provided with a second control device and under the action of this control devices allows the mouth fold back rearwardly, then ensures, by a stopper, the closing of the mouth. The trawl-net with controlled opening and closing is advantageously used for selective gathering of pelgic micro-necton.