Schematic diagram of trawl fishing method

Trawl fishing generally adopts large mesh net and purse seine method, and the schematic diagram is as follows:

1, large mesh weaving method

(1) The net used in the large mesh dragnet method is determined according to the fishing specifications. Fish that do not meet the market specifications are basically filtered out of the net and will not go online, thus shortening the operation time and avoiding the occurrence of hypoxia. This method is also inevitable for fish, especially herring and grass carp, which are between fingerling and adult fish. These caught fish are generally injured in the gills, almost unable to survive, and the economic value of barely selling is also extremely poor.

(2) The net can catch fish with high perching water, and the fish with high perching water (such as green scale fish, white-leafed horse horn fish, boat fish) increased obviously (more than 86%). Fishing boats using this net can increase production by 30% and increase value by more than 2%, which has remarkable economic benefits and is the reform direction of trawl fishing gear.

2, purse seine fishing method

(1) The fishing net method is to fill the pond with fresh water 2-3 hours before pulling the net, so that most of the fish in the pond are concentrated in the new waters. At this time, the fishing work can be completed only by winding the net at the corner of the pond, which greatly shortens the time of pulling the net. Because it works in new waters, it will not cause fish to die of lack of oxygen.

(2) However, this method is only suitable for the early stage when there is little water in the pond. At this time, the stimulation response of pond fish to new water is obvious, and the effect of purse seine is very good. In summer, when the fish in the pond are full of water, the response to the stimulation of new water is not strong, and the effect is often not good.