It depends on the object of fishing and the amount of fishing. If it is fishing for crabs and shrimps, it is more suitable to be placed in shallow water, because shrimps and crabs cannot go to deep water, because they need to breathe, they can only stay in shallow water, so To catch them, it is best to drop the ground cage net in the diving area.
Of course, if fishing is carried out in large rivers or even sea areas, the targets of fishing are generally big fish. These big fish generally live in deep water areas, so the ground cage nets need to be placed in deep water areas for fishing.
Crabs (páng xiè) belong to the soft armor class, decapods, and are crustaceans whose bodies are protected by a hard shell and breathe by gills. In terms of taxonomy, it is the same animal as a shrimp, lobster, and hermit crab.
Most species of crabs live in or near the sea, and some live in freshwater or land. Common crabs include swimming crab, sea swimming crab, blue crab, and Chinese mitten crab (river crab, hairy crab, clear water crab), and so on.
Physical characteristics:
The body of the crab is divided into the cephalothorax and the abdomen. The back of the cephalothorax is covered with a carapace, the shape of which varies from species to species. The center of the forehead has the first and second pairs of antennae, and the outer side is a compound eye with a stalk. Mouthparts include 1 pair of large jaws, 2 pairs of small jaws, and 3 pairs of maxillopods.
There are 5 pairs of thoracic feet on both sides of the carapace. The abdomen degenerated, flattened, and curved on the ventral surface of the cephalothorax. The abdomen of males is narrow and long, mostly triangular, and only the first two pairs of appendages are deformed into junctions; the abdomen of females is broad, with a pair of double-branched appendages on each of the 2nd to 5th segments, densely covered with setae, which are used to hold eggs. Most crabs are marine, with the most species in tropical shallow seas.