Research On Structure Optimization Of The Bottom Trawl In The North Of The Yellow Sea

The bottom trawl is one of the main fishing gears in the Yellow sea.Due to a large number of bycatch and the capture of juveniles,the fishery resources decline rapidly.It could cause the wasting of ocean resources,especially the juvenilefishes and shrimps.Then it could lead to the decline of the fishery resources.Therefore,in order to protect juveniles resources and reduce by catch,the fifth nets of original net was increased from 30 mm to 60 mm.A comparative test was carried out on the sea.The results showed that the weight of the test net reduce 69.87 kg than the original net and the two kinds of fishing nets caught a total of 28 species of fish.Fish species in test net was less than that of original net.Bycatch was reduced in test net.Comparing to the original net,the minimum length of fish increased in the test net.This illustrates that the test net could release juveniles,protect juveniles resources and capture high-quality fish.The study suggests that the size of the trawl mesh in the northern part of the Yellow Sea is too small and capture a large number of by-catch and juvenile fish.It is suggested that the mesh size of the fifth section should be changde to 60 mm.By analyzing the behavioral habits of fish and the behavior of the fish during trawling,In the original trawl net to expand the corresponding mesh size,so as to achieve the purpose of the release of juvenile fish.The results of the study can provide reference for the optimization of trawl fishing gear and the protection of fishery resources.