The kelp knots are the main product for exporting and earning foreign exchange in Chinese kelp culture provinces, but there are no mechanical processing devices. Therefore, the kelp knots are usually tied manually. Based on the principle of bionics, this paper offered an automatic knotting machine which could make the kelp forming a circle and passing through it to form a knot with the logic circuit. The test verified that this knotting machine was able to complete the operational requirements for kelp knotting accurately, which showed that this design was reasonable and feasible, and had the value of promotion and application after further optimization. It could also provide certain reference for the design and application of relevant knotting equipment.

The velocity of fluid in the aquaculture cage is closely related to the growth of fish.In order to study the characteristics of the flow field around the aquaculture plane net,the flow field of a rigid plane net was simulated numerically based on CFD theory and by using the porous media model.Firstly,the uncertainty analysis of the flow field was carried out,and then the numerical calculations were carried out in the plane net at different angles and velocity,and the results were compared with the experimental results.The results showed that the calculation results of the resistance and the lift of the plane net were consistent with the experimental results,which indicated that the method can accurately predict the force of the plane net and the flow field around the plane net.The velocity of the fluid near the net decreased quickly,then after a certain length the velocity of the fluid changed slowly.The blocking effect of the plane net on the flow gradually decreased when the velocity of the flow increased.The numerical simulation method in this paper could be used to simulate the flow field of the plane net,which had some academic research value and engineering practical value.

Methods of cleaning the fouling organisms in the process of aquaculture is related to production benefit, because of the aquaculture facilities, mariculture objects or aquaculture process can be affected by fouling organisms.The present paper investigated the treatment methods for fouling organisms of marine aquaculture facilities in the main aquaculture areas of Fujian Province.According to the survey, there was a lack of effective preventive measures while manual removal was the main way.Actually, the fish farmers usually ignored it, even if needed to clean, dry or manual removal were the preferred methods.Only a few were treated with a screen washer or sprayed with formalin.The survey showed that the main treatment methods for fouling organisms in Fujian province were traditional, time-consuming, inefficient, and labor intensive, even more, advanced technique and equipment were difficult to adapt to actual production.