Selection of artificial fish nest material and influencing factors of implementation effects

To determine the optimal artificial fish nest material, and to promote the restoration technology of spawning grounds for fish species with adhesive eggs, we had made fish nests with six kinds of materials (Arundo donax, Miscanthus sp., Pennisetum purpureum, Livistona chinensis, simulation aquatic plants and nylon mesh) at Zhaoqing section in Xijiang River from March to May in 2019, and studied the effects of materials and environmental factors on the implementation of fish nests. Common carps (Cyprinus carpio) had strong preference for adhesion medium, and Arundo donax was the best material for making fish nests, since the eggs adhesion ratio and the number of eggs in each nest were significantly higher for A. donax than for the other materials (P<0.05). The eggs adhesion ratio and the number of eggs decreased with the increase of days of entering water. The principal component analysis reveals that days of entering water are the most important influencing factor on the implementation effect. The increase of discharge and rise of water level can promote common carps to gather to nests and lay eggs, but weather condition had little effect. Besides, we discussed the effects of implement time and location.