When the temperature runs up to 20℃,the male Oreochromis nilotica will excavate holes on the sides or the bottom of the pool. Oreochromis nilotica will hide in the holes when scared by the fishing haul or other provocation. This would make the fishing operation very difficult, and the fishing rate very low. With the ordinary seine net,the fishing rate of first haul is always under 30%, and the total fishing rate for the first three hauls is about 50%. On the basis of the study on the behavior of Oreochromis nilotica, a new fishing gear, a seine with a curtain net, is designed. On the newly designed seine, there is a curtain net between the sink line and the bolch line. The bolch line is much longer than the foot line, and will be loose enough in fishing operation to get into the hole to scare out the fish which is hidden in the hole. The newly designed seine was tested in four Oreochromis nilotica pools in Yantai and two Oreochromis nilotica pools in Taian respectively. The results show that the fishing rate is over 60% for the first haul, and the total fishing rate for the first three hauls is above 90%. The newly designed seine is more suitable for the fishing operation in the pool with harder bottom.
