循环水养殖模式下鱼生长对水环境因子的响应模型构建

为探究鱼类生长对水环境的响应,预测鱼类在养殖水环境多因子协同作用下的生长速度,进行了室内曝气推流循环水养殖罗非鱼试验,试验持续周期为8周。结果表明,在一定范围内,随着溶解氧质量浓度的增加,鱼的食物转化效率和特定生长率均有所提高;随着非离子氨质量浓度的增加,鱼的食物转化效率和特定生长率均有所降低;而亚硝酸盐质量浓度由于变化不大且均处于安全质量浓度范围,该试验中对鱼的食物转化效率和特定生长率未产生显著影响。基于这一系列试验结果对罗非鱼特定生长率进行了非线性拟合,建立了鱼的生长预测模型,R2为0.82,并通过实测数据验证了模型的有效性和普适性。预测模型表明,养殖初始鱼质量、养殖密度、非离子氨以及亚硝酸盐质量浓度的增加,均会导致鱼生长速度减缓,而提高溶解氧质量浓度则可以提高鱼生长速度。该预测模型虽然是在曝气推流循环养殖模式下获得的,但对其他养殖模式同样适用,使鱼生长对水环境因子的响应变得可测,为促进养殖鱼类的健康发展、养殖系统的优化和养殖效益的提高提供了便利和参考。

Response model construction of fish growth to water environmental factors in recirculating aquaculture mode

With the improvement of aquaculture scale, the disadvantages of traditional aquaculture mode are constantly emerging, including waste and pollution of water sources. On this basis, the recirculating aquaculture system with aeration plug-flow device in pond is an exploration of efficient and energy-saving aquaculture mode, which has been developed rapidly at home and abroad. Water environment, as the place where fish live, is crucial to the growth of fish. A large number of studies have shown that dissolved oxygen, ammonia nitrogen and nitrite are the three important factors that affect the growth of fish. There are synergistic effects among dissolved oxygen, ammonia nitrogen and nitrite. Insufficient dissolved oxygen and high mass concentrations of non-ionic ammonia and nitrite can cause metabolic dysfunction of fish body and decrease of immunity, leading to the occurrence of fish diseases. Therefore, in order to explore the response of fish growth to water environment, and predict the growth rate of fish under the synergistic effect of water environment factors, the experiment was conducted on indoor recirculating aquaculture tilapia test with aerated plug-flow device with a continuous duration of 8 weeks. By changing the aeration flow, three conditions were set up in the experiment to observe the growth of tilapia during the breeding period, and the mass of the fish and water quality parameters such as dissolved oxygen, non-ionic ammonia and nitrite were regularly measured. The results showed that within a certain range, with the increase of dissolved oxygen mass concentration, the food conversion efficiency and specific growth rate of fish increased; with the increase of non-ionic ammonia mass concentration, the food conversion efficiency and specific growth rate of fish decreased. However, due to the small change in nitrite mass concentration and the safe mass concentration range, there was no significant effect on the food conversion efficiency and specific growth rate of fish in this experiment. Based on the results of the experiment, the specific growth rate of tilapia was nonlinearly fitted, and the growth prediction equation of fish was established, with R2 of 0.82. The validity and universality of the equation were verified by the measured data. The growth prediction equation showed that the increase of the initial mass of fish, stocking density, non-ionic ammonia and nitrite concentration could slow down the growth rate of the fish; while increasing the dissolved oxygen concentration could increase the growth rate of the fish. In the current situation of increasingly tight land, intensive farming is often adopted to improve the level of farming. With the increase of aquaculture density, the concentration of non-ionic ammonia and nitrite in the water environment increases, which have a negative impact on the growth rate of fish. It could improve the water environment and promote the healthy growth of fish by increasing dissolved oxygen. Although this prediction model is obtained under the aeration push flow cycle cultivation mode, it is also applicable to the other aquaculture water modes, making the response of fish growth to measurable water environmental factors, which provides convenience and reference for promoting the healthy development of aquaculture fish, the optimization of aquaculture system and the improvement of aquaculture benefits.