漂流性鱼卵的孵化特性及水动力需求研究进展

Review of Research on the Hydrodynamic Requirements for Sustained Drifting and Hatching of Buoyant Fish Eggs

鱼卵运动规律研究是鱼类产卵场位置推算、水库生态调度和鱼类资源保护的基础。对于产漂流性卵鱼类,当流水环境不足以维持鱼卵漂流时,鱼卵便下沉死亡而无法孵化成幼鱼。通过对照中国内陆鱼类名录,查阅国内重要流域及地方鱼类志中有关产漂流性卵鱼类的繁殖条件,梳理了典型鱼类的产卵水温、产卵时间和孵化时长等相关信息。针对现有鱼类志中对于鱼卵基本物理性质及鱼卵孵化所需水动力条件信息缺失的情况,补充查阅了国内外相关文献,归纳总结了漂流性鱼卵安全漂流的水动力条件。一种观点认为鱼卵在水体中是否能安全漂流取决于水体的流速,另一种观点认为控制漂流性鱼卵悬浮或下沉的关键参数是湍流状态或剪切速度,而不是水流的线速度,现有漂流性鱼卵孵化的关键水动力条件和阈值尚有争议,仍需加强鱼卵运动规律的相关试验研究。目前国内外对鱼卵的漂流输移研究方法和手段,主要采用野外监测、室内实验和模型模拟。已有研究大多只是针对鱼卵运动规律本身进行单一试验或模型验证,如何通过水库调度最大程度保障漂流性鱼卵的漂流孵化条件是未来鱼类保护的重要方向。

Ascertaining the principles of fish egg movement in rivers is the basis for calculating the position of spawning grounds, managing the ecology of reservoirs and protecting fish resources. However, for species that release buoyant(drifting) eggs, the eggs will sink and perish if the hydrodynamic conditions are not sufficient to keep the eggs drifting. In this paper, we described the hatching and hydrodynamic requirements of fish species with buoyant eggs. First, relevant information on hatching characteristics such as spawning water temperature, spawning month and hatching duration of typical fish with buoyant eggs were obtained from the list of inland fish in China and ichthyology books covering major river basins in China. Then, we consulted relevant national and international literature and summarized research advances on the hydrodynamic conditions that are appropriate for drifting eggs. One view holds that sustained drifting of buoyant eggs depends on a minimum flow velocity, while the other holds that the key parameters controlling floating or sinking of buoyant eggs are turbulence or shear velocity. The key hydrodynamic conditions and threshold for hatching of buoyant eggs remain controversial, and the principles of buoyant egg motion needs further study. Finally, the current research methods for discerning the principles of buoyant egg motion in water were summarized and include mainly field observation, laboratory experiments and model simulation. Previous research added greatly to our understanding of the mechanisms of fish egg movement, but most studies focused on a single problem of egg motion using one experimental approach or model. The creation of hydrological conditions needed for egg hatching through ecological operation of water conservancy projects is a key research field for the future.