鱼类克服流速能力的试验

EXPERIMENTS ON THE CURRENT OVERCOMING ABILITY OF SOME FRESHWATER FISHES

为了解鱼类克服流速的能力,确定鱼道过鱼孔口流速、对鲤、鲫、鲢、草鱼、梭鱼、团头鲂、鮊、乌鳢、鲶等鱼进行试验。 各种鱼类的感应流速多在0.2米/秒左右,适应流速是0.3米/秒,到0.8米/秒之间,极限流速的差别较大。以适应流速的上限值作为确定鱼道过鱼孔口的选定值是适宜的。 试验结果还表明,鱼类克服流速能力,受其体型、体长、水温和所处环境条件等影响。 从本试验结果及已建鱼道的观察资料分析,不同鱼类各体长组所能克服流速值的增长率是有差异的。选用时可按经验公式:V=(1.19-1.66)L^(1/2),进行推算。

In desiging the magnitude of current velocity at the inlet of a fishway, the currentovercoming ability of fishes should be considered at first. A series of experiments wereconducted in the flume of a hydraulic laboratory. Various kinds of fishes were selectedfor experiments, such as carps (Cyprinus cxrpio); Crucian carps (Carassius auratus);silver carps (Hypophthalmichys molitrix); grass carps (Ctenopharyngodon idellus);mullets (Liza soiuy); whitefish (Erythroculter erythropterus); snake head (Ophiocephalusargus); catfishes(Parasilurusasotus); blunt--headed bream(Megalobrama amblycephala)etc. At the water temperature 10--27℃, and water depth 25--50 cm., the starting velocityfor various kinds of fishes is about 0.2m/sec. The optimum velocity ranges from thelower limit of 0. 3--0. 4 m/sec. to the upper limit of 0. 5--0. 8 m/sec., But the limitingvelocity for different kinds of fishes varies comparatively large. The upper limit of optimum velocity is generally considered as the preferable veloci-ty for fishway inlet. The value is about 15--30% less than the limiting velocity. The experiments denots denote that the current overcoming ability of fishes concernsmainly with their body shapes, body length and the variation of the water temperature. By analyzing the resllts of the experimentsand the observed date from some existingfishways, it indirates that the current overcoming ability of a fish is closely related to itsbody length. so that an empirical formula is proposed for estimation.