测定鱼苗体长时所面临的主要技术难题是既要测得精确而又不损害鱼苗。对活鱼苗虽可直接进行测量,或麻醉后测量更为容易,但这都会压伤和损害鱼苗。由于鱼苗身体近乎透明,用测量幼鱼和成鱼的普通照相技术(Christensin 等,1977;Martin,1 967)来测量也不行。作者将奥尔纳((Ortner)等(1979)用高速黑白照相测量和鉴别浮游动物的简便方法移用来测量鱼苗。 The main technical challenge in determining the length of a fry is that it requires both accurate measurements and no damage to fry. Although the live fry can be measured directly or measured after anesthesia easier, but it will crush and damage fry. Due to the almost transparent body of the fry, it is not possible to measure with normal photographic techniques for measuring young and adult fish (Christensin et al., 1977; Martin, 1967). The authors used the method of Ortner et al. (1979) for the rapid measurement of fry with high-speed black and white photography and the facile identification of zooplankton.