Studies on incidence mechanism and prevention of injury caused by fish themselves

1.从预防感染、防病防病、防病防病、防病保质等方面防止鱼的伤害。在不同的光照强度、触发开关深度、投喂方式和食物条件下，对自喂器饲养的虹鳟鱼进行了研究。研究结果如下：1.研究结果。触发深度对规格异质性、死亡率、饲料消耗量、饲料转化率(FCR)、尾鳍和背鳍裂开和侵蚀的发生率没有显著影响。上触发鱼的背鳍裂口随时间延长而减小，而下触发鱼的背鳍裂口则不随时间延长而减少。上下游大鱼的尾鳍侵蚀随时间延长而增加。摄食方式对尾鳍上鳍、尾鳍下鳍或背鳍的裂鳍或侵蚀的发生率没有显著影响，裂鳍的发生率不随时间的变化而变化，与摄食方式无关。有趣的是，1餐方案显著阻碍了背鳍侵蚀的恢复，而在1餐和自由进入方案中，尾鳍对上尾叶的侵蚀随着时间的推移而显著增加。在人工饲养的鱼中，背鳍损伤的发生率明显更高，但尾鳍损伤的发生率并不明显。自食鱼的背鳍损伤随时间延长而减少，而手投鱼的背鳍损伤不随时间延长而减少。在自食性和手饲性鱼类中，尾鳍损伤都随着时间的推移而减少，尽管自食性鱼类只有一个不显著的恢复趋势。在上述实验中，大多数个体在背鳍和/或尾鳍受损时显示出较深的身体颜色。较深的身体颜色似乎是由损伤造成的压力造成的。然后，对人体颜色进行图像分析，得出人体侧体局部区域亮度随应激程度变化的相对值。这种非接触式和侵入式图像分析方法的实验使测量鱼的应力成为可能。

1. Fish injury should be avoided from the view points of prevention for infection, disease and production quality. Studies were conducted using rainbow trout reared by self-feeder under various conditions of light intensity, trigger switch depth, feeding method, and food regime. Following results were obtained.2. Trigger depth had no significant effect on size heterogeneity, mortality feed wastage, feed conversion ratio (FCR) or the incidence of caudal and dorsal fin splitting and fin erosion. Dorsal fin splitting decreased with time in upper trigger but not in lower trigger fish. Caudal fin erosion increased with time in upper and lower bigger fish.3. Feed regime had no significant effect on the incidence of fin splitting or fin erosion to the caudal upper, caudal lower or dorsal fins, and the incidence of fin splitting did not change over time, irrespective of feed regime. Interestingly, the 1-meal regime significantly hindered recovery from dorsal fin erosion, whilst caudal fin erosion to the upper caudal lobe significantly increased with time in the 1-meal and free access regime.4. The incidence of dorsal, but not caudal, fin damage was significantly greater in hand-fed fish. Dorsal fin damage decreased with time in self-fed but not hand-fed fish. Caudal fin damage decreased with time in both self-fed and hand-fed fish, although there was only a non-significant trend for recovery in self-fed fish.5. In the above experiments, most individuals displayed darker body color when they were damaged in their dorsal and/or caudal fin. The darker body color seemed to be originated from the stress due to damages. Then, image analysis of body color was made to obtain relative value of brightness in local area of lateral body changing with the degree of stress. This experiment of image analysis for non-contact and -invade method made possible to measure fish stress.