鲈鲤仔鱼饥饿试验及不可逆生长点的确定

张建明 姚金忠 姜伟 郭文涛

摘要：【目的】全面掌握鱸鲤仔鱼早期培育过程的摄食特点和饥饿耐受力，为其苗种规模化培育提供技术支撑。【方法】在18.5～21.9 ℃水温条件下，利用人工繁殖孵化获得的鲈鲤初孵仔鱼进行饥饿试验，研究饥饿胁迫对鲈鲤仔鱼生长、发育、存活、卵黄囊吸收、摄食率及摄食强度的影响，并确定鲈鲤仔鱼的不可逆生长点（PNR）。【结果】饥饿对鲈鲤仔鱼全长、体长、体高及肛前长等生长指标有极显著影响（P<0.01，下同），对眼径和鳔等组织器官发育也有明显影响。鲈鲤仔鱼5日龄开口摄食，进入混合营养期，10日龄时仔鱼卵黄囊基本消耗殆尽，鲈鲤仔鱼混合营养期维持5 d。鲈鲤仔鱼5日龄开始摄食外源性营养，初次摄食率约20%，随后逐步提高，至13日龄时达最高值（100%），之后开始下降，在17日龄时下降至40%，低于最大初次摄食率的50%。根据PNR定义，即17日龄是鲈鲤仔鱼的PNR。在5～11日龄期间（饥饿7 d内），鲈鲤仔鱼的初次摄食强度和摄食能力随着饥饿天数的增加呈上升趋势，12日龄后（饥饿7 d以上）则随着饥饿天数的增加呈迅速下降趋势。饥饿组仔鱼的累计死亡率在17日龄（饥饿13 d）时剧增，到18日龄（饥饿14 d）时其累计死亡率达88.00%，而摄食组仔鱼的累计死亡率仅为14.75%;至19日龄（饥饿15 d）时饥饿组仔鱼的累计死亡率高达100.00%，摄食组仔鱼的累计死亡率仍为14.75%。饥饿组鲈鲤仔鱼的50.00%累计死亡率出现日龄为18日龄，即在PNR出现之后。【结论】在18.5～21.9 ℃水温条件下，鲈鲤仔鱼混合营养期为5 d，PNR发生在17日龄。鲈鲤仔鱼可在5日龄后开始投喂，最佳投喂时间为8日龄，但最晚投喂时间不宜超过13日龄。

关键词： 鲈鲤;仔鱼;饥饿;摄食率;摄食强度;不可逆生长点（PNR）

中图文分类号： S965.199                          文献标志码： A 文章编号：2095-1191（2020）10-2565-08

Experimental starvation on Percocypris pingi larvae and determination of the point of no return

ZHANG Jian-ming1，2， YAO Jin-zhong3*， JIANG Wei1，2， GUO Wen-tao1，2

（1Institute of Chinese Sturgeon Research， China Three Gorges Project Corporation， Yichang， Hubei  443100， China; 2Hubei Key Laboratory of Three Gorges Project for Conservation of Fishes，Yichang， Hubei  443100， China;

3China Three Gorges Corporation Operation and Administration Center for River Basin Hydro Complex，

Yichang， Hubei  443100， China）

Abstract：【Objective】To study the feeding characteristicsandstarvation tolerance of Percocypris pingi during the early development of larvae， and provide technical support for the large-scale breeding of larvae. 【Method】Under the condition of water temperature of 18.5-21.9 ℃， the experimental ecology method was used to conduct starvation experiments on the newly hatched larvae obtained by artificial breeding and hatching. Analyze and study the effects of starvation stress on the growth， development， survival， yolk sac absorption， feeding rate and feeding intensity of larvae， and initially determine the point of no return（PNR） of larvae. 【Result】The growth index of the full length， body length， body height and anal length of the larvae of P. pingi had extremely significant effect（P<0.01， the same below）， and had obvious effects on the development of tissues and organs such as eye diameter and sputum. The larvae of P. pingi were fed at 5 d of age and entered the mixed nutrition period. At 10 d of age， the yolk sac of the larvae was basically consumed， and the mixed nutrition period for larvae of P. pingi were 5 d. The larvae of P. pingi began to eat exogenous nutrition at the age of 5 d. The initial feeding rate was about 20%， and then the initial feeding rate gradually increased. The initial feeding rate of the 13-day-old larvae reached the highest value of 100%. Then， the initial feeding rate began to decline. By the 17 d of age， the initial feeding rate dropped to 40%， which was lower than 50% of the maximum initial feeding rate. According to the definition of PNR ， the 17 d of age was PNR for larvae of P. pingi. The larvae of P. pingi initial feeding intensity and feeding ability increased with the increase of starvation days during 5-11 d of age（starved within 7 d）. After 12 d of age（starved over 7 d）， the initial feeding intensity and feeding ability of larvae decreased rapidly with the increase of hunger days. The cumulative mortality rate  of starved group increased sharply on 17 days old（starved for 13 d）. When the starved group was 18 days old（starved for 14 d）， the cumulative mortality rate reached 88.00%， and the cumulative mortality rate of the larvae in the feeding group was 14.75%. At 19 d of age， the cumulative mortality rate of the hunger fish in the starved group was 100.00%， while the cumulative mortality rate of the larvae in the feeding group was 14.75%. 50.00% cumulative mortality of larvae in the hunger-stricken fish in starved group was 18 days old， after PNR. 【Conclusion】Under the condition of water temperature of 18.5-21.9 ℃， the mixed nutrition period for larvae of P. pingi were 5 d， and PNR occurs at 17 d of age. Larvae of P. pingi can be fed after 5 d of age. The best feeding time is 8 d of age， but the latest feeding time should not exceed 13 d of age.

Key words： Percocypris pingi; larvae; starvation; feeding rate; feeding intensity; point of no return（PNR）

Foundation item：National Key Research and Development Program of China（2016YFC0502210）; National Natural Science Foundation of China（51779016）; Science and Technology Planning Project of China Three Gorges Project Corporation（ZHX2017025，JG/18001B）

0 引言

【研究意义】鲈鲤（Percocypris pingi）又称青脖、金甲鱼或花鱼，隶属于鲤科（Cyprinidae）鲃亚科（Barbinae）鲈鲤属（Percocypris），在我国长江上游的干支流、西江流域、南盘江等水系均有分布（詹会祥等，2016）。由于过度捕捞及环境污染等因素的影响，鲈鲤资源逐年衰减，在长江鱼类受威胁程度定量分析中已达到长江一级急切保护程度（刘军，2004），為四川省珍稀保护鱼类。在鱼类生活史中，仔鱼期是鱼类对环境条件最敏感的生活阶段，极易受各种外界因素的影响而发生死亡，其中饥饿是引起仔鱼死亡最主要的原因之一（叶忠平等，2012;段国庆等，2013）。初次摄食期遭受饥饿胁迫引起死亡是自然状况下仔鱼数量变动的主要原因，而不可逆生长点（PNR）是衡量仔鱼耐饥饿能力的常用评判标准（夏连军等，2004）。孵化出膜后的仔鱼需经历从内源性营养过渡到外源性营养，在此期间若不能建立主动摄食机制度过耐受期，将无法恢复摄食能力，到达PNR而最终死亡（杨育凯等，2019）。……