温度和孵化方式对大鳍鳠受精卵孵化效果的影响

Effect of temperatures and hatching methods on the hatching of Mystus macropterus fertilized eggs

为探究大鳍鳠(Mystus macropterus)受精卵的最适孵化温度及孵化方式,采用单因子设计实验研究了不同温度(22、24、26、28和30℃)、不同孵化方式(脱黏孵化(蛋白酶脱黏、滑石粉脱黏)、挂网孵化、孵化框孵化)对大鳍鳠受精卵孵化效果的影响。结果表明:大鳍鳠仔鱼出膜率随孵化温度的升高呈先升高后降低的趋势,分别为22℃组(0)<30℃组(12.51%)<24℃组(17.95%)<26℃组(25.40%)<28℃组(30.51%),不同温度组差异显著,二项式拟合得到最适孵化温度为26.8℃;出膜后24 h成活率表现为24℃组(54.76%)显著低于26℃组(95.45%)、28℃组(91.67%)和30℃组(92.59%),后三者之间差异不显著;96 h成活率分别为52.38%、90.91%、92.59%和40.74%,表明低温(24℃)和高温(30℃)都显著影响成活率。仔鱼出膜时间随温度的上升而逐渐缩短,范围为46~88 h。4种孵化方式的24 h好卵率结果表明挂网组(48.11%)>孵化框组(45.05%)>蛋白酶脱黏组(19.98%)>滑石粉脱黏组(15.32%),四个实验组之间差异显著。出膜率表现为挂网组(16.07%)>蛋白酶脱黏组(12.08%)>孵化框组(9.61%)>滑石粉脱黏组(9.26%)。出膜率/24 h好卵率显示脱黏组的值最大(均为60.46%),显著高于挂网组(33.40%)和孵化框组(21.32%)。在实验设置的3个蛋白酶脱黏浓度梯度下,24 h和48 h好卵率均表现为0.75 g/L组显著高于3 g/L组和1.5 g/L组,后两者之间差异不显著,出膜率则表现为随浓度降低而显著降低的趋势,说明卵膜对受精卵起到较好的保护作用,同时对出膜过程造成困难,导致出膜率降低。可见,温度和孵化方式均对大鳍鳠受精卵孵化有显著影响,大鳍鳠的最适孵化温度为26.8℃,孵化方式优先选择蛋白酶脱黏孵化,浓度为3 g/L。

Mystus macropterus,which belongs to the Bagrdae family of the Siluriformes order of Osteichthyes,was a fast-growing and large economic fish species found naturally in the mainstream and tributaries of the Yangtze and Pearl Rivers.It had high levels of protein,fat,essential amino acids,and umami amino acids,making it highly valued for consumption.However,the lack of breakthroughs in large-scale breeding of this species had hindered its industrial development.Temperature was an important environmental factor that affected the early growth and development of fish,playing a key physiological role in embryo hatching and metabolism regulation and serving as one of the decisive factors affecting embryo survival,fertilization rate,and hatching rate.M.macropterus fertilized eggs had weak adhesion,and hanging net hatching was currently the main method used in production.However,due to difficulties in water quality management,fertilized eggs were prone to generate water mold,resulting in unstable hatching outcomes.Therefore,exploring suitable temperature and hatching methods for M.macropterus fertilized eggs was also an important research area in the artificial breeding process of this species.In order to achieve the above objectives,a single-factor experimental design was used to study the effects of different temperatures(22℃,24℃,26℃,28℃,and 30℃)and hatching methods(degumming hatching[protease degumming,talcum powder degumming],hanging net hatching,and incubation box hatching)on hatching of M.macropterus embryos.The results showed that the hatching rate of M.macropterus larvae increased first and then decreased with the increase in hatching temperature,with the order of 22℃group(0)<30℃(12.51%)<24℃(17.95%)<26℃group(25.40%)<28℃group(30.51%).The differences among different temperature groups were significant,and the binomial fitting obtained the optimal hatching temperature of 26.8℃.The survival rate after 24 hours of hatching showed that the 24℃group(54.76%)was significantly lower than the 26℃group(95.45%),28℃group(91.67%),and 30℃group(92.59%),and the differences between the latter three groups were not significant.The survival rates after 96 hours were 52.38%,90.91%,92.59%,and 40.74%,indicating that both low temperature(24℃)and high temperature(30℃)significantly affected the survival rate.The hatching time of larvae gradually shortened with the increase of temperature,and the range was 46~88 h.The results of the 24-hour good egg rate of the four hatching methods showed that the net hanging group(48.11%)was greater than the incubation box group(45.05%),protease degumming group(19.98%),and talcum powder degumming group(15.32%),and the differences among the four experimental groups were significant.The hatching rate was in the order of net hanging group(16.07%)>protease degumming group(12.08%)>incubation box group(9.61%)>talcum powder degumming group(9.26%).The hatching rate/good egg rate of the degumming group was the largest(all 60.46%),which was significantly higher than the net hanging group(33.40%)and incubation box group(21.32%).Under the three protease degumming concentration gradients set in the experiment,the 24-hour and 48-hour good egg rates were significantly higher in the 0.75 g/L group than in the 3g/L and 1.5 g/L groups,and there was no significant difference between the latter two.The hatching rate showed a significant decreasing trend with the decrease of concentration,indicating that the egg membrane has a good protective effect on fertilized eggs while causing difficulties in the hatching process and leading to a decrease in the hatching rate.In Conclusion,temperature and hatching methods significantly affect the hatching.The optimal hatching temperature for M.macropterus is 26.8℃,and the preferred hatching method is protease degumming hatching,and the use concentration of protease was 3 g/L.The results of this experiment can help to achieve large-scale and efficient breeding of Grouper fish.