埃及品系尼罗罗非鱼三个世代耐寒性能的选育

采用闭锁群体继代选育法,以埃及品系尼罗罗非鱼的自然种群作为选育种群进行自繁,通过耐寒与生长性能评价及低温选育,获得埃及品系尼罗基础群和核心群各1个,基础群1 180尾,选留率30.50%;P0代核心群292尾,雌雄比例为1∶1,选留率16.48%;P1代核心群均由10个家系组成,每个家系选留80～100尾,选留率25%左右,核心群的个体在400尾左右。在核心群选育的基础上,应用巢式配对的方法配对P1代家系283个,产苗家系137个,配对成功率48.41%,产苗135 550尾;配对P2代家系91个,产苗家系42个,配对成功率46.13%,产苗30 400尾。选留的10个家系耐寒和生长性能结果表明,P1和P2代的平均半致死温度分别为8.07°C和7.75°C,比自然种群低7.88%和13.98%,平均相对存活率分别提高21.52%和26.35%,平均生长速度提高9.77%和18.90%;其中P1和P2代耐寒性能最好家系的半致死温度分别比自然种群降低9.13%和18.98%,平均相对存活率提高25.29%和30.34%,生长速度提高15.87%和33.00%。埃及品系尼罗罗非鱼耐寒选育P1、P2代的所有家系和核心群的耐寒和生长性能均高于自然种群。

Selection Effects of Cold Tolerance Capacity in Egyptian Strain of Nile Tilapia Three Generation

The method of closure group generation breeding and low temperature breeding was conducted in this paper.Egyptian strain of Nile tilapia natural population was selected as breeding group,by assessing their cold tolerance capability and growth performance,a basic group and a core were obtained.The number of fish in the basic group is 1 180,selected rate is 30.50%;the number of fish in the P0 generation core group is 292,the ratio male and female is 1∶1,selected rate is 16.48%.And the number of fish in the P1 generation core group is about 400 from 10 different families,selected rate is about 25%.Base on the core group breeding,by the nest matching method,283 families of P1 generation have been matched,and seeding families are 137,seeding flies are 135 550,the rate of success matching is 48.41%.And 91 families of P2 generation have been matched,and seeding families are 42,seeding flies are 30 400,the rate of success matching is 46.13%.The cold tolerance capability of 10 selected Oreochromis aureus families show that:the average of LT50 of P1 generation and P2 generation are 8.07 °C and 7.75 °C,which are 7.88% and 13.98% lower than the natural population,where as their average relative survival rates are 21.52% and 26.35% higher,and their average growth speeds are 9.77% and 18.90% higher;LT50 of the best cold tolerance capability P1 generation and P2 generation families are 9.13% and 18.98% lower than the natural population,while their average relative survival rates are 25.29% and 30.34% higher,and their average growth speeds are 15.87% and 33.00% higher.The cold tolerance capability and growth performance of all the P1 generation and P2 generation families and core group are higher than the natural population.